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  • 1.
    Ali pour, Nazanin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Enebro, J.
    Strömberg, Emma
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Qualitative characterization of nanoclay particle emissions from PP nanocomposites after thermal degradation2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    The use of nanomaterials in polymeric materials is a rapidly expanding field, and the polymer nanocomposites are being introduced into various markets. But there is still little known about the fate of nanocomposites and nanoparticles during service life and end-of-life of the materials. To avoid possible environmental, health and safety problems, simulating different scenarios for nanoparticles release from the polymer matrix plays a key role in commercialization of these advanced materials. The polymer/nanoclay nanocomposites show superior material properties in comparison with the pure polymers, such as improved mechanical properties, heat resistance, flame retardancy and decreased gas permeability. Polypropylene (PP) nanocomposites have attracted a considerable interest due to the material's low cost, low density and extensive production volumes. In this study, in order to obtain reliable results regarding the release of nanoclays from PP nanocomposites, homogenous composite with predetermined content of nanoclay was produced and characterized to obtain information regarding content, dispersion and size of the nanoclays in the matrix. The PP nanocomposite was degraded under controlled conditions and the surface morphology as well as oxidation of the material was characterized with scanning electron microscopy (SEM) and infrared spectroscopy during degradation. A prototype environmental chamber was designed in order to collect nano-sized particles in a controlled manner and subsequent characterization of the released or formed particles was performed with transmission electron microscopy (TEM) and the exposed nanocomposite was analysed with thermogravimetric analysis (TGA). 

  • 2.
    Arzpeima, Minoodokht
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Rosén, Annika
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Sanchez, Javier
    Björling, Gunilla
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Chemotherapy-Induced Surface Degradation and Thrombogenicity of Intravascular Catheters: A Preliminary In-Vitro Study with Focus on Breast Cancer2012Conference paper (Refereed)
  • 3.
    Atari Jabarzadeh, Sevil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Mendoza Álvarez, Ana Isabel
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hillborg, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. ABB, Corporated Resarch, Sweden.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. Univ Skovde, S-54128 Skovde, Sweden.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Design of nanocomposite surfaces with antibiofouling properties for outdoor insulation applicationsManuscript (preprint) (Other academic)
  • 4.
    Atari Jabarzadeh, Sevil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Nilsson, Fritjof
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. ABB, Corp Res, S-72178 Vasteras, Sweden.
    Hillborg, Henrik
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. ABB, Corp Res, S-72178 Vasteras, Sweden.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. Univ Skovde, S-54128 Skovde, Sweden.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling2015In: International Journal of Polymer Science, ISSN 1687-9422, E-ISSN 1687-9430, article id 390292Article in journal (Refereed)
    Abstract [en]

    This study focuses on how the texture of the silicone rubber material affects the distribution of microbial growth on the surface of materials used for high voltage insulation. The analysis of surface wetting properties showed that the textured surfaces provide higher receding contact angles and therefore lower contact angle hysteresis. The textured surfaces decrease the risk for dry band formation and thus preserve the electrical properties of the material due to a more homogeneous distribution of water on the surface, which, however, promotes the formation of more extensive biofilms. The samples were inoculated with fungal suspension and incubated in a microenvironment chamber simulating authentic conditions in the field. The extent and distribution of microbial growth on the textured and plane surface samples representing the different parts of the insulator housing that is shank and shed were determined by visual inspection and image analysis methods. The results showed that the microbial growth was evenly distributed on the surface of the textured samples but restricted to limited areas on the plane samples. More intensive microbial growth was determined on the textured samples representing sheds. It would therefore be preferable to use the textured surface silicone rubber for the shank of the insulator.

  • 5.
    Atari Jabarzadeh, Sevil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Salas Lacamprett, Carla
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. Univ Skovde, S-54128 Skovde, Sweden.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Use of essential oils for the prevention of biofilm formation on silicone rubber high voltage insulators2015In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 6, no 4, p. 119-136Article in journal (Refereed)
    Abstract [en]

    The prevention of biofilm formation on high voltage insulators is important to avoid changes in the surface properties of the material and the subsequent failure of the application. Antimicrobial silicone rubber samples were prepared by the addition of thymol and eugenol to Sylgard 184 to determine the possibility of using natural antimicrobial agents present in essential oils in materials used for high voltage insulators. The antimicrobial effects of thymol and eugenol were studied for different fungal strains and for green algae identified in the biofilms formed on insulators in Tanzania, Sri Lanka and Sweden. It was successfully demonstrated that samples containing high amount of eugenol and different concentrations of thymol could inhibit the fungal growth of strains from Sri Lanka and Tanzania and the growth of green algae. The growth of strains from Sweden was also suppressed. The addition of eugenol to the material resulted in a noncrosslinked system and therefore, the antimicrobial effect of the additive in the material could not be assessed. The addition of thymol did not significantly influence the thermal and mechanical properties of Sylgard184. Although thermal analysis revealed that a large amount of the antimicrobial agent was lost during sample preparation, the materials were effective against microbial growth, even at low thymol concentrations.

  • 6.
    Atarijabarzadeh, Sevil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Biofilm formation on silicone materials containing various antimicrobial agents2010Conference paper (Refereed)
    Abstract [en]

    The colonisation of microorganisms and subsequent biofilm formation on the surface of polymeric high voltage insulators affect the surface properties and can lead to failure of the insulators.  In this study, silicone materials were prepared with different antimicrobial agents. The materials were analysed for the changes in the physical, chemical, surface and mechanical properties before and after biological growth test.

     

    Microorganisms used for the biological tests were fungi defined in the international standard test ISO 846 for electrical applications (Aspergillus niger van Tieghem, Penicillium funiculosum Thom, Paecilomyces variotii Bainier, Chaetomium globosum Kunze: Fries, Aspergillus terreus Thom, Aureobasidium pullulans (de Bary) Arnaud & Penicillium ochrochloron Biourge) and algae isolated from insulators in Sri Lanka and Tanzania (Chlorella vulgaris var. Autotrophica + various bacterial strains). Fungi growth test was performed by inoculation of the fungi on the surface of the materials and incubation in an oven at 28°C and 98% humidity for a specific period. Algae growth test was performed by inoculation on the material surface and subsequent incubation in room temperature under a constant fluorescent lamps for a specific period.

     

    The results indicated that some of the samples could prevent the biofilm formation on the surface of the materials while the microbial growth was unaffected on the pure silicone rubber.

  • 7.
    Atarijabarzadeh, Sevil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Biofilm formation on silicone nanocomposites containing different antimicrobial agents2010Conference paper (Refereed)
    Abstract [en]

    In this study three types of clay/silicon nanocomposites were prepared. Clay was modified with two different antimicrobial agents (p-aminobenzoic acid and partially aminated poly(vinylbenzyl chloride) and used for preparation of the nanocomposites, which aimed to show antimicrobial properties and also easy dispersion of the clay into the polymeric matrix. Reference nanocomposites were made through the modification of the clay with a siloxane surfactant to make an easy dispersion of the clay into the silicone rubber. Nanocomposites were studied for resistancy against biological attack according to the international standard tests. Growth test results indicated that some of the nanocomposites can inhibit biological growth more than pristine nanocomposites. Modified clay was studied with x-ray diffraction technique. Materials were also studied with scanning electron microscopy before and after biological growth to analyse the biofilm formation on the surface.

  • 8.
    Atarijabarzadeh, Sevil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Design of antimicrobial silicone nanocomposites for high voltage insulationManuscript (preprint) (Other academic)
  • 9.
    Atarijabarzadeh, Sevil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Inhibition of biofilm formation on silicone rubber samples using various antimicrobial agents2011In: International Biodeterioration & Biodegradation, ISSN 0964-8305, E-ISSN 1879-0208, Vol. 65, no 8, p. 1111-1118Article in journal (Refereed)
    Abstract [en]

    High-temperature-cured silicone rubber samples (silicone rubber (SIR) based on polydimethylsiloxane (PDMS)) and SIR samples containing three different antimicrobial agents, sodium benzoate (NaB), DCOIT (4,5 Dichloro-2-octyl-2H-isothiazolone-one) and p-aminobenzoic acid (PABA) were inoculated with fungal spore suspensions and incubated for 28 days at 29 +/- 1 degrees C and >= 90% humidity, according to the ISO 846:1997(E) protocol. Prior to the biodegradation test, a powder test was conducted to study the efficacy of the chosen antimicrobial compounds and to determine the correct concentration of the compounds for sample preparation. The extent of the microbial growth was studied visually and by Scanning Electron Microscopy (SEM). Changes in surface hydrophobicity and surface chemical composition were studied by contact angle measurements and Fourier Transform Infrared (FTIR) spectroscopy, respectively. Microbial growth and biofilm formation were observed on the surface of reference samples. DCOIT was the most effective antimicrobial agent, as demonstrated by the lack of microbial growth and unaltered surface hydrophobicity. On the surface of samples containing NaB, an initiation of microbial growth and therefore a slight change in surface hydrophobicity was observed. PABA did not inhibit the fungal growth.

  • 10. Badia, J. D.
    et al.
    Kittikorn, Thorsak
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Santonja-Blasco, L.
    Martizez-Felipe, A.
    Ribes-Greus, A.
    Ek, Monica
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Water absorption and hydrothermal performance of PHBV/sisal biocomposites2014In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 108, p. 166-174Article in journal (Refereed)
    Abstract [en]

    The performance of biocomposites of poly(hydroxybutyrate-co-valerate) (PHBV) and sisal fibre subjected to hydrothermal tests at different temperatures above the glass transition of PHBV (T-H = 26, 36 and 46 degrees C) was evaluated in this study. The influences of both the fibre content and presence of coupling agent were focused. The water absorption capability and water diffusion rate were considered for a statistical factorial analysis. Afterwards, the physico-chemical properties of water-saturated biocomposites were assessed by Fourier-Transform Infrared Analysis, Size Exclusion Chromatography, Differential Scanning Calorimetry and Scanning Electron Microscopy. It was found that the water diffusion rate increased with both temperature and percentage of fibre, whereas the amount of absorbed water was only influenced by fibre content. The use of coupling agent was only relevant at the initial stages of the hydrothermal test, giving an increase in the diffusion rate. Although the chemical structure and thermal properties of water-saturated biocomposites remained practically intact, the physical performance was considerably affected, due to the swelling of fibres, which internally blew-up the PHBV matrix, provoking cracks and fibre detachment.

  • 11. Badia, J. D.
    et al.
    Reig-Rodrigo, P.
    Teruel-Juanes, R.
    Kittikorn, Thorsak
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Prince of Songkla University, Thailand.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ribes-Greus, A.
    Effect of sisal and hydrothermal ageing on the dielectric behaviour of polylactide/sisal biocomposites2017In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 149, p. 1-10Article in journal (Refereed)
    Abstract [en]

    The dielectric properties of virgin polylactide (PLA) and its reinforced composites with different weight amounts of sisal fibres were assessed at broad temperature (from −130 °C to 130 °C) and frequency ranges (from 10−2–107 Hz), before and after being subjected to accelerated hydrothermal ageing. The synergetic effects of both the loading of sisal and hydrothermal ageing were analysed by means of dielectric relaxation spectra. The relaxation time functions were evaluated by the Havriliak-Negami model, substracting the ohmic contribution of conductivity. The intramolecular and intermolecular relaxations were respectively analysed by means of Arrhenius and Vogel-Fulcher-Tammann-Hesse thermal activation models. The addition of fibre increased the number of hydrogen bonds, which incremented the dielectric permittivity and mainly hindered the non-cooperative relaxations of the biocomposites by increasing the activation energy. Hydrothermal ageing enhanced the formation of the crystalline phase at the so-called transcrystalline region along sisal. This fact hindered the movement of the amorphous PLA fraction, and consequently decreased the dielectric permittivity and increased the dynamic fragility.

  • 12. Badia, J. D.
    et al.
    Strömberg, E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, A.
    Karlsson, S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-mechanical degradation mechanisms of poly (ethylene terephthalate)2011In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 692, no 1-2, p. 85-95Article in journal (Refereed)
    Abstract [en]

    The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measure of PET stated that the best combination of factors and levels was the following: matrix (dithranol), proportion analyte/matrix/cationization agent (1/15/1, V/V/V), and concentration of cationization agent (2 g L-1). In a second part, multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PET under mechanical recycling. The application of MALDI-TOF-MS showed that thermo-mechanical degradation primarily affected initially predominant cyclic species. Several degradation mechanisms were proposed, remarking intramolecular transesterification and hydrolysis. The ether links of the glycol unit in PET were shown to act as potential reaction sites, driving the main reactions of degradation.

  • 13. Badia, J. D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kittikorn, Thorsak
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Prince of Songkla University,Thailand.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ribes-Greus, A.
    Relevant factors for the eco-design of polylactide/sisal biocomposites to control biodegradation in soil in an end-of-life scenario2017In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 143, p. 9-19Article in journal (Refereed)
    Abstract [en]

    The eco-design considers the factors to prepare biocomposites under an end-of-life scenario. PLA/sisal biocomposites were obtained from amorphous polylactide and sisal loadings of 10, 20 and 30 wt% with and without coupling agent, and subjected to biodegradation in soil according to standard ISO846. Mass-loss, differential scanning calorimetry and size-exclusion chromatography were used for monitoring biodegradation. A statistical factorial analysis based on the molar mass Mn and crystallinity degree XC pointed out the relevance and interaction of amount of fibre and use of coupling agent with the time of burial in soil. During the preparation of biocomposites, chain scission provoked a similar reduction of Mn for coupled and non-coupled biocomposites. The amount of fibre was relevant for the increase of XC due to the increase of nucleation sites. The coupling agent accelerated the evolution of both factors: reduction of Mn and the consequent increase of XC, mainly during biodegradation in soil. Both factors should be balanced to facilitate microbial assimilation of polymer segments, since bacterial digestion is enhanced by chain scission but blocked by the promotion of crystalline fractions.

  • 14. Badia, J. D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, A.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Assessing the MALDI-TOF MS sample preparation procedure to analyze the influence of thermo-oxidative ageing and thermo-mechanical degradation on poly (Lactide)2011In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 47, no 7, p. 1416-1428Article in journal (Refereed)
    Abstract [en]

    Multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PLA under mechanical recycling. Likewise, an accelerated thermal ageing over PLA glass transition was performed in order to simulate its service life. MALDI-TOF MS was used for the analysis and the sample preparation procedure was assessed by means of a statistical Design of Experiments (DoE). The quality effects in use for the analysis were signal-to-noise ratio and Resolution. Different matrixes, analyte/matrix proportions and the use of NaTFA as cationization agent were considered. A deep inspection of the statistical results provided a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measurement of PLA stated that the best combination of factors (levels) was the following: matrix (s-DHB), proportion analyte/matrix (1/5 V/V), and no use of cationization agent. Degradation primarily affected the initially predominant cyclic [LA(C)](n) and linear H-[LA(L)](n)-OH species, where LA stands for a PLA repeating unit. Intramolecular and intermolecular transesterifications as well as hydrolytic and homolytic reactions took place during the formation and disappearance of oligomeric species. In both degradation mechanisms induced by thermal ageing and thermo-mechanical degradation, the formation of H-[LA(L)](n)-O-CH(3) by intermolecular transesterifications was highlighted.

  • 15. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, A.
    Material valorisation of amorphous polylactide. Influence of thermo-mechanical degradation on the morphology, segmental dynamics, thermal and mechanical performance2012In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 4, p. 670-678Article in journal (Refereed)
    Abstract [en]

    This paper reports the effects of multiple mechanical recycling on the structure and properties of amorphous polylactide (PIA). The influence of the thermo-mechanical degradation induced by means of five successive injection cycles was initially addressed in terms of macroscopic mechanical properties and surface modification. A deeper inspection on the structure and morphology of PLA was associated to the thermal properties and viscoelastic behaviour. Although FT-IR analysis did not show significant changes in functional groups, a remarkable reduction in molar mass was found by viscometry. PIA remained amorphous throughout the reprocessing cycles, but the occurrence of a cold-crystallization during DSC and DMTA measurements, which enthalpy increased with each reprocessing step, suggested chain scission due to thermo-mechanical degradation. The effect of chain shortening on the glass-rubber relaxation studied by DMTA showed an increase in free volume affecting the segmental dynamics of PLA, particularly after the application of the second reprocessing step, in connection to the overall loss of performance showed by the remaining properties.

  • 16. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, A
    The role of crystalline, mobile amorphous and rigid amorphous fractions on the performance of recycled poly (ethylene terephthalate) (PET)2012In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 1, p. 98-107Article in journal (Refereed)
    Abstract [en]

    The action of thermo-mechanical degradation induced by mechanical recycling of poly(ethylene terephthalate) was simulated by successive injection moulding cycles. Degradation reactions provoked chain scissions and a reduction in molar mass mainly driven by the reduction of diethyleneglycol to ethylene glycol units in the flexible domain of the PET backbone, and the formation ofeOH terminated species with shorter chain length. The consequent microstructural changes were quantified taking into account a three-fraction model involving crystalline, mobile amorphous (MAF) and rigid amorphous fractions (RAF). A remarkable increase of RAF, to a detriment of MAF was observed, while the percentage of crystalline fraction remained nearly constant. A deeper analysis of the melting behaviour, the segmental dynamics around the glass-rubber relaxation, and the macroscopic mechanical performance, showed the role of each fraction leading to a loss of thermal, viscoelastic and mechanical features, particularly remarkable after the first processing cycle.

  • 17. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, Amparo
    Characterization of Induced Thermo-mechanical Degradation on Poly (ethylene terephthalate)2011Conference paper (Refereed)
  • 18. Badia, J.D.
    et al.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ribes-Greus, Amparo
    STUDY OF THERMO-MECHANICAL AND THERMO-OXIDATIVE DEGRADATION OF POLYLACTIDE BYMALDI-TOF MS. A STATISTICAL DESIGN OF EXPERIMENTS TO OPTIMIZE THE SAMPLE PREPARATIONPROCEDURES2011Conference paper (Refereed)
  • 19.
    Edvardsson Björnberg, Karin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, Philosophy.
    Skogh, Inga-Britt
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, Philosophy.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Integrating social sustainability in engineering education at the KTH Royal Institute of Technology2015In: International Journal of Sustainability in Higher Education, ISSN 1467-6370, E-ISSN 1758-6739, Vol. 16, no 5, p. 639-649Article in journal (Refereed)
    Abstract [en]

    Purpose - The purpose of this paper is to investigate what are perceived to be the main challenges associated with the integration of social sustainability into engineering education at the KTH Royal Institute of Technology, Stockholm. Design/methodology/approach - Semi-structured interviews were conducted with programme leaders and teachers from four engineering programmes. The paper focuses on how the concept of social sustainability is defined and operationalised in the selected engineering programmes, how social sustainability is integrated and taught, and what resources are required to support teachers and programme leaders as social sustainability educators. Findings - The findings show that programme leaders and teachers at KTH struggle to understand the concept of social sustainability. The vague and value-laden nature of the concept is considered a challenge when operationalising educational policy goals on social sustainability into effective learning outcomes and activities. A consequence is that the responsibility for lesson content ultimately falls on the individual teacher. Study visits and role-play are seen as the most effective tools when integrating social sustainability into the engineering curriculum. Allocation of specific resources including supplementary sustainability training for teachers and economic incentives are considered crucial to successful integration of social sustainability. The findings indicate that social sustainability education needs to be built on a theoretical foundation. It is therefore suggested that a literature canon be established that clarifies the contours of social sustainability. Practical implications - The findings of the paper can be used as a basis for discussion regarding measures for improving social sustainability training in engineering education, a subject which has attracted relatively little attention, to date. Originality/value - There is a noticeable lack of empirical research on how technical universities integrate social sustainability into engineering education. The paper provides an account of how actors directly involved in this work - programme leaders and teachers - define and operationalise the social dimension of sustainable development in their engineering curricula, the pedagogical tools they consider effective when teaching social sustainability issues to engineering students, and the resources they believe are needed to strengthen those efforts.

  • 20.
    Edvardsson Björnberg, Karin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, Philosophy.
    Skogh, Inga-Britt
    KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, Philosophy.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Integrating social sustainability into the engineering curriculum at the Royal Institute of Technology (KTH): A pilot study2013Conference paper (Other academic)
    Abstract [en]

    In recent years, significant efforts have been made at the Royal Institute of Technology (KTH) in Stockholm to integrate sustainable development in the university’s Bachelor and Master education. However, a self-evaluation study carried out in 2012 showed that many programme coordinators and teachers at KTH still struggle with how to integrate social sustainability in their programmes. Based on interviews with programme coordinators at four engineering programmes at KTH we analyse what are perceived to be the main challenges associated with integration of social sustainability in the university’s engineering education. The paper reports on data acquired through the interviews, focusing on three questions: (1) How is the concept of social sustainability defined and operationalized in the selected engineering programmes? (2) How is social sustainability taught in the selected engineering programmes (learning objectives, teaching methods, pedagogical strategies/tools)? (3) What resources (training efforts, material/tools, etc.) are (according to the informants) required in order to support teachers and programming coordinators in their professional roles as (social) sustainability educators?

  • 21.
    Finnveden, Göran
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Environmental Strategies Research (fms).
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Developing sustainability learning outcomes for engineering2013In: Proceedings of the EESD13 Conference, 2013Conference paper (Refereed)
  • 22. Frostell, Claes
    et al.
    Bjorling, Gunilla
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Aune, Ragnhild E.
    Tracheal implants revisited2017In: The Lancet, ISSN 0140-6736, E-ISSN 1474-547X, Vol. 389, no 10075, p. 1191-1191Article in journal (Refereed)
  • 23. Garcia-Garcia, D.
    et al.
    Lopez-Martinez, J.
    Balart, R.
    Strömberg, Emma
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Moriana, Rosana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. HIS-University of Skövde, Skövde.
    Reinforcing capability of cellulose nanocrystals obtained from pine cones in a biodegradable poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) thermoplastic blend2018In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 104, p. 10-18Article in journal (Refereed)
    Abstract [en]

    In this work, different loads (3, 5 and 7 wt%) of pine cone cellulose nanocrystals (CNCs) were added to films of poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) blends with a composition of 75 wt% PHB and 25 wt% PCL (PHB75/PCL25). The films were obtained after solvent casting followed by melt compounding in an extruder and finally subjected to a thermocompression process. The influence of different CNCs loadings on the mechanical, thermal, optical, wettability and disintegration in controlled compost properties of the PHB75/PCL25 blend was discussed. Field emission scanning electron microscopy (FESEM) revealed the best dispersion of CNCs on the polymeric matrix was at a load of 3 wt%. Over this loading, CNCs aggregates were formed enhancing the films fragilization due to stress concentration phenomena. However, the addition of CNCs improved the optical properties of the PHB75/PCL25 films by increasing their transparency and accelerated the film disintegration in controlled soil conditions. In general, the blend with 3 wt% CNCs offers the best balanced properties in terms of mechanical, thermal, optical and wettability.

  • 24. Gil-Castell, O.
    et al.
    Badia, J. D.
    Kittikorn, Thorsak
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Prince of Songkla University, Thailand.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Skövde University, Sweden.
    Ribes-Greus, A.
    Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites2016In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Article in journal (Refereed)
    Abstract [en]

    The influence of the combined exposure to water and temperature on the behaviour of polylactide/sisal biocomposites coupled with maleic acid anhydride was assessed through accelerated hydrothermal ageing. The biocomposites were immersed in water at temperatures from 65 to 85 °C, between the glass transition and cold crystallisation of the PLA matrix. The results showed that the most influent factor for water absorption was the percentage of fibres, followed by the presence of coupling agent, whereas the effect of the temperature was not significant. Deep assessment was devoted to biocomposites subjected to hydrothermal ageing at 85 °C, since it represents the extreme degrading condition. The morphology and crystallinity of the biocomposites were evaluated by means of X-Ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The viscoelastic and thermal performance were assessed by means of dynamic mechanic thermal analysis (DMTA) and thermogravimetry (TGA). The presence of sisal generally diminished the thermal stability of the biocomposites, which was mitigated by the addition of the coupling agent. After composite preparation, the effectiveness of the sisal fibre was improved by the crystallisation of PLA around sisal, which increased the storage modulus and reduced the dampening factor. The presence of the coupling agent strengthened this effect. After hydrothermal ageing, crystallisation was promoted in all biocomposites therefore showing more fragile behaviour evidencing pores and cracks. However, the addition of coupling agent in the formulation of biocomposites contributed in all cases to minimise the effects of hydrothermal ageing.

  • 25. Gil-Castell, O.
    et al.
    Badia, J. D.
    Kittikorn, Thorsak
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Prince of Songkla University Songkhla, Thailand.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Martinez-Felipe, A.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. University of Skövde, Sweden.
    Ribes-Greus, A.
    Hydrothermal ageing of polylactide/sisal biocomposites. Studies of water absorption behaviour and Physico-Chemical performance2014In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 108, p. 212-222Article in journal (Refereed)
    Abstract [en]

    An accelerated hydrothermal degrading test was designed in order to analyse the synergic effect of water and temperature on PLA/sisal biocomposites with and without coupling agent. As well, the physicochemical properties of biocomposites were monitored along the hydrothermal test by means of Scanning Electron Microscopy, Size Exclusion Chromatography and Differential Scanning Calorimetry. The addition of fibre induced higher water absorption capability and promoted physical degradation, as observed in the surface topography. During the processing of biocomposites and throughout the hydrothermal ageing, a reduction of molecular weight due to chain scission was found. As a consequence, a faster formation of crystalline domains in the PIA matrix occurred the higher the amount of fibre was, which acted as a nucleating agent. Higher crystallinity was considered as a barrier against the advance of penetrant and a reduction in the diffusion coefficient was shown. The addition of coupling agent presented a different influence depending on the composition, showing an inflection point around 20% of sisal fibre.

  • 26. Gil-Castell, O.
    et al.
    Badia, J. D.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Skövde University, Sweden.
    Ribes-Greus, A.
    Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds2017In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 87, p. 174-187Article in journal (Refereed)
    Abstract [en]

    The hydrolysis of the polycaprolactone (PCL) as a function of the dissolution time in a formic/acetic acid mixture was considered as a method for tailoring the morphology of nanofibrous PCL scaffolds. Hence, the aim of this research was to establish a correlation between the dissolution time of the polymer in the acid solvent with the physico-chemical properties of the electrospun nanofibrous scaffolds and their further service life behaviour. The physico-chemical properties of the scaffolds were assessed in terms of fibre morphology, molar mass and thermal behaviour. A reduction of the molar mass and the lamellar thickness as well as an increase of the crystallinity degree were observed as a function of dissolution time. Bead-free fibres were found after 24 and 48 h of dissolution time, with similar diameter distributions. The decrease of the fibre diameter distributions along with the apparition of beads was especially significant for scaffolds prepared after 72 h and 120 h of dissolution time in the acid mixture. The service life of the obtained devices was evaluated by means of in vitro validation under abiotic physiological conditions. All the scaffolds maintained the nanofibrous structure after 100 days of immersion in water and PBS. The molar mass was barely affected and the crystallinity degree and the lamellar thickness increased along immersion, preventing scaffolds from degradation. Scaffolds prepared after 24 h and 48 h kept their fibre diameters, whereas those prepared after 72 h and 120 h showed a significant reduction. This PCL tailoring procedure to obtain scaffolds that maintain the nanoscaled structure after such long in vitro evaluation will bring new opportunities in the design of long-term biomedical patches.

  • 27.
    Högfeldt, Anna-Karin
    et al.
    KTH, School of Education and Communication in Engineering Science (ECE), Learning.
    Malmi, Lauri
    Alto University.
    Jerbrant, Anna
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Kinnunen, Päivi
    Alto University.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmqvist, Johan
    Chalmers University of Technology.
    Villadsen, Jørgen
    Technical University of Denmark (DTU).
    Baggerud, Bjørn
    Norwegian University of Science and Technology (NTNU).
    Berglund, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Munkebo Hussmann, Peter
    Technical University of Denmark (DTU).
    Program leadership from a nordic perspective: Program leaders' power to influence their program2013In: Proceedings of the 9th International CDIO Conference, 2013Conference paper (Refereed)
    Abstract [en]

    In this paper a continuation research at five technical universities in Nordic countries (N5T network) in 2012 is presented, wheretheaim was to find out how the program leadersconceived their function, role and mandate, and the work situations between the universitieswere compared. The previous research demonstrated that programleadershave quite different positions, strategies and methods when it comes to monitoring and developing their programs.In this paper, a deeper investigationis carried out ofthe (im-) possibilitiesto make realinfluence on the study courses that constitutesthe respective Engineering study programs. Eightprogram leaders from thefiveN5Tuniversities have been interviewed, and theanalysis of these studies, has culminatedina model for the analysis of program leadership for Engineering educationdevelopment.

  • 28.
    Högfeldt, Anna-Karin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Learning.
    Malmi, Lauri
    Aalto Univ, Dept Comp Sci, Helsinki, Finland.;Aalto Univ, Deans Unit, Sch Business, Helsinki, Finland..
    Kinnunen, Paivi
    Aalto Univ, Dept Comp Sci, Helsinki, Finland.;Aalto Univ, Deans Unit, Sch Business, Helsinki, Finland..
    Jerbrant, Anna
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Strömberg, Emma
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Management.
    Berglund, Anders
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Villadsen, Jorgen
    DTU Tech Univ Denmark, Dept Appl Math & Comp Sci, Copenhagen, Denmark..
    Leading the teacher team - balancing between formal and informal power in program leadership2018In: Tertiary Education and Management, ISSN 1358-3883, E-ISSN 1573-1936, Vol. 24, no 1, p. 49-65Article in journal (Refereed)
    Abstract [en]

    This continuous research within Nordic engineering institutions targets the contexts and possibilities for leadership among engineering education program directors. The IFP-model, developed based on analysis of interviews with program leaders in these institutions, visualizes the program director's informal and formal power. The model is presented as a tool for starting a shared discussion on the complexities of the leadership of engineering program development. The authors liken program development to hunting in teams. Each individual expert in the program is needed, and all experts will need to work and collaborate for the same target. This calls for strategic and long-term thinking of engineering education development. Institutions should support the development of both formal structures as well as informal leadership skills among their program directors, but never fall for the temptation to see the program director as the only actor on the stage.

  • 29.
    Johansson, Jan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Luttropp, Conrad
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vilaplana, Francisco
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Polymer recycling of sorted WEEE at a refrigerator recycling plantManuscript (Other academic)
  • 30.
    Kaali, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Pérez-Madrignal, Maria M.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Czel, Gyorgy
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    The influence of Ag(+), Zn(2+) and Cu(2+) exchanged zeolite on antimicrobial and long term in vitro stability of medical grade polyether polyurethane2011In: Express Polymer letters, ISSN 1788-618X, Vol. 5, no 12, p. 1028-1040Article in journal (Refereed)
    Abstract [en]

    This study aims to investigate the limitations and applicability of different ion exchanged zeolites as antimicrobial additive in thermoplastic polyether type polyurethanes. These composites were designed to improve the health quality of hospitalized patients by expressing both biocompatibility and relevant antimicrobial activity. The zeolites were exchanged with silver, copper and zinc ions and single, binary and ternary ion-exchanged zeolite-polyurethane composites were prepared. The antimicrobial activity and the resistance of the composites against the human environment play vital role in the applicability of the materials as a medical device therefore these properties were investigated. The antimicrobial test were performed on Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Candida tropicalis. The tests showed that the efficiency of the silver ions is superior to the other single ionic systems. Besides, the binary and ternary ion-exchanged samples had similar antimicrobial efficiency regardless the type of the ions in the zeolite. The biocompatibility tests were carried out in-vitro in artificial body fluids for a period of 12 weeks. As a result of the in-vitro test, degradation of the composites were observed and the structural changes of the materials were detected and described by Scanning Electron Microscopy, Contact Angle measurements and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy.

  • 31.
    Kaali, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Czel, Gyoergy
    Department of Polymer Engineering, University of Miskolc.
    Momcilovic, Dane
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Antimicrobial properties of Ag+ loaded zeolite polyester polyurethane and silicone rubber and long-term properties after exposure to in-vitro ageing2010In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 95, no 9, p. 1456-1465Article in journal (Refereed)
    Abstract [en]

    In biomedical applications, tubes (e.g. catheters etc.) are commonly produced from polyurethane (PU) and silicone rubber which are known to be biocompatible materials. Several studies have shown that tubes, which are connected to the body (invasive) (especially urinary, tracheotomy and central venous catheters) are associated with infections. The present study reports the development of a new method aiming at obtaining antibacterial properties for PU and silicone rubber by mixing respective material with a natural antibacterial agent (Ag+ loaded zeolite) in different weight fractions. The influence of the zeolite content on the antimicrobial properties were analysed by exposure to bacteria (ISO 22196) and mixtures of fungi (ISO 846). The materials were also subject to artificial body fluids (Artificial Lysosomal Fluid (ALF) and Gamble's solution) for periods up to three months and the subsequent changes in the chemical properties after in-vitro exposure were determined by Matrix Assisted Laser Deposition/Ionization Time Of Flight Mass Spectrometry (MALDI-TOF MS) and Attenuated Total Reflection Fourier Transform Infra Red spectroscopy (ATR-FTIR). It was established that the antimicrobial effect of the materials increased with the increase of the zeolite content. The wettability of the materials was found to decrease significantly during the in-vitro exposure, but this could not be correlated to the zeolite content. In the PU samples, the formation of free carbonyl and -OH groups was observed, which corresponds to oxidative degradation. In case of the silicone rubber the ratio of cyclic PDMS to linear PDMS (H, CH3 and dimethyl terminated) decreased, which indicates a change in the concentration of the compounds. The formation and increase of the O-H bond during the exposure was also confirmed by the infrared spectra of the material which corresponds to hydrolysis of the silicone rubber.

  • 32.
    Kaali, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Czel, Gyorgy
    Modelling the ion distribution in single, binary and ternary ion exchanged Azeolite2011In: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093Article in journal (Other academic)
  • 33.
    Kaali, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Prevention of Biofilm Associated Infections and Degradation of Polymeric Materials Used in Biomedical Applications2011In: Biomedical Engineering, Trends in Materials Science / [ed] Anthony N. Laskovski, InTech , 2011Chapter in book (Refereed)
  • 34.
    Kittikorn, Thorsak
    et al.
    Prince Songkla Univ, Dept Mat Sci & Technol, Fac Sci, Hat Yai 90112, Thailand..
    Malakul, Raminatun
    Prince Songkla Univ, Dept Microbiol, Fac Sci, Hat Yai 90112, Thailand..
    Strömberg, Emma
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Enhancement of mechanical, thermal and antibacterial properties of sisal/polyhydroxybutyrate-co-valerate biodegradable composite2018In: JOURNAL OF METALS MATERIALS AND MINERALS, ISSN 0857-6149, Vol. 28, no 1, p. 52-61Article in journal (Refereed)
    Abstract [en]

    Lignocellulosic biocomposite is a promising biodegradable materials, though improvement of the interfacial adhesion between cellulose fibre and polymer matrix is still challenged. Therefore, this work investigated the effect of propionylation of sisal reinforced fibre in the sisal/polyhydroxybutyrate-co-valerate (PHBV) biocomposite. Propionylation involved esterification substitution of propionic anhydride to hydroxyl group of sisal fibre, where ester group (COOR) of propionylated fibre was successfully observed by Fourier transform Infrared spectroscopy (FTIR). Then mechanical and thermal properties were evaluated and biodegradation characteristics were assessed. The tensile strength and modulus of propionylated sisal/PHBV biocomposite were greater than unmodified sisal/PHBV, which revealed better compatibility at the interface. In addition, propionate moieties of sisal fibre could induce crystalline formation of PHBV, as determined by an increase of crystalline phase. The higher decomposition temperature (Td) and activation energy (Ea) of 155 kJ.mol(-1), determined by thermal gravimetric analyser (TGA), were strong confirmation of good thermal resistance of the propionylated sisal biocomposite. The storage modulus, as characterized by dynamic mechanical thermal analyser (DMTA), also revealed the improvement of stiffness. Bacterial growth tests evaluated the inhibition of bacterial growth on the PHBV biocomposites. It was clear that propionylation of sisal fibre decreased colonization of Staphylococcus aureus (SA) and Escherichia coli (E.coli).

  • 35.
    Kittikorn, Thorsak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Chemical surface modification of empty fruit bunch oil palm fibre in PP biocomposites2009Conference paper (Other academic)
  • 36.
    Kittikorn, Thorsak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Comparison of Water Uptake as Function of Surface Modification of Empty Fruit Bunch Oil Palm Fibres in PP Biocomposites2013In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, no 2, p. 2998-3016Article in journal (Refereed)
    Abstract [en]

    Empty fruit bunch oil palm (EFBOP) fibres were surface modified by four different methods, propionylation, vinyltrimethoxy silanization, PPgMA dissolution modification, and PPgMA blending, and integrated into a polypropylene (PP) matrix. The designed biocomposites were subjected to an absorption process at different temperatures. Their water uptake behaviour was compared with the unmodified fibre biocomposites. An increased fibre content and temperature resulted in increased water uptake for all of the biocomposites. The biocomposites containing modified fibres showed a reduction in water uptake, rate of diffusion, sorption, and permeation in comparison with unmodified fibre composites. Comparing the 20 wt% fibre composites at ambient temperature, the performance in water absorption followed the sequence silanization < propionylation < PPgMA dissolution modification < PPgMA blending < no modification. Furthermore, the lowest water absorption was obtained from the silanized fibre/PP composite with 40% fibre content at ambient temperature. Dissolution or blending of PPgMA gave similar water uptake results. The reduction of diffusion, sorption, and permeation confirmed that the modification of fibres was potentially effective at resisting water penetration into the composites.

  • 37.
    Kittikorn, Thorsak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Effect of surface modifications on microbial growth and biodegradation in sisal/PLA biocomposites2013Manuscript (preprint) (Other academic)
  • 38.
    Kittikorn, Thorsak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Susceptibility to biodegradation by fungi for sisal/PLA and sisal/PHBV biocomposites2013Manuscript (preprint) (Other academic)
  • 39.
    Kittikorn, Thorsak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    The effect of surface modifications on the mechanical and thermal properties of empty fruit bunch oil palm fibre PP biocomposites2012In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 3, no 3, p. 79-100Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study the effect of chemical surface modifications on empty fruit bunch oil palm fibre/polypropylene composite properties. By FTIR spectra, propionylated fibre and PPgMA-modified fibre showed the presence of a carbonyl group of esters while vinyltrimethoxysilane-treated fibre showed a peak of silicate, confirming that the modifications were successful. PPgMAmodified fibre PP composite at fibre content 20% demonstrated the highest modulus of 0.71 GPa while the modulus of unmodified fibre PP composite was 0.56 GPa. By DSC analysis, PPgMA-modified fibre and vinyltrimethoxysilane-treated fibre PP composite at the same fibre content of 5% showed the highest crystallinity of 46% and 44% respectively whereas unmodified fibre PP composite showed a lower crystallinity of 38%. The DMTA analysis showed that after 60°C, the modified fibre PP composites exhibited a higher stiffness than pure polypropylene.

  • 40.
    Kittikorn, Thorsak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. Skövde University.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The mechanical properties of natural cellulosic fiber/biodegradable polymer biocomposites2011In: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC, 2011, p. 1330-1333Conference paper (Refereed)
    Abstract [en]

    The aim of this work was to investigate a methodology for the improvement of the mechanical properties of sustainable biodegradable biocomposites based on polylactide (PLA). Cellulosic fibre was incorporated as a reinforcing agent for improvement of the mechanical properties of the biocomposites. A coupling agent was synthesized and employed in order to enhance the interfacial adhesion of two components via a melt blending process. FT-IR spectra showed presences of specific functional groups of maleic anhydride on the backbone of the PLA after the grafting. The modulus of PLA was considerably raised after incorporation of the fibre. Furthermore, an addition of a coupling agent in PLA biocomposites was also able to remarkably increase the stiffness of the material.

  • 41.
    Kittikorn, Thorsak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The mechanical properties of natural cellulosic fibre/biodegradable polymer biocomposites2011In: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC: Volume 2, 2011, p. 1330-1333Conference paper (Refereed)
    Abstract [en]

    Theaim of this work was to investigate a methodology fortheimprovement ofthemechanicalpropertiesof sustainablebiodegradablebiocompositesbased on polylactide (PLA).Cellulosicfibrewas incorporated as a reinforcing agent for improvement ofthemechanicalpropertiesofthebiocomposites. A coupling agent was synthesized and employed in order to enhancetheinterfacial adhesion of two components via a melt blending process. FT-IR spectra showed presences of specific functional groups of maleic anhydride onthebackbone ofthePLA afterthegrafting.Themodulus of PLA was considerably raised after incorporation ofthefibre. Furthermore, an addition of a coupling agent in PLAbiocompositeswas also able to remarkably increasethestiffness ofthematerial.

  • 42.
    Luttropp, Conrad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Johansson, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Vilaplana, Francisco
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Design for material hygiene - An ecodesign strategy for improved recycling of polymers2010In: Proceedings of the 8th International Symposium on Tools and Methods of Competitive Engineering, TMCE 2010, 2010, p. 1223-1231Conference paper (Refereed)
    Abstract [en]

    Recycling of polymers has come into focus lately. Many polymers carry a backpack of energy from manufacturing, which is lost in present recycling of e.g. automotives and small house hold appliances. This calls for higher efficiency in recycling. To take a step in this direction a literature study is made and an experiment at a recycling plant for refrigerators and freezers. A batch of 30m3 of electronic waste was collected and processed in a so-called Hurricane machine. The experiment showed that recycling of polymers can be made on higher levels of efficiency with the used machine, if complemented with sorting and some initial processing before shredding. In order to improve polymer recycling a set of process steps must be designed in order to get secondary polymer fractions that can be used in products.

  • 43.
    Luttropp, Conrad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Eco Quality Polymers-EQP2011In: Glocalized Solutions for Sustainability in Manufacturing - Proceedings of the 18th CIRP International Conference on Life Cycle Engineering, 2011, p. 482-485Conference paper (Refereed)
    Abstract [en]

    Polymers are materials worth recycling rather than incinerate. This calls for higher efficiency in recycling. To take a stepin this direction a study is made on how much of the polymer fraction of an electric product that is allocated to thehousing of the product.The study showed that a presorting of products according to polymer content of the shell and afterwards a fragmentingprocess where polymers and metals are separated would give a polymer fraction dominated by the housing polymer.

  • 44.
    Mendoza Alvarez, Ana Isabel
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Moriana Torro, Rosana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials. HIS Hogskolan I Skovde, Engn Sci, Hogskolevagen 1, SE-54128 Skovde, Sweden ; SLU Swedish Univ Agr Sci, Almas Alle 5, SE-75007 Uppsala, Sweden.
    Hillborg, Henrik
    ABB Corp Res, Power Technol, SE-72226 Vasteras, Sweden..
    Strömberg, Emma
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Super-hydrophobic zinc oxide/silicone rubber nanocomposite surfaces2019In: SURFACES AND INTERFACES, ISSN 2468-0230, Vol. 14, p. 146-157Article in journal (Refereed)
    Abstract [en]

    This study presents comparative assessments on hydrophilic and hydrophobic ZnO nanoparticles and their deposition methods on the surface hydrophobicity of silicone rubber (PDMS) and glass substrates. The influence on the surface hydrophobicity and wettability of all the variables regarding the deposition methodologies and the interaction of the nanoparticles with the substrates were within the scope of this study. The different surfaces created by spraying, dipping and drop-pipetting deposition methods were assessed by static contact angle measurements and contact angle hysteresis from advancing and receding angles, as well as by the calculation of the sliding angle and the surface energy parameters. An accurate methodology to determine the contact angle hysteresis was proposed to obtain repetitive and comparative results on all surfaces. All the measurements have been correlated with the morphology and topography of the different surfaces analysed by FE-SE microscopy. The spray-deposition of hydrophobic ZnO nanoparticles on PDMS resulted in super-hydrophobic surfaces, exhibiting hierarchical structures with micro-and nanometer features which, together with the low surface energy, promotes the Cassie-Baxter wetting behavior. This study provides the fundamental approach to select critically the most promising combination in terms of materials and deposition techniques to create silicone-based super-hydrophobic surfaces with potential to be applied in high voltage outdoor insulation applications.

  • 45.
    Mendoza, Ana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Hillborg, H.
    Strömberg, Emma
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Superhydrophobic self-regenerative silicone rubber nanocomposites for electrical outdoor insulation2015In: ICCM International Conferences on Composite Materials, International Committee on Composite Materials , 2015Conference paper (Refereed)
    Abstract [en]

    The overall objective of this project is to develop new structural composite materials for high voltage outdoor insulation applications using silicone rubber (PDMS) coated with micro- and nanoparticles. The goal is to obtain hierarchical superhydrophobic surfaces, with antifogging, antifouling and self-cleaning ability. This will minimize surface leakage currents and subsequent surface flash over of the insulator. In order to achieve both the superhydrophobic and self-cleaning ability, a combination of different surface chemistry of the particles has been investigated. Three different deposition techniques, including spraying of ROD ultrasonicated ZnO suspensions were investigated. Pure silicone rubber (SYLGARD® 184) was coated with hydrophobic and hydrophilic inorganic micro- and nanoparticles (ZnO). The effect of the different factors, such as particle surface chemistry and the deposition method, on the hydrophobicity of the surface has been investigated using static and dynamic contact angle measurements. The objective has been to achieve the highest static contact angle combined with the lowest possible hysteresis. The results showed that the spraying method was more suitable when using PDMS as matrix. The link between superhydrophobicity and the surface structure has been assessed by Scanning Electron Microscopy. The next step towards a self-regenerative composite material is approached by the incorporation of the optimal functionalised nanoparticles into the bulk material. The dynamic behaviour of silicone rubber presents a challenge for the stability of micro- and nanocomposites. Different mechanical techniques and methods of integration are being investigated for improvement of the homogeneity of the composites. Preliminary studies have been performed evaluating the effect of the curing time of the PDMS on the degree of incorporation of the nanoparticles in the surface and uniformity within the bulk. The behaviour of the nanocomposite and the evolution of the different properties with time and environmental conditions will be studied in the next phase of the project. 

  • 46. Moliner, C.
    et al.
    Badia, J. D.
    Bosio, B.
    Arato, E.
    Kittikorn, T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. e Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Songkhla, Thailand .
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Teruel-Juanes, R.
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ribes-Greus, A.
    Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites2018In: Chemical Engineering Communications, ISSN 0098-6445, E-ISSN 1563-5201, Vol. 205, no 2, p. 226-237Article in journal (Refereed)
    Abstract [en]

    The decomposition behaviours of composites made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and sisal were assessed in terms of thermal stability and decomposition kinetics, under inert and oxidative conditions, by means of multi-rate linear non-isothermal thermogravimetric experiments. A statistical design of experiments was applied to study the influence of the addition of sisal (0–10–20–30%wt), the presence coupling agent (Yes/No) and the applied conditions of work (inert or oxidative). An improvement of the thermal and thermo-oxidative stability of PHBV with the addition of sisal was observed for all cases. An accurate methodology based on iso-conversional methods was applied to simulate the potential of thermal recovery technologies, such as pyrolysis and controlled combustion, to use these biocomposites after the end of their service life. The mathematical descriptions of both thermo-chemical reactions were helpful in the evaluation of the eventual optimal operational conditions to carry out a suitable energetic valorisation. A minimum of 240°C and 137 kJ/mol of activation energy in inert conditions and 236°C and 118 kJ/mol in oxidative conditions ensured the feasibility of the reactions regardless the composition of the PHBV/sisal biocomposites, which may ease the operability of further energy valorisation with the aim to turn biowaste into new fuels.

  • 47.
    Moliner, C.
    et al.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy.;Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Badia, J. D.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain.;Univ Valencia, Escola Tecn Super Engn, Dept Engn Quim, Av Univ S-N, E-46100 Burjassot, Spain..
    Bosio, B.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy..
    Arato, E.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy..
    Teruel-Juanes, R.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Kittikorn, Thorsak
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Prince Songkla Univ, Fac Sci, Dept Mat Sci & Technol, Hat Yai 90112, Thailand..
    Strömberg, Emma
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ek, Monica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ribes-Greus, A.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Thermal kinetics for the energy valorisation of polylactide/sisal biocomposites2018In: Thermochimica Acta, ISSN 0040-6031, E-ISSN 1872-762X, Vol. 670, p. 169-177Article in journal (Refereed)
    Abstract [en]

    The thermal stability and decomposition kinetics of PLA/sisal biocomposites was discussed to evaluate the suitability of their use in energy recovery processes such as pyrolysis and combustion. The influence of the addition of sisal up to 30%wt, the presence of coupling agent, and the atmosphere of operation, i.e. inert or oxidative was discussed by means of multi-rate linear non-isothermal thermogravimetric experiments. All biocomposites showed a mean high heating value of 15 MJ/kg indicating their suitability for energy recovery processes. The thermal requirements of PLA/sisal decomposition were assessed in terms of onset decomposition temperature and apparent activation energy. A minimum of 240 degrees C and 174 kJ mol(-1) in inert environment and 225 degrees C and 190 kJ mol(-1) in oxidative environment ensured the feasibility of the reactions regardless the composition of the PLA/sisal biocomposites. The atmosphere of work lead to a greater amount of residue in case of pyrolysis reactions that would need further treatment whereas an oxidative atmosphere resulted in nearly zero final waste stream. The similar kinetics obtained for all samples regardless the amount of sisal or use of coupling agent eases the operability of energy facilities aimed of turning these biowastes into new fuels.

  • 48.
    Moriana, Rosana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Strömberg, Emma
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Ribes, Amparo
    Univ Politecn Valencia, Sch Design Engn ETSID, ITM, E-46022 Valencia, Spain..
    Karlsson, Sigbritt
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Degradation Behaviour of Natural Fibre Reinforced Starch-Based Composites under Different Environmental Conditions2014In: Journal of Renewable Materials, ISSN 2164-6325, E-ISSN 2164-6341, Vol. 2, no 2, p. 145-156Article in journal (Refereed)
    Abstract [en]

    The purpose of this work was to study the effect of hydrothermal, biological and photo degradation on natural fibres reinforced biodegradable starch-based (Mater-BiKE) composites to characterize the structural changes occurring under exposure to different environments. The composites water-uptake rate was hindered by the interfacial interactions between matrix and fibres. Thermal, structural and morphological analysis provided useful information about the irreversible changes in the properties of the composites caused by degradation in soil and photodegradation, and their synergetic effects. The effects due to the photo-oxidation and degradation in soil on the composites depended on the different chemical composition of each fibre. The composite with more hemicellulose and lignin in its formulation was more affected by both types of degradation, but still the end result properties were better than the ones shown for the degraded Mater-BiKE. The photo-oxidation of all the studied materials achieved enhanced degradation rate in soil. The Mater-BiKE/kenaf was shown to have the slowest water-uptake rate and better thermal properties once photo-oxidized, indicating better service life conditions. At the same time, the Mater-BiKE/kenaf was affected to a major extent by the synergetic effects of both photo-oxidation and soil burial test, showing a faster degradative rate and better disposal conditions.

  • 49.
    Möller, Johanna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Comparison of extraction methods for sampling of low molecular compounds in polymers degraded during recycling2008In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 44, no 6, p. 1583-1593Article, review/survey (Refereed)
    Abstract [en]

    The demand for mechanical recycling of plastic waste results in an increasing amount of recycled polymeric materials available for development of new products. In order for recycled materials to find their way into the material market, high quality is demanded. Thereby, a complete and closed loop of polymeric materials can be achieved successfully. The concept of high quality for recycled plastics imply that besides a pure fraction of e.g. polyethylene (PE) or polypropylene (PP), containing only minor trace amount of foreign plastics, knowledge is required about the type and amount of low molecular weight (LMW) compounds. During long-term use (service-life), products made of polymeric materials will undergo an often very slow degradation where a series of degradation products are formed, in parallel, additives incorporated in the matrix may also degrade. These compounds migrate at various rates to the surrounding environment. The release rate of LMW products from plastics depends on the initiation time of degradation and the degradation mechanisms. For polymers the formation of degradation products may be initiated already during processing, and subsequent use will add products coming from the surrounding environment, e.g. fragrance and aroma compounds from packaging. During recycling of plastics, emissions which contain a series of different LMW compounds may reach the environment leading to unwanted exposure to additives and their degradation residues as well as degradation products of polymers. Several extraction techniques are available for sampling of LMW compounds in polymers before chromatographic analysis. This paper reviews and compares polymer dissolution, accelerated solvent extraction (ASE), microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), super critical fluid extraction (SFE), soxhlet extraction, head-space extraction (HS), head-space solid phase micro extraction (HS-SPME), and head-space stir bar sorptive extraction (HSSE) as appropriate sampling methods for LMW compounds in recycled polymers. Appropriate internal standards useful for these kinds of matrices were selected, which improved the possibility for later quantification. Based on the review of extraction methods, the most promising techniques were tested with industrially recycled samples of HDPE and PP and virgin HDPE and PP for method comparison.

  • 50.
    Strömberg, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Long-term Properties of Sustainable Polymeric Materials: Mechanical Recycling and Use of Renewable Resources2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    New strategies for management of the accumulating amounts of plastic waste are required, to achieve a sustainable development in terms of material production and use. After service life, the materials should be recovered and recycled efficiently to provide a valuable resource for future applications. Optimised use of amended recycled polymeric materials, e.g. reinforced with natural fibres, and polymers from renewable resources give rise to polymeric materials with lower environmental impact. The recovery of plastic waste by means of mechanical recycling is a favourable route for preservation of raw materials and energy. Deficient knowledge about the overall quality of the recyclates, such as the degree of degradation, mixing and contamination, has resulted in restricted subsequent application of the recycled materials. Therefore, quality assessment of the recycled polymers is required for guaranteed performance in future applications.

    Recycling and service life of polyolefins (PP and HDPE) were modelled by multiple reprocessing and thermo-oxidation. The material properties of the polyolefins were affected by both thermo-oxidation and thermo-mechanical degradation. PP showed higher susceptibility to reprocessing and elevated formation of low molecular weight compounds compared to HDPE. Release of the compounds during service life is anticipated on account of the extensive migration of these volatiles during thermal ageing.

    Microenvironment chambers simulating outdoor environmental conditions were designed to monitor biofilm formation on silicon rubber composite materials. Furthermore, the microenvironments were successfully used to determine the long-term properties of biocomposites, consisting of conventional or biodegradable polymeric matrices and natural fibres as reinforcement, by subjecting the materials to a hydrolytic environment and microbiological degradation. Facilitated surface colonisation due to the presence of cellulose fibres in the composites was mainly attributed to water uptake. Biodegradation of PP biocomposites influenced mainly the surface properties whereas for PLA the bulk properties were also highly affected.

    PP-clay nanocomposites were subjected to simulated environmental degradation by thermo-oxidation, daylight photo-oxidation and exposure to forest soil. Increased crystallinity and surface oxidation were detected after thermo-oxidation of the materials. The presence of clay promoted formation of carbonyl compounds during photo-oxidation and water uptake during exposure to soil.

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