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Moliner, C., Badia, J. D., Bosio, B., Arato, E., Kittikorn, T., Strömberg, E., . . . Ribes-Greus, A. (2018). Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites. Chemical Engineering Communications, 205(2), 226-237
Open this publication in new window or tab >>Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites
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2018 (English)In: Chemical Engineering Communications, ISSN 0098-6445, E-ISSN 1563-5201, Vol. 205, no 2, p. 226-237Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Taylor and Francis Ltd., 2018
Keyword
Biocomposites, kinetics, natural fibres, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), sisal, thermal decomposition, thermo-oxidative decomposition, waste-to-fuel, Activation energy, Composite materials, Coupling agents, Decomposition, Design of experiments, Enzyme kinetics, Natural fibers, Oxidation resistance, Pyrolysis, Thermal oil recovery, Waste incineration, Bio-composites, Mathematical descriptions, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), Statistical design of experiments, Thermo-gravimetric experiments, Thermo-oxidative stability
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-223164 (URN)10.1080/00986445.2017.1384921 (DOI)000428042400005 ()2-s2.0-85038352550 (Scopus ID)
Note

Export Date: 13 February 2018; Article; CODEN: CEGCA; Correspondence Address: Ribes-Greus, A.; Instituto de Tecnología de los Materiales (ITM), Universidad Politècnica de València (UPV), Camino de Vera S/N, Spain; email: aribes@ter.upv.es; Funding details: Generalitat Valenciana; Funding details: UPOV13-3E-1947; Funding details: ENE2014-53734-C2-1-R; Funding details: PSU, Prince of Songkla University. QC 20180314

Available from: 2018-03-14 Created: 2018-03-14 Last updated: 2018-04-11Bibliographically approved
Lugoye, M., Ndazi, B. S., Tesha, J., Nyahumwa, C. & Karlsson, S. (2017). Characterising technical cashew nut shell liquid using Maldi-ToF MS. Natural Products Journal, 7(4), 281-285
Open this publication in new window or tab >>Characterising technical cashew nut shell liquid using Maldi-ToF MS
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2017 (English)In: Natural Products Journal, ISSN 2210-3155, Vol. 7, no 4, p. 281-285Article in journal (Refereed) Published
Abstract [en]

Background: Various techniques have been applied for detecting anacardic acid, cardanol, cardol, and 2-methylcardol and their degrees of unsaturation in a complex mixture of a highly corrosive cashew nut shell liquid found in the cashew (anacardium occidentale) nut shells. However, very little has been reported on the applicability of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry for the same. The aim of this paper is to report the application of this technique for identifying those components in technical cashew nut shell liquid obtained by a hot-roasting process. Methods: The cashew nut shell liquid analyte was diluted in acetone before adding a matrix of 2,5- dihydroxybenzoic acid, which contained acetone in a volumetric ratio of 1:2. This was followed by doping the analyte with either sodium or silver trifluoroacetate. Results: The mass spectra obtained by both sodium trifluoroacetate and silver trifluoroacetate dopants revealed existence of well-resolved peaks ascribed to cardanol and cardol in the analyte. It was further observed that the peaks corresponding to 2-methyl cardol and anacardic acid in the analyte could only be detected by using sodium trifluoroacetate dopant. The results have further revealed the possibility of the material to contain traces of other components between 0.3 and 23%. Peaks associated with those components may have been overlapped with peaks ascribed to the phenolic components. Conclusion: The results therefore suggest that this technique may be applicable for characterising the composition of technical cashew nut shell liquids when proper sample preparation is done and appropriate solvents, dopants and matrices are used.

Place, publisher, year, edition, pages
Bentham Science Publishers B.V., 2017
Keyword
2-methyl cardol, Anacardic acid, Cardanol, Cardol, Maldi-ToF, Saturation
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-221646 (URN)10.2174/2210315507666170609114447 (DOI)000424000700005 ()2-s2.0-85040220133 (Scopus ID)
Funder
Sida - Swedish International Development Cooperation Agency
Note

QC 20180118

Available from: 2018-01-18 Created: 2018-01-18 Last updated: 2018-02-16Bibliographically approved
Gil-Castell, O., Badia, J. D., Strömberg, E., Karlsson, S. & Ribes-Greus, A. (2017). Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds. European Polymer Journal, 87, 174-187
Open this publication in new window or tab >>Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds
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2017 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 87, p. 174-187Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2017
Keyword
Electrospinning, Hydrolysis, In vitro validation, Polycaprolactone (PCL), Scaffold, Chemical properties, Dissolution, Fibers, Mixtures, Molar mass, Nanofibers, Polycaprolactone, Crystallinity degree, Diameter distributions, In-vitro, Nano-scaled structures, Nanofibrous scaffolds, Physicochemical property, Physiological condition, Polycaprolactone scaffolds, Scaffolds
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-201951 (URN)10.1016/j.eurpolymj.2016.12.005 (DOI)000395210900015 ()2-s2.0-85007427983 (Scopus ID)
Note

Funding text: The European Regional Development Funds and the Spanish Ministry of Economy and Competitiveness are acknowledged for the projects POLYCELL (ENE2014-53734-C2-1-R) and UPOV13-3E-1947. The Spanish Ministry of Education, Culture and Sports is thanked for the pre-doctoral FPU grant of O. Gil-Castell (FPU13/01916) and the scholarship for a research stage of O. Gil-Castell in Kungliga Tekniska Högskolan (KTH). Generalitat Valenciana is thanked for the APOSTD/2014/041 for J.D. Badia. Universitat de València (UV) and IIS LaFe are acknowledged for the DERMASAFE project. The financial support given by the KTH Royal Institute of Technology and the Universitat Politècnica de València (UPV) are gratefully acknowledged. IESMAT S.A. and Malvern Instruments Ltd are recognised for their grateful collaboration.

QC 20170303

Available from: 2017-03-03 Created: 2017-03-03 Last updated: 2017-11-29Bibliographically approved
Frostell, C., Bjorling, G., Strömberg, E., Karlsson, S. & Aune, R. E. (2017). Tracheal implants revisited. The Lancet, 389(10075), 1191-1191
Open this publication in new window or tab >>Tracheal implants revisited
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2017 (English)In: The Lancet, ISSN 0140-6736, E-ISSN 1474-547X, Vol. 389, no 10075, p. 1191-1191Article in journal (Refereed) Published
Place, publisher, year, edition, pages
ELSEVIER SCIENCE INC, 2017
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-205042 (URN)000397143700024 ()28353438 (PubMedID)2-s2.0-85016169571 (Scopus ID)
Note

QC 20170519

Available from: 2017-05-19 Created: 2017-05-19 Last updated: 2017-05-19Bibliographically approved
Gil-Castell, O., Badia, J. D., Kittikorn, T., Strömberg, E., Ek, M., Karlsson, S. & Ribes-Greus, A. (2016). Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites. Polymer degradation and stability
Open this publication in new window or tab >>Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites
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2016 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
Biocomposites, Degradation, Hydrothermal ageing, Mechanical fibre effectiveness, Natural fibres, Performance, Polylactide (PLA), Sisal, Coupling agents, Enamels, Fibers, Field emission microscopes, Glass transition, Natural fibers, Polyesters, Scanning electron microscopy, Thermoanalysis, Thermodynamic stability, Thermogravimetric analysis, Viscoelasticity, Water absorption, X ray diffraction, Bio-composites, Poly lactide, Composite materials
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:kth:diva-186799 (URN)10.1016/j.polymdegradstab.2016.03.038 (DOI)000393846000011 ()2-s2.0-84962695727 (Scopus ID)
Note

QC 20160523

Available from: 2016-05-23 Created: 2016-05-13 Last updated: 2017-11-30Bibliographically approved
Vilaplana, F., Nilsson, J., Sommer, D. V. P. & Karlsson, S. (2015). Analytical markers for silk degradation: comparing historic silk and silk artificially aged in different environments. Analytical and Bioanalytical Chemistry, 407(5), 1433-1449
Open this publication in new window or tab >>Analytical markers for silk degradation: comparing historic silk and silk artificially aged in different environments
2015 (English)In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 407, no 5, p. 1433-1449Article in journal (Refereed) Published
Abstract [en]

Suitable analytical markers to assess the degree of degradation of historic silk textiles at molecular and macroscopic levels have been identified and compared with silk textiles aged artificially in different environments, namely (i) ultraviolet (UV) exposure, (ii) thermo-oxidation, (iii) controlled humidity and (iv) pH. The changes at the molecular level in the amino acid composition, the formation of oxidative moieties, crystallinity and molecular weight correlate well with the changes in the macroscopic properties such as brightness, pH and mechanical properties. These analytical markers are useful to understand the degradation mechanisms that silk textiles undergo under different degradation environments, involving oxidation processes, hydrolysis, chain scission and physical arrangements. Thermo-oxidation at high temperatures proves to be the accelerated ageing procedure producing silk samples that most resembled the degree of degradation of early seventeenth-century silk. These analytical markers will be valuable to support the textile conservation tasks currently being performed in museums to preserve our heritage.

Keyword
Silk, Conservation, Multivariate analysis, Amino acid composition, Infrared spectroscopy, Mechanical properties
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-161108 (URN)10.1007/s00216-014-8361-z (DOI)000349336400015 ()25492090 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20150324

Available from: 2015-03-24 Created: 2015-03-09 Last updated: 2017-12-04Bibliographically approved
Atari Jabarzadeh, S., Nilsson, F., Hillborg, H., Karlsson, S. & Strömberg, E. (2015). Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling. International Journal of Polymer Science, Article ID 390292.
Open this publication in new window or tab >>Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling
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2015 (English)In: International Journal of Polymer Science, ISSN 1687-9422, E-ISSN 1687-9430, article id 390292Article in journal (Refereed) Published
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.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-170710 (URN)10.1155/2015/390292 (DOI)000356264100001 ()
Note

QC 20150707

Available from: 2015-07-07 Created: 2015-07-03 Last updated: 2017-12-04Bibliographically approved
Atari Jabarzadeh, S., Salas Lacamprett, C., Karlsson, S. & Strömberg, E. (2015). Use of essential oils for the prevention of biofilm formation on silicone rubber high voltage insulators. Polymers from Renewable Resources, 6(4), 119-136
Open this publication in new window or tab >>Use of essential oils for the prevention of biofilm formation on silicone rubber high voltage insulators
2015 (English)In: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 6, no 4, p. 119-136Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Rapra Technology Ltd., 2015
Keyword
Algae, Biofilms, Elastomers, Electric insulation, Electric insulators, Essential oils, Microorganisms, Phenols, Rubber, Silicones, Thermoanalysis, Anti-microbial effects, Biofilm formation, High voltage insulators, Microbial growth, Natural-antimicrobials, Sample preparation, Silicone rubber, Thermal and mechanical properties
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-174283 (URN)2-s2.0-84952893692 (Scopus ID)
Note

QC 20170111

Available from: 2015-10-02 Created: 2015-10-02 Last updated: 2017-03-24Bibliographically approved
Moriana, R., Vilaplana, F., Karlsson, S. & Ribes, A. (2014). Correlation of chemical, structural and thermal properties of natural fibres for their sustainable exploitation. Carbohydrate Polymers, 112, 422-431
Open this publication in new window or tab >>Correlation of chemical, structural and thermal properties of natural fibres for their sustainable exploitation
2014 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 112, p. 422-431Article in journal (Refereed) Published
Abstract [en]

The potential of lignocellulosic natural fibres as renewable resources for thermal conversion and material reinforcement is largely dependent on the correlation between their chemical composition, crystalline structure and thermal decomposition properties. Significant differences were observed in the chemical composition of cotton, flax, hemp, kenaf and jute natural fibres in terms of cellulose, hemicellulose and lignin content, which influence their morphology, thermal properties and pyrolysis product distribution. A suitable methodology to study the kinetics of the thermal decomposition process of lignocellulosic fibres is proposed combining different models (Friedman, Flynn-Wall-Ozawa, Criado and Coats-Redfern). Cellulose pyrolysis can be modelled with similar kinetic parameters for all the natural fibres whereas the kinetic parameters for hemicellulose pyrolysis show intrinsic differences that can be assigned to the heterogeneous hemicellulose sugar composition in each natural fibre. This study provides the ground to critically select the most promising fibres to be used either for biofuel or material applications.

Keyword
Natural fibres, Cellulose, Hemicellulose, Lignin, Crystalline content, Thermal properties
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-153234 (URN)10.1016/j.carbpol.2014.06.009 (DOI)000341464600056 ()2-s2.0-84903648921 (Scopus ID)
Note

QC 20141016

Available from: 2014-10-16 Created: 2014-10-03 Last updated: 2017-12-05Bibliographically approved
Gil-Castell, O., Badia, J. D., Kittikorn, T., Strömberg, E., Martinez-Felipe, A., Ek, M., . . . Ribes-Greus, A. (2014). Hydrothermal ageing of polylactide/sisal biocomposites. Studies of water absorption behaviour and Physico-Chemical performance. Polymer degradation and stability, 108, 212-222
Open this publication in new window or tab >>Hydrothermal ageing of polylactide/sisal biocomposites. Studies of water absorption behaviour and Physico-Chemical performance
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2014 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 108, p. 212-222Article in journal (Refereed) Published
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.

Keyword
Biocomposites, Polylactide (PLA), Natural fibres, Sisal, Hydrothermal degradation, Water absorption
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-156127 (URN)10.1016/j.polymdegradstab.2014.06.010 (DOI)000343380800026 ()2-s2.0-84903221897 (Scopus ID)
Note

QC 20141217

Available from: 2014-12-17 Created: 2014-11-21 Last updated: 2017-12-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5394-7850

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