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  • 251.
    Gemeda, Aveke Elias
    KTH, Skolan för kemivetenskap (CHE).
    Depletion of antioxidants and polymer degradation in polyethylene pipes distributing chlorinated water2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Tap water disinfected by chlorine dioxide is oxidizing polymers and influences the properties of distributing pipes that usually made in polyethylene. Though it kills bacteria in drinking water, chlorine dioxide and its byproducts potentially shorten the polyethylene pipes service time.

    Squalane, which is a liquid hydrocarbon, is used in the squalane test. The chlorinated water and squalane forms dual-phase which makes easier for sampling from the squalane phase. The samples for tape test were pressed by Fontune press and were suspended in ClO2 water. In both tests ClO2 water was changed every 30 min to keep the concentration of chlorine constant.

    The oxidation induction time (OIT), which proportional to the concentration of the antioxidants, was used to analyze the depletion time of the antioxidants. Increasing chlorinated water bath temperature did not increase the degradation rate of the antioxidants in squalane test. However the OIT results from tape test showed a temperature-dependence manner.

    Tensile test on the materials that exposed to chlorinated water at concentration of 10 ppm of chlorine dioxide until depletion of antioxidants showed the depletion of antioxidants did not significantly affect the mechanical properties of the host material. There was a small decrease in tensile strain at break and tensile strain at tensile strength.

    Scanning electron microscopy (SEM) images showed there were micro-cracks formed on the surface of solid specimen after exposed to water containing chlorine dioxide and tensile test. However, the same sample without expose

  • 252. Geng, Lihong
    et al.
    Mittal, Nitesh
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Zhan, Chengbo
    Ansari, Farhan
    Sharma, Priyanka R.
    Peng, Xiangfang
    Hsiao, Benjamin S.
    Söderberg, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Centra, Wallenberg Wood Science Center.
    Understanding the Mechanistic Behavior of Highly Charged Cellulose Nanofibers in Aqueous Systems2018Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 51, nr 4, s. 1498-1506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanistic behavior and flow properties of cellulose nanofibers (CNFs) in aqueous systems can be described by the crowding factor and the concept of contact points, which are functions of the aspect ratio and concentration of CNF in the suspension. In this study, CNFs with a range of aspect ratio and surface charge density (380-1360 mu mol/g) were used to demonstrate this methodology. It was shown that the critical networking point of the CNF suspension, determined by rheological measurements, was consistent with the gel crowding factor, which was 16. Correlated to the crowding factor, both viscosity and modulus of the systems were found to decrease by increasing the charge density of CNF, which also affected the flocculation behavior. Interestingly, an anomalous rheological behavior was observed near the overlap concentration (0.05 wt %) of CNF, at which the crowding factor was below the gel crowding factor, and the storage modulus (G') decreased dramatically at a given frequency threshold. This behavior is discussed in relation to the breakup of the entangled flocs and network in the suspension. The analysis of the mechanistic behavior of CNF aqueous suspensions by the crowding factor provides useful insight for fabricating high-performance nanocellulose-based materials.

  • 253. Ghirardello, Mattia
    et al.
    Öberg, Kim
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Staderini, Samuele
    Renaudet, Olivier
    Berthet, Nathalie
    Dumy, Pascal
    Hed, Yvonne
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Marra, Alberto
    Malkoch, Michael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Dondoni, Alessandro
    Thiol-Ene and Thiol-Yne-Based Synthesis of Glycodendrimers as Nanomolar Inhibitors of Wheat Germ Agglutinin2014Inngår i: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 52, nr 17, s. 2422-2433Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alkene and alkyne functional polyester-based dendrimers of generation 1 to 4 have been prepared and reacted under free-radical conditions with 2-acetamido-2-deoxy-1-thio--D-glucose (GlcNAc-SH). As the alkene-dendrimers underwent the addition of one thiyl radical per ene group whereas each yne group of alkyne-dendrimers was saturated by two thiyl radicals, a collection of glycodendrimers with glycan density ranging from six to ninety-six GlcNAc per dendrimer was obtained. The recognition properties of the prepared glycodendrimers toward the wheat germ agglutinin (WGA) were evaluated by enzyme-linked lectin assay (ELLA). The eight glycodendrimers were excellent ligands showing IC50 values in the nanomolar range and relative potencies per sugar unit up to 2.27 e(6) when compared to monosaccharidic GlcNAc used as monovalent reference.

  • 254. Gil-Castell, O.
    et al.
    Badia, J. D.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Skövde University, Sweden.
    Ribes-Greus, A.
    Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 87, s. 174-187Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 255.
    Gimåker, Magnus
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Nygårds, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.). KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Östlund, Sören
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.). KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Shear strength development between couched papers during dryingManuskript (preprint) (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    The out-of-plane properties (e.g., out-of-plane shear strength) of paper materials are very important for their performance during converting and end use. There is, however, a lack of published data on how shear strength develops throughout the stages of paper manufacturing. The present study investigates how the shear strength developed between couched sheets during drying in a Rapid-Köthen laboratory sheet drier. The shear strength of sheets was measured, starting from sheets with a solids content of approximately 35% all the way to fully dry sheets. Shear strength development was examined between both never-dried and rewetted sheets made of unbeaten and beaten pulp. The results indicate that the shear strength increased with increasing solids content at all solids contents investigated. The shear strength was low (<120 kPa) up to a solids content of approximately 60–70%, after which it increased rapidly with increasing solids content, suggesting that interactions important for the shear strength of dry paper start to develop at this particular dry content.

  • 256.
    Glauser, T
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Johansson, M
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Hult, A
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Electron-beam curing of thick thermoset composite matrices1999Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 40, s. 5297-5302Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electron-beam (EB) curing of two epoxy resins, one acrylated and one methacrylated, has been investigated. The change in thermomechanical properties, such as T-g, and the change of residual unsaturation have been studied as a function of dose. These results, in combination with in situ measurements of the temperature during cure, have shown the importance of sample geometry for the final properties of the thermoset. The thermal history of the sample during cure greatly affects the properties of the cured resin. (C) 1999 Elsevier Science Ltd. All rights reserved.

  • 257. Glauser, T
    et al.
    Johansson, Mats
    Hult, Anders
    Electron-beam curing of thick thermoset composite matrices1999Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 40Artikkel i tidsskrift (Fagfellevurdert)
  • 258.
    Glavas, Lidija
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Redox responsiveness and electroactivity for preparation of smart micelles2014Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248Artikkel i tidsskrift (Annet vitenskapelig)
  • 259.
    Glavas, Lidija
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Olsén, Peter
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Achieving Micelle Control through Core Crystallinity2013Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, nr 11, s. 4150-4156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have designed a pathway for controlling the critical micelle concentration and micelle size of polyester-based systems. This was achieved by creating an array of different copolymers with semicrystalline or amorphous hydrophobic blocks. The hydrophobic block was constructed through ring-opening polymerization of epsilon-caprolactone, L-lactide, and epsilon-decalactone, either as homopolymers or random copolymers, using PEG as both the initiator and the hydrophilic block. Micelles formed with amorphous cores exhibited considerably higher critical micelle concentrations than those with semicrystalline cores. Micelles with amorphous cores also became larger in size with an increased molecular weight of the hydrophobic bock, in contrast to micelles with semicrystalline cores, which displayed the opposite behavior. Hence, core crystallinity was found to be a potent tool for tailoring micelle properties and thereby facilitating the optimization of drug delivery systems. The introduction of PEG-P epsilon DL also proved to be a valuable asset in the tuning of micelle properties.

  • 260. Golda-Cepa, M.
    et al.
    Brzychczy-Wloch, M.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Aminlashgari, Nina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Kotarba, A.
    Microbiological investigations of oxygen plasma treated parylene C surfaces for metal implant coating2015Inngår i: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 52, s. 273-281Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Parylene C surface was modified by the use of oxygen plasma treatment and characterized by microscopic and surface-sensitive techniques (E-SEM, AFM, XPS, LDI-TOF-MS, contact angle). The influence of the treatment on surface properties was investigated by calculations of surface free energy (Owens-Wendt method). Moreover, early adhesion (Culture Plate Method, Optical Microscopy Test) and biofilm formation ability (Cristal Violet Assay) on the parylene C surface was investigated. The bacteria strains which are common causative agents of medical device-associated infections (Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa - reference strains and clinical isolates) were used. It was concluded that chemical (oxygen insertion) and physical (nanotopography generation) changes, have a significant impact on the biocompatibility in terms of increased hydrophilicity (θw of unmodified sample = 88° ± 2°, θw of 60 min modified sample = 17.6° ± 0.8°) and surface free energy (SFE of unmodified sample = 42.4 mJ/m2, and for 60 min modified sample = 70.1 mJ/m2). At the same time, no statistical effect on biofilm production and bacteria attachment to the modified surface of any of the tested strains was observed.

  • 261. González-Ausejo, J.
    et al.
    Sanchez-Safont, E.
    Lagaron, J. M.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gamez-Perez, J.
    Cabedo, L.
    Assessing the thermoformability of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(acid lactic) blends compatibilized with diisocyanates2017Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 62, s. 235-245Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a renewable alternative to conventional barrier packaging polymers due to its thermoplastic properties, biodegradability and gas barrier performance but its potential industrial applications are limited by its high price and difficult processability. A thorough study concerning the thermoforming ability of PHBV, and blends with poly(lactic acid) (PLA) incorporating three different diisocyanates as compatibilizers (hexamethylene diisocyanate, poly(hexamethylene) diisocyanate and 1,4-phenylene diisocyanate) is herein presented after component melt blending. A straightforward universal qualitative method is proposed to assess the thermoformability, based on a visual inspection of a thermoformed specimen and the ability to reproduce the mold shape, and the thermoforming window of the material. The results reveal a significant improvement in the thermoforming capacity and a widening of the thermoforming windows as the correct amounts of diisocyanates are incorporated. The barrier properties and the biodisintegrability of the blends was also studied, confirming a predictable slight decrease of the barrier performance when PLA is added, but without negatively affecting the disintegrability under composting conditions with respect to pristine PHBV.

  • 262. Groning, M.
    et al.
    Eriksson, Henrik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Numerisk Analys och Datalogi, NADA.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Phenolic prepreg waste as functional filter with antioxidant effect in polypropylene and polyamide-62006Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 91, nr 8, s. 1815-1823Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Milled phenol-formaldehyde glass-fibre scrap (prepreg) was mixed with polypropylene (PP) and polyamide-6 (PA6). The oxidation induction time (OIT) of PP/prepreg composite measured by both chemiluminescence (CL) and Differential Scanning Calorimetry (DSC) was significantly longer than the oxidation induction time of unstabilised base PP. In addition, mechanical testing showed that the prepreg filter stabilised both PP and PA6 towards oxidation during long-term accelerated ageing. Headspace-gas chromatography/mass spectrometry (HS-GC/MS) showed that PP/prepreg composites emit somewhat larger amounts of volatile compounds compared to the reference PP/glass fibre composites, while the amount of volatile components emitted from PA6/prepreg composites was similar to the reference PA6/glass fibre composites. The new prepreg composites could have potential in thermally demanding applications especially if a secondary phosphite stabiliser is added to further increase the oxidative stability through synergy effects.

  • 263. Groning, M.
    et al.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Headspace solid-phase microextraction with gas chromatography/mass spectrometry reveals a correlation between the degradation product pattern and changes in the mechanical properties during the thermooxidation of in-plant recycled polyamide 6,62002Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 86, nr 13, s. 3396-3407Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The increased susceptibility of in-plant recycled polyamide 6,6 toward thermooxidation was shown by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME/GC-MS), tensile testing, differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). A correlation between the deterioration in mechanical properties and the formation of degradation products due to thermooxidation was found, and the most prominent decrease in mechanical properties coincided with the largest increase in the abundance of degradation products. The recycled materials had a shorter induction period toward oxidation, and their mechanical properties deteriorated faster than the mechanical properties of virgin material. The same trend was observed with HS-SPME/GC-MS because degradation products were found for recycled materials after oxidation times shorter than those for virgin material. Furthermore, larger amounts of degradation products were formed in the recycled materials. The high sensitivity of HS-SPME/GC-MS as an analytical tool was demonstrated because it was able to detect changes caused by oxidation considerably earlier than the other methods. Unlike DSC and FTIR, it could also show differences between samples recycled for different times. Four groups of degradation products-cyclic imides, pyridines, chain fragments, and cyclopentanones-were identified in thermooxidized polyamide 6,6. After 1200 h of thermooxidation, 1-pentyl-2,5-pyrrolidinedione was the most abundant degradation product. Approximately four times more 1-pentyl-2,5-pyrrolidinedione was formed in polyamide recycled three times than in virgin polyamide. Pyridines and chain fragments behaved toward oxidation and repeated processing like cyclic imides; that is, their amounts increased during oxidation, and larger amounts were formed in recycled materials than in virgin material. The cyclopentanone derivatives were present already in unaged material, and their amounts decreased during oxidation. Cyclopentanones were not formed because of the thermooxidation of polyamide 6,6.

  • 264.
    Groning, Mikael
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Multiple headspace solid-phase microextraction of 2-cyclopentyl-cyclopentanone in polyamide 6.6: possibilities and limitations in the headspace analysis of solid hydrogen-bonding matrices2004Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1052, nr 02-jan, s. 61-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interactions between a polar analyte, 2-cyclopentyl-cyclopentanone, and a solid polar matrix, polyamide 6.6, during multiple headspace solid-phase microextraction (MHS-SPME) were studied. Strong hydrogen bonding between the analyte and the matrix was observed and shown to cause slow migration and adsorption of the analyte. These matrix effects led to erroneous quantitation despite the use of multiple headspace extraction. Addition of water disrupted the hydrogen bonding between the analyte and the matrix and a valid quantitation was achieved. The addition of water also increased the sensitivity and allowed the identification of 2,5-bis(cyclopentyl)-1-cyclopentanone. The amount of 2-cyclopentyl-cyclopentanone in five different polyamide 6.6 samples was measured using the developed multiple headspace solid-phase microextraction method with water-displacer. The measured concentrations were in the range of 1.44-15.61 mug/g. These concentrations were up to 30% higher than the concentrations measured after microwave-assisted extraction (MAE), which indicates incomplete recovery by MAE. The use of water as a displacer eliminated the matrix effects and complete recovery of the analyte was achieved by MHS-SPME.

  • 265. Gröning, M.
    et al.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Headspace solid-phase microextraction - a tool for new insights into the long-term thermo-oxidation mechanism of polyamide 6.62001Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 932, nr 02-jan, s. 1-11Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low-molecular-mass products formed. during thermo-oxidation of polyamide 6.6 at 100 degreesC were extracted by headspace solid-phase microextraction and identified by GC-MS. A total of 18 degradation products of polyamide 6.6 were identified. In addition some low-molecular-mass products originating from the lubricants were detected. The identified degradation products were categorized into four groups where compounds within each group contain the same structural feature. In groups A, B and C several new thermo-oxidation products of polyamide 6.6 were identified including cyclic imides, pyridines and structural fragments from the original polyamide chain. 1-Pentyl-2,5-pyrrolidinedione (pentylsuccinimide) showed the largest increase in abundance during oxidation. The cyclopentanones in group D were already present in the un-aged material. Their amounts decreased during ageing and they are thus not formed during thermo-oxidation of polyamide 6.6 at 100 degreesC. The identified thermo-oxidation products can be formed as a result of extensive oxidation of the hexamethylenediamine unit in the polyamide backbone. The degradation products pattern shows that the long-term thermo-oxidative degradation, just like thermal degradation and photo-oxidation of polyamide 6.6, starts at the N-vicinal methylene groups.

  • 266.
    Gröning, Mikael
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Correlation between emitted and total amount of 2-cyclopentyl-cyclopentanone in polyamide 6.6 allows rapid assessment by HS and HS-SPME under non-equilibrium conditions2004Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1052, nr 02-jan, s. 151-159Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A correlation was found between the emitted and total amount of 2-cyclopentyl-cyclopentanone in polyamide 6.6. The emitted amounts were measured by GC-MS after headspace (HS) or headspace solid-phase microextraction (HS-SPME) and the total content was determined after microwave-assisted extraction (MAE). The correlation was valid also under non-equilibrium conditions, which allows rapid assessment of 2-cyclopentyl-cyclopentanone content in polyamide 6.6 by headspace techniques. The incubation time needed for non-equilibrium headspace analysis could be reduced from 5 h to 45 min if the PA66 granules were milled to powder prior to extraction. However, to reach equilibrium between the analyte in the solid sample and the headspace still required 12 h of incubation at 80degreesC. The long incubation time is explained by slow diffusion rate due to the strong hydrogen bonding between analyte and matrix and the relatively high crystallinity of polyamide 6.6. The headspace extraction profile showed several equilibrium-like patterns that are easily mistaken for the real equilibrium.

  • 267.
    Gröning, Mikael
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Quantitative determination of volatiles in polymers and quality control of recycled materials by static headspace techniques2008Inngår i: CHROMATOGRAPHY FOR SUSTAINABLE POLYMERIC MATERIALS: RENEWABLE, DEGRADABLE AND RECYCLABLE, Berlin: Springer Verlag , 2008, Vol. 211, s. 51-84Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    A presentation is given of headspace (HS) extraction and headspace solid-phase microextraction (HS-SPME) techniques and their combination with multiple headspace (MHS) extraction to enable quantitative determination of volatiles in solid polymer matrixes. As an example, the development of HS, HS-SPME, and MHS-SPME methods for extraction of volatiles from thermo-oxidized and/or recycled polyamide 6.6 is reviewed with special focus on the problems encountered when extracting analytes from solid-sample matrixes including excessively long equilibrium times and adsorption of analytes to the sample matrix. Examples are also given of the application of HS-SPME in quality control of recycled materials, in durability assessment of polymeric materials and in degradation studies.

  • 268.
    Gröning, Mikael
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner, Polymerteknologi.
    Recycling of glass fibre reinforced phenolic prepreg waste. part 1. Recovery and reuse of glass fibres in PP and PA62004Inngår i: Polymers & polymer composites, ISSN 0967-3911, E-ISSN 1478-2391, Vol. 12, nr 6, s. 491-500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present paper describes a feasible process to reuse glass fibres separated from phenolic prepreg waste as reinforcing filler in polypropylene (PP) and polyamide 6 (PA6). Prior to compounding, the recovered glass fibres were cut into 50 mm long fibre bundles and surface treated with gamma-aminopropyltriethoxysilane (APS) for increased composite interfacial strength. Electron Spectroscopy for Chemical Analysis (ESCA) and Atomic Force Microscopy (AFM) showed that the silane coupling agent was attached to the surface of the glass fibres but the silane layer was somewhat uneven, probably due to the presence of small amounts of organic contaminants. In addition it was found necessary to clean the glass fibres from organic contaminants by thermal treatment in order to attach silane coupling agent to the surfaces. The tensile strengths obtained for PP and PA6 composites with 30 wt% filler level of surface treated recovered glass fibres were 49 MPa and 101 MPa, respectively. This should be compared to 30 MPa and 75 MPa for composites containing untreated glass fibres and 19 MPa and 52 MPa for pure PP and PA6. Addition of 5 wt% PP-g-MA compatibiliser to the PP composite increased the tensile strength by another 14%, i.e. to 56 MPa. The good interfacial compatibility achieved by APS surface treatment and compatibilisation was verified by Scanning Electron Microscopy (SEM).

  • 269.
    Gröning, Mikael
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner, Polymerteknologi.
    Recycling of glass-fibre reinforced phenolic prepreg waste. Part 2. Milled prepreg as functional filler in PP and PA62004Inngår i: Polymers & polymer composites, ISSN 0967-3911, E-ISSN 1478-2391, Vol. 12, nr 6, s. 501-509Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phenolic resin impregnated glass-fibre prepreg waste was milled and used as reinforcing filler in polypropylene (PP) and polyamide 6 (PA6). Prepreg was particularly suitable to be used as filler in PA6. The fibres were homogeneously distributed during compounding and the addition of 20 wt% prepreg increased the tensile strength of PA6 by 63%, from 52 MPa to 85 MPa. Milled prepreg alone did not significantly increase the tensile strength of PP. However, if compounded together with maleic anhydride grafted polypropylene (PP-g-MA, Epolene G3003) compatibiliser, prepreg can be used as reinforcing filler in PP as well. Addition of 20 wt% prepreg together with 5 wt% Epolene G3003 increased the tensile strength of PP from 26 MPa to 43 MPa. In order to mill the prepreg for compounding with thermoplastics it has to be cured. A 2 kg batch of prepreg had to be cured for at least 2 hours at 200 degreesC to prevent the phenolic resin from falling off the glass-fibres. Milling should be performed using screens with holes larger than 3 mm in diameter to reduce the amount of prepreg fibres shorter than 2 mm, as they jam the hopper when feeding the recyclate to the extruder. The initial prepreg fibre length is of little importance to the composite mechanical properties, as the fibres are shortened to approximately the same length during compounding.

  • 270.
    Guerzoni, Samuele
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Deplaine, Harmony
    El Haskouri, Jamal
    Amoros, Pedro
    Monleon Pradas, Manuel
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Gallego Ferrer, Gloria
    Combination of silica nanoparticles with hydroxyapatite reinforces poly (L-lactide acid) scaffolds without loss of bioactivity2014Inngår i: Journal of bioactive and compatible polymers (Print), ISSN 0883-9115, E-ISSN 1530-8030, Vol. 29, nr 1, s. 15-31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Composite scaffolds of poly(l-lactide acid) and hydroxyapatite are of great interest in bone tissue engineering, but their mechanical properties are typically inferior to scaffolds of pure poly(l-lactide acid) due to agglomeration of the particles and weak interfacial component interaction. Fabrication strategies like double sonication of hydroxyapatite or increasing the amount of this inorganic filler do not effectively enhance the mechanical performance. In this study, poly(l-lactide acid) composites combining two types of fillers, mesoporous silica (SiO2) nanoparticles and hydroxyapatite, were developed to reinforce the poly(l-lactide acid) scaffold without any loss of bioactivity. A 5% addition of SiO2 nanoparticles to hydroxyapatite nanopowder and subjecting the scaffold formulation to double sonication increased the Young's modulus from 5 MPa (pure poly(l-lactide acid) scaffold) to almost 7 MPa (poly(l-lactide acid)/hydroxyapatite/SiO2 scaffold). In addition, the composite was able to deposit a layer of biomimetic hydroxyapatite both on the surface and interior of the scaffold after 21 days of immersion in a simulated body fluid. The manufacturing method was straightforward and economically viable and does not require any chemical modification of the particles' surfaces.

  • 271. Guo, Juan
    et al.
    Song, Kunlin
    Salmen, Lennart
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. Innventia AB, Sweden .
    Yin, Yafang
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Changes of wood cell walls in response to hygro-mechanical steam treatment2015Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 115, s. 207-214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of compression combined with steam treatment (CS-treatment), i.e. a hygro-mechanical steam treatment on Spruce wood were studied on a cell-structure level to understand the chemical and physical changes of the secondary cell wall occurring under such conditions. Specially, imaging FT-IR microscopy, nanoindentation and dynamic vapour absorption were used to track changes in the chemical structure, in micromechanical and hygroscopic properties. It was shown that CS-treatment resulted in different changes in morphological, chemical and physical properties of the cell wall, in comparison with those under pure steam treatment. After CS-treatment, the cellular structure displayed significant deformations, and the biopolymer components, e.g. hemicellulo se and lignin, were degraded, resulting in decreased hygroscopicity and increased mechanical properties of the wood compared to both untreated and steam treated wood. Moreover, CS-treatment resulted in a higher degree of degradation especially in earlywood compared to a more uniform behaviour of wood treated only by steam.

  • 272.
    Gustafsson, Emil
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Tailoring Adhesion and Wetting Properties of Cellulose Fibres and Model Surfaces Using Layer-by-Layer Technology2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The versatile layer-by-layer (LbL) technique, for consecutive adsorption of polyelectrolytes and charged nanoparticles onto a substrate, was used to modify cellulose fibres and model surfaces for improved mechanical and wetting properties. In addition to being used to modify cellulose substrates, the LbL technique was also used to create cellulose surfaces suitable for high resolution adhesion measurements. LbL assembly of cellulose nanofibrils and polyethylenimine was used to prepare cellulose model surfaces on polydimethylsiloxane hemispheres which allowed for the first known Johnson-Kendall-Roberts (JKR) adhesion measurements between cellulose and smooth, well-defined model surfaces of cellulose, lignin and glucomannan. The work of adhesion on loading and the adhesion hysteresis were comparable for all three systems which suggest that adhesion between wood constituents is similar. The LbL technique was also used to decrease the hydrophilicity of paper, while improving the dry strength, by coating cellulose fibres with a polylallylamine hydrochloride (PAH) and polyacrylic acid (PAA) LbL film, followed by adsorption of anionic wax particles. Paper sheets made from the modified fibres were highly hydrophobic with a contact angle of 150°, while retaining, and in some cases improving, the tensile index of the paper. It was also observed that PAH/PAA modified sheets without the addition of wax became hydrophobic when heat treated. The mechanism behind the increased hydrophobicity was studied by the interface sensitive technique, vibrational sum frequency spectroscopy, which indicated that the increased hydrophobicity is a result of the reorientation of polymer chains to expose more hydrophobic CH2 and CH groups at the polymer-air interface. Paper sheets prepared from LbL-modified bleached softwood fibres using PAH and the biopolymer hyaluronic acid (HA) exhibited a 6.5% strain at break and a tensile index which was increased 3-fold compared to unmodified fibres. The wet adhesive properties of the PAH/HA system were studied by colloidal probe atomic force microscopy and correlated to film growth and viscoelastic behavior. The presence of background salt was a crucial parameter for achieving high adhesion but time in contact and LbL film thickness also strongly affected the adhesion. Finally, the wet adhesive properties of carboxymethylcellulose (CMC), which had been irreversibly adsorbed to regenerated cellulose, and polyvinylamine (PVAm) were evaluated by means of 90° peel tests. Strong wet adhesion was achieved for dried rewetted samples without any obvious chemical crosslinking, which was attributed to interdigitation and complex formation in PVAm-CMC films. This system also gave significant wet adhesion for non-dried systems at water contents around 45%.

  • 273.
    Gustafsson, Emil
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Hedberg, Jonas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Larsson, Per A.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Johnson, C. Magnus
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Vibrational sum frequency spectroscopy on polyelectrolyte multilayers – effect of molecular surface structure on macroscopic wetting propertiesManuskript (preprint) (Annet vitenskapelig)
  • 274.
    Gustafsson, Emil
    et al.
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Pelton, Robert
    McMaster University.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Polyelectrolyte Entanglement across Interfaces and Wet Adhesion- Influence of Polyvinylamine on Wet Adhesion between Cellulose Model Surfaces Modified with CarboxymethylcelluloseManuskript (preprint) (Annet vitenskapelig)
  • 275.
    Gustafsson, Emil
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center. McMaster University, Canada.
    Pelton, Robert
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Rapid Development of Wet Adhesion between Carboxymethylcellulose Modified Cellulose Surfaces Laminated with Polyvinylamine Adhesive2016Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, nr 36, s. 24161-24167Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The surface of regenerated cellulose membranes was modified by irreversible adsorption-of carboxymethylcellulose (CMC). Pairs of wet CMC-modified membranes were laminated with polyvinylamine (PVAm) at room, temperature, and the delamination force for wet membranes was measured for both dried and never-dried laminates. The wet adhesion was, studied as a function of PVAm molecular weight, amine :content,: and deposition pH of the polyelectrolyte. Surprisingly the PVAm CMC system gave substantial wet adhesion that exceeded that of TEMPO-oxidized membranes with PVAm for both dried and never-dried laminates. The greatest wet adhesion was achieved for fully hydrolyzed high molecular weight PVAm. Bulk carboxymethylation of cellulose membranes gave inferior wet adhesion combined with PVAm as compared to CMC adsorption which indicates,that a CMC layer of the order of 10 nm Was necessary. There are no obvious covalent cross linking reactions between CMC and PVAm at room temperature, and on the basis of our results, we are instead attributing the wet adhesion to complex formation between the PVAm and the irreversibly adsorbed CMC at the cellulose surface. We propose that interdigitation of PVAm chains into the CMC layer is responsible for the wet adhesion values.

  • 276.
    Gustafsson, Emil
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.
    Utsel, Simon
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Marais, Andrew
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Johansson, Erik
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellens Centrum BiMaC Innovation.
    Pettersson, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    Wågberg, Lars
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Fiberteknologi.
    The use of thin, tailored Layer-by-Layer (LbL) films to improve the mechanical properties of fibrous networks2012Konferansepaper (Annet vitenskapelig)
  • 277.
    Göransson, Helena
    KTH, Skolan för kemivetenskap (CHE).
    Biodegradable PLA-g-PEG Bioconjugates for Targeted Drug Delivery2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Polymer therapeutics as drug delivery systems have gained significant interest during the last years. The reason being their possibility to circumvent many of the drawbacks connected to drugs used today. Conventional polyesters have several favorable properties necessary for the mentioned purpose but their lack of functional groups often limits their use.

     

    In this study we will try to overcome this limitation by presenting the first steps of a new synthesis pathway to achieve a telechelic-functionalized polymer scaffold. By providing the polymer with functional handles further post-polymerization steps are made possible. Polylactide (PLA) chains featuring azide functionality were successfully grafted from an initiating species on a peptide with the amino acid sequence Gly-Arg-Gly-Asp-Ser (GRGDS) via ring-opening polymerization. Incorporation of oligo(ethylene glycol) chains featuring azide moieties into the PLA backbone will allow for active drug delivery. In future studies, a cell-penetrating peptide for improved cellular uptake and a third functionality enabling attachment of homing devices to promote targeted delivery will be installed.

     

    Ring-opening polymerization of lactide showed to initiate successfully from the peptide as was confirmed by proton nuclear magnetic resonance spectroscopy (1H NMR). Liquid chromatography mass spectrometry (LCMS) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF MS) also confirmed the formation of a polymer-peptide conjugate and PLA chains with a degree of polymerization (DP) between 1 and 4 were detected. 1H NMR and Correlation spectroscopy (COSY) showed a downfield shift of the peak originating by the protons next to the terminal hydroxyl group. This indicates that initiation solely occurs from the hydroxyl group and not from other nucleophilic groups also present on the peptide. This was further confirmed by Nuclear Overhauser Effect spectroscopy (NOESY) and Heteronuclear single quantum coherence spectroscopy (HSQC) where a correlation between the PLA chain and the peptide strand was detected.

  • 278.
    Göthe, Viktoria
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Green Nanocomposites from Cereal Husk2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The aim of this master thesis study was to investigate the possibility to extract cellulose nanocrystals (CNC) from cereal husks and their capability to be used as reinforcement systems of hemicellulosic biopolymers. CNC were isolated from rye husk and used as reinforcement in nanocomposites. To obtain the isolated CNC the rye husk was processed through alkaline treatments, bleaching treatments and finally an acid hydrolysis. The cellulose extraction was optimized and optimal conditions were reached when 3wt% of rye husk were used for both alkaline and bleaching treatments. Acid hydrolysis was performed at 45°C for 30 minutes. The total yield from the rye husk to the CNCs was approximately 11wt%. The isolation process from macro to nano size was monitored via different chemico-physical characterization methods.

    Via Scanning Electron Microscopy (SEM) analysis, the isolation of the cellulose fibers from rye husk could be assessed. The chemical composition was evaluated via carbohydrate analysis, ash, extractives and lignin Klason determination. From these chemical data, it was verified that most of the amorphous components of the rye husk were removed reaching 73.17% of cellulose for the isolated cellulose fibers. Fourier transform infrared spectroscopy (FTIR) was used to follow the chemical structural changes through the CNC isolation process. From the FTIR spectra, it could be seen that the bleached husk and CNC materials were similar to a cellulose fiber compared to the rye husk and alkaline treated husk, which had FTIR spectra typical for lignocellulosic biomass. This fact indicates that most of the hemicellulose and lignin were removed due to the chemical treatments the rye husk was submitted to. Crystalline index of the samples was also determined with FTIR and an increasing crystallinity trend was observed through the isolation, from rye husk to CNC. The Thermogravimetric Analysis (TGA) was used to assess the thermal stability and it was observed that the bleached and CNC samples had an increased thermal stability with respect to the lignocellulosic and alkaline samples, indicating the most labile components of the rye husk were removed. The rye husk CNC exhibited a length of 335.4 nm, diameter of 2.86 nm and a zeta potential of -35.8 mV together with a high purity (>98% of cellulose) crystallinity and thermal stability.

    Green nanocomposites based on commercial arabinoxylan from rye and CNC isolated from rye husk were prepared. The method employed to produce the nanocomposite films was solvent casting. Different amounts of CNC were added to the arabinoxylan matrix: 0, 5, 10 and 20wt% of CNC. Mechanical and thermal properties of the nanocomposites were evaluated. The nanocomposite films exhibited an increase in the thermal stability, Young modulus and tensile strength due to the addition of the CNC indicating a good compatibility and interaction between the raw materials.

  • 279.
    Hafeez, Asif
    KTH, Skolan för kemivetenskap (CHE).
    Synthesis and characterization of renewable cellulose based plasticizer for polyvinyl chloride (PVC)2011Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Acid catalyzed liquefaction of brown paper handtowel was performed using a mixture of diethylene glycol and glycerol andaddition of minute amount of p-toluenesulphonic acid as a catalyst. TheLiquefied brown paper was used as a polyhydroxy alcohol during the estersynthesis as large number of hydroxyl groups is available in liquefied brownpaper products. Esterification was performed by using hexanoic acid along withdibutyl tin (IV) oxide as a catalyst. The product was characterized by usingFTIR, SEC and SEM. PVC films were prepared by solution casting. They wereplasticized by the prepared liquefied brown paper ester and by traditionaldiisooctyl phthalate. Comparison of both plasticizers on the basis ofmechanical, thermal properties and plasticizer migration was elaborated.

  • 280. Haider, Nadejzda
    et al.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    A rapid ultrasonic extraction technique to identify and quantify additives in poly(ethylene)1999Inngår i: Analyst (Cambridge, United Kingdom), Vol. 124, nr 5, s. 797-800Artikkel i tidsskrift (Fagfellevurdert)
  • 281. Haider, Nadejzda
    et al.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Migration and release profile of Chimassorb 944 from low-density polyethylene film (LDPE) in simulated landfills1999Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 64, nr 2, s. 321-328Artikkel i tidsskrift (Fagfellevurdert)
  • 282.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Aliphatic polyesters: Abiotic and biotic degradation and degradation products2002Inngår i: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 157, s. 113-138Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper reviews the degradation behavior of aliphatic polyesters of current interest, including polylactide, polycaprolactone, poly(3-hydroxybutyrate) and their copolymers. Special focus is given to degradation products formed in different abiotic and biotic environments. The influence of processing and processing additives on the properties and degradation behavior is also briefly discussed.

  • 283.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Developments in multiple headspace extraction2007Inngår i: Journal of Biochemical and Biophysical Methods, ISSN 0165-022X, E-ISSN 1872-857X, Vol. 70, nr 2, s. 229-233Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper reviews new developments in multiple headspace extraction (MHE), especially its combination with two miniaturized extraction techniques, solid-phase microextraction (SPME) and single-drop microextraction (SDME). The combination of the techniques broadens the applicability of SPME and SDME to quantitative determination of analytes in complex liquid and solid matrixes. These new methods offer several advantages over traditional liquid-solid, liquid-liquid and headspace extraction techniques. The potential applications include extraction of volatiles and semivolatiles from environmental and physiological samples and from different polymer products such as medical and biomedical materials, food packaging and building materials. The theoretical principals of the techniques are also briefly reviewed.

  • 284.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Electrospray Ionization-Mass Spectrometry for Molecular Level Understanding of Polymer Degradation2012Inngår i: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 248, s. 175-204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The stability and durability of polymeric materials under different external influences (e.g., sunlight, humidity, heat, chemicals, or microorganisms) is of outmost importance in applications such as coatings, building materials, and automotive parts, whereas a rapidly degradable material is preferable in temporary short-term applications. There are considerable economic and environmental benefits if we can design polymers for short or long lifetimes as well as prevent the release of harmful substances from the materials during their lifetime. The recent developments in mass spectrometric techniques facilitate possibilities for molecular level characterization of the changes taking place in the polymer matrix as well as for identification of the released degradation products. This review presents an overview of the application of electrospray ionization-mass spectrometry (ESI-MS) for the analysis of polymer degradation. The great potential of the technique for revealing detailed insights into the degradative reactions taking place is demonstrated with examples ranging from degradable polymers and biomaterials to degradation of coatings, paints, polymer electrolyte membranes, food packaging, and materials in the nuclear industry.

  • 285.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Migration of monomeric and polymeric PVC plasticizers2008Inngår i: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 211, s. 159-185Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper summarizes current literature on the migration of monomeric and polymeric PVC plasticizers from medical materials, food packaging, and toys. Especially highlighted is macromolecular engineering as a tool to increase the plasticizing efficiency and migration resistance for polymeric plasticizers. The effect of branching, molecular weight, end-group functionality, and polydispersity on plasticizer performance was evaluated by quantification of low-molecular-weight hydrolysis products, measurements of mechanical properties, weight loss, surface segregation, as well as the preservation of material properties during aging. A more migration-resistant polymeric plasticizer that also better preserved its material properties during aging was obtained by combining a low degree of branching, hydrolysis-protecting end-groups, and higher molecular weight.

  • 286.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Multiple headspace single-drop micro-extraction for quantitative determination of lactide in thermally-oxidized polylactide2010Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 95, nr 3, s. 270-273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Single-drop micro-extraction (SDME), an emerging micro-extraction technique, was combined with multiple headspace (MHS) extraction to allow quantitative determination of lactide in thermally-oxidized polylactide Different solvents, drop sizes and extraction times were tested to obtain best extraction efficiency and the method was further developed to obtain a linear regression plot for the Multiple extractions. The combination of SDME and MHS extraction offered several advantages over traditional liquid-solid and headspace extraction techniques No concentration step was needed and loss of volatiles was prevented as the ageing and extraction were performed in a closed system Matrix effects, that disturb the quantitation of analytes in solid samples, were removed by the multiple headspace extraction.

  • 287.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    New PVC materials for medical applications - the release profile of PVC/polycaprolactone-polycarbonate aged in aqueous environments2003Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 80, nr 3, s. 451-458Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Medical grade PVC plasticised with polycaprolactone-polycarbonate (PCL-PC) was subjected to aqueous environments at different temperatures. The release profile during ageing was determined by solid phase microextraction (SPME) and GC-MS. At the same time changes in the surface composition due to, for example, migration of PCL-PC from the blend were followed by FTIR. Almost no changes in the material or its surface composition were observed during 98 days at 37 degreesC in water or phosphate buffer. Only trace amount of 6-hydroxyhexanoic acid the final hydrolysis product of PCL-PC was detected in the GC-MS chromatograms and the weight loss was negligible. Even when the ageing temperature was raised to 70 degreesC only minor increase in the amount of 6-hydroxyhexanoic acid was observed and the weight loss after 98 days was under 1%. Changes in the FTIR spectra indicating migration of PCL-PC towards the surface of the PVC/PCL-PC tubing were observed first after 70 days at 70 degreesC. Large increase in the hydrolysis rate of PCL-PC and almost complete depletion of PCL-PC from the blend was observed when the ageing temperature was raised to 100 degreesC.

  • 288.
    Hakkarainen, Minna
    KTH, Tidigare Institutioner, Polymerteknologi.
    Qualitative and quantitative solid-phase microextraction gas chromatographic-mass spectrometric determination of the low-molecular-mass compounds released from poly(vinyl chloride)/polycaprolactone-polycarbonate during ageing2003Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1010, nr 1, s. 9-16Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A solid-phase microextraction (SPME) method was developed to quantitatively determine the amount of 6-hydroxyhexanoic acid in aqueous solutions. The SPME method in combination with GC-MS was then applied to identify and quantify the low-molecular-mass compounds migrating from a new poly(vinyl chloride) (PVC) material, PVC/polycaprolactone-polycarbonate (PCL-PC) during ageing in water. It was shown that only a small amount of 6-hydroxyhexanoic acid, the final hydrolysis product of PCL-PC, migrated from the blend during ageing at 37 and 70 degreesC. If, however, the temperature was raised to 100 degreesC rapid hydrolysis of PCL-PC resulted. In addition to 6-hydroxyhexanoic acid, 6-hydroxyhexanoic acid dimer, caprolactone, different carboxylic acids, acetophenone and phenol were identified. SPME-GC-MS was also applied to monitor the low-molecular-mass compounds migrating from the PVC/PCL-PC blend during thermo-oxidation.

  • 289.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Solid phase microextraction for analysis of polymer degradation products and additives: Renewable, Degradable and Recyclable2008Inngår i: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 211, nr 1, s. 23-50Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Commercial plastics and rubbers always contain low molecular weight additives. Other low molecular weight compounds are formed due to degradation of polymers and additives during synthesis, processing, use and after disposal. Knowledge of these compounds is important for evaluating the environmental impact and interaction of polymeric materials, to investigate long-term properties and degradation mechanisms, to verify ingredients, to investigate manufacturing problems, to quality control polymeric materials, to identify odorants, to avoid workplace exposure and to insure safety of food packaging and medical products. Solid-phase microextraction (SPME) is a solvent-free extraction technique that has in recent years found an increasing number of applications in different fields. This paper presents a review of SPME technique in different polymer related applications including analysis of degradation products and polymer additives, monomer-rests, odor compounds, migrants from food packaging and medical products, extraction of polymer additives from environmental samples and biological fluids. Future possibilities are also discussed.

  • 290.
    Hakkarainen, Minna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Adamus, Grazyna
    Centre of Polymer and Carbon Materials, Polish Academy of Sciences.
    Höglund, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Kowalczuk, Marek
    Centre of Polymer and Carbon Materials, Polish Academy of Sciences.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    ESI-MS reveals the influence of hydrophilicity and architecture on the water-soluble degradation product patterns of biodegradable homo- and copolyesters of 1,5-dioxepan-2-one and epsilon-caprolactone2008Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 41, nr 10, s. 3547-3554Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hydrolytic degradation process and degradation product patterns of biodegradable homo- and copolyesters of 1,5-dioxepan-2-one (DXO) and epsilon-caprolactone (CL) were monitored by electrospray ionization mass spectrometry (ESI-MS). The degradation product patterns were compared to mass loss, molecular weight changes, copolymer composition, and pH changes after various hydrolysis times. Water-soluble oligomers up to heptadecamer were identified after hydrolysis of hydrophilic PDXO, while only oligomers up to hexamer were detected after hydrolysis of the more hydrophobic PCL. The product pattern of DXO-CL-DXO triblock copolymer mainly consisted of DXO-based oligomers, whereas the CL/DXO multiblock copolymer degradation product pattern contained DXO and CL oligomers as well as oligomers containing both DXO and CL units. The DXO-rich oligomers, however, dominated the product patterns. ESI-MS gave valuable insights into the hydrolysis process of hydrophobic and hydrophilic polyesters and showed that hydrophilicity of the polymer as well as copolymer architecture both greatly influenced the water-soluble degradation product patterns.

  • 291.
    Hakkarainen, Minna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Degradation products of aliphatic and aliphatic-aromatic polyesters2008Inngår i: Chromatography For Sustainable Polymeric Materials: Renewable, Degradable And Recyclable, BERLIN: SPRINGER-VERLAG , 2008, Vol. 211, s. 85-116Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Analysis of degradation products needs to be included in degradability testing to ensure the environmental adaptability of degradable polymers. Identification of breakdown products from environmental degradation is important for understanding the degradation process, environmental interaction and impact of degradable polymers. with regard to degradability aliphatic polyesters are a particularly interesting group of polymers. They are susceptible to hydrolysis and biological attack due to the ester groups in the main chain. This paper summarizes the work done on the chromatographic analysis of degradation products from the most common aliphatic and aliphatic-aromatic polyesters under different abiotic and biotic conditions including simulated, accelerated and real environmental conditions.

  • 292.
    Hakkarainen, Minna
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner, Polymerteknologi.
    Environmental degradation of polyethylene2004Inngår i: LONG-TERM PROPERTIES OF POLYOLEFINS, Berlin, 2004, Vol. 169, s. 177-199Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The environmental degradation of polyethylene proceeds by synergistic action of photo- and thermo-oxidative degradation and biological activity. Since biodegradation of commercial high molecular weight polyethylene proceeds slowly, abiotic oxidation is the initial and rate-determining step. Enhanced environmentally degradable polyethylene is prepared by blending with biodegradable additives or photo-initiators or by copolymerisation. One of the key questions for successful development and use of environmentally degradable polymers is to understand the interaction between degradation products and nature. Polymer fragments and degradation products should be environmentally assimilable and should not accumulate or negatively affect the environment. Determination of abiotic and biotic oxidation products is an important step towards establishing the environmental degradation mechanism and environmental impact of the material. More than 200 different degradation products including alkanes, alkenes, ketones, aldehydes, alcohols, carboxylic acid, keto-acids, dicarboxylic acids, lactones and esters have been identified in thermo- and photo-oxidised polyethylene. In biotic environment these abiotic oxidation products and oxidised low molecular weight polymer can be assimilated by microorganisms. In future we will probably see a development of new polyethylenes with tailor-made structures specially designed for environmental degradation through different pathways. Paralleled with the development of these new materials we need to obtain better understanding of the environmental impact of degradable polymers and the interactions between nature and degradation products in a dynamic system.

  • 293.
    Hakkarainen, Minna
    et al.
    KTH, Tidigare Institutioner (före 2005), Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner (före 2005), Polymerteknologi.
    Heterogeneous biodegradation of polycaprolactone - Low molecular weight products and surface changes2002Inngår i: Macromolecular Chemistry and Physics, ISSN 1022-1352, E-ISSN 1521-3935, Vol. 203, nr 11-okt, s. 1357-1363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gas chromatography-mass spectrometry (GC-MS) analysis showed that caprolactone, 6-hydroxyhexanoic acid, cyclic dimer and cyclic trimer were rapidly assimilated from the surface of polycaprolactone (PCL) films aged in mineral medium inoculated with a mixed culture of compost microorganisms. The degradation in biotic medium proceeded heterogeneously and scanning electron micrographs revealed the formation of parallel grooves, spherical and non-spherical holes in the films. The parallel grooves seen in the scanning electron micrographs after 14 d suggest that the degradation starts preferentially at the amorphous regions. At longer time scales, even the crystalline regions are degraded producing large spherical and non-spherical holes. Comparison of the degradation of melt-pressed and film-blown films made from the same PCL granules in different biotic and abiotic environments showed that both the type of microorganism used and the initial morphology of the films influence the surface erosion pattern and biodegradation mechanism. Rapid degradation and molecular weight decrease required the combined effect of temperature and microorganisms obtained during a biodegradation process, such as composting.

  • 294.
    Hakkarainen, Minna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Indicator products: A new tool for lifetime prediction of polymeric materials2005Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, nr 2, s. 775-779Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possible correlation between the degree of degradation in the polymer matrix and the release of indicator products was investigated. The degree of degradation was measured by following the molar mass changes by size exclusion chromatography, while indicator products were analyzed by gas chromatography -mass spectrometry. The degree of degradation in polyethylene and polyethylene vinyl acetate matrix after thermooxidation was found to be in correlation with the amount of dicarboxylic acids and lactones formed during aging, while the degree of degradation in photooxidized polyethylene could be predicted from the amount of dicarboxylic acids. The relative amount of lactones compared to the relative amount of dicarboxylic acids increased if the oxidation temperature was increased. However, the total amount of indicator products was in correlation with the remaining number average molar mass and the number of chain scissions caused by oxidation. The amount of butanedioic acid and butyrolactone correlated well with the total amount of dicarboxylic acids and lactones, respectively. Thus, instead of the whole compound classes, butanedioic acid or butyrolactone alone could be used as indicators of oxidation. The detected correlation offers a novel tool for making lifetime predictions and studying the long-term properties of polymeric materials.

  • 295.
    Hakkarainen, Minna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Kalrsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Weight losses and molecular weight changes correlated with the evolution of hydroxyacids in simulated in vivo degradation of homo-and copolymers of PLA and PGA1996Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 52, s. 283-291Artikkel i tidsskrift (Fagfellevurdert)
  • 296.
    Hakkarainen, Minna
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner, Polymerteknologi.
    Migration and emission of plasticizer and its degradation products during thermal aging of nitrite rubber2003Inngår i: IJPAC. International journal of polymer analysis and characterization, ISSN 1023-666X, E-ISSN 1563-5341, Vol. 8, nr 4, s. 279-293Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The behavior of nitrile rubber during long-term thermal aging was evaluated by following the migration of low-molecular-weight additives and additive degradation products from the material. Headspace-GC-MS analysis showed that at 60degreesC the number of low-molecular-weight compounds released was rather low, but a significant increase in the number and amount of products was observed when the temperature was raised from 60degrees to 80degreesC, e.g., several degradation products of tris(2-butoxyethyl)phosphate plasticizer including 2-butoxyethanol and 1-butanol were identified. Oxidation of the plasticizer was also seen in the FTIR spectra. The color of the material changed from light brown to almost black during the aging.

  • 297.
    Hakkarainen, Minna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Solid phase microextraction (SPME) as an effective means to isolate degradation products in polymers1997Inngår i: Journal of environmental polymer degradation, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 5, s. 67-73Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new sample preparation technique, solid phase microextraction (SPME), was compared with direct headspace-GC-MS with respect to the type and amount of identified compounds. Three types of LDPE films containing photosensitising additives according to the Scott-Gilead patents and pure LDPE were used as model substances. The polyethylene films were thermally aged at 80 degrees C after the induction period was surpassed by subjecting the materials to 100 h of UV radiation. The new SPME method was developed using nonpolar poly(dimethylsiloxane) and polar carbowax fibers to extract the low molecular weight products formed in the polyethylene films during aging. Many more products were identified after SPME followed by CC-MS than after direct headspace-GC-MS of the samples. The SPME method allowed the identification of homologous series of carboxylic acids, ketones, and furanones, while direct headspace-GC-MS identified only a few carboxylic acids (C1-C6) and small amounts of some ketones and furanones. In general, SPME was more effective in extracting less volatile products, and in particular, the polar carbowax fiber identified also C7-C12 carboxylic acids and 4-oxopentanoic acid. By SEC and FTIR we confirmed that the number and amount of former degradation products correlated well with the decrease in molecular weights and the amount of formed carbonyl compounds.

  • 298.
    Hakkarainen, Minna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Solid-phase extraction and subsequent gas-chromatography-mass spectrometry analysis for identification of complex mixtures of degradation products in starch-based polymers1996Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 741, s. 251-263Artikkel i tidsskrift (Fagfellevurdert)
  • 299.
    Hakkarainen, Minna
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Susceptibility of starch-filled and starch-based LDPE to oxygen in water and air1997Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 66, s. 959-967Artikkel i tidsskrift (Fagfellevurdert)
  • 300. Hakkarainen, Minna
    et al.
    Albertsson, Ann-Christine
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Weight losses and molecular weight changes correlated with the evolution of hydroxy acids in simulated in vivo degradation of homo- and copolymers of PLA and PGA1996Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 52, nr 3, s. 283-291Artikkel i tidsskrift (Fagfellevurdert)
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