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Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 51.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Barrier layers for packaging laminates and packaging laminates comprising such barrier layers2009Patent (Övrig (populärvetenskap, debatt, mm))
  • 52.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Efficient conversion of wood hydrolysates into renewable materials2012Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 244Artikel i tidskrift (Övrigt vetenskapligt)
  • 53.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    New matrices for controlled drug delivery.2000Ingår i: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, American Chemical Society (ACS), 2000Konferensbidrag (Refereegranskat)
  • 54.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Novel release systems from biodegradable polymers1998Ingår i: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, American Chemical Society (ACS), 1998Konferensbidrag (Refereegranskat)
  • 55.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Vedrester blir förnybar råvara2009Ingår i: Miljöforskning, ISSN 1650-4925, nr 5, s. 20-21Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Cellulosa används sedan länge i många produkter. Än så länge gäller det främst inom trävaru-, pappers- och massaindustrin. Men veden innehåller även andra ämnen, som idag mest ses som onödiga restprodukter. Aktuell forskning vid KTH visar att sådana produkter i framtiden kan bli användbara i till exempel förpackningar, läkemedelsindustri och jordbruk.

  • 56.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Wood hydrolysates: From fractions to products2015Ingår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Artikel i tidskrift (Övrigt vetenskapligt)
  • 57.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Wood hydrolysates turned valuable2012Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 243Artikel i tidskrift (Övrigt vetenskapligt)
  • 58.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Källrot, Martina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Surface modification of degradable polymers2005Ingår i: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, American Chemical Society (ACS), 2005Konferensbidrag (Refereegranskat)
  • 59.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Varma, Indra Kumari
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Synthesis, Chemistry and Properties of Hemicelluloses2011Ingår i: Biopolymers: New Materials for Sustainable Films and Coatings / [ed] David Plackett, Chichester: John Wiley & Sons, 2011, 1, s. 135-150Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 60.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Erlandsson, Bengt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Molecular weight changes and polymeric matrix changes correlated with the formation of degradation products in biodegraded polyethylene1999Ingår i: Journal of environmental polymer degradation, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 64, s. 91-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products, The samples were thermooxidized for 6 days at 100 degrees C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono- and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in (M) over bar(n) from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene.

  • 61.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Finne-Wistrand, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradable polymers with tailored properties for biomedical materials2009Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 238Artikel i tidskrift (Övrigt vetenskapligt)
  • 62.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Groning, M.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Emission of volatiles from polymers - A new approach for understanding polymer degradation2006Ingår i: Journal of polymers and the environment, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 14, nr 1, s. 8-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Emission of low molar mass compounds from different polymeric materials was determined and the results from the volatile analysis were applied to predict the degree of degradation and long-term properties, to determine degradation rates and mechanisms, to differentiate between biotic and abiotic degradation and for quality control work. Solid-phase microextraction and solid-phase extraction together with GC-MS were applied to identify and quantify the low molar mass compounds. Volatiles were released and monitored at early stages of degradation before any matrix changes were observed by e.g. SEC, DSC and tensile testing. The analysis of volatiles can thus also be applied to detect small differences between polymeric materials and their susceptibility to degradation. The formation of certain degradation products correlated with the changes taking place in the polymer matrix, these indicator products could, thus, be analysed to rapidly predict the degree of degradation in the polymer matrix and further to predict the long-term properties and remaining lifetime of the product.

  • 63.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Gröning, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Chromatographic analysis as a tool for predicting material performance2005Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, s. 247-248Artikel i tidskrift (Övrigt vetenskapligt)
  • 64.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradable polymers and their interaction with the environment2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 223, s. 566-567Artikel i tidskrift (Övrigt vetenskapligt)
  • 65.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Designed to degrade Suitably designed degradable polymers can play a role in reducing plastic waste2017Ingår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 358, nr 6365, s. 872-873Artikel i tidskrift (Refereegranskat)
  • 66.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    The three stages in the degradation of polymers- polyethylene as a model substance1988Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 35, s. 1289-1302Artikel i tidskrift (Refereegranskat)
  • 67.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Kumari Varma, Indra
    Centre for Polymer Science and Engineering, Indian Institute of Technology, New Dehli, India.
    Srivastava, Rajiv K.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Polyesters from Large Lactones2009Ingår i: Handbook of Ring-Opening Polymerization / [ed] Philippe Dubois, Olivier Coulembier, Jean-Marie Raquez, Wiley-VCH Verlagsgesellschaft, 2009, 1, s. 287-306Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 68.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Källrot, Martina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    POLY 585-Covalent surface modification of degradable polymers2007Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234Artikel i tidskrift (Övrigt vetenskapligt)
  • 69.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Finne-Wistrand, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Controlled synthesis of star-shaped homo- and co-polymers of aliphatic polyesters2006Ingår i: 7th International Biorelated Polymers Symposium, 2006, s. 37-38Konferensbidrag (Refereegranskat)
    Abstract [en]

    The challenges in finding a material with the proper characteristics for a given tissue engineering application are several. One solution is improving the ability to tailor the mechanical and physical properties along with the degradation profile of aliphatic polyesters, by for example alterations in their composition and architecture. In this study, well-defined star-shaped aliphatic polyesters constituted of four arms were synthesized. As a model system, L,L-lactide and a spirocyclic tin initiator was chosen and the affect of the solvent, temperature and monomer-to-initiator ratio on the number average molecular weight, the molecular weight distribution and the conversion of the polymers was shown. Consecutively, we proved that well-defined star-shaped block copolymers composed of 1,5-dioxepan-2-one and L,L-lactide with narrow molecular weight distributions and controlled block lengths can be synthesized using this system.

  • 70. Albertsson, Ann-Christine
    et al.
    Renstad, Rasmus
    Erlandsson, Bengt
    Eldsäter, Carina
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Effect of processing additives on (bio)degradability of film-blown poly(ε-caprolactone)1998Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 70, nr 1, s. 61-74Artikel i tidskrift (Refereegranskat)
  • 71.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Srivastava, Rajiv K.
    Recent developments in enzyme-catalyzed ring-opening polymerization2008Ingår i: Advanced Drug Delivery Reviews, ISSN 0169-409X, E-ISSN 1872-8294, Vol. 60, nr 9, s. 1077-1093Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    An exponential growth has been observed in the last decade where enzymes were used as catalysts for polymerization of different monomers and due to enzyme's origin from natural sources they have been taken as a substitute for the metal-based catalytic systems. Mild polymerization conditions, high enantio- and regio-selectivity and recyclability of enzymes give them an extra edge over the use of organo-metallic catallysts. Though the enzyme-catalyzed polymerizations are environmentally highly advantageous, the high cost, large quantity of enzymes required for polymerization and formation of relatively low molecular weight polymers obstruct their employment in the industry. Due to these reasons, this technique is still at die stage of infancy to generate polymeric materials which can be converted to any useful physical form. In this article enzyme-catalyzed ring-opening polymerization of lactones, lactides, cyclic carbonates and depsipeptides has been reviewed with special focus on the molecular weight of the polymers synthesized hitherto using enzyme catalysis. It is necessary to obtain polymers of sufficient molecular weight from enzyme catalysis to withstand the specific requirements of their end applications if this technique is desired to be escalated to commercial level.

  • 72.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Varma, Indra Kumari
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Lochab, Bimlesh
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Finne Wistrand, Anna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Kumar, Kamlesh
    Centre for Polymer Science and Engineering, Indian Institute of Technology, Dehli, India.
    Design and Syntesis of Different Types of Poly(Lactic acid)2010Ingår i: Poly(Lactic Acid): Synthesis, Structures, Properties, Processing and Applications / [ed] Rafael Auras, Loong-Tak Lim, Susan E. M. Selke, Hideto Tsuji, John Wiley & Sons, 2010, s. 43-58Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 73.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Voepel, Jens
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Dahlman, Olof
    Soderqvist-Lindblad, Margaretha
    Design of Renewable Hydrogel Release Systems from Fiberboard Mill Wastewater2010Ingår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, nr 5, s. 1406-1411Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new route for the design of renewable hydrogels is presented. The soluble waste from masonite production was isolated, fractionized, and upgraded. The resulting hemicellulose rich fraction was alkenyl-functionalized and used in the preparation of covalently cross-linked hydrogels capable of sustained release of incorporated agents. Said hydrogels showed a Fickian diffusion-based release of incorporated bovine serum albumin. Also, a method for the coating of seeds with hydrogel was developed. The sustained release of incorporated growth retardant agents from the hydrogel coating on rape seeds was shown to enable the temporary inhibition of germination.

  • 74.
    Alin, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Analytical tools for identification and quantification of migrants from food packaging2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Polymers are frequently used as packaging material for food and therefore it is of concern that migrating substances such as additives or degradation products could contaminate the food. Sometimes also processing or microwave heating of food is performed directly inside the food package, which could lead to increased migration. Chromatographic and mass spectrometric analysis techniques can be used to detect, identify and quantify compounds that are released from polymers during such scenarios and, with suitable extraction and analysis techniques for example solid phase micro extraction coupled to gas chromatography – mass spectrometry (SPME-GC-MS), the migrating substances can be identified and quantified. We have previously detected the emission of low molecular weight substances from polymers using SPME-GC-MS [1,2]. With these analysis techniques we have shown that significant antioxidant degradation takes place during microwave heating of the polypropylene (PP) packages in the fatty food simulants, which further led to increased migration of potentially toxic degradation products into the food [3]. No antioxidant degradation was observed in aqueous food simulants or during conventional heating at the same temperature. Electrospray ionization-mass spectrometry (ESI-MS) was shown to be a valuable tool for studying the less volatile migrants. Antioxidant migration rates from three PP materials to fatty food simulants differed largely with respect to the PP type and increased with decreasing degree of crystallinity in the materials, as determined by high performance liquid chromatography (HPLC) [4]. The extraction efficiency of a headspace - solid phase microextraction (HS-SPME) method could be predicted from the analyte properties using a partial least squares (PLS) regression model [5].

     

    References

    [1] M Gröning, M Hakkarainen, Journal of Chromatography, (2001) 932, 1-11

    [2] M Hakkarainen, Journal of Chromatography, (2003)  1010, 9-16

    [3] J. Alin and M. Hakkarainen, Journal of Agricultural and Food Chemistry, (2011) DOI: 10.1021/jf1048639

    [4] J. Alin and M. Hakkarainen, Journal of Applied Polymer Science, (2010) 118, 1084-1093

    [5] J. Alin and M. Hakkarainen, manuscript

  • 75.
    Alin, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Microwave heating effects on degradation and migration of additives from polypropylene packaging2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Effekten av olika typer av mat, polymermaterial och mikrovågor på total och specifik migrering under mikrovågsvärmning av plastförpackningar undersöktes för att bättre förstå interaktioner mellan förpackningar och mat samt effekten av mikrovågor på förpackningarna. Denna licetiatavhandling behandlar migrering av ämnen till matsimulerande ämnen (food simulants) från vanliga matförpackningar av polypropen, inköpta från matvaruaffärer. Förpackningsmaterialen var polypropen homopolymer (PP), co-polymer (PP-C) och random co-polymer (PP-R). Genom att mäta kristallinitetsgrad i proven före och efter mikrovågsvärmning kunde eventuella förändringar orsakade av värming samt matsimulanterna detekteras. Antioxidanterna Irgafos 168 och Irganox 1010 fanns i samtliga tre förpackningar. Andra flyktiga ämnen, främst nedbrytningsprodukter från antioxidanterna, detekterades och identifierades i de oåldrade förpackningarna. Betydande nedbrytning av antioxidanter inträffade under mikrovågsvärmning av förpackningarna i de feta mat-simulanterna 90/10 isooktan/etanol och etanol, vilket resulterade i bildning och migrering av nedbrytningsprodukter medan ingen betydande nedbrytning av antioxidanter skedde under vanlig värmning i samma simulanter. Migreringshastigheter för antioxidanterna Irgafos 168 och Irganox 1010 var annars samma under mikrovågsvärmning som under vanlig värmning i 90/10 isooktan/etanol och etanol och diffusionskoefficienterna för antioxidanterna var likvärdiga med tidigare uppmätta värden under vanlig värmning. Skillnader i antioxidanternas migreringshastigheter var stora mellan de olika PP-typerna och ökade med minskad andel kristallin fas i materialen, PP-R visade därför högst migreringshastighet. Svällning i isooktan ökade diffusionskoefficienterna med faktorer på 100-1000 under 80 ºC och minskade migreringshastighetens temperaturberoende. Den ökade även global migrering till över satta gränsvärden under både mikrovågsvärmning och vanlig värmning. Elektrospray-joniserings-masspektrometri (ESI-MS) visade sig vara ett användbart verktyg för analys av migrerade högmolekylära ämnen vilka ej var detekterbara med HPLC eller GC-MS.

     

    

  • 76.
    Alin, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Migration from plastic food packaging during microwave heating2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Mikrovågsuppvärmning av mat har ökat markant under de senaste åren. Detta ökar risken för att ämnen i plast migrerar från matförpackningar till mat. Den specifika effekten av mikrovågsvärmning i kontrast till konventionell värmning på total och specifik migrering från vanliga matförvaringslådor av plast studerades i denna avhandling. Syftet var i huvudsak att bestämma interaktionseffekter mellan olika typer av plaster och olika typer av mat under mikrovågsvärmning. Studien fokuserades på förpackningar av polykarbonat (PC), polyetentereftalat (PET), polypropylen homopolymer (PP), copolymer (PP-C) och random copolymer (PP-R). Migreringstesterna utfördes under kontrollerade tider och temperaturer genom att använda MAE. Migranterna analyserades med hjälp av GC-MS och HPLC. ESI-MS-analys utvärderades också som ny analysmetod för migreringstester. Absorption av mat- och matsimulanter samt förändringar i kristallinitetsgrad följdes också.

    Signifikant nedbrytning av antioxidanterna Irgafos 168 och Irganox 1010 i PP-förpackningar inträffade under mikrovågsvärmning av förpackningarna i etanol-innehållande matsimulanter, vilket resulterade i bildning av nedbrytningsprodukter från antioxidanterna. Nedbrytning av PC genom en Fries omfördelningsreaktion, vilket orsakade bildning av 9,9-dimetylxanten, samt transesterifikation av PET, vilket orsakade bildning av dietyltereftalat, observerades också efter mikrovågsvärmning av förpackningarna i etanol och 90/10 isooktan/etanol. Dessa reaktioner observerades ej efter konventionell värmning av förpackningarna under samma temperatur och ej heller efter mikrovågsvärmning av förpackningarna i riktig mat (kokosmjölk). Mikrovågsvärmningen ökade också betydelsefullt migrering av cykliska oligomerer från PET till etanol och isooktan under 80 °C. Specifika ämnens migrering till kokosmjölk var alla något lägre än migreringsvärden beräknade m. h. a. EU's officiella matematiska modell för förutsägelse av migrering från matförpackningar till mat. Dessa resultat visar att användandet av etanol som matsimulant för fet mat under mikrovågsvärmning kan leda till betydande överestimering av migrering, samt nedbrytning av polymer och additiv i polymeren.

    Andra detekterade migranter var till exempel dimetylbenzaldehyd, 4-etoxy-etylbenzoat, benzofenon, m-tertbutylfenol och 1-metylnaftalen. Alla identifierade migranter med tillhörande ‘specific migration limit’ (SML)-värden migrerade i betydelsefullt mindre mängder än ämnenas tillhörande SML-värden under 1 h mikrovågsvärmning under 80°C. Diffusionskoefficienterna för antioxidanterna i PP-förpackningarna visade större relativa skillnader än förpackningarnas motsvarande kristallinitetsgrader och migrering av antioxidanter var snabbast från PP-R.

  • 77.
    Alin, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Quality control of polymeric packaging and recycled materials by chromatographic and mass spectrometric techniques2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    During the lifetime polymers can emit degradation products and additives to the surrounding environment. The development of analytical techniques to identify and quantify migrated compounds is essential to assess the safety of the plastic products. This is especially important when plastic materials are used in demanding or otherwise sensitive applications such as toys, medical products, food packaging or water pipes as well as when new types of polymeric materials such as nanocomposites, degradable materials, functional materials or recycled materials are developed. We have in several studies applied chromatographic and mass spectrometric techniques for analysis of emissions from different polymeric materials. As an example we have shown that microwave heating can lead to accelerated degradation of additives incorporated in the polypropylene (PP)packages, which further led to increased migration of potentially toxic degradation products into the food [1]. Significant antioxidant degradation was shown to take place during microwave heating of the packages in the fatty food simulants, while no degradation of antioxidants was detected during conventional heating of the packages in the fatty food simulants. No antioxidant degradation was observed in aqueous food simulants. Antioxidant migration rates from three PPmaterials to fatty food simulants differed largely with respect to the PP type and increased with decreasing degree of crystallinity in the materials [2]. Stereocomplexation improved the migration resistance of novel polylactide based packaging materials in contact with food simulants [3]. When polymeric materials are recycled one point of concern is the presence of unknown low molecular weight products in the materials. In addition the recycled materials could be more susceptible for further degradation even when further stabilized. We have shown that increasing amounts of degradation products are formed during aging of in-plant recycling of polyamide 6.6[4]. The amount of degradation products could also be correlated to deterioration of material properties such as mechanical properties. The odor coming polypropylene materials containing recycled milled phenol-formaldehyde glass-fiber scrap was shown to be caused by the presence of phenol in the materials [5].

    1. J. Alin and M. Hakkarainen, Journal of Agricultural and Food Chemistry (2011) 59(10), 5418-5427

    2. J. Alin and M. Hakkarainen, Journal of Applied Polymer Science (2010) 118(2), 1084-1093.

    3. Y. Bor, J. Alin and M. Hakkarainen, Packaging Technology and Science, DOI: 10.1002/pts.990.

    4. M. Gröning and M. Hakkarainen, Journal of Applied Polymer Science, (2002) 86, 3396-3407

    5. M. Gröning, H. Eriksson, M. Hakkarainen and A.-C. Albertsson, Polymer Degradation andStability, (2006) 91, 1815-1823

  • 78.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Combined Chromatographic and Mass Spectrometric Toolbox for Fingerprinting Migration from PET Tray during Microwave Heating2013Ingår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 61, nr 6, s. 1405-1415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A combined chromatographic and mass spectrometric toolbox was utilized to determine the interactions between poly(ethylene terephthalate) (PET) food packaging and different food simulants during microwave heating. Overall and specific migration was determined by combining weight loss measurements with gas chromatography-mass spectrometry (GC-MS) and electrospray ionization mass spectrometry (ESI-MS). This allowed mapping of low molecular weight migrants in the molecular range up to 2000 g/mol. Microwave heating caused significantly faster migration of cyclic oligomers into ethanol and isooctane as compared to migration during conventional heating at the same temperature. This effect was more significant at lower temperature at which diffusion rates are generally lower. It was also shown that transesterification took place between PET and ethanol during microwave heating, leading to formation of diethyl terephthalate. The detected migrants included cyclic oligomers from dimer to hexamer, in most cases containing extra ethylene glycol units, and oxidized Irgafos 168. ESI-MS combined with CID MS-MS was an excellent tool for structural interpretation of the nonvolatile compounds migrating to the food simulants. The overall migration was below the overall migration limit of 10 mg/dm(2) set by the European commission after 4 h of microwave heating at 100 degrees C in all studied food simulants.

  • 79.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Microwave heating causes rapid degradation of antioxidants in polypropylene packaging leading to greatly increased specific migration to food simulants as shown by ESI-MS and GC-MS2011Ingår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 59, nr 10, s. 5418-5427Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microwave heating of commercial microwavable polypropylene packaging in contact with fatty food simulants caused significant antioxidant degradation and increased specific migration as shown by electrospray ionization-mass spectrometry (ESI-MS) and gas chromatography-mass spectrometry (GC-MS). Degradation of the antioxidants Irgafos 168 and Irganox 1010 was not detected during conventional heating of polypropylene packaging at the same temperature. The migration into aqueous food simulants was primarily restricted by the water solubility of the migrants. Using isooctane as fatty food simulant caused significant swelling and greatly enhanced overall migration values compared to the other fatty food simulant, 99.9% ethanol, or the aqueous food simulants 10% ethanol, 3% acetic acid, or water. ESI-MS spectra clearly reflected the overall migration values, and the number and amount of compounds detected decreased as the hydrophilicity of the food simulant increased. ESI-MS was shown to be an excellent tool for the analysis of semivolatile migrants and a good complement to GC-MS analysis of volatile migrants.

  • 80.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Migration from polycarbonate packaging to food simulants during microwave heating2012Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, nr 8, s. 1387-1395Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The interactions between polycarbonate (PC) packaging and different food simulants during microwave heating were evaluated by identifying the compounds migrating into aqueous, alcoholic and fatty food simulants. The migration of compounds, such as 9,9-dimethylxanthene and m-tert-butyl-phenol, from the PC package to ethanol and isooctane increased significantly during microwave heating as compared to conventional heating. The increase in migration can be explained by degradation caused by microwave heating and/or stronger food simulant interactions. Depending on the food simulant the migrants were quantified either by multiple headspace–solid-phase micro-extraction (MHS-SPME) or direct injection in combination with gas chromatography-mass spectrometry. A partial least squares (PLS) regression model was developed to predict the extraction efficiency for headspace–solid-phase micro-extraction (HS-SPME) of food package migrants from the analyte properties. The most significant property for prediction of the enrichment factors was the octanol-water partition coefficient (log Kow). Polydimethylsiloxane (PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibers were compared for the extraction of the migrants. High correlation was found between the PDMS and PDMS/DVB enrichment factors (R2=0.98), but the extraction by PDMS/DVB fiber was much more efficient compared to the extraction by PDMS fiber. The detection limits after SPME extraction by PDMS/DVB fiber were 1, 0.1 and 3 ng/L for 4-ethoxy-ethyl-benzoate, 2,4-di-tert-butyl-phenol and benzophenone, respectively.

  • 81.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    The significant effect of polypropylene material on the migration of antioxidants from food container to food simulants2010Konferensbidrag (Övrigt vetenskapligt)
  • 82.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Type of Polypropylene Material Significantly Influences the Migration of Antioxidants from Polymer Packaging to Food Simulants During Microwave Heating2010Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 118, nr 2, s. 1084-1093Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three different polypropylene materials, polypropylene homopolymer (PP), propylene-ethylene random copolymer (PP-R), and propylene-ethylene copolymer (PP-C) are commonly used in plastic containers designed for microwave heating of food. Migration of antioxidants, Irganox 1010 and Irgafos 168, from PP. PP-R, and PP-C during microwave heating in contact with different food simulants was investigated by utilizing microwave assisted extraction (MAE) and high performance liquid chromatography (HPLC). The polypropylene material significantly influenced the migration rate, which decreased in the order of increasing degree of crystallinity in the materials. PP homopolymer was the most migration resistant of the studied materials especially in contact with fatty food simulants. The use of isooctane as fatty food simulant resulted in rapid depletion of antioxidants, while migration to another fatty food simulant, 96% ethanol, was much more limited. Migration to aqueous and acidic food simulants was in most cases under the detection limits irrespective of microwaving time and temperature. The diffusion coefficients were similar to what have been found previously under similar conditions but without microwaves. The effect of swelling was shown by the large increase in the calculated diffusion coefficients when isooctane was used as food simulant instead of 96% ethanol. (C) 2010 Wiley Periodicals, Inc. I Appl Polym Sci 118: 1084-1093,2010

  • 83.
    Alipour, Nazanin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Structure and Mechanical/Transport properties of Single and Multilayer Polyethylene-based Materials2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The current study discusses the structure, mechanical and transport properties of polyethylene-based materials into two parts. The first part deals with the migration and chemical depletion of active substance such as insecticides from moulded polyethylene sheets. Deltamethrin (DM) and synergist piperonyl butoxide (PBO) are often used for insect control purpose. It was found that DM as a powder was incapable of recrystallization and remained in liquid state after cooling to room temperature, and that the evaporation of a DM/PBO solution was greater than that predicted from the evaporation rates of pristine separate material components. Infrared spectroscopy and liquid chromatography showed that the loss of DM and PBO through polyethylene sheets was negligible over 30 days, when aged in air at 80 °C (60 and 80 %RH). However, significant migration of the active species was observed in aged polyethylene sheets which were exposed in liquid water (at 80 and 95 °C). In the second part, the structure and properties of multi–layered polymer films were studied in terms of crystallization kinetics, mechanical and transport properties. Previously, it has been shown that when the layer thickness decreases from micrometre-scale to nanometre-scale, leading to improvement of the film performance such as crack propagation and oxygen barrier properties. In this work, two multi-layered systems were considered based on compatible (i) or incompatible layers (ii). In the first case (i), metallocene polyethylene (mPE) and low-density polyethylene (LDPE) where investigated as 2, 24, and 288 adjacent layers. In the second case (ii) poly(ethylene-co-vinyl alcohol) (EVOH) and polyethylene adhesive was evaluated as 5 and 19 layers. The crystallization kinetic studies showed that the crystallization rate was retarded as the layers became thinner with increasing number of layers in the multi-layered films as compared to the reference films (2 and 5 layers). The observation was suggested to stem from greater association between layers (inter layer mixing) in the case of mPE/LDPE films with 2 layers. Furthermore, the crack growth resistance increased with increasing number of layers. The x-ray scattering and tensile testing showed that the films were orientated more in extrusion direction than in the transverse direction, besides the EVOH films (the incompatible system) showed higher orientation in the extrusion direction than mPE/LDPE films. The uptake of n-hexane was reduced significantly in multi-layered EVOH films due to the effective protective role of EVOH. Furthermore, it was revealed that non-homogenous swelling causing a folding/curling of bilayer films when exposed to the vapour of the solvent.

  • 84.
    Alipour, Nazanin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Andersson, Richard L.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    VOC-Induced Flexing of Single and Multilayer Polyethylene Films As Gas Sensors2016Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, nr 15, s. 9946-9953Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The differential swelling and bending of multilayer polymeric films due to the dissimilar uptake of volatile organic compounds (VOCs; n-hexane, limonene) in the different layers was studied. Motions of thin polyethylene films triggered by the penetrant were investigated to learn more about how their deformation is related to VOC absorption. Single layers of metallocene or low-density polyethylene, and multilayers (2-288-layers) of these in alternating positions were considered. Single-, 24-, and 288 layer films displayed no motion when uniformly subjected to VOCs, but they could display simple curving modes when only one side of the film was wetted with a liquid VOC. Two-layer films displayed simple bending when uniformly subjected to VOCs due to the different swelling in the two layers, but when the VOC was applied to only one side of the film, more complex modes of motion as well as dynamic oscillations were observed (e.g., constant amplitude wagging at 2 Hz for ca. 50 s until all the VOC had evaporated). Diffusion modeling was used to study the transport behavior of VOCs inside the films and the different bending modes. Finally a prototype VOC sensor was developed, where the reproducible curving of the two-layer film was calibrated with n-hexane. The sensor is simple, cost-efficient, and nondestructive and requires no electricity.

  • 85.
    Alipour, Nazanin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Yu, Shun
    Roth, Stephan
    Brüning, Karsten
    Vieyres, Arnaud
    Schneider, Konrad
    Structure and properties of polyethylene-based and EVOH-based multilayered films with layer thicknesses of 150 nm and greater2015Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 64, s. 36-51Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the structure and properties of two multilayered systems where polymers in adjacent layers were either miscible or immiscible. The miscible system consisted of 2, 17, 18, 24 and nominally 288 layers of alternating low-density (LDPE) and low-density/linear-low density (mPE) polyethylene layers with observed thicknesses ranging from 150 nm to 20 urn. The immiscible system consisted of 5 and 19 layer films with a combination of poly(ethylene-co-vinyl alcohol) (EVOH) (thickness: 9 and 1 gm, respectively), LDPE (17 and 7 gm) and a polyethylene adhesive (3 and 1 gm). The purpose of the multi-layering was to increase the crack growth resistance and, in the EVOH-based system, to decrease the oxygen transmission rate. Indeed, the crack growth resistance, as measured on tensile-tested notched films, increased with increasing number of layers. The thinnest polyethylene and polyethylene adhesive layers showed a clear ductile failure when fractured even in liquid nitrogen. Simultaneous synchrotron wide-angle/small-angle X-ray scattering and tensile testing indicated no new deformation features with changes in the layer thickness. The oxygen permeability was the same in the 5- and 19-layer EVOH-based films, but the uptake of n-hexane was strongly reduced in the 19-layer films, demonstrating the effective protective role of the EVOH layers. The n-hexane desorption data of the 2-layer LDPE/mPE film was successfully modeled using the diffusivities and solubilities of the single layers. Crystallization was slower and more confined in the films with thinner layers. The interlayer mixing in the melt (measured by isothermal crystallization from melts of initially layered polyethylene-based systems) was, as expected, significantly faster in the 24- and 288-multilayer films than in the 2-layer film.

  • 86.
    Aljure, M.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Becerra, M.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Pallon, L. K. H.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Electrical conduction currents of a mineral oil-based nanofluid in needle-plane configuration2016Ingår i: 2016 IEEE CONFERENCE ON ELECTRICAL INSULATION AND DIELECTRIC PHENOMENA (IEEE CEIDP), IEEE conference proceedings, 2016, s. 687-690Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present experiments and simulations on the electrical conduction currents of purified transformer oil with and without surface-modified MgO nanoparticles. Results show that on the injection regime of the voltage-current characteristics, nanoparticles increase the charge production in the fluid. It is also found that the conduction currents in the space-charge-limited regime increased at a lower rate as a function of the voltage in the presence of nanoparticles. The numerical simulations suggest electron attachment is increased due to the nanoparticles, leading to larger accumulation of negative ionic space charge close to the needle in the space-charge-limited regime. It is concluded that electron attachment may be significantly increased with nanoparticles, becoming an important process of electrical conduction in nanofluids.

  • 87. Alm, Hajer Kamal
    et al.
    Ström, Göran
    Karlström, Katarina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Schoelkopf, Joachim
    Gane, Patrick A. C.
    Effect of excess dispersant on surface properties and liquid interactions on calcium carbonate containing coatings2010Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, nr 1, s. 82-92Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this work was to identify what effects excess amount of sodium polyacrylate, a commonly used dispersant, has on the coating properties and the interaction between ink and the paper coating in offset printing. Since polyacrylate strongly interacts with calcium ions, soluble calcium salt was added to some coating colours to illustrate the impact of charge neutralization by calcium ions. It was found that the coating structure was only slightly affected by the extra addition of polyacrylate, showing some weak flocculation, whereas the surface chemistry was strongly influenced. The coatings became more polar and interacted more strongly with water. This resulted in slower ink setting and reduced ink-paper coating adhesion, especially in the presence of applied water/dampening solution, which are identified as contributory factors in ink piling and print mottle.

  • 88. Almgren, Karin
    et al.
    Gamstedt, Kristofer E.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Nygård, P.
    Malmberg, F.
    Lindblad, J.
    Lindström, M.
    Role of fibre-fibre and fibre-matrix adhesion in stress transfer in composites made from resin-impregnated paper sheets.2009Ingår i: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 29, nr 5, s. 551-557Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Paper-reinforced plastics are gaining increased interest as packaging materials, where mechanical properties are of great importance. Strength and stress transfer in paper sheets are controlled by fibre-fibre bonds. In paper-reinforced plastics, where the sheet is impregnated with a polymer resin, other stress-transfer mechanisms may be more important. The influence of fibre-fibre bonds on the strength of paper-reinforced plastics was therefore investigated. Paper sheets with different degrees of fibre-fibre bonding were manufactured and used as reinforcement in a polymeric matrix. Image analysis tools were used to verify that the difference in the degree of fibre-fibre bonding had been preserved in the composite materials. Strength and stiffness of the composites were experimentally determined and showed no correlation to the degree of fibre-fibre bonding, in contrast to the behaviour of unimpregnated paper sheets. The degree of fibre-fibre bonding is therefore believed to have little importance in this type of material, where stress is mainly transferred through the fibre-matrix interface.

  • 89.
    Almgren, Karin M.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Wood-fibre composites: Stress transfer and hygroexpansion2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Wood fibres is a type of natural fibres suitable for composite applications. The abundance of wood in Swedish forests makes wood-fibre composites a new and interesting application for the Swedish pulp and paper industry. For large scale production of composites reinforced by wood fibres to be realized, the mechanical properties of the materials have to be optimized. Furthermore, the negative effects of moisture, such as softening, creep and degradation, have to be limited. A better understanding of how design parameters such as choice of fibres and matrix material, fibre modifications and fibre orientation distribution affect the properties of the resulting composite material would help the development of wood-fibre composites.

    In this thesis, focus has been on the fibre-matrix interface, wood-fibre hygroexpansion and resulting mechanical properties of the composite. The importance of an efficient fibre-matrix interface for composite properties is well known, but the determination of interface properties in wood-fibre composites is difficult due to the miniscule dimensions of the fibres. This is a problem also when hygroexpansion of wood fibres is investigated. Instead of tedious single-fibre tests, more straightforward, macroscopic approaches are suggested. Halpin-Tsai’s micromechanical models and laminate analogy were used to attain efficient interface characteristics of a wood-fibre composite. When Halpin-Tsai’s model was replaced by Hashin’s concentric cylinder assembly model, a value of an interface parameter could be derived from dynamic mechanical analysis. A micromechanical model developed by Hashin was used also to identify the coefficient of hygroexpansion of wood fibres. Measurements of thickness swelling of wood-fibre composites were performed. Back-calculation through laminate analogy and the micromechanical model made it possible to estimate the wood-fibre coefficient of hygroexpansion. Through these back-calculation procedures, information of fibre and interface properties can be gained for ranking of e.g. fibre types and modifications.

    Dynamic FT-IR (Fourier Transform Infrared) spectroscopy was investigated as a tool for interface characterization at the molecular level. The effects of relative humidity in the test chamber on the IR spectra were studied. The elastic response of the matrix material increased relative to the motion of the reinforcing cellulose backbone. This could be understood as a stress transfer from fibres to matrix when moisture was introduced to the system, e.g. as a consequence of reduced interface efficiency in the moist environment. The method is still qualitative and further development is potentially very useful to measure stress redistribution on the molecular level.

  • 90.
    Almgren, Karin M.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Gamstedt, E. Kristofer
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Characterization of interfacial stress transfer ability by dynamic mechanical analysis of cellulose fiber based composite materials2010Ingår i: Composite interfaces (Print), ISSN 0927-6440, E-ISSN 1568-5543, Vol. 17, nr 9, s. 845-861Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The stress transfer ability at the fiber-matrix interface of wood fiber composites is known to affect the mechanical properties of the composite. The evaluation of interface properties at the level of individual fibers is however difficult due to the small dimensions and variability of the fibers. The dynamical mechanical properties of composite and constituents, in this case wood fibers and polylactide matrix, was here used together with micromechanical modeling to quantify the stress transfer efficiency at the fiber-matrix interface. To illustrate the methodology, a parameter quantifying the degree of imperfection at the interface was identified by inverse modeling using a micromechanical viscoelastic general self-consistent model with an imperfect interface together with laminate analogy on the composite level. The effect of moisture was assessed by comparison with experimental data from dynamic mechanical analysis in dry and moist state. For the wood fiber reinforced polylactide, the model shows that moisture absorption led to softening and mechanical dissipation in the hydrophilic wood fibers and biothermoplastic matrix, rather than loss of interfacial stress transfer ability.

  • 91.
    Almgren, Karin M.
    et al.
    Innventia.
    Gamstedt, E. Kristofer
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Berthold, Fredrik
    Innventia.
    Lindström, Mikael
    Innventia.
    Moisture uptake and hygroexpansion of wood fiber composite materials with polylactide and polypropylene matrix materials2009Ingår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 30, nr 12, s. 1809-1816Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Effects of butantetracarboxylic acid (BTCA) modification, choice of matrix, and fiber volume fraction on hygroexpansion of wood fiber composites have been investigated. Untreated reference wood fibers and BTCA-modified fibers were used as reinforcement in composites with matrices composed of polylactic acid (PLA), polypropylene (PP), or a mixture thereof. The crosslinking BTCA modification reduced the out-of-plane hygroexpansion of PLA and PLA/PP composites, under water-immersed and humid conditions, whereas the swelling increased when PP was used as matrix material. This is explained by difficulties for the BTCA-modified fibers to adhere to the PP matrix. Fiber volume fraction was the most important parameter as regards out-of-plane hygroexpansion, with a high-fiber fraction leading to large hygroexpansion. Fiber-matrix wettability during processing and consolidation also showed to have a large impact on the dimensional stability and moisture uptake. POLYM. COMPOS., 30:1809-1816, 2009.

  • 92. Almgren, Karin M.
    et al.
    Gamstedt, E. Kristofer
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Varna, Janis
    Luleå tekniska universitet, LTU.
    Contribution of wood fiber hygroexpansion to moisture induced thickness swelling of composite plates2010Ingår i: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 31, nr 5, s. 762-771Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the main drawbacks of wood fiber-based composite materials is their propensity to swell due to moisture uptake. Because the wood fibers are usually the main contributor to hygroexpansion, it is of interest to quantify the hygroexpansion coefficient of wood fibers, to compare and rank different types of fibers. This investigation outlines an inverse method to estimate the transverse hygroexpansion coefficient of wood fibers based on measurements of moisture induced thickness swelling of composite plates. The model is based on composite micromechanics and laminate theory. Thickness swelling has been measured on polylactide matrix composites with either bleached reference fibers or crosslinked fibers. The crosslinking modification reduced the transverse hygroexpansion of the composites and the transverse coefficient of hygroexpansion of the fibers was reduced from 0.28 strain per relative humidity for reference fibers to 0.12 for cross-linked fibers

  • 93. Amanizadeh, Farhad
    et al.
    Akhlaghi, Shahin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Mobarakeh, Hamid Salehi
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Starve fed emulsion copolymerization of vinyl acetate and 1-hexene at ambient pressure2014Ingår i: Polymer international, ISSN 0959-8103, E-ISSN 1097-0126, Vol. 63, nr 10, s. 1850-1855Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel emulsion copolymer of vinyl acetate (VAc) and 1-hexene was synthesized at ambient pressure. The feeding technique, initiation system and reaction time of the copolymerization were optimized based on molecular characteristics such as the weight contribution of 1-hexene in the copolymer chains and glass transition temperature (T-g) as well as on bulk properties like minimum film-formation temperature (MFFT) and solid content. According to nuclear magnetic resonance spectroscopy and differential scanning calorimetry results, the combination of starve feeding and redox initiation, within a reaction time of 4h, effectively led to the copolymerization at ambient pressure between highly reactive polar VAc monomers and non-polar 1-hexene monomers of low reactivity. The copolymer showed a lower T-g and MFFT, and a reasonable solid content compared to the poly(vinyl acetate) (PVAc) homopolymer. The consumption rate, hydrolysis of acetate groups and chain transfer reactions during the polymerization were followed using infrared spectroscopy. Based on the results, the undesirable reactions between the VAc blocks were hindered by the neighbouring 1-hexene molecules. Tensile testing revealed an improvement in the toughness and elongation at break of VAc-1-hexene films compared to PVAc films.

  • 94.
    Aminlashgari, Nina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    LDI-MS strategies for analysis of polymer degradation products, additives and drugs2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The advancement of mass spectrometry (MS) has been and continues to be a prominent analytical technique for highly accurate determination of analytes. The goal of this thesis was to develop new laser desorption ionization-mass spectrometric (LDI-MS) methods for analysis of polymer degradation products, additives and drugs. Modifications in the sample preparation were evaluated in the presence and absence of surface assisting materials. Various nanoparticles were evaluated as effective absorbents for energy transfer in the LDI procedure of the small molecules.

    In paper I and II, LDI-MS methods were developed for following the progression of chemical reactions. First, the procedure to optimize microwave assisted hydrothermal degradation products of cellulose were analyzed; second, the synthesis of glucose hexanoate ester plasticizers was monitored as a function of reaction time. The LDI-MS method provided rapid detection for the elucidation of the chemical products and their relative ratios. In contrast, the electrospray ionization-mass spectrometry (ESI-MS) analysis produced a noisy spectrum primarily containing peaks from salt clusters. A surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) method was developed in paper III enabling the identification of poly(e-caprolactone) and its degradation products by using nanoparticles as the substrate. Similar analysis by matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) was not as successful due to convolution of the analyte peaks with clusters released from the matrix. ESI-MS analysis verified the SALDI-MS method as comparable degradation product patterns were observed. Furthermore, the possibility of using polylactide based nanocomposites as surfaces in the analysis of drugs was evaluated in paper IV. An advantage was the ease of handling compared to the use of free nanoparticles. Paper V introduces the potential of direct examination of oxygen plasma modified parylene C surfaces by a LDI-MS methodology. 

  • 95.
    Aminlashgari, Nina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    SALDI-MS Method Development for Analysis of Pharmaceuticals and Polymer Degradation Products2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) was evaluated as a new tool for analysis of polymer degradation products. A SALDI method was developed enabling rapid analysis of low molecular mass polyesters and their degradation products. In addition, the possibility to utilize nanocomposite films as easy-to-handle surfaces for analysis of pharmaceutical compounds was investigated.

    Poly(ε-caprolactone) was used as a model compound for SALDI-MS method development. The signal-to-noise values obtained by SALDI-MS were 20 times higher compared to traditional matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) of the same samples with 2,5-dihydroxybenzoic acid as a matrix. Halloysite nanoclay and magnesium oxide showed best potential as surfaces and clean backgrounds in the low mass range were observed. The SALDI-MS method for the analysis of polyester degradation products was also verified by electrospray ionization-mass spectrometry (ESI-MS). An advantage over ESI-MS is the possibility to directly analyze degradation products in buffer solutions. Compared to gas chromatography-mass spectrometry (GC-MS) it is possible to analyze polar compounds and larger molecular mass ranges at the same time as  complicated extraction steps are avoided.

    The possibility to use nanocomposite films as surfaces instead of free nanoparticles was evaluated by solution casting of poly(lactide) (PLA) films with eight inorganic nanoparticles. The S/N values of the pharmaceutical compounds, acebutolol, propranolol and carbamazepine, analyzed on the nanocomposite surfaces were higher than the values obtained on the surface of plain PLA showing that the nanoparticles participated in the ionization/desorption process even when they are immobilized. Beside the ease of handling, the risk for instrument contamination is reduced when nanocomposites are used instead of free nanoparticles. The signal intensities depended on the type of drug, type and concentration of nanoparticle. PLA with 10 % titanium oxide or 10 % silicon nitride functioned best as SALDI-MS surfaces.

  • 96.
    Aminlashgari, Nina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. ABB, Sweden.
    Becerra, Marley
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. ABB, Sweden.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Characterization of degradation fragments released by arc-induced ablation of polymers in air2016Ingår i: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 49, nr 5, artikel-id 055502Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polymers exposed to high intensity arc plasmas release material in a process called arc-induced ablation. In order to investigate the degradation fragments released due to this process, two different polymeric materials, poly(oxymethylene) copolymer (POM-C) and poly(methyl methacrylate) (PMMA), were exposed to a transient, high-power arc plasma in air. A small fraction of the ablated material drifting away from the arcing volume was deposited on a fixed glass substrate during the total duration of a 2 kA ac current semicycle. In addition, another fraction of the released material was deposited on a second moving substrate to obtain a time-resolved streak 'image' of the arc-induced ablation process. For the first time, mass spectra of degradation fragments produced by arc-induced ablation were obtained from the material deposited on the substrates by using laser desorption ionization time-of-flight mass spectrometry (LDI-ToF-MS). It was found that oligomers with mean molecular weight ranging between 400 and 600 Da were released from the surface of the studied polymers. The obtained spectra suggest that the detected degradation fragments of POM could be released by random chain scission of the polymer backbone. In turn, random chain scission and splitting-off the side groups are suggested as the main chemical mechanism leading to the release of PMMA fragments under arc-induced ablation.

  • 97.
    Aminlashgari, Nina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Emerging Mass Spectrometric Tools for Analysis of Polymers and Polymer Additives2012Ingår i: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 248, s. 1-38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The field of mass spectrometry has experienced enormous developments in the last few years. New interesting mass spectrometric techniques have arrived and there have been further developments in the existing methods that have opened up new possibilities for the analysis of increasingly complex polymer structures and compositions. Some of the most interesting emerging techniques for polymer analysis are briefly reviewed in this paper. These include new developments in laser desorption ionization techniques, like solvent-free matrix-assisted laser desorption ionization (solvent-free MALDI) and surface-assisted laser desorption ionization (SALDI) mass spectrometry, and the developments in secondary ion mass spectrometry (SIMS), such as gentle-SIMS and cluster SIMS. Desorption electrospray ionization (DESI) mass spectrometry and direct analysis in real time (DART) mass spectrometry offer great possibilities for analysis of solid samples in their native form, while mobility separation prior to mass spectrometric analysis in ion mobility spectrometry (IMS) mass spectrometry further facilitates the analysis of complex polymer structures. The potential of these new developments is still largely unexplored, but they will surely further strengthen the position of mass spectrometry as an irreplaceable tool for polymer characterization.

  • 98.
    Aminlashgari, Nina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    SALDI-MS for analysis of polyester degradation products2012Ingår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 244Artikel i tidskrift (Övrigt vetenskapligt)
  • 99.
    Aminlashgari, Nina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Surface Assisted Laser Desorption Ionization-Mass Spectrometry (SALDI-MS) for Analysis of Polyester Degradation Products2012Ingår i: Journal of the American Society for Mass Spectrometry, ISSN 1044-0305, E-ISSN 1879-1123, Vol. 23, nr 6, s. 1071-1076Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Novel surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) method was developed for rapid analysis of low molecular mass polyesters and their degradation products by laser desorption ionization-mass spectrometry. Three polycaprolactone materials were analyzed by the developed method before and after hydrolytic degradation. The signal-to-noise values obtained by SALDI-MS were 20-100 times higher compared with the ones obtained by using traditional MALDI-MS matrices. A clean background at low mass range and higher resolution was obtained by SALDI-MS. Different nanoparticle, cationizing agent, and solvent combinations were evaluated. Halloysite nanoclay and magnesium hydroxide showed the best potential as SALDI surfaces. The SALDI-MS spectrum of the polyester hydrolysis products was verified by ESI-MS. The developed SALDI-MS method possesses several advantages over existing methods for similar analyses.

  • 100.
    Aminlashgari, Nina
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Höglund, Odd V
    Borg, Niklas
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradation profile and preliminary clinical testing of a resorbable device for ligation of blood vessels2013Ingår i: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 9, nr 6, s. 6898-904Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A resorbable device for ligation of blood vessels was developed and tested in vitro to reveal the degradation profile of the device and to predict the clinical performance in terms of adequate mechanical support during a healing period of I week. In addition, preliminary clinical testing was performed that showed complete hemostasis and good tissue grip of renal arteries in five pigs. The device was made by injection molding of poly(glycolide-co-trimethylene carbonate) triblock copolymer, and it consisted of a case with a locking mechanism connected to a partly perforated flexible band. A hydrolytic degradation study was carried out for 7, 30 and 60 days in water and buffer medium, following the changes in mass, water absorption, pH and mechanical properties. A new rapid matrix-free laser desorption ionization-mass spectrometry (LDI-MS) method was developed for direct screening of degradation products released into the degradation medium. The combination of LDI-MS and electrospray ionization-mass spectrometry analyses enabled the comparison of the degradation product patterns in water and buffer medium. The identified degradation products were rich in trimethylene carbonate units, indicating preferential hydrolysis of amorphous regions where trimethylene units are located. The crystallinity of the material was doubled after 60 days of hydrolysis, additionally confirming the preferential hydrolysis of trimethylene carbonate units and the enrichment of glycolide units in the remaining solid matrix. The mechanical performance of the perforated band was followed for the first week of hydrolysis and the results suggest that sufficient strength is retained during the healing time of the blood vessels.

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