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  • 51. Flodberg, G.
    et al.
    Hellman, A.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Sadiku, E. R.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Barrier properties of blends based on liquid crystalline polymers and polyethylene2000Inngår i: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 40, nr 9, s. 1969-1978Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Blends of an extrusion-grade polyethylene and two different liquid crystalline polymers of Vectra type were prepared by melt mixing using poly(ethylene-co-methacrylic acid) as compatibilizer. Oxygen and water vapor permeability, transparency and welding strength of compression molded and film blown specimens were studied. The compression molded blends showed gas permeabilities conforming to the Maxwell equation assuming low permeability liquid crystalline polymer spheres in a high permeability polyethylene matrix One of the liquid crystalline polymers with suitable rheological properties formed a more continuous phase in the film blown blends and a substantial decrease in oxygen and water vapor permeability was observed in these blends. The compression molded blends with 50% liquid crystalline polymer and some of blow molded blends showed very high gas permeabilities. It is believed that voids forming continuous paths through the structure were present in these samples. The blends showed significantly higher opacity than pure polyethylene.

  • 52. Flodberg, G.
    et al.
    Hojvall, L.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Migration of monomers from liquid crystalline poly(p-hydroxybenzoic acid-co-2-hydroxy-6-naphthoic acid)2002Inngår i: Food Additives and Contaminants, ISSN 0265-203X, E-ISSN 1464-5122, Vol. 19, nr 5, s. 492-501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Liquid-crystalline co-polyesters (e.g. a random co-polyester based on p-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (HNA) known as Vectra A950) offer good barrier properties, but for food-contact use require overall and specific migration testing. For Vectra A950 films, the highest overall migration level obtained was 2.3 mg kg(-1) in olive oil (10 days at 40degrees C) well below the EC limit of 60 mg kg(-1). The highest specific migration for p-hydroxybenzoic acid was 15.2 mug dm(-2) in olive oil (2 h at 175degreesC). For 2-hydroxy-6-naphthoic acid, the highest value obtained was 4.3 mug dm(-2) in 10% ethanol (4 h at 100degrees C), although it was not on the EC positive and cannot yet be used for food-contact materials. At conditions considered as severe, the estimated daily intake for p-hydroxybenzoic acid was calculated as 11.9 mug/person day(-1) and for 2-hydroxy-6-naphthoic acid it was 5.3 mug/person day(-1). The results exceed the threshold of regulation of 1.5 mug/person day(-1).

  • 53. Gallstedt, M.
    et al.
    Brottman, A.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Packagin-related properties of protein- and chitosan-coated paper2005Inngår i: Packaging technology & science, ISSN 0894-3214, E-ISSN 1099-1522, Vol. 18, nr 4, s. 161-170Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanical and gas-barrier properties of paper and paperboard coated with chitosan-acetic acid salt (chitosan), whey protein isolate, whey protein concentrate and wheat gluten protein were studied. Paper sheets were solution-coated using a hand applicator. In addition, bi-layer composites of wheat gluten and paper or paperboard were produced by compression moulding, and the chitosan solution was also applied on paperboard using curtain coating. Young's modulus, fracture stress, fracture strain, tearing strength, air permeance and oxygen permeability were assessed. The mechanical and air permeance measurements of solution-coated paper showed that chitosan was the most effective coating on a coat weight basis. This was due to its high viscosity, which limited the degree of penetration into the paper. ne proteins, however, also enhanced the strength and toughness of the paper. Compression-moulded wheat gluten/paper or paperboard, as well as curtain-coated chitosan paperboard laminates, showed oxygen barrier properties comparable to those of paper and paperboard coated with commercial barrier materials. None of the composites could be delaminated without fibre rupture, indicating good adhesion between the coatings and the substrates.

  • 54. Gallstedt, M.
    et al.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Oxygen and water barrier properties of coated whey protein and chitosan films2002Inngår i: Journal of polymers and the environment, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 10, nr 02-jan, s. 1-4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Films of whey protein and chitosan acetic acid salt have lower oxygen permeability than, for example, ethylene-co-vinylalcohol under dry conditions, but water and water vapor seriously impair the gas barrier properties. To reduce the oxygen permeability at 90% relative humidity and the water-vapor transmission rate at 100% relative humidity, the films were coated with an alkyd, a beeswax compound, or a nitrocellulose lacquer. Permeability and transmission rate measurements were performed in accordance with standard methods and showed that the beeswax compound and the nitrocellulose were appropriate as water-vapor barriers. Overall migration to water was measured after 10 days exposure time, with the coated surface exposed to the water, showing that the alkyd-coated and the nitrocellulose-coated films were both below the safety limit for food contact. Water absorbency tests, performed by the Cobb method, showed that the films coated with the beeswax compound or with nitrocellulose lacquer exhibit lower absorbency than the alkyd-coated films.

  • 55. Gallstedt, M.
    et al.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Packaging-related mechanical and barrier properties of pulp-fiber-chitosan sheets2006Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 63, nr 1, s. 46-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to investigate ways of incorporating an oxygen- or air-barrier component, in this case chitosan or chitosan-acetic acid salt (chitosan salt), at an early stage in the paper-making process, sheets of chitosan and pulp fiber were produced in a hand sheet mould or solution cast in petri dishes. Some sheets were buffered in an alkaline solution, in order to reduce the moisture sensitivity. The sheets were characterized with respect to air permeance, oxygen permeability, fracture stress and strain, young's modulus and moisture content. The addition of the chitosan solution to the pulp slurry led to a substantial loss of fiber and chitosan through the wire screen and consequently a low grammage and high sheet porosity and air permeance. Forming a wet pulp fiber sheet before introducing the chitosan solution increased the grammage and the amount of remaining chitosan, the latter revealed by infrared spectroscopy. In addition, pressing the sheets before drying reduced the porosity and the air permeance. Air mixing, included in conventional laboratory sheet making, yielded a more heterogeneous sheet and inferior mechanical and barrier properties. In general, the paper sheets prepared in the hand sheet mould became weaker, softer and less ductile with increasing content of chitosan. Only solution casting in petri dishes resulted in good barrier properties. Scanning electron microscopy showed that holes were absent in this case. In addition, optical microscopy and infrared spectroscopy revealed that the chitosan-salt formed a continuous phase and that it was uniformly distributed in the sheet. Interestingly, the problem of shrinkage when chitosan salt sheets are buffered for improved high-moisture gas-barrier proper-ties, was reduced significantly by the restraining action of the pulp fibers.

  • 56. Gallstedt, M.
    et al.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Packaging-related properties of alkyd-coated, wax-coated, and buffered chitosan and whey protein films2004Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 91, nr 1, s. 60-67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Packaging-related properties of coated films of chitosan-acetic acid salt and whey protein concentrate (WPC) were studied. Chitosan (84.7% degree of deacetylation) and WPC (65-67% protein) were solution cast to films. These films are potential oxygen barriers for use in packaging. Coatings of wax or alkyds were used to enhance the water-barrier properties. The packaging-related properties of chitosan films treated in a buffering solution, with a pH of 7.8, were also investigated. The coated films were characterized with respect to Cobb absorbency, overall migration to water, water vapor transmission rate, and oxygen permeability. The creasability and bending toughness were determined. The wax was a more efficient barrier to liquid water and 90-95% relative humidity than the alkyd. However, the alkyd-coated material had superior packaging-converting properties. The alkyd-coated WPC and chitosan-salt films were readily folded through 180degrees without any visible cracks or delamination. The overall migration from the alkyd-coated materials was below the safety limit, provided the coat weight was higher than 7.5 mg/cm(2) on WPC and 2.1 mg/cm(2) on chitosan-salt. The barrier properties of chitosan film under moist conditions were improved by the buffer treatment. However, the buffering also resulted in shrinkage of the film.

  • 57. Gallstedt, M.
    et al.
    Mattozzi, Alessandro
    KTH, Tidigare Institutioner, Polymerteknologi.
    Johansson, E.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Transport and tensile properties of compression-molded wheat gluten films2004Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 5, nr 5, s. 2020-2028Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanical and transport properties were assessed on wheat gluten films with a glycerol content of 25-40%, prepared by compression molding for 5-15 min at temperatures between 90 and 130 degreesC. Effects of storing the films up to 24 days, in 0 and 50% relative humidity (RH), were assessed by tensile measurements. The films were analyzed with respect to methanol zero-concentration diffusivity, oxygen permeability (OP), water vapor permeability (WVP), Cobb(60) and sodium dodecyl sulfate (SDS) solubility coupled with sonication. The SDS solubility and methanol diffusivity were lower at the higher molding temperature. Higher glycerol content resulted in higher OP (90-95% RH), WVP, and Cobb(60) values, due to the plasticizing and hygroscopic effects. Higher glycerol contents gave a lower fracture stress, lower Young's modulus, lower fracture strain, and less strain hardening. The mold time had less effect on the mechanical properties than mold temperature and glycerol content. The fracture stress and Young's modulus increased and the fracture strain decreased with decreasing moisture content.

  • 58. Gallstedt, M.
    et al.
    Tornqvist, J.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Properties of nitrocellulose-coated and polyethylene-laminated chitosan and whey films2001Inngår i: Journal of Polymer Science Part B: Polymer Physics, ISSN 0887-6266, E-ISSN 1099-0488, Vol. 39, nr 10, s. 985-992Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Chitosan (chitosan acetic acid salt) and whey (65% protein) films were coated with a nitrocellulose lacquer or laminated with polyethylene to enhance their water resistance and gas barrier properties in humid environments. The barrier properties were measured by the Cobb,, test and water-vapor (100% relative humidity) transmission and oxygen (90% relative humidity) permeability tests. Mechanical properties were obtained with tensile tests. Packaging properties were studied with crease and folding tests. The Cobb,, test revealed that the coated films were resistant to liquid water, at least for a short exposure time, if the coating thickness was at least 10-17 mum. Water-vapor transmission rates comparable to those of polyethylene-laminated films were obtained for coated chitosan at a coating thickness of 5-7 mum. The coated films possessed low oxygen permeability despite the high humidity. Coated films dried for 3 weeks showed oxygen permeabilities at 90% relative humidity that were similar to values for dry ethylene-co-vinyl alcohol at 0% relative humidity. The lacquer partly penetrated the whey films, and this led to excellent adhesion but poor lacquer toughness. The lacquer coating on chitosan was tougher, and it was possible to fold these films 90 degrees without the coating fracturing if the coating thickness was small. The coated whey films were readily creasable.

  • 59. Gallstedt, Mikael
    et al.
    Pettersson, Henrik
    Johansson, Therese
    Newson, William R.
    Johansson, Eva
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Film Extrusion of Crambe abyssinica/Wheat Gluten Blends2017Inngår i: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, nr 119, artikkel-id e54770Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a high-protein crambe meal that has limited value, as it is not fit for food or feed use. However, it contains proteins that could potentially make it a suitable raw material for higher-value products. The purpose of this study was to find methods of making this side stream into extruded films, showing that products with a higher value can be produced. The study mainly considered the development of material compositions and methods of preparing and extruding the material. Wheat gluten was added as a supportive protein matrix material, together with glycerol as a plasticizer and urea as a denaturant. The extrudate was evaluated with respect to mechanical (tensile testing) and oxygen barrier properties, and the extrudate structure was revealed visually and by scanning electron microscopy. A denser, more homogeneous material had a lower oxygen transmission rate, higher strength, and higher extensibility. The most homogeneous films were made at an extruder die temperature of 125-130 degrees C. It is shown here that a film can be extruded with promising mechanical and oxygen barrier properties, the latter especially after a final compression molding step.

  • 60.
    Gedde, Ulf W
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Richard Hays Boyd in memorial2017Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 118, s. 305-306Artikkel i tidsskrift (Fagfellevurdert)
  • 61. Ghorbani, Fereshte Mohammad
    et al.
    Kaffashi, Babak
    Shokrollahi, Parvin
    Akhlaghi, Shahin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Effect of hydroxyapatite nano-particles on morphology, rheology and thermal behavior of poly(Caprolactone)/chitosan blends2016Inngår i: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 59, s. 980-989Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of hydroxyapatite nano-particles (nHA) on morphology, and rheological and thermal properties of PCL/chitosan blends was investigated. The tendency of nHA to reside in the submicron-dispersed chitosan phase is determined using SEM and AFM images. The presence of electrostatic interaction between amide sites of chitosan and ionic groups on the nHA surface was proved by FTIR. It is shown that the chitosan phase is thermodynamically more favorable for the nano-particles to reside than the PCL phase. Lack of implementation of Cox-Merz theory for this system shows that the polymer-nano-particle network is destructed by the flow. Results from dynamic rheological measurements and Zeiler fractional model show that the presence of nHA increases the shear moduli and relaxation time of the PCL/chitosan blends. DSC measurements showed that nHA nano-particles are responsible for the increase in melting and crystallization characteristics of the PCL/chitosan blends. Based on thermogravimetric analysis, the PCL/chitosan/nHA nano-composites exhibited a greater thermal stability compared to the nHA-free blends.

  • 62. Gällstedt, Mikael
    et al.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Türe, Hasan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Production, Chemistry and Properties of Proteins2011Inngår i: Biopolymers: New Materials for Sustainable Films and Coatings / [ed] David Plackett, Chichester: John Wiley & Sons, 2011, s. 107-132Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 63. Hansen, Natanya M. L.
    et al.
    Blomfeldt, Thomas O. J.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Plackett, David V.
    Properties of plasticized composite films prepared from nanofibrillated cellulose and birch wood xylan2012Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 19, nr 6, s. 2015-2031Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Xylans, an important sub-class of hemicelluloses, represent a largely untapped resource for new renewable materials derived from biomass. As with other carbohydrates, nanocellulose reinforcement of xylans is interesting as a route to new bio-materials. With this in mind, birch wood xylan was combined with nanofibrillated cellulose (NFC) and films were cast with and without glycerol, sorbitol or methoxypolyethylene glycol (MPEG) as plasticizers. Microscopy revealed some NFC agglomeration in the composite films as well as a layered nanocellulose structure. Equilibrium moisture content in plasticized films increased with glycerol content but was independent of xylan:NFC ratio in unplasticized films. Sorbitol- and MPEG-plasticized films showed equilibrium moisture contents of approximately 10 wt% independent of plasticizer content. Tensile testing revealed increases in tensile strength with increased NFC content in the xylan:NFC composition range from 50:50 to 80:20 and plasticizer addition generally provided less brittle films. The oxygen permeability of unplasticized xylan-NFC films fell into a range which was similar to that for previously measured pure NFC films and was statistically independent of the xylan:NFC ratio. Water vapor permeability values of 1.9-2.8.10(-11) g Pa-1 m(-1) s(-1) were found for unplasticized composite films, but these values were significantly reduced in the case of films plasticized with 10-40 wt% sorbitol.

  • 64.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Barrier Packaging Materials2012Inngår i: Handbook of Environmental Degradation of Materials: Second Edition, Elsevier, 2012, s. 833-862Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 65.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Barrier Packaging Materials2005Inngår i: Handbook of Environmental Degradation of Materials, Norwich, NY: William Andrew Inc. , 2005, s. 547-563Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This chapter deals with the barriers in packaging materials. Plastic packaging materials offer toughness, lighter weight, and a level of design flexibility that glass and metal cannot meet. They are permeable to gases, vapors, and liquids, and this limits their use to products that do not require the highest barrier protection. Several ways to improve their barrier properties and to make them competitive with glass and metal are discussed. No other material group offers the same huge range in permeability as polymers do. The success in obtaining a packaging material with optimal barrier properties requires knowledge on all levels, from atomistic details to converting and handling properties. The chapter explains the way the introduction of new molecular groups affects the molecular rigidity, the material crystallinity, the interlayer adhesion, and the folding/sealing properties. All these parameters have an impact on the final packaging barrier properties. The important factors that determine and enhance the barrier properties are described with practical examples in packaging. The chapter also discusses the problems associated with selecting packaging materials for food.

  • 66.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Barrier packaging materials2018Inngår i: Handbook of Environmental Degradation Of Materials: Third Edition, Elsevier Inc. , 2018, s. 559-581Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 67.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Editorial2017Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 57Artikkel i tidsskrift (Fagfellevurdert)
  • 68.
    Hedenqvist, Mikael S.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Backman, A.
    Gallstedt, M.
    Boyd, R. H.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Morphology and diffusion properties of whey/montmorillonite nanocomposites2006Inngår i: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 66, nr 13, s. 2350-2359Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The diffusion of methanol in solution-cast whey-protein-isolate/poly(vinylidene pyrrolidone)-coated montmorillonite composite films was studied. The filler content was 0-4.8 vol%. Desorption experiments on samples saturated in methanol were conducted in a nitrogen-purged chamber at 294 K or in a thermogravimeter at 333, 348 and 363 K. The desorption curves were fitted using a two-phase diffusion model; where diffusion occurred first in the rubbery and later in the glassy state. A free volume model was used to analyze desorption at 363 K which occurred only within the rubbery phase and it enabled the geometrical impedance factor and free volume constraints from the nanoparticles to be assessed. Transmission electron microscopy showed a partial exfoliation of the nanoparticles. The geometrical impedance factor increased markedly with increasing filler content in accordance with the high aspect ratio of the nanoparticle aggregates. Transmission electron microscopy, in combination with model calculations, revealed that the clay sheets were oriented preferentially in the plane of the film which was an important factor underlying the high geometrical impedance factor obtained for the nanocomposites. A small but significant reduction in the fractional free volume of the polymer matrix was observed for the rubbery polymer in the presence of montmorillonite.

  • 69.
    Hedenqvist, Mikael S.
    et al.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Doghieri, F.
    The significance of the zero-concentration diffusivity value obtained from integral desorption data2002Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 43, nr 1, s. 223-226Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    n-Hexane zero-concentration diffusivity in high density polyethylene obtained 'indirectly' from integral desorption measurements using the free volume concept was compared with the zero-concentration diffusivity obtained directly at low-n-hexane activities using a quartz-ring system. The difference between the results obtained by the indirect and direct methods was within the experimental error. The concentration dependence of the diffusivity predicted by the Cohen-Turnll-Fujita free volume theory was in accordance with experimental data.

  • 70.
    Hedenqvist, Mikael S.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Johansson, Eva
    Swedish Univ Agr Sci, Dept Plant Breeding, Alnarp, Sweden..
    Newson, William
    Swedish Univ Agr Sci, Dept Plant Breeding, Alnarp, Sweden..
    Gallstedt, Mikael
    Innventia AB, Stockholm, Sweden..
    Kuktaite, Ramune
    Swedish Univ Agr Sci, Alnarp, Sweden..
    Ullsten, Henrik
    Karlsted Univ, Dept Engn & Chem Sci, Karlstad, Sweden..
    Ture, Hasan
    Ordu Univ, Fac Marine Sci, Ordu, Turkey..
    Extrusion of protein plastics2017Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Artikkel i tidsskrift (Annet vitenskapelig)
  • 71.
    Hedenqvist, Mikael S.
    et al.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Johansson, K. S.
    Barrier properties of SiOx-coated polymers: multi-layer modelling and effects of mechanical folding2003Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 172, nr 1, s. 7-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The oxygen permeability properties of poly(ethylene terephthalate), low- and high-density polyethylenes and polypropylene coated with SiOx using cold plasma were studied. A previously developed computer model for the calculation of transport properties in laminates containing very different layer thickness was fitted to experimental permeability data to obtain the oxygen transport properties of the SiOx coating. For the first time, to the best of our knowledge, it was possible to obtain the oxygen diffusivity and solubility of a SiOx coating on a polymer substrate. The effects of folding the laminates through 90degrees on the permeability properties of the SiOx coating were also investigated. The surface roughness of the substrates was obtained by atomic force microscopy and the morphology of the laminate surfaces was analysed by scanning electron microscopy. The oxygen diffusivity and solubility of a 45-nm-thick SiOx coating deposited on a 4000-fold thicker polypropylene substrate were 5 x 10(-12) cm(2) s(-1) and 0.72 cm(2) (STP) cm(-3) atm(-1), respectively. The diffusivity was approximately four orders of magnitude lower than that of the polymer substrate and, surprisingly, the solubility was higher than that of the polypropylene film. A hypothesis to explain these results is that the coating contained voids and, according to the permeability time lag, these were not continuous through the coating. The oxygen permeability of the coating increased with increasing substrate surface roughness, and was consequently lowest for poly(ethylene terephthalate). The folding operation initiated cracks in the coating, and the resulting increase in oxygen permeability was greater in the rougher substrates.

  • 72.
    Hedenqvist, Mikael S.
    et al.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Krook, M.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Two-stage sorption in rubbery semicrystalline polymers: transport of primary alcohols in polyesteramide2002Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 43, nr 10, s. 3061-3068Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper deals with the two-stage sorption of methanol, 1-propanol and I-hexanol in a rubbery semicrystalline polyesteramide. This is the first time two-stage sorption is reported for a semicrystalline rubbery polymer. Mass uptake, specimen geometry and surface concentration were measured independently. The two-stage sorption curve describes two overlapping processes; a very rapid diffusion (mode 1) superimposed onto a normal s-shaped sorption curve (mode 2). Mode I swelling was uni-dimensional and mode 2 swelling was initially uni-dimensional and later three-dimensional. It was possible to model the sorption curves by assuming time-dependent solute-surface-concentration conditions, similar to those used to describe simple s-shaped sorption. The obtained time dependence, characterised by a single relaxation time, agreed with experimental values of the surface concentration obtained by infrared spectroscopy. The relaxation time increased exponentially with increasing size of the diffusing alcohol molecule. The solubility of the alcohols in the polymer increased with increasing hydroxyl-group density. The diffusivity of alcohol decreased nonlinearly with increasing length of the molecule, size effects being less important for larger solutes.

  • 73.
    Hedenqvist, Mikael S.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Merveille, A.
    Odelius, Karin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Bergman, G.
    Adhesion of microwave-plasma-treated fluoropolymers to thermoset vinylester2005Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 98, nr 2, s. 838-842Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly(tetrafluoroethylene) and a fluoroethylene copolymer were surface treated with a 2.45-GHz microwave plasma to enhance their adhesion to a vinylester thermoset. The plasmas were generated with an inert gas (Ar) and with reactive gases (H-2, O-2, and N-2). The lap-joint shear stress was measured on fluoropolymer samples glued with the vinylester. In general, the stress at failure increased with increasing plasma-energy dose. The H, plasma yielded the best adhesion, and X-ray photoelectron spectroscopy revealed that it yielded the highest degree of defluorination of the fluoropolymer surface. The defluorination efficiency declined in the order H-2, Ar, O-2, and N-2. Contact angle measurements and scanning electron microscopy revealed that the surface roughness of the fluoropolymer depended on the rate of achieving the target energy dose. High power led to a smoother surface, probably because of a greater increase in temperature and partial melting.

  • 74.
    Hedenqvist, Mikael S.
    et al.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Ritums, J. E.
    Conde-Brana, M.
    Bergman, G.
    Sorption and desorption of tetrachloroethylene in fluoropolymers: Effects of the chemical structure and crystallinity2003Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 87, nr 9, s. 1474-1483Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In 18 fluoropolymers with different repeating-unit structures and crystallinities, the solubility, diffusivity, and permeability at 70degreesC of a polarizable nonpolar solute (tetrachloroethylene) were studied. The transport properties were mostly controlled by the polarity of the polymer and to a lesser degree by the polymer crystallinity. The highest permeability was observed in the dipole-containing ethylene-chlorotrifluoroethylenes because of their high tetra chloroethylene solubility. The lowest permeability was observed in the hydrogen-bonding poly(vinylidene fluoride) polymers because of the combination of low solute solubility and solute diffusivity. The tetrachloroethylene diffusivity was solute-concentration-dependent, and sorption curves were S-shaped, indicating that the solute surface concentration was time-dependent. The rate at which the surface concentration approached the saturation level was proportional to the product of Young's modulus, the square of the thickness of the dry polymer, and the logarithm of the solute diffusivity. Data for the water-hyperbranched polymer and limonene-polyethylene conformed to the same relationship. Therefore, this provides a new tool for predicting the solute-surface-concentration time dependence from data obtained by independent measurements.

  • 75.
    Hedenqvist, Mikael S.
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Ritums, Janis
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Conde-Brana, M.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Bergman, Gunnar
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Structure and properties of poly(ethylene-co-chlorotrifluoroethylene) and polyvinylidene fluoride exposed to water, hydrochloric acid, hydrobromic acid and tetrachloroethylene2004Inngår i: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 44, nr 1, s. 113-122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The transport of water, hydrochloric acid. hydrobromic acid and tetrachloroethylene in poly(ethylene-co-chlorotrifluoroethylene) and polyvinylidene fluoride were studied at 70degreesC by the sorption/desorption technique. The effects on the structure and mechanical properties were studied using size-exclusion chromatography, infrared spectroscopy, differential scanning calorimetry and tensile testing. Solute concentrations in the polymers indicated that both the water and HCl/HBr components diffused into the polymers on exposure to acid solutions. The calculated water contents of the diffusing acids generally differed from the water content in the solution. The ratio of water content in the diffusing acid to that in the surrounding acid solution was generally a function of the relative vapor activity of water and HCl/HBr. It was possible to describe the 35% HCl and 47% HBr desorption data using a two-component model. It was assumed that the water and HCl/HBr diffused separately, each having its own constant diffusion coefficient. The water diffusivity was obtained from the pure water system, and this allowed the HCl/HBr diffusivity to be calculated. It was found that the diffusivity decreased, in a non-simple way, as a function of solute size. The exposure to solute did not lower the molar mass of the polyvinylidene fluoride. Differential scanning calorimetry indicated the development of low-melting point polyvinylidene fluoride crystals during the exposure to all solutes. This seemed to be a consequence of the long-term exposure (175 to 376 days) at 70degreesC. The long-term exposure stiffened several of the polyvinylidene fluoride resins and occasionally made them less ductile. The poly(ethylene-co-chlorotrifluoroethylene) also became stiffer, but it was otherwise unaffected as far as observation by the other available techniques was concerned.

  • 76.
    Hedenqvist, Mikael S.
    et al.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Yousefi, Hamid Reza
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Malmström, Eva
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Johansson, Mats K. G.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hult, Anders
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Trollsas, M.
    Hedrick, J. L.
    Transport properties of hyperbranched and dendrimer-like star polymers2000Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 41, nr 5, s. 1827-1840Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Moisture transport properties were assessed by sorption and desorption measurements on hydroxyl-functional hyperbranched polyesters based on 2,2-bis(methylol) propionic acid (bis-MPA) as AB(2)-monomer with ethoxylated pentaerythritol. A series of these polymers with different molar masses were studied. For the first time, it is reported that sigmoidal sorption curves were successfully modelled using a time-dependent surface boundary concentration, where the relaxation time was obtained from the mechanical stress relaxation data. The zero concentration diffusivities were very small and comparable with the values of fully amorphous poly(vinyl alcohol). Both the diffusivity data and the stress relaxation data indicated that these materials were plasticized by moisture. Ethylene glycol transport properties were measured on a hexadecanoate(C16)-terminated bis-MPA hyperbranched polymer. The replacement of the hydroxyl groups with C16 paraffin tails resulted in an increase in solute diffusivity despite the fact that these polymers became semicrystalline. The shape of the desorption curves indicated that continuous micropores were present and facilitated mass transport. The moisture transport properties were also measured on a series of semicrystalline dendrimer-like star poly(epsilon-caprolactone(s)). The low measured densities of these highly crystalline dendrimers confirmed that the porosity, as indicated by the shape of the desorption curves, had to be discontinuous. The porosity in the (C16)-terminated and the poly(epsilon-caprolactone(s)) was impossible to eliminate by applying a high external pressure during crystallization. A collective view of all the results obtained confirm that the transport properties are primarily controlled by the hydroxyl group concentration.

  • 77. Henrik Ullsten, N.
    et al.
    Gällstedt, M.
    Spencer, G. M.
    Johansson, E.
    Marttila, S.
    Ignell, R.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Extruded high quality materials from wheat gluten2010Inngår i: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 1, nr 4, s. 173-186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, we report that the addition of ammonium hydroxide (NH4OH)significantly enhance the properties of extruded WG-based materials. The grainystructure disappeared and the extrudate became more uniform and glossy. Thebarrier properties improved and the oxygen permeability at dry conditions was aslow as that for a number of petroleum-based plastics (poly(ethylene terephthalateand polyamide 66). The protein structure in this material was extensivelyaggregated, which improved the strength and stiffness; there was a ca 4-foldincrease in maximum stress compared to that of the NH4OH-free samples. Theprotein solubility decreased to almost zero. Even a severe sonication treatmentin sodium dodecyl sulphate (SDS) did not increase the solubility. The only typeof protein that it was possible to extract was the 'thermo-resistant' w-gliadinslacking disulfide-bonds. Our result provides new opportunities to develop a WGbasedfilm extrudate for potential use as e.g. a renewable barrier layer in foodand non-food laminate packagings.

  • 78.
    Holder, Shima
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Nilsson, Fritjof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Understanding and modelling the diffusion process of low molecular weight substances in polyethylene pipes2019Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, s. 301-309Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Peroxides are widely used as crosslinkers in polyethylene (PE) drinking water pipes. Cross-linked polyethylene (PEX) has better mechanical properties than PE, but peroxide decomposition by-products can migrate from PEX water pipes into the drinking water unless sufficient preventive actions are undertaken. This work systematically examines the migration of tert-Butyl methyl ether (MTBE), a dominating crosslinking by-product from PEX water pipes, into tap water by utilizing both experimental techniques and finite element (FEM) diffusion modeling. The effects of pipe geometry, tap water temperature (23–80 °C), boundary conditions (air or water interface) and degasing (at 180 °C) were considered. The MTBE diffusivity increased strongly with increasing temperature and it was concluded that a desired water quality can be achieved with proper degasing of the PEX pipes. As the FEM simulations were in excellent agreement with the experimental results, the model can accurately predict the MTBE concentration as a function of time, water temperature and PEX pipe geometry, and enable the pipe manufacturers to aid in ensuring desirable drinking water quality.

  • 79. Jansson, S. E. A.
    et al.
    Edsman, C. J.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Packaging materials for fermented milk: Effects of material crystallinity and polarity on food quality2001Inngår i: Packaging technology & science, ISSN 0894-3214, E-ISSN 1099-1522, Vol. 14, nr 3, s. 119-127Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ability of a packaging material to protect the food product and extend its shelf-life depends on several material properties. In this work the effects of material crystallinity and polarity on the quality of fermented milk were studied. The fermented milk is a high-quality Swedish product, similar to yoghurt. The quality of the food product was determined as a function of storage time by containing the liquid in pouches of different materials. The material crystallinity was varied by using very low-density polyethylene, high-density polyethylene and aluminium laminate as packaging materials. Aluminium was used on account of its '100%' gas-tightness. The polarity was varied by comparing an aliphatic polyketone with polyethylene of similar crystallinity. The carbon dioxide (CO2) and oxygen (O-2) contents in the headspace of the pouches were determined. The food quality was determined by measuring whey syneresis, viscosity and the content of desired Bifidobacteria, as well as of undesired yeast and mould. A trained taste panel determined the degree of acidity and of the sparkling taste. It was found that the content of CO2 increased and that of O-2 decreased in the pouches with increasing degree of crystallinity and increasing polarity. The sparkling taste of fermented milk was a clear function of the headspace CO2 content. The data presented here could thus be used to 'design' a package for a desired sparkling taste of the fermented milk by selecting a certain material crystallinity. Whey syneresis, viscosity and content of Bifidobacteria were found to be independent of pouch material. While the degree of whey syneresis and the viscosity increased with increasing storage time, the content of Bifidobacteria slowly decreased. The content of yeast and mould in the liquid was below the existing limit values for foodstuffs. The degrees of acidity and sparkling taste were highest for the liquids contained in aluminium and polyketone pouches, although the differences in acidulous taste between the various pouch materials were small.

  • 80. Jansson, S. E. A.
    et al.
    Gallet, G.
    Hefti, T.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Packaging materials for fermented milk Part 2: Solute-induced changes and effects of material polarity and thickness on food quality2002Inngår i: Packaging technology & science, ISSN 0894-3214, E-ISSN 1099-1522, Vol. 15, nr 6, s. 287-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work is a continuation of the application of a developed methodology for the selection of packaging material for a specific food product, in this case the 'demanding' food product. fermented milk. The effects of different packaging material parameters on the quality of fermented milk were studied. Food quality after storage was determined as a function of material polarity and pouch thickness by storing the liquid in pouches of different materials. The material polarity was varied by using laminates with polyethylene, poly(ethylene-co-vinyl alcohol) with two different ethylene contents and an aliphatic polyketone. The effects of pouch thickness were studied using high-density polyethylene films of different thicknesses between 25 mum and 200 mum. The interactions between the milk product and the pouch material were analysed by oxygen and water permeability, gas chromatography-mass spectrometry and tensile testing. The CO2 and O-2 contents in the headspace of the pouches were determined. The food quality was determined by measuring whey syneresis and the contents of Bifidobacteria, Enterobacteriaceae, yeast and mould. A trained taste panel determined the sensory properties. The content of CO2, and consequently the sparkling taste, increased with increasing polarity and/or pouch thickness. The CO2 content was affected more easily by changes in material polarity than by changes in pouch thickness. The increase in whey syneresis and the decrease in Bifidobacteria content with time were independent Of material polarity and pouch thickness. The contents Of Enterobacteriaceae, yeast and mould in the liquid were always below existing limits for foodstuffs. A newly developed method was used by which the CO2 and 02 permeabilities of the pouch/packaging could be estimated, using the kinetics of the gas composition in the pouch headspace. Permeability values, as estimated by the method, revealed that the CO2 production and the O-2 consumption rates of the fermented milk were dependent on the CO2 and O-2 headspace concentrations. An increase in permeability, determined by conventional methods, suggested that both the non-polar and the polar polymers were plasticized by fermented milk. The plasticization was, however, modest and undetectable when the polyethylene tensile test data were analysed.

  • 81. Johansson, E.
    et al.
    Malik, A. H.
    Hussain, A.
    Rasheed, F.
    Newson, W. R.
    Plivelic, T.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gällstedt, M.
    Kuktaite, R.
    Wheat gluten polymer structures: The impact of genotype, environment, and processing on their functionality in various applications2013Inngår i: Cereal Chemistry, ISSN 0009-0352, E-ISSN 1943-3638, Vol. 90, nr 4, s. 367-376Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For a number of applications, gluten protein polymer structures are of the highest importance in determining end-use properties. The present article focuses on gluten protein structures in the wheat grain, genotype- and environment-related changes, protein structures in various applications, and their impact on quality. Protein structures in mature wheat grain or flour are strongly related to end-use properties, although influenced by genetic and environment interactions. Nitrogen availability during wheat development and genetically determined plant development rhythm are the most important parameters determining the gluten protein polymer structure, although temperature during plant development interacts with the impact of the mentioned parameters. Glutenin subunits are the main proteins incorporated in the gluten protein polymer in extracted wheat flour. During dough mixing, gliadins are also incorporated through disulfide-sulfhydryl exchange reactions. Gluten protein polymer size and complexity in the mature grain and changes during dough formation are important for breadmaking quality. When using the gluten proteins to produce plastics, additional proteins are incorporated in the polymer through disulfide-sulfhydryl exchange, sulfhydryl oxidation, β-eliminations with lanthionine formation, and isopeptide formation. In promising materials, the protein polymer structure is changed toward β-sheet structures of both intermolecular and extended type and a hexagonal close-packed structure is found. Increased understanding of gluten protein polymer structures is extremely important to improve functionality and end-use quality of wheat- and gluten-based products.

  • 82. Johansson, K. S.
    et al.
    Chen, H.
    Hofmann, J. L.
    Swerin, A.
    Hedenqvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Dubreuil, M.
    Vangeneugden, D.
    Gällstedt, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Surface modification of wheat gluten films for improved water resistance2010Inngår i: ACS National Meeting Book of Abstracts, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Renewable packaging materials are of interest for a more sustainable environment, and wheat gluten (WG) is one of the most interesting candidates to replace petroleum-based oxygen-barrier polymers for packaging applications. This is due to its attractive combination of flexibility and strength, high gas (especially O 2) barrier properties under low humidity conditions and renewability. The main drawback of WG, as with most biopolymers, is its water and moisture sensitivity. The aim of this study was therefore to improve the hydrophobicity of WG films by means of surface modification while maintaining the excellent O 2 barrier properties. The surface modification work included a combination of electrospinning of WG fibers and different plasma surface modifications. The latter involved He plasma treatment for crosslinking the WG film prior to the deposition of electrospun WG fibers, O 2/Ar plasma etching of the WG films with and without electrospun WG fibers for increasing the surface roughness, and plasma polymerization of hexamethyldisiloxane (HMDSO) and other hydrophobic precursors for hydrophobicity. The plasma polymerization trials were performed both at reduced and atmospheric pressure conditions. The aim of the combined work was to maximize the hydrophobicity by combining a suitable nano-microstructure of the WG fibers with the hydrophobicity of the plasma-deposited coatings. The surface modification work was mainly evaluated by means of water contact angle measurements (hydrophobicity), Scanning Electron Microscopy (surface structures), Water Vapor Transmission Rate (WVTR) (moisture barrier) and Oxygen Transmission Rate (OTR) measurements (oxygen barrier). The surface modification work resulted in significantly improved hydrophobic properties of the WG films. The initial water contact angle increased from 65 to 110-130 degrees, depending on the combinations of electrospinning and plasma modification conditions. The plasma coatings prepared at ambient conditions resulted in slightly lower contact angles compared the plasma coating prepared at reduced pressure. The WVTR and OTR measurements are still in progress and will be reported at the meeting.

  • 83.
    Kallio, Kai J.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Ageing properties of polyamide-12 pipes exposed to fuels with and without ethanol2008Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 93, nr 10, s. 1846-1854Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The chemical and physical properties of polyamide-12 (PA12) fuel pipes/lines, aged for <= 2400 h at 110 degrees C, have been investigated. The pipes, containing fuel with or without ethanol, were either of a single PA12 layer, or of two PA12 layers surrounding a poly(vinylidene fluoride) barrier layer. The molar mass of the inner surface region obtained by size-exclusion chromatography was reduced during ageing. and optical microscopy revealed a surface that was partly dissolved in the presence of ethanol. Infrared spectroscopy revealed a rapid loss of plasticiser, especially in the presence of ethanol, and the fuel contained plasticiser and other polymer related components. Immersion tests at 60 degrees C showed that the swelling of the pipe and the amount of dissolved material were greatest for the fuels with intermediate ethanol content (50 vol.%). Aged samples experienced an increase in melting point, presumably, to a large extent, due to the loss of plasticiser and/or PA12-related components. In addition, for several samples, the crystallinity seemed to increase with ageing. (C) 2008 Elsevier Ltd. All rights reserved.

  • 84.
    Kallio, Kai J.
    et al.
    Volvo Car Corporation, Polymer Centre.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Effects of ethanol content and temperature on the permeation of fuel through polyamide-12-based pipes2010Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 29, nr 5, s. 603-608Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new test method has been developed which enables the fuel permeation properties of polyamide-12 (PA-12) - based pipes to be investigated. Fuel lines were exposed to circulating fuel with equal volume contents of toluene, isooctane and 0, 25 or 85 vol.% ethanol for up to 6 months at 60-110 degrees C. The pipes were either of a single PA12-layer or a multi-layer type, the latter having a poly(vinylidene fluoride) barrier layer between two PA12 sections. With a Thwing-Albert cup attached to the fuel line, it was possible to expose a pipe-section to surrounding air running in a separate pipe loop at a controlled flow-rate. Gas/vapour samples were collected from this loop using a syringe and, subsequently, analysed with a flame ionization detector. It was observed in the case of multi-layer pipes that the presence of ethanol increased the permeability (average values) of the "total" fuel as well as of the individual hydrocarbons. In addition, the 60 degrees C fuel permeability (85 vol.% ethanol) increased after a high temperature (110 degrees C peak) cycle, whereas the ethanol-free fuel flux seemed to decrease.

  • 85.
    Kallio, Kai J.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenvist, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Degradation of Polyamide-12 pipes aged in fuelInngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    In this work properties of polyamide-12 (PA12) fuel lines, exposed for ≤2400 h at 110°C and ≤26000 h at 50°C, containing fuels with different ethanol contents, were investigated. Dynamic mechanical thermal analysis indicated a sizeable loss of plasticiser during ageing. Viscosity measurements suggested that chain scission was an important mechanism of degradation at the higher temperature and size exclusion chromatography suggested that this was probably the case also at 50°C after long ageing times. The molar mass and polydispersity data indicated that the most degraded samples were those exposed to high ethanol contents at 110°C. Thermogravimetry showed that the onset temperature of the main degradation stage was 340-410°C (depending on heating rate). X-ray fluorescence spectroscopy and high performance liquid chromatography indicated migration of stabiliser and in the three-layered pipe, having two PA12 layers divided by a poly(vinylidene fluoride) barrier layer, the migration occurred preferentially from the inner pipe layer into the fuel.

  • 86.
    Kallio, Kai J.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Nageye, Arbi S.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Ageing properties of car fuel-lines;accelerated testing in “close-to-real” service conditions2010Inngår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 29, nr 1, s. 41-48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The use of ethanol-based fuels and tougher restrictions on fuel emissions put a higher demand on car fuel-line (pipe) systems. In this context, it is important to be able to establish and predict properties based on measurements on pipes exposed to real or “close-to-real” environments. This paper presents a new method to age pipes in accelerated “close-to-real” conditions. In this method, the pipe is exposed to circulating fuel on the inside and to air on the outside. The method/equipment allows for non-destructive mechanical testing on “continuous” pipes. The usefulness of the ageing method/system was illustrated on polyamide-12 (PA12) pipes exposed to fuels with varying ethanol content at 50 °C and 110 °C for a maximum of, respectively, ca 3 years and 100 days. “Non-destructive” three-point bending as well as tensile testing was used to assess the ageing-induced changes in mechanical properties. The most conclusive information was that the lowest pipe extensibility (ductility) of dried, previously fuel-exposed pipes was observed at the end of the ageing periods and at the higher ethanol contents. In fact, optical microscopy showed that the tensile fractured pipes, exposed to 25/30 vol. % ethanol at 110 °C (100 h), showed no signs of macroscopic yielding. The trends were interpreted, based also on findings from previous work, as being due to the loss of plasticiser (possibly also PA12 monomers/oligomers) and material “degradation/annealing” processes, the latter involving possibly stabiliser issues.

     

  • 87. Kaptan, Navid
    et al.
    Jafari, Seyed Hassan
    Mazinani, Saeedeh
    Akhlaghi, Shahin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Fazilat, Hakimeh
    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.
    Naderi, Ali
    Monfared, Alireza
    Thermal Behavior and Degradation Kinetics of Compatibilized Metallocene-Linear Low Density Polyethylene/Nanoclay Nanocomposites2014Inngår i: Polymer-plastics technology and engineering (Softcover ed.), ISSN 0360-2559, E-ISSN 1525-6111, Vol. 53, nr 9, s. 890-902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Morphology, thermal degradation and kinetics of metallocene-linear-low-density polyethylene (m-LLDPE)/m-LLDPE-graft-maleic anhydride (m-LLDPE-g-MA)/nanoclay nanocomposites were compared with m-LLDPE/nanoclay, m-LLDPE-g-MA/nanoclay and m-LLDPE/m-LLDPE-g-MA systems. X-ray diffraction measurements revealed intercalated and "highly intercalated'' morphologies for the nanocomposites. Thermogravimetric analysis demonstrated that although thermal degradation of m-LLDPE systems were delayed upon the inclusion of nanoclay in air, an inverse effect was perceived for the nanoclay under inert atmosphere. This conclusion was supported by kinetic analysis in terms of reaction order and activation energy. The results obtained from kinetics models also put forward the contribution of m-LLDPE-g-MA, as a compatibilizer, to the thermal stability enhancement through intermolecular cross-linking augmentation.

  • 88. Karlsson, G. E.
    et al.
    Johansson, T. S.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Determining limonene diffusion in molten polyethylene from within 0.1 mu s molecular dynamics trajectories2002Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 35, nr 19, s. 7453-7459Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Molecular dynamics simulations of the diffusion of limonene into molten polyethylene were performed in order to explore the possibility of using atomistic simulations to predict the diffusion of larger solute molecules in polymers. The system contained 6000 anisotropic united atom methylene units with a molar mass of 84 000 g mol(-1). A united atom limonene molecule (C10H16) was introduced into the polyethylene matrix. Limonene trajectories were generated for 2-100. ns at 77-227 degreesC. The simulated diffusivities were compared with experimental zero-concentration diffusivities of limonene in natural rubber and ultrahigh molar mass polyethylene, obtained from desorption measurements in the same temperature range. The simulated diffusivities and activation energy were within 30%. and 16% of the experimental thermodynamic diffusivities and activation energies, respectively. The simulated average diffusivities, obtained from 10 trajectories, changed by only 33% when the simulation time was shortened from 100 ns to 500 ps. The limonene molecule vibrated in a cagelike fashion on a 1-2 ps scale, whereas on a larger time scale the jumping was liquidlike. The limonene molecule showed tumbling during its motion through the polyethylene matrix.

  • 89. Karlsson, G. E.
    et al.
    Johansson, T. S.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Physical properties of dense amorphous poly(vinyl alcohol) as revealed by molecular dynamics simulation2002Inngår i: Journal of macromolecular science. Physics, ISSN 0022-2348, E-ISSN 1525-609X, Vol. B41, nr 2, s. 185-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dense amorphous poly(vinyl alcohol) (PVAL) built from a chain with 145 repeating units was studied by constant number of particles, pressure, and temperature-molecular dynamics simulations at temperatures between 400 and 527K. The results of the simulations were compared with pressure-volume-temperature data, solubility parameter, x-ray scattering pattern, and data for the characteristic ratio. The fractional free-volume distribution was computed and the diffusion characteristics of water in the polymer were studied. Experimental water desorption data were obtained and they were compared with the results obtained from the simulations. The AMBER-force field was initially adopted to generate the dynamics, but this force field yielded structures with too high specific volumes. The size of the oxygen atoms was then decreased until the maximum difference between experimental and simulated specific volumes was within 2.2%. This modification of the force field resulted in satisfactory agreement between experimental and simulated data for the volume expansion coefficient and the compressibility in the temperature range from 402 to 502K. The essential features in the local packing of the atoms as revealed by wide-angle x-ray scattering were also present in the simulated structures. Simulated values for the characteristic ratio were in agreement with earlier reported experimental values. The solubility parameter showed only minor deviations from reported experimental values. Water-molecule trajectories yielded diffusivity in accordance with the experimental zero-concentration diffusivity. The water molecule makes well-resolved jumps (cage-like penetrant motion) even at the highest temperature of simulation, 510K. The water molecule rotates much faster than it makes jumps in the PVAL matrix. The lifetimes of the hydrogen bonds between polymer chain segments were longer than for those of the hydrogen bonds formed between water and polymer chain segments. This finding suggests that the primary rate-controlling factor for water diffusion in this polymer is the constraining effect of hydrogen bonds formed between polymer chain segments.

  • 90. Karlsson, G.
    et al.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    A new method for determining solute diffusivity in polymers from data obtained by non-isothermal thermogravimetry2000Inngår i: Thermochimica Acta, ISSN 0040-6031, E-ISSN 1872-762X, Vol. 356, nr 02-jan, s. 133-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A numerical method for determining solute diffusivity in polymers over wide temperature ranges was developed based on non-isothermal thermogravimetry (TG). The method combines the Fickian equations with a heat transfer equation in order to take into account temperature gradients within the polymer sample during a heating scan. The requirement of thermal equilibrium in the specimen during the heating scan need not be fulfilled, and this permits the study of desorption of solute from thick specimens at high heating rates. The numerical procedure is capable of considering concentration-dependent solute diffusivity and temperature-dependent thermal diffusivity. The method was tested on the desorption of n-hexane in polyethylene between 25 and 120 degrees C. The results obtained agreed with experimental data obtained at heating rates from 10 to 40 degrees C/min up to 90 degrees C and yielded an activation energy of 46 kJ/mol, which is in agreement with earlier reported experimental data.

  • 91.
    Karlsson, Gunder E.
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Molecular dynamics simulation of oxygen diffusion in dry and water-containing poly(vinyl alcohol)2004Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 45, nr 11, s. 3893-3900Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The kinetics and mechanisms of diffusion of oxygen and water in dry and water-containing amorphous syndiotactic poly(vinyl alcohol) were studied at 502 K and normal pressure by molecular dynamics simulation. Penetrant molecule trajectories were obtained in a system with 600 repeating units of poly(vinyl alcohol) and 0, 40 (2.6 wt%) and 80 (5.2 wt%) water molecules. Under dry conditions, oxygen molecules jumped in a cage-like fashion. The oxygen molecule diffused in a liquid-like fashion while water diffusion was cage-like in the system with 5.2 wt% water. The hydrogen bond lifetimes among the water molecules were significantly shorter than those formed between water and the polymer and between different polymer segments. The hydrogen bond lifetimes among all species were, within experimental error, unaffected by the content of water, even though the oxygen diffusivity increased exponentially and the water diffusivity increased to some extent with increasing water content. It seemed that the diffusivity was sensitive primarily to the decrease in concentration of polymer-polymer hydrogen bonds. which followed from the increase in water content. This finding was consonant with the analysis of the oxygen molecule motion relative to the nearest polymer backbone, which revealed that it jumped preferentially along the polymer chain and towards the backbone. This behavior was more pronounced when the dynamics were analyzed over longer distances (5 Angstrom) and it was less pronounced in the water-rich systems. The simulations indicated that water clustering was absent and consequently that water was homogeneously distributed in the polymer systems.

  • 92.
    Koemmling, Anja
    et al.
    Bundesanstalt Mat Forsch & Prufung, D-12200 Berlin, Germany..
    Jaunich, Matthias
    Bundesanstalt Mat Forsch & Prufung, D-12200 Berlin, Germany..
    Pourmand, Payam
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Wolff, Dietmar
    Bundesanstalt Mat Forsch & Prufung, D-12200 Berlin, Germany..
    Hedenqvist, Mikael S.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Analysis of O-Ring Seal Failure under Static Conditions and Determination of End-of-Lifetime Criterion2019Inngår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 11, nr 8, artikkel-id 1251Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Determining a suitable and reliable end-of-lifetime criterion for O-ring seals is an important issue for long-term seal applications. Therefore, seal failure of ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) O-rings aged in the compressed state at 125 degrees C and at 150 degrees C for up to 1.5 years was analyzed and investigated under static conditions, using both non-lubricated and lubricated seals. Changes of the material properties were analyzed with dynamic-mechanical analysis and permeability experiments. Indenter modulus measurements were used to investigate DLO effects. It became clear that O-rings can remain leak-tight under static conditions even when material properties have already degraded considerably, especially when adhesion effects are encountered. As a feasible and reliable end-of-lifetime criterion for O-ring seals under static conditions should include a safety margin for slight dimensional changes, a modified leakage test involving a small and rapid partial decompression of the seal was introduced that enabled determining a more realistic but still conservative end-of-lifetime criterion for an EPDM seal.

  • 93. Krook, M.
    et al.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Barrier and mechanical properties of montmorillonite/polyesterarnide nanocomposites2002Inngår i: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 42, nr 6, s. 1238-1246Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The barrier and mechanical properties of biodegradable melt-mixed polyesteramide/octadecylamine-treated montmorillonite clay (filler) have been studied. Extruded films containing 5 and 13 wt% filler were prepared by melt-mixing. Samples compression molded after extrusion was also studied. Oxygen and water transmission rates were measured. X-ray diffraction was used to assess the periodic distance of the clay layers and transmission electron microscopy was used to assess the composite morphology. An increase of the periodic distance from 23.7 Angstrom for pure filler to 32-36 Angstrom for the processed composites was observed. This suggested that the collapsed stacks of clay particle of the first order X-ray reflection became intercalated upon extrusion. A decrease in the intensity with increasing rotation speed was observed, which suggested that higher shear rates promoted delamination, especially in composites with higher filler content. Transmission electron microscopy indicated that a sizable portion of the clay stacks were delaminated into smaller aggregates, containing generally one to three clay sheets. Density measurements indicated that shear-induced voids were formed in the nanocomposite, and these were, according to transmission electron microscopy, almost exclusively located between the clay sheets. The presence of voids limited the improvement in barrier properties with increasing filler content. However, the very large improvement in stiffness and strength with filler content indicated that these properties were unaffected by these voids.

  • 94. Krook, M.
    et al.
    Gallstedt, M.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    A study on montmorillonite/polyethylene nanocomposite extrusion-coated paperboard2005Inngår i: Packaging technology & science, ISSN 0894-3214, E-ISSN 1099-1522, Vol. 18, nr 1, s. 11-20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Extrusion coating was used to obtain montmorillonite/polyethylene-coated paperboard. The coating was prepared from a master batch containing maleated polyethylene, low-density polyethylene and 32 wt.% polyvinylpyrrolidone-surface-modified montmorillonite clay, which was blended with different amounts of low-density polyethylene to yield composites with 4 wt.% and 8.3 wt.% montmorillonite. X-ray diffraction revealed that the clay stacks in the coating were more extensively intercalated than in the original surface-modified clay. Transmission electron microscopy showed that the clay stacks were, to a large extent, separated by the high shear forces during extrusion into smaller evenly distributed entities. This was, unfortunately, achieved at the expense of the formation of a great many voids and pinholes, as revealed by transmission electron microscopy and dye staining. This had strong negative effects on the oxygen barrier properties but only a modest effect on the water vapour permeability. Tensile tests showed that the coating was always ductile and that the coating paperboard adhesion decreased with increasing clay content. The creasability was good and unaffected by the presence of the filler in the coating. Thermogravimetry showed that the degradation temperature in air of the filled coatings were of the order of 10degreesC higher than that of unfilled polyethylene.

  • 95. Krook, M.
    et al.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hellman, A.
    Iversen, T.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Barrier and mechanical properties of pulp fiber/polymer laminates and blends2000Inngår i: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 40, nr 1, s. 143-156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Paperboard laminates coated with two grades of poly(epsilon-caprolactone) (PCL), poly(hydroxy butyrate-co-valerate) (PHBV) or a liquid crystalline copolyester (LCP) were prepared by compression molding, and the influence of the processing conditions and polymer content of the laminate on the laminate properties was studied. Ligno-cellulose fiber/polymer blends were prepared from wet pulps and PCL and PHBV. The morphology, water vapor transmission rates, creasability, curl and twist and mechanical properties of the laminates and blends were studied. LCP and slowly cooled high molar mass PCL laminated paperboards showed the best creasing properties and the paperboards that were penetrated by the polymer showed the smallest degree of curl and twist. Extensive penetration occurred during compression molding of the paperboard with the low molar mass PCL at all temperatures and with PHBV and LCP at the higher molding temperatures. The water vapor transmission rates ranged from 1 to 300 times that of polyethylene depending on the polymer used and on the thermal history. In the case of blends, competitive properties were obtained only in those with a high polymer content. The laminate stiffness decreased and the strength increased in two polymer concentration regions, at similar to 20 wt% due to fiber-fiber separation and at similar to 60 wt% due to phase inversion.

  • 96. Krook, M.
    et al.
    Morgan, G.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Barrier and mechanical properties of injection molded montmorillonite/polyesterarnide nanocomposites2005Inngår i: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 45, nr 1, s. 135-141Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Properties of injection-molded biodegradable polyester-amide composites containing 5 and 13 wt% octadecylammonium-treated montmorillonite clay have been studied. Oxygen transmission rates and mechanical properties were measured. X-ray diffraction was used to assess the degree of intercalation of the clay layer stacks, and transmission electron microscopy (TEM) was used to assess the morphology and degree of layer delamination. A substantial reduction in oxygen permeability was observed when clay was added to the composites. The oxygen permeability of the 13 wt% clay sample was only 20% of that of the pure polymer. The in-plane stiffness and in-plane strength of the sheets were greatly improved without any embrittlement. These beneficial effects were probably due to the high degree of clay layer exfoliation and orientation observed by TEM. Heat shrinkage, toughness analysis, and cutting operations suggested that the polymer chains and the clay layers were oriented parallel to the plane of the sheet. TEM and X-ray showed that stacked layers were still present but that these were significantly intercalated. The clay-layer periodic spacing increased from 25 Angstrom to approximately 35 Angstrom during processing.

  • 97. Kuktaite, R.
    et al.
    Plivelic, T. S.
    Türe, Hasan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gällstedt, M.
    Marttila, S.
    Johansson, E.
    Changes in the hierarchical protein polymer structure: Urea and temperature effects on wheat gluten films2012Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 2, nr 31, s. 11908-11914Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding bio-based protein polymer structures is important when designing new materials with desirable properties. Here the effect of urea on the wheat gluten (WG) protein structure in WG-urea films was investigated. Small-angle X-ray scattering indicated the formation of a hexagonal close-packed (HCP) hierarchical structure in the WG-urea materials. The HCP structure was influenced significantly by the urea concentration and processing conditions. The interdomain distance d I between the HCP scattering objects increased with increasing content of urea and the objects seemed to be oriented in the extrusion direction. Additionally, the effect of temperature on the HCP structure was studied and it was shown that at ≥55°C the HCP structure disappeared. Transmission electron microscopy revealed a rather denatured pattern of both HMW-glutenins and gliadins in the WG-urea films. The molecular packing of the WG protein polymer can be highly affected by an additive and the processing method used.

  • 98. Kuktaite, Ramune
    et al.
    Newson, William R.
    Rasheed, Faiza
    Plivelic, Tomas S.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gallstedt, Mikael
    Johansson, Eva
    Monitoring Nanostructure Dynamics and Polymerization in Glycerol Plasticized Wheat Gliadin and Glutenin Films: Relation to Mechanical Properties2016Inngår i: ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN 2168-0485, Vol. 4, nr 6, s. 2998-3007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gliadin and glutenin proteins with 10, 20, 30 and 40% of glycerol were compression molded into films (130 degrees C) and evaluated for protein polymerization, beta-sheet structure and nano-structural morphology. Here, for the first time we show how different amounts of glycerol impact the nano-structure and functional properties of the gliadin and glutenin films. Most polymerized protein was found in the gliadin films with 20 and 30% glycerol, and in all the glutenin films (except 10%), by RP-HPLC. A beta-sheet-rich protein structure was found to be high in the 10 and 20% glycerol gliadin films, and in the 20 and 30% glycerol glutenin films by FT-IR. Glycerol content of 20, 30 and 40% impacted the nano-structural morphology of the gliadin glycerol films observed by SAXS, and to a limited extent for 10 and 20% glycerol gliadin films revealed by WAXS. No ordered nano-structure was found for the glutenin glycerol films. The 20%, 30% and 40% glycerol films were the most tunable for specific mechanical properties. For the highest stiffness and strength, the 10% glycerol protein films were the best choice.

  • 99. Kuktaite, Ramune
    et al.
    Plivelic, Tomas S.
    Cerenius, Yngve
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Gallstedt, Mikael
    Marttila, Salla
    Ignell, Rickard
    Popineau, Yves
    Tranquet, Oliver
    Shewry, Peter R.
    Johansson, Eva
    Structure and Morphology of Wheat Gluten Films: From Polymeric Protein Aggregates toward Superstructure Arrangements2011Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, nr 5, s. 1438-1448Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Evaluation of structure and morphology of extruded wheat gluten (WG) films showed WG protein assemblies elucidated on a range of length scales from nano (4.4 angstrom and 9 to 10 angstrom, up to 70 angstrom) to micro (10 mu m). The presence of NaOH in WG films induced a tetragonal structure with unit cell parameters, a = 51.85 angstrom and c = 40.65 angstrom, whereas NH4OH resulted in a bidimensional hexagonal close-packed (HCP) structure with a lattice parameter of 70 angstrom. In the WG films with NH4OH, a highly polymerized protein pattern with intimately mixed glutenins and gliadins bounded through SH/SS interchange reactions was found. A large content of beta-sheet structures was also found in these films, and the film structure was oriented in the extrusion direction. In conclusion, this study highlights complexities of the supramolecular structures and conformations of wheat gluten polymeric proteins in biofilms not previously reported for biobased materials.

  • 100. Kuktaite, Ramune
    et al.
    Türe, Hasan
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Gallstedt, Mikael
    Plivelic, Tomas S.
    Gluten Biopolymer and Nanoclay-Derived Structures in Wheat Gluten-Urea-Clay Composites: Relation to Barrier and Mechanical Properties2014Inngår i: ACS SUSTAIN CHEM ENG, ISSN 2168-0485, Vol. 2, nr 6, s. 1439-1445Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here, we investigated the structure of natural montmorillonite (MMT) and modified Cloisite C15A (MMT pre-intercalated with a dimethyl-dehydrogenated tallow quaternary ammonium surfactant) nanoclays in the wheat gluten-urea matrix in order to obtain a nanocomposite with improved barrier and mechanical properties. Small-angle X-ray scattering indicated that the characteristic hexagonal closed packed structure of the wheat gluten-urea matrix was not found in the CISA system and existed only in the 3 and 5 wt % MMT composites. SAXS/WAXS, TGA, and water vapor/oxygen barrier properties indicated that the dispersion of the C15A clay was somewhat better than the natural MMT clay. Confocal laser scanning microscopy showed MMT clay clusters and C15A clay particles dispersed in the protein matrix, and these were preferentially oriented in the extrusion direction only at 5 wt % of the CIS clay. The water vapor/oxygen barrier properties were improved with the presence of clay. Independent of the clay content used, the stiffness decreased and the extensibility increased in the presence of C15A due to the surfactant induced changes on the protein. The opposite "more expected" clay effect (increasing stiffness and decreasing extensibility) was observed for the MMT composites.

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