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- Johansson, Kenth S., et al.
(författare)
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Surface modification of wheat gluten films for improved water resistance
- 2010
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Ingår i: Abstracts of Papers of the American Chemical Society. - : American Chemical Society (ACS). - 0065-7727. ; 240
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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 O2) 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 O2 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, O2/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.
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- Plackett, David, et al.
(författare)
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Physical Properties and Morphology of Films Prepared from Microfibrillated Cellulose and Microfibrillated Cellulose in Combination with Amylopectin
- 2010
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 117:6, s. 3601-3609
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Tidskriftsartikel (refereegranskat)abstract
- Two types of microfibrillated cellulose (MFC) were prepared using either a sulfite pulp containing a high amount of hemicellulose (MFC 1) or a carboxymethylated dissolving pulp (MFC 2). MFC gels were then combined with amylopectin solutions to produce solvent-cast MFC-reinforced amylopectin films. Tensile testing revealed that MFC 2-reinforced films exhibited a more ductile behavior and that MFC 1-reinforced films had higher modulus of elasticity (E-modulus) at MFC loadings of 50 wt % or higher. Pure MFC films had relatively low oxygen permeability values when data were compared with those for a variety of other polymer films. MFC 1 and MFC 2 films had similar opacity but differences in appearance which were attributed to the presence of some larger fibers and nanofiber agglomerates in MFC 2. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to illustrate the morphology of MFC nanofibers in pure films and in an amylopectin matrix.
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- Cho, Sung-Woo, et al.
(författare)
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Effects of glycerol content and film thickness on the properties of vital wheat gluten films cast at pH 4 and 1
- 2010
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 117:6, s. 3506-3514
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with the optical properties and plasticizer migration properties of vital wheat gluten (WG) films cast at pH 4 and 11. The films contained initially 8, 16, and 25 wt % glycerol and were aged at 23 degrees C and 50% relative humidity for at least 17 weeks on a paper support to simulate a situation where a paper packaging is laminated with an oxygen barrier film of WG. The films, having target thicknesses of 50 and 250 mu m, were characterized visually and with ultraviolet/visible and infrared spectroscopy; the mass loss was measured by gravimetry or by a glycerol-specific gas chromatography method. The thin films produced at pH 4 were, in general, more heterogeneous than those produced at pH 11. The thin pH 4 films consisted of transparent regions surrounding beige glycerol-rich regions, the former probably rich in gliadin and the latter rich in glutenin. This, together with less Maillard browning, meant that the thin pH 4 films, in contrast to the more homogeneous (beige) thin pH 11 films, showed good contact clarity. The variations in glycerol content did not significantly change the optical properties of the films. All the films showed a significant loss of glycerol to the paper support but, after almost 9 months, the thick pH 11 film containing initially 25 wt % glycerol was still very flexible and, despite a better contact to the paper, had a higher residual glycerol content than the pH 4 film, which was also more brittle.
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- Cho, Sung-Woo, et al.
(författare)
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Effects of glycerol content and film thickness on the properties of vital wheat gluten films cast at pH 4 and 11
- 2010
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Ingår i: Journal of Applied Polymer Science. - : John Wiley & Sons, Inc.. - 0021-8995 .- 1097-4628. ; 117:6, s. 3506-3514
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with the optical properties and plasticizer migration properties of vital wheat gluten (WG) films cast at pH 4 and 11. The films contained initially 8, 16, and 25 wt.% glycerol and were aged at 23 °C and 50% relative humidity for at least 17 weeks on a paper support to simulate a situation where a paper packaging is laminated with an oxygen barrier film of WG. The films, having target thicknesses of 50 and 250 μm, were characterized visually and with ultraviolet/visible and infrared spectroscopy; the mass loss was measured by gravimetry or by a glycerol-specific gas chromatography method. The thin films produced at pH 4 were, in general, more heterogeneous than those produced at pH 11. The thin pH 4 films consisted of transparent regions surrounding beige glycerol-rich regions, the former probably rich in gliadin and the latter rich in glutenin. This, together with less Maillard browning, meant that the thin pH 4 films, in contrast to the more homogeneous (beige) thin pH 11 films, showed good contact clarity. The variations in glycerol content did not significantly change the optical properties of the films. All the films showed a significant loss of glycerol to the paper support but, after almost 9 months, the thick pH 11 film containing initially 25 wt.% glycerol was still very flexible and, despite a better contact to the paper, had a higher residual glycerol content than the pH 4 film, which was also more brittle.
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- Cho, Sung-Woo, et al.
(författare)
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Properties of Wheat Gluten/Poly(lactic acid) Laminates
- 2010
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 58:12, s. 7344-7350
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Tidskriftsartikel (refereegranskat)abstract
- Laminates of compression-molded glycerol-plasticized wheat gluten (WG) films surrounded and supported by poly(lactic acid) (PLA) films have been produced and characterized. The objective was to obtain a fully renewable high gas barrier film with sufficient mechanical integrity to function in, for example, extrusion-coating paper/board applications. It was shown that the lamination made it possible to make films with a broad range of glycerol contents (0-30 wt %) with greater strength than single unsupported WG films. The low plasticizer contents yielded laminates with very good oxygen barrier properties. In addition, whereas the unsupported WO films had an immeasurably high water vapor transmission rate (WVTR), the laminate showed values that were finite and surprisingly, in several cases, also lower than that of PLA. Besides being a mechanical support (as evidenced by bending and tensile data) and a shield between the WG and surrounding moisture, the PLA layer also prevented the loss of the glycerol plasticizer from the WG layer. This was observed after the laminate had been aged on an "absorbing" blotting paper for up to 17 weeks. The interlayer adhesion (peel strength) decreased with decreasing glycerol content and increasing WG film molding temperature (130 degrees C instead of 110 degrees C). The latter effect was probably due to a higher protein aggregation, as revealed by infrared spectroscopy. The lamination temperature (110-140 degrees C) did not, however, have a major effect on the final peel strength.
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- Henrik Ullsten, N., et al.
(författare)
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Extruded high quality materials from wheat gluten
- 2010
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Ingår i: Polymers from Renewable Resources. - : SAGE Publications. - 2041-2479 .- 2045-1377. ; 1:4, s. 173-186
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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