Change search
Refine search result
1 - 39 of 39
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1.
    Adekunle, K.
    et al.
    University of Borås, School of Engineering.
    Cho, S.-W.
    University of Borås, School of Engineering.
    Ketzscher, R.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Mechanical properties of natural fiber hybrid composites based on renewable thermoset resins derived from soybean oil, for use in technical applications2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 124, no 6, 4530-4541 p.Article in journal (Refereed)
    Abstract [en]

    Natural fiber composites are known to have lower mechanical properties than glass or carbon fiber reinforced composites. The hybrid natural fiber composites prepared in this study have relatively good mechanical properties. Different combinations of woven and non-woven flax fibers were used. The stacking sequence of the fibers was in different orientations, such as 0°, +45°, and 90°. The composites manufactured had good mechanical properties. A tensile strength of about 119 MPa and Young's modulus of about 14 GPa was achieved, with flexural strength and modulus of about 201 MPa and 24 GPa, respectively. For the purposes of comparison, composites were made with a combination of woven fabrics and glass fibers. One ply of a glass fiber mat was sandwiched in the mid-plane and this increased the tensile strength considerably to 168 MPa. Dynamic mechanical analysis was performed in order to determine the storage and loss modulus and the glass transition temperature of the composites. Microstructural analysis was done with scanning electron microscopy.

  • 2.
    Adekunle, K.
    et al.
    University of Borås, School of Engineering.
    Cho, S.-W.
    University of Borås, School of Engineering.
    Patzelt, C.
    Blomfeldt, T.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Impact and flexural properties of flax fabrics and Lyocell Fiber reinforced bio-based thermoset for automotive and structural applications2012Conference paper (Refereed)
  • 3.
    Adekunle, K.
    et al.
    University of Borås, School of Engineering.
    Ghoreishi, R.
    Ehsani, M.
    Cho, S.-W.
    University of Borås, School of Engineering.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Jute fiber reinforced methacrylated soy bean oil based thermoset composites prepared by vacuum injection molding technique2012In: Journal of Biobased Materials and Bioenergy, ISSN 1556-6560, E-ISSN 1556-6579, Vol. 6, no 2, 172-177 p.Article in journal (Refereed)
    Abstract [en]

    Bio-based composites based on soybean oil thermoset resin were manufactured with vacuum injection molding technique. Methacrylated soybean oil (MMSO) was processed with vacuum injection molding technique without blending with styrene. The composites produced had comparatively good mechanical properties like jute composite reinforced acrylated epoxidised soybean oil (AESO) resin blended with styrene. Although the tensile strength of the jute reinforced AESO composites are slightly higher than the jute reinforced MMSO composites which was attributed to blending of AESO with styrene. However, the difference in Youngs' modulus was negligible because they have approximately equal stiffness between 2.6 GPa and 2.8 GPa. The jute reinforced AESO composites showed relatively higher flexural strengths and moduli than the MMSO counterparts. This difference was also attributed to the blending of AESO with reactive diluent such as styrene. In order to determine the dimensional stability of the composite manufactured, water absorption test was carried out and the conclusion was that the moisture uptake of the jute reinforced composites was the same, this was expected.

  • 4.
    Adekunle, Kayode
    et al.
    University of Borås, School of Engineering.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Patzelt, Christian
    Blomfeldt, Thomas
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Impact and flexural properties of flax fabrics and Lyocell fiber-reinforced bio-based thermoset2011In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 30, no 8, 685-697 p.Article in journal (Refereed)
    Abstract [en]

    A bio-based thermoset resin was reinforced with flax fabrics and Lyocell fiber. The effect of different weave architectures was studied with four flax fabrics with different architectures: plain, twill (two different types), and dobby. The effect of the outer ply thickness was studied and characterized with flexural and impact testing. Composites manufactured with plain weave reinforcement had the best mechanical properties. The tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength were 280 MPa, 32 GPa, 250 MPa, 25 GPa, and 75 kJ/m2, respectively. Reinforcements with twill-weave architecture did not impart appreciable flexural strength or flexural modulus even when the outer thickness was increased. Plain- and dobby (basket woven style)-weave architectures gave better reinforcing effects and the flexural properties increased with an increase in outer thickness.Water absorption properties of the composites were studied and it was observed that the hybridization with Lyocell fiber reduced the water uptake. Fieldemission scanning electron microscopy was used to study the micro-structural properties of the composites.

  • 5.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Aging and Heat-Sealing Properties of Films based on Wheat Gluten2007Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Recently the research interest of the possibility of using wheat gluten (WG) as packaging material has greatly increased due to its combination of high gas barrier, attractive mechanical, film-forming and renewable properties. The source is also readily available and inexpensive on a worldwide basis. The glycerol-plasticized WG films cast from pH 4 and pH 11 solutions were investigated in order to understand the mechanisms behind the undesired aging. The film prepared from the pH 11 solution was mechanically more stable upon aging than the pH 4 film, which was initially very ductile but turning brittle with time. It was revealed that the protein structure of the pH 4 film was initially less polymerized/aggregated and the polymerization increased during storage but it did not reach the degree of aggregation of the pH 11 film, whereas deamidation was occurred and increased in the pH 11 film. During aging, the pH 4 film lost more mass than the pH 11 film mainly due to migration of glycerol but also due to some loss of volatile mass and the greater plasticizer loss of pH 4 film was presumably due to its initial lower degree of protein aggregation /polymerization. The glycerol migration of cast films exposed to a porous paper was further investigated with respect to pH of cast solution, glycerol content and film thickness since it was the main reason for deterioration of the properties. The opacity was also characterized. The glycerol migration was quantified using GC method in order to determine only glycerol content, but not other volatile substances. Glycerol content did not significantly change the opacity and pH 4 films showed good contact clarity because of less Maillard reaction. Glycerol was extensively migrating to the paper support and the migration seemed to be diffusion controlled. The heat sealability of WG films was investigated, using an impulse-hear sealer. It was observed that the WG films were readily sealable keeping up their integrity. The sealing temperature had a negligible effect on the lap-shear strength, but the peel strength increased with sealing temperature. The lap-shear strength increased with increasing mold temperature and the failure mode changed.

  • 6.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Protein-based packaging films, sheets and composites: process development and functional properties2009Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The depletion of the petroleum resources and a number of environmental concerns led to considerable research efforts in the field of biodegradable materials over the last few decades. Of the diverse range of biopolymers, wheat gluten (WG) stands out as an alternative to synthetic plastics in packaging applications due to its attractive combination of flexibility and strength, high gas barrier properties under low humidity conditions and renewability. The availability of raw materials has also been largely increased with an increase in the production of WG as a low-cost surplus material due to increasing demand for ethanol as fuel. In this study, WG was processed into films, sheets and composites using some of the most widely used techniques including solution casting, compression molding, extrusion and injection molding, accompanying process optimizations and characterization of their functional properties. This thesis consists mainly of six parts based on the purpose of the study. The first part addresses the aging and optical properties of the cast film in order to understand the mechanisms and reasons for the time-dependant physical and chemical changes. The films plasticized with glycerol were cast from acidic (pH 4) and basic (pH11) solutions. The film prepared from the pH 11 solution was mechanically more stable upon aging than the pH 4 film, which was initially very ductile but became brittle with time. It was revealed that the protein structure of the pH 4 film was initially less polymerized/aggregated and the polymerization increased during storage but it did not reach the degree of aggregation of the pH 11 film. During aging, the pH 4 film lost more mass than the pH 11 film mainly due to migration of glycerol but also due to some loss of volatile mass. In addition the greater plasticizer loss of the pH 4 film was presumably due to its initial lower degree of protein aggregation/polymerization. Glycerol content did not significantly change the opacity and pH 4 films showed good contact clarity because of less Maillard reaction. In the second part, the heat-sealability of WG films was investigated, using an impulse-heat sealer, as the sealability is one of the most important properties in the use of flexible packaging materials. It was observed that the WG films were readily sealable while preserving their mechanical integrity. The sealing temperature had a negligible effect on the lap-shear strength, but the peel strength increased with sealing temperature. The lap-shear strength increased with increasing mold temperature and the failure mode changed. The third part describes the possibility of using industrial hemp fibers to reinforce wheat gluten sheets based on evaluation of the fiber contents, fiber distribution and bonding between the fibers and matrix. It was found that the hemp fibers enhanced the mechanical properties, in which the fiber contents played a significant role in the strength. The fiber bonding was improved by addition of diamine as a cross-linker, while the fiber distribution needed to be improved. The fourth part presents a novel approach to improve the barrier and mechanical properties of extruded WG sheets with a single screw extruder at alkaline conditions using 3-5wt.% NaOH with or without 1 wt.% salicylic acid. The oxygen barrier, at dry conditions, was improved significantly with the addition of NaOH, while the addition of salicylic acid yielded poorer barrier properties. It was also observed that the WG sheets with 3 wt.% NaOH had the most suitable combination of low oxygen permeability and relatively small time-dependant changes in mechanical properties, probably due to low plasticizer migration and an optimal protein aggregation/polymerization. In the fifth part WG/PLA laminates were characterized for the purpose of improving the water barrier properties. The lamination was performed at 110°C and scanning electron microscopy showed that the laminated films were uniform in thickness. The laminates significantly suppressed the mass loss and showed promising water vapor barrier properties in humid conditions indicating possible applications in packaging. The final part addresses the development of injection molding processes for WG. Injection-molded nanocomposites of WG/MMT were also characterized. WG sheets were successively processed using injection molding and the process temperatures were found to preferably be in a range of 170-200°C, which was varied depending on the sample compositions. The clay was found to enhance the processability, being well dispersed in the matrix. The natural clay increased the tensile stiffness, whereas the modified clay increased the surface hydrophobicity. Both clays decreased the Tg and increased the thermal stability of the nanocomposites. The overall conclusion was that injection molding is a promising method for producing WG items of simple shapes. Further studies will reveal if gluten can also be used for making more complex shapes.

  • 7.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Adekunle, Kayode
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Mechanical properties of renewable thermoset composites reinforced with natural fibers2010Conference paper (Other academic)
    Abstract [en]

    The focus in this presentation has been to evaluate whether natural fibers can be used as reinforcement in composites based on renewable thermoset resin. Thermoset resins made from renewable resources as alternatives to crude oils are a relatively unexplored and important research area and could be used for a broad range of applications including coatings, inks, adhesives and composites. The common raw materials used in the preparation of biobased thermoset resins are vegetable oils such as soybean oil, rapeseed oil and linseed oil, which are low cost and abundant. Natural fibers as reinforcement have many advantages compared to synthetic fibers, for instance they are biodegradable, low weight and cost, nontoxic and recyclable. In the previous study, a novel thermoset resin [methacrylic anhydride modified soybean oil (MMSO)] was synthesized through the reaction of epoxidized soybean oil with methacrylic acid and used here as matrices. The studied composites based on the neat MMSO resin and the reisn blended with 30 wt.% styrene reinforced with non-woven flax fiber and woven flax fiber mats in different orientations [0°(warp direction), 45°, 90°(weft direction)] were manufactured using compression molding technique. The glass fiber reinforced composite was also prepared for the comparison purpose. The results show that it was possible to produce composite with high mechanical properties when the load is especially applied along the fiber direction, which implies that the structural composites having several plies of natural fiber mats in different orientations could be interesting candidates for use in technical applications.

  • 8.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Hedenqvist, Mikael S.
    Biodegradable laminate films based on wheat gluten2008Conference paper (Other academic)
  • 9.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Hedenqvist, Mikael S.
    Effects of glycerol content and film thickness on the properties of vital wheat gluten films cast at pH 4 and 112010In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 117, no 6, 3506-3514 p.Article in journal (Refereed)
    Abstract [en]

    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.

  • 10.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Hedenqvist, Mikael S.
    Properties of Wheat Gluten/Poly(lactic acid) Laminates2010In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 58, no 12, 7344-7350 p.Article in journal (Refereed)
    Abstract [en]

    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, extrusioncoating 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 WG 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 °C instead of 110 °C). The latter effect was probably due to a higher protein aggregation, as revealed by infrared spectroscopy. The lamination temperature (110-140 °C) did not, however, have a major effect on the final peel strength.

  • 11.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Hedenqvist, Mikael S.
    Renewable packaging materials with oxygen and water barrier properties2009Conference paper (Other academic)
  • 12.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Johansson, Eva
    Hedenqvist, Mikael S.
    Injection-molded nanocomposites and materials based on wheat gluten2011In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 48, no 1, 146-152 p.Article in journal (Refereed)
    Abstract [en]

    This is, to our knowledge, the first study of the injection molding of materials where wheat gluten (WG) is the main component. In addition to a plasticizer (glycerol), 5 wt.% natural montmorillonite clay was added. X-ray indicated intercalated clay and transmission electron microscopy indicated locally good clay platelet dispersion. Prior to feeding into the injection molder, the material was first compression molded into plates and pelletized. The filling of the circular mold via the central gate was characterized by a divergent flow yielding, in general, a stronger and stiffer material in the circumferential direction. It was observed that 20–30 wt.% glycerol yielded the best combination of processability and mechanical properties. The clay yielded improved processability, plate homogeneity and tensile stiffness. IR spectroscopy and protein solubility indicated that the injection molding process yielded a highly aggregated structure. The overall conclusion was that injection molding is a very promising method for producing WG objects.

  • 13.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Ullsten, Henrik
    Wretfors, Christer
    Johansson, Eva
    Hedenqvist, Mikael S.
    Influence of thermoforming techniques on mechanical properties of wheat gluten bioplastics2010Conference paper (Other academic)
  • 14.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Ullsten, Henrik
    Wretfors, Christer
    Johansson, Eva
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Hedenqvist, Mikael S.
    Characteristics of wheat gluten bioplastics in relation to processing methods2010Conference paper (Other academic)
  • 15.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Ullsten, Henrik
    Wretfors, Christer
    Johansson, Eva
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Hedenqvist, Mikael S.
    Protein-based bioplastics and nanocomposites from a processing perspective2010Conference paper (Other academic)
  • 16.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Hedenqvist, Mikael S.
    Development of biodegradable gluten-PLA laminate films2008Conference paper (Other academic)
  • 17.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Hedenqvist, Mikael S.
    Heat sealability of wheat gluten films2006Conference paper (Other academic)
  • 18.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Hedenqvist, Mikael S.
    Sealing properties of wheat gluten films2006Conference paper (Other academic)
  • 19.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Olabarrieta, Idoia
    Gällstedt, Mikael
    Sarasua, Jose-Ramon
    Johansson, Eva
    Hedenqvist, Mikael S.
    Assessing aging properties of plasticized wheat gluten films2007Conference paper (Other academic)
  • 20.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Olabarrieta, Idoia
    Ullsten, Henrik
    Gällstedt, Mikael
    Sarasua, Jose-Ramon
    Johansson, Eva
    Gräslund, Astrid
    Hedenqvist, Mikael S.
    Wheat gluten plastics: a competitive alternative?2008Conference paper (Other academic)
  • 21.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Olabarrieta, Idoia
    Ullsten, Henrik
    Gällstedt, Mikael
    Sarasua, Jose-Ramon
    Johansson, Eva
    Hedenqvist, Mikael S.
    Investigation of process windows and properties of wheat gluten plastics2008Conference paper (Other academic)
  • 22.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Persson, Maria
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Melt spun fibres of poly(lactic acid) and hydroxyapatite nanoparticles for use as tissue engineering scaffolds2011Conference paper (Refereed)
  • 23.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Persson, Maria
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Three dimensional woven bone tissue engineering scaffolds of melt-spun poly(lactic acid) fibres2011Conference paper (Refereed)
  • 24.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Ullsten, Henrik
    Gällstedt, Mikael
    Hedenqvist, Mikael S.
    Heat-sealing properties of compression-molded wheat gluten films2007In: Journal of Biobased Materials and Bioenergy, ISSN 1556-6560, E-ISSN 1556-6579, Vol. 1, no 1, 56-63 p.Article in journal (Refereed)
    Abstract [en]

    The impulse heat-sealing properties of wheat gluten films were investigated. Films containing 30 wt% glycerol were compression molded at 100-130 °C and then sealed in a lap-shear or peel-test geometry at 120-175 °C. The tensile properties of the pristine films and the lap-shear and peel strength of the sealed films were evaluated and the seals were examined by scanning electron microscopy. Glycerol was added to the film surfaces prior to sealing in an attempt to enhance the seal strength. It was observed that the wheat gluten films were readily sealable. At a 120 °C sealing temperature and without glycerol as adhesive, the lap-shear strength was greater than or similar to that of polyethylene film, although the peel strength was poorer. The sealing temperature had a negligible effect on the lap-shear strength, but the peel strength increased with sealing temperature. The lap-shear strength increased with increasing mold temperature and the failure mode changed, especially in the absence of glycerol adhesive, from a cohesive (material failure) to an adhesive type. From previous results, it is known that the high-temperature (130 °C) compression-molded film was highly cross-linked and aggregated, and this prevents molecular interdiffusion and entanglement and thus leads to incomplete seal fusion and, in general, adhesive failure. The presence of glycerol adhesive had a beneficial affect on the peel strength but no, or only a minor, effect on the lap-shear strength.

  • 25.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Ullsten, Henrik
    Gällstedt, Mikael
    Spencer, Gwen
    Johansson, Eva
    Kuktaite, Ramune
    Marttila, Salla
    Ignell, R.
    Nimmermark, S.
    Blomfeldt, Thomas
    Olsson, Richard
    Menon, Mohan
    Plackett, David
    Hedenqvist, Mikael S.
    Wheat gluten: a renewable source for plastic products2010Conference paper (Other academic)
  • 26.
    Cho, Sung-Woo
    et al.
    University of Borås, School of Engineering.
    Ullsten, Henrik
    Gällstedt, Mikeal
    Spencer, Gwen
    Johansson, Eva
    Kuktaite, Ramune
    Marttila, Salla
    Ignell, R.
    Blomfeldt, Thomas
    Olsson, Richard
    Menon, Mohan
    Plackett, David
    Hedenqvist, Mikael S.
    Wheat gluten technology: making plastic products2009Conference paper (Other academic)
  • 27. Granström, Jimmy
    et al.
    Gällstedt, Mikael
    Arias, Oscar
    Blomfeldt, Thomas
    Sojoudi, Hossein
    Kim, Yongjin
    Kim, Hyungchul
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Graham, Samuel
    Hedenqvist, Mikael
    Measurement technologies and encapsulation approaches for multi-layer barrier films2011Conference paper (Other academic)
  • 28. Gällstedt, Mikael
    et al.
    Hedenqvist, Mikael S.
    Olabarrieta, Idoia
    Ullsten, Henrik
    Lindskog, Bo
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Svensson, Martin
    GluPack: A renewable packaging concept based on wheat gluten2005Conference paper (Other academic)
  • 29. Hooshmand, S.
    et al.
    Cho, S-W.
    University of Borås, School of Engineering.
    Skrifvars, M.
    University of Borås, School of Engineering.
    Mathew, A.P.
    Oksdamn, K.
    Preparation of bio-nanocomposite fibers by melt spinning of cellulose acetate butyrate (CAB) and cellulose nanowhiskers (CNW)2012Conference paper (Other academic)
  • 30. Johansson, Eva
    et al.
    Newson, Bill
    Blomfeldt, Thomas
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Hedenqvist, Mikael
    Gällstedt, Mikael
    Kuktaite, Ramune
    Use of gluten for materials production2009Conference paper (Other academic)
  • 31. Johansson, Eva
    et al.
    Newson, William
    Blomfeldt, Thomas
    Türe, Hasan
    Rasheed, F.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Hedenqvist, Mikael
    Johansson, Therese
    Gällstedt, Mikael
    Kuktaite, Ramune
    Use of plant protein for materials production2011Conference paper (Other academic)
  • 32. Kumar, Hemanathan
    et al.
    Mahimaisenan, Pirabasenan
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Adekunle, Kayode
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Casein films and its composites with regenerated cellulose fibre for packaging applications2011Conference paper (Other academic)
    Abstract [en]

    A novel approach in the production of protein based films and composites were performed, using the bovine milk protein casein and regenerated cellulose fibres (lyocell). The films were prepared by first dissolving the casein protein in an aqueous alkaline solution in the presence of glycerol as a plasticizer. Further the composite films were prepared by the addition of fibres on aqueous alkaline solution with casein. The casein films and composites were thereafter prepared by casting the solution mixture on Teflon coated glass plate and drying for 48 hr. The effects of glycerol content and lyocell fibre reinforcements on the mechanical, thermal and physiological properties of the casein films were characterized. The results revealed that the increase in the addition of glycerol content decreases the tensile strength, young’s modulus, thermal stability of the film and increases the elongation percentage. Tensile property and thermal stability of the films was improved by the increase in the addition of the fibre content with a gradual decrease in the elongation percentage. The casein film made of 20% glycerol and 20% fibre content showed the maximum tensile strength of 23.5 MPa, E-modulus of 1.5 GPa and glass transition temperature (Tg) of 67.1±1.5 ºC. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that there was no significant change in the molecular weight of the protein during sample preparation. The inter molecular networks have taken place in the casein films and composites, when analyzed under Fourier Transform Infrared Spectroscopy (FTIR), and proper bonding between fibres and protein was observed by scanning electron microscope (SEM).

  • 33. Olabarrieta, Idoia
    et al.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Gällstedt, Mikael
    Sarasua, Jose-Ramon
    Johansson, Eva
    Hedenqvist, Mikael S.
    Aging properties of films of plasticized vital wheat gluten cast from acidic and basic solutions2006In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 7, no 5, 1657-1664 p.Article in journal (Refereed)
    Abstract [en]

    In order to understand the mechanisms behind the undesired aging of films based on vital wheat gluten plasticized with glycerol, films cast from water/ethanol solutions were investigated. The effect of pH was studied by casting from solutions at pH 4 and pH 11. The films were aged for 120 days at 50% relative humidity and 23 °C, and the tensile properties and oxygen and water vapor permeabilities were measured as a function of aging time. The changes in the protein structure were determined by infrared spectroscopy and size-exclusion and reverse-phase high-performance liquid chromatography, and the film structure was revealed by optical and scanning electron microscopy. The pH 11 film was mechanically more stable with time than the pH 4 film, the latter being initially very ductile but turning brittle toward the end of the aging period. The protein solubility and infrared spectroscopy measurements indicated that the protein structure of the pH 4 film was initially significantly less polymerized/aggregated than that of the pH 11 film. The polymerization of the pH 4 film increased during storage but it did not reach the degree of aggregation of the pH 11 film. Reverse-phase chromatography indicated that the pH 11 films were to some extent deamidated and that this increased with aging. At the same time a large fraction of the aged pH 11 film was unaffected by reducing agents, suggesting that a time-induced isopeptide cross-linking had occurred. This isopeptide formation did not, however, change the overall degree of aggregation and consequently the mechanical properties of the film. During aging, the pH 4 films lost more mass than the pH 11 films mainly due to migration of glycerol but also due to some loss of volatile mass. Scanning electron and optical microscopy showed that the pH 11 film was more uniform in thickness and that the film structure was more homogeneous than that of the pH 4 film. The oxygen permeability was also lower for the pH 11 film. The fact that the pH 4 film experienced a larger and more rapid change in its mechanical properties with time than the pH 11 film, as a consequence of a greater loss of plasticizer, was presumably due to its initial lower degree of protein aggregation/ polymerization. Consequently, the cross-link density achieved at pH 4 was too low to effectively retain volatiles and glycerol within the matrix.

  • 34. Persson, Maria
    et al.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Berglin, Lena
    University of Borås, Swedish School of Textiles.
    Tuukkanen, J
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Poly (Lactid Acid)/Hydroxipatite Composite Fibres for 3D Osteoconductive Woven Scaffolds2012Conference paper (Refereed)
    Abstract [en]

    This study presents a method to melt-spun biocompatible composite fibres from poly(lactic acid) (PLA) and nano-sized hydroxyapatite (HAp) particles. Different loading concentrations of HAp particles in the PLA fibres and solid-state draw-ratios (SSDR) were evaluated in order to study their influence on the mechanical, thermal and morphological properties. The results showed that the incorporation of the HAp particles was homogeneously distributed in the PLA fibres towards their surface and that the SSDR played an important role in order to improve the mechanical properties. The melt-spun PLA/HAp composite fibres, produced in this study, had also the potential to be processed into a fibrous scaffold, which was demonstrated by a 3D woven structure.

  • 35.
    Persson, Maria
    et al.
    University of Borås, School of Engineering.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Woven Scaffolds of Melt-Spun Poly(lactic acid) Fibres for Bone Tissue Engineering2011Conference paper (Other academic)
  • 36.
    Skrifvars, Mikael
    et al.
    University of Borås, School of Engineering.
    Persson, Maria
    University of Borås, School of Engineering.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Resorbable porous scaffolds fabricated via melt spinning and weaving of the fibres: novel means for engineering bone tissues2011Conference paper (Refereed)
  • 37. Ullsten, Henrik
    et al.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Spencer, Gwen
    Gällstedt, Mikael
    Johansson, Eva
    Hedenqvist, Mikael S.
    Properties of extruded vital wheat gluten sheets with sodium hydroxide and salicylic acid2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 3, 479-488 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel approach to improve the barrier and mechanical properties of extruded glycerolplasticized vital wheat gluten sheets. The sheets were extruded with a single screw extruder at alkaline conditions using 3-5 wt % NaOH. Salicylic acid (SA), known to improve the extrudability of wheat gluten, was also added alone or in combination with NaOH. Oxygen transmission rate and volatile mass measurements, tensile tests, protein solubility, glycerol migration, infrared spectroscopy, and electrophoresis were used to assess the properties of the extrudate. Electrophoresis showed that the gluten/glycerol sheet and the sheet with 3 wt % NaOH and 1 wt % SA contained the same building blocks in terms of proteins and protein subunits, although the protein solubility in these samples was different. The oxygen barrier, at dry conditions, was improved significantly with the addition of NaOH. On the other hand, the addition of salicylic acid yielded poorer barrier properties. The extrudate was placed on a blotting paper and its aging properties were investigated during the first 120 days. It was observed that the extrudate with 3 wt % NaOH had the most suitable combination of properties (low oxygen permeability, large strain at break, and relatively small aging-induced changes in mechanical properties); the reason is probably due to low plasticizer migration and an optimal protein aggregation/polymerization.

  • 38. Wretfors, Christer
    et al.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Hedenqvist, Mikael S.
    Marttila, Salla
    Nimmermark, S.
    Johansson, Eva
    Use of industrial hemp fibers to reinforce wheat gluten plastics2009In: Journal of polymers and the environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 17, no 4, 259-266 p.Article in journal (Refereed)
    Abstract [en]

    The next generation of manufactured products must be sustainable and industrially eco-efficient, making materials derived from plants an alternative of particular interest. Wheat gluten (WG) is an interesting plant material to be used for production of plastic similar materials due to its film-forming properties. For usage of plastics in a wider range of applications, composite materials with improved mechanical properties are demanded. The present study investigates the possibilities of reinforcing WG plastics with hemp fibers. Samples were manufactured using compression molding (130 °C, 1600 bar, 5 min). Variation in fiber length, content (5, 10, 15 and 20 wt%) and quality (poor, standard, good) were evaluated. Mechanical properties and structure of materials were examined using tensile testing, light and scanning electron microscopy. Hemp fiber reinforcement of gluten plastics significantly influenced the mechanical properties of the material. Short hemp fibers processed in a high speed grinder were more homogenously spread in the material than long unprocessed fibers. Fiber content in the material showed a significant positive correlation with tensile strength and Young's modulus, and a negative correlation with fracture strain and strain at maximum stress. Quality of the hemp fibers did not play any significant role for tensile strength and strain, but the Young's modulus was significantly and positively correlated with hemp fiber quality. Despite the use of short hemp fibers, the reinforced gluten material still showed uneven mechanical properties within the material, a result from clustering of the fibers and too poor bonding between fibers and gluten material. Both these problems have to be resolved before reinforcement of gluten plastics by industrial hemp fibers is applicable on an industrial scale.

  • 39. Wretfors, Christer
    et al.
    Cho, Sung-Woo
    University of Borås, School of Engineering.
    Kuktaite, Ramune
    Hedenqvist, Mikael S.
    Marttila, Salla
    Nimmermark, S.
    Johansson, Eva
    Effects of fiber blending and diamines on wheat gluten materials reinforced with hemp fiber2010In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 45, no 15, 4196-4205 p.Article in journal (Refereed)
    Abstract [en]

    Wheat gluten (WG) is a promising base material for production of "green'' plastics, although reinforcement is needed in more demanding applications. Hemp fiber is a promising reinforcement source but difficulties exist in obtaining desired properties with a WG-based matrix. This study aimed at improving fiber dispersion and fiber-matrix interactions using a high speed blender and a diamine as a cross-linker. Samples were manufactured using compression molding, two types of blenders and addition of diamine. Mechanical properties were assessed with tensile testing. Tensile-fractured surfaces were examined with scanning electron microscopy (SEM). Protein polymerization and fiber-protein matrix interactions were examined using high performance liquid chromatography (HPLC) and confocal laser scanning microscopy (CLSM). The results showed that a higher-speed grinding yielded a more even distribution of fibers and a more polymerized protein structure compared to a lower-speed grinding. However, these improvements did not result in increased strength, stiffness, and extensibility for the higher-speed grinding. The strength was increased when the grinding was combined with addition of a diamine (Jeffamine EDR-176). HPLC, SEM, and CLSM, indicated that diamine added samples showed a more "plastic'' appearance together with a stiffer and stronger structure with less cracking compared to samples without diamine. The use of the diamine also led to an increased polymerization of the proteins, although no effect on the fiber-protein matrix interactions was observed using microscopical techniques. Thus, for future successful use of hemp fibers to reinforce gluten materials, an appropriate method to increase the fiber-protein matrix interaction is needed.

1 - 39 of 39
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf