| 1. |
|
|
| 2. |
- Blomfeldt, Thomas O. J., et al.
(författare)
-
Mechanical Properties and Network Structure of Wheat Gluten Foams
- 2011
-
Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 12:5, s. 1707-1715
-
Tidskriftsartikel (refereegranskat)abstract
- This Article reports the influence of the protein network structure on the mechanical properties of foams produced from commercial wheat gluten using freeze-drying. Foams were produced from alkaline aqueous solutions at various gluten concentrations with or without glycerol, modified with bacterial cellulose nanosized fibers, or both. The results showed that 20 wt % glycerol was sufficient for plasticization, yielding foams with low modulus and high strain recovery. It was found that when fibers were mixed into the foams, a small but insignificant increase in elastic modulus was achieved, and the foam structure became more homogeneous. SEM indicated that the compatibility between the fibers and the matrix was good, with fibers acting as bridges in the cell walls. IR spectroscopy and SE-HPLC revealed a relatively low degree of aggregation, which was highest in the presence of glycerol. Confocal laser scanning microscopy revealed distinct differences in HMW-glutenin subunits and gliadin distributions for all of the different samples.
|
|
| 3. |
- Blomfeldt, Thomas O. J., et al.
(författare)
-
Novel Foams Based on Freeze-Dried Renewable Vital Wheat Gluten
- 2010
-
Ingår i: Macromolecular materials and engineering. - : Wiley. - 1438-7492 .- 1439-2054. ; 295:9, s. 796-801
-
Tidskriftsartikel (refereegranskat)abstract
- A new way of producing rigid or semi-rigid foams from vital wheat gluten using a freeze-drying process is reported. Water/gluten-based mixtures were frozen and freeze-dried. Different foam structures were obtained by varying the mixing process and wheat gluten concentration, or by adding glycerol or bacterial cellulose nanofibers. MIP revealed that the foams had mainly an open porosity peaking at 93%. The average pore diameter ranged between 20 and 73 mm; the sample with the highest wheat gluten concentration and no plasticizer had the smallest pores. Immersion tests with limonene revealed that the foams rapidly soaked up the liquid. An especially interesting feature of the low-wheat-concentration foams was the "in situ'' created soft-top-rigid-bottom foams.
|
|
| 4. |
- Blomfeldt, Thomas O. J., et al.
(författare)
-
Novel freeze-dried foams from glutenin- and gliadin-rich fractions
- 2012
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 2:16, s. 6617-6627
-
Tidskriftsartikel (refereegranskat)abstract
- This is the first study on freeze-dried foams prepared from glutenin- and gliadin-rich fractions of wheat gluten and blends thereof. It was found that the foam density and stiffness could be controlled by a suitable choice of the glutenin/gliadin ratio. The glutenin-rich samples had the highest foam densities and the density decreased with increasing gliadin content. The compression modulus also decreased with increasing gliadin content, which was explained by the decrease in foam density, a more open porosity and the more aggregated/polymerized structure in the presence of glutenin. IR and SE-HPLC revealed that the least aggregated foams were those consisting only of the gliadin-rich fraction. Confocal laser scanning microscopy revealed the presence of both HMW-glutenin and gliadin (to a certain extent probably resisting the ethanol extraction process) in the glutenin-rich foams. SAXS indicated that the gliadin-rich fraction contributed with weakly correlated protein aggregates with a characteristic distance of 40-43 Å.
|
|
| 5. |
- Blomfeldt, Thomas O. J., et al.
(författare)
-
Thermal Conductivity and Combustion Properties of Wheat Gluten Foams
- 2012
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 4:3, s. 1629-1635
-
Tidskriftsartikel (refereegranskat)abstract
- Freeze-dried wheat gluten foams were evaluated with respect to their thermal and fire-retardant properties, which are important for insulation applications. The thermal properties were assessed by differential scanning calorimetry, the laser flash method and a hot plate method. The unplasticised foam showed a similar specific heat capacity, a lower thermal diffusivity and a slightly higher thermal conductivity than conventional rigid polystyrene and polyurethane insulation foams. Interestingly, the thermal conductivity was similar to that of closed cell polyethylene and glass-wool insulation materials. Cone calorimetry showed that, compared to a polyurethane foam, both unplasticised and glycerol-plasticised foams had a significantly longer time to ignition, a lower effective heat of combustion and a higher char content. Overall, the unplasticised foam showed better fire-proof properties than the plasticized foam. The UL 94 test revealed that the unplasticised foam did not drip (form droplets of low viscous material) and, although the burning times varied, self-extinguished after flame removal. To conclude both the insulation and fire-retardant properties were very promising for the wheat gluten foam.
|
|
| 6. |
- Cho, Sung-Woo, et al.
(författare)
-
Wheat Gluten-Laminated Paperboard with Improved Moisture Barrier Properties : A New Concept Using a Plasticizer (Glycerol) Containing a Hydrophobic Component (Oleic Acid)
- 2012
-
Ingår i: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9422 .- 1687-9430. ; , s. 454359-
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel approach to reduce the water vapor transmission rate (WVTR) and water absorbance of wheat gluten/paperboard laminates by introducing a hydrophobic component (oleic acid (OA)) into the hydrophilic plasticizer (glycerol). Whereas the paperboard showed immeasurably high WVTR, the laminate with gluten/glycerol yielded finite values. More importantly, by incorporating 75wt.% OA into the plasticizer, the WVTR and water absorbance were reduced by, respectively, a factor of three and 1.5-2. Of particular interest was that the mechanical properties were not changing dramatically between 0 and 50 wt.% OA. The results showed clear benefits of combining a gluten film with paperboard. Whereas the paperboard provided toughness, the WG layer contributed with improved moisture barrier properties. In addition, WVTR indicated that the paperboard reduced the swelling of the outer gluten/glycerol layer in moist conditions; a free standing gluten/glycerol film would yield infinite, rather than finite, WVTR values.
|
|
| 7. |
- Hansen, Natanya M. L., et al.
(författare)
-
Properties of plasticized composite films prepared from nanofibrillated cellulose and birch wood xylan
- 2012
-
Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 19:6, s. 2015-2031
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 8. |
- Introzzi, Laura, et al.
(författare)
-
Ultrasound-Assisted Pullulan/Montmorillonite Bionanocomposite Coating with High Oxygen Barrier Properties
- 2012
-
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:30, s. 11206-11214
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, the preparation and characterization of oxygen barrier pullulan sodium montmorillonite (Na+-MMT) nanocomposite coatings are presented for the first time. Full exfoliation of platelets during preparation of the coating water dispersions was mediated by ultrasonic treatment, which turned out to be a pivotal factor in the oxygen barrier performance of the final material even at high relative humidity (RH) conditions [oxygen permeability coefficients similar to 1.43 +/- 0.39 and 258.05 +/- 13.78 mL.mu m.m(-2).(24 h)(-1).atm(-1) at 23 degrees C and 0% RH and 70% RH, respectively]. At the micro- and nanoscale, the reasons are discussed. The final morphology of the coatings revealed that clay lamellae were stacked on top of one another, probably due to the forced confinement of the platelets within the coating thickness after solvent evaporation. This was also confirmed by modeling the experimental oxygen permeability data with the well-known Nielsen and Cussler permeation theoretical models, which suggested a reasonable aspect ratio (alpha) of similar to 100. Electron microscopic analyses also disclosed a peculiar cell-like arrangement of the platelets. The stacking of the clay lamellae and the cell-like arrangement create the excellent oxygen barrier properties. Finally, we demonstrated that the slight haze increase in the bionanocomposite coating materials arising from the addition of the clays depends on the clay concentration but not so much on the sonication time, due to the balance of opposite effects after sonication (an increase in the number of scattering centers but a reduction in their size).
|
|
| 9. |
- Sarossy, Zsuzsa, et al.
(författare)
-
Composite Films of Arabinoxylan and Fibrous Sepiolite : Morphological, Mechanical, and Baffler Properties
- 2012
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 4:7, s. 3378-3386
-
Tidskriftsartikel (refereegranskat)abstract
- Hemicelluloses represent a largely unutilized resource for future bioderived films in packaging and other applications. However, improvement of film properties is needed in order to transfer this potential into reality. In this context, sepiolite, a fibrous clay, was investigated as an additive to enhance the properties of rye flour arabinoxylan. Composite films cast from arabinoxylan solutions and sepiolite suspensions in water were transparent or semitransparent at additive loadings in the 2.5-10 wt % range. Scanning electron microscopy showed that the sepiolite was well dispersed in the arabinoxylan films and sepiolite fiber aggregation was not found. FT-IR spectroscopy provided some evidence for hydrogen bonding between sepiolite and arabinoxylan. Consistent with these findings, mechanical testing showed increases in film stiffness and strength with sepiolite addition and the effect of poly(ethylene glycol) methyl ether (mPEG) plasticizer addition. Incorporation of sepiolite did not significantly influence the thermal degradation or the gas barrier properties of arabinoxylan films, which is likely a consequence of sepiolite fiber morphology. In summary, sepiolite was shown to have potential as an additive to obtain stronger hemicellulose films although other approaches, possibly in combination with the use of sepiolite, would be needed if enhanced film barrier properties are required for specific applications.
|
|
