| 1. |
- Eguees, Itziar, et al.
(författare)
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Corncob arabinoxylan for new materials
- 2014
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 102, s. 12-20
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Tidskriftsartikel (refereegranskat)abstract
- Corncob agricultural waste was used as a source of arabinoxylan for preparation of films. Three arabinoxylan samples were prepared: crude extract (CCAX), purified by a washing step, and purified by bleaching CCAX. Films prepared with untreated CCAX were water soluble, yellowish in color and had poor mechanical properties. After the purification processes the Young's modulus increased from similar to 293 MPa to similar to 1400-1600 MPa, and strength was improved from similar to 9 MPa to around 53 MPa, while the strain at break was kept at similar to 8% both in untreated and purified CCAX. The contact angle was increased from similar to 21.3 degrees to 67-74 degrees after washing or bleaching CCAX. Acetylation of bleached CCAX showed the highest thermal resistance (325 degrees C), had low T-g (125 degrees C) and a high contact angle (80 degrees), and its films were stronger (strength similar to 67 MPa; Young's modulus similar to 2241 MPa) and more flexible (similar to 13%). These characteristics make purified CCAX a suitable material to be used as a matrix for film applications.
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| 2. |
- Hemmilä, Venla, 1987-, et al.
(författare)
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Characterization of Wood-based Industrial Biorefinery Lignosulfonates and Supercritical Water Hydrolysis Lignin
- 2020
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Ingår i: Waste and Biomass Valorization. - : Springer. - 1877-2641 .- 1877-265X. ; 11:11, s. 5835-5845
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the properties of any particular biorefinery or pulping residue lignin is crucial when choosing the right lignin for the right end use. In this paper, three different residual lignin types [supercritical water hydrolysis lignin (SCWH), ammonium lignosulfonate (A-LS), and sodium lignosulfonate (S-LS)] were evaluated for their chemical structure, thermal properties and water vapor adsorption behavior. SCWH lignin was found to have a high amount of phenolic hydroxyl groups and the highest amount of beta-O-4 linkages. Combined with a low ash content, it shows potential to be used for conversion into aromatic or platform chemicals. A-LS and S-LS had more aliphatic hydroxyl groups, aliphatic double bonds and C=O structures. All lignins had available C-3/C-5 positions, which can increase reactivity towards adhesive precursors. The glass transition temperature (T-g) data indicated that the SCWH and S-LS lignin types can be suitable for production of carbon fibers. Lignosulfonates exhibited considerable higher water vapor adsorption as compared to the SCWH lignin. In conclusion, this study demonstrated that the SCWH differed greatly from the lignosulfonates in purity, chemical structure, thermal stability and water sorption behavior. SCWH lignin showed great potential as raw material for aromatic compounds, carbon fibers, adhesives or polymers. Lignosulfonates are less suited for conversion into chemicals or carbon fibers, but due to the high amount of aliphatic hydroxyl groups, they can potentially be modified or used as adhesives, dispersants, or reinforcement material in polymers. For most value-adding applications, energy-intensive purification of the lignosulfonates would be required. [GRAPHICS] .
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| 3. |
- Hosseinpourpia, Reza, 1983-, et al.
(författare)
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Modification of Pea Starch and Dextrin Polymers with Isocyanate Functional Groups
- 2018
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 10:9
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Tidskriftsartikel (refereegranskat)abstract
- Pea starch and dextrin polymers were modified through the unequal reactivity of isocyanate groups in isophorone diisocyanate (IPDI) monomer. The presence of both urethane and isocyanate functionalities in starch and dextrin after modification were confirmed by Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR). The degree of substitution (DS) was calculated using elemental analysis data and showed higher DS values in modified dextrin than modified starch. The onsets of thermal degradation and temperatures at maximum mass losses were improved after modification of both starch and dextrin polymers compared to unmodified ones. Glass transition temperatures (Tg) of modified starch and dextrin were lower than unmodified control ones, and this was more pronounced in modified dextrin at a high molar ratio. Dynamic water vapor sorption of starch and dextrin polymers indicated a slight reduction in moisture sorption of modified starch, but considerably lower moisture sorption in modified dextrin as compared to that of unmodified ones.
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| 4. |
- Hosseinpourpia, Reza, 1983-, et al.
(författare)
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Polyurethane films prepared with isophorone diisocyanate functionalized wheat starch
- 2021
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Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 161
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Tidskriftsartikel (refereegranskat)abstract
- This study reports the fabrication and performance of sustainable polyurethane (PU) films based on wheat starch (native NS, modified MS), bio-polyols (1,3-propanediol PD, glycerol Gly), and polymeric diphenylmethane diisocyanate (pMDI). NS was successfully modified with isophorone diisocyanate, confirmed by Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR). Various PU films were prepared using NS, PD or Gly, MS and pMDI. For comparison, reference films were also synthesized without MS. PU films were analyzed from the viewpoint of their chemical, thermomechanical and flexural properties, and microstructural morphology. FTIR spectra demonstrated the total consumption of NCO groups, while the scanning electron microscopy micrographs of the films revealed that MS addition promoted the interactions between the compounds, enhancing in consequence their mechanical and thermomechanical performance. The study supported the suitability of functionalized carbohydrates to substitute petrochemical compounds in the synthesis of more environmentally-friendly PUs.
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| 5. |
- Hosseinpourpia, Reza, 1983-, et al.
(författare)
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Polyurethane Wood Adhesives Prepared from Modified Polysaccharides
- 2022
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 14:3
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the performance of polyurethane adhesives prepared with various combinations of wheat starch that had been modified by isophorone diisocyanate (MS), two polyol types (1,3-propanediol (PD) and glycerol (Gly)), native wheat starch (NS), and 4,4′-diphenylmethane diisocyanate (pMDI) at a NCO:OH weight ratio of 1:1. Two more adhesives were also synthesized with NS, PD, or Gly and pMDI blends and served as controls. The thermal behavior of the adhesives before and after the curing process, as well as their rheological performance and lap shear strength, were analyzed. Differential scanning calorimetry (DSC) showed a reduction in curing temperature and heat by adding MS. The thermal stability of the cured adhesives was slightly increased by MS addition. The viscosity of the adhesives that contained MS substantially increased at a linear ascendant ramp of shear, while the controls exhibited relatively low viscosity during the whole shear rate spectrum from 0.1 to 100 s−1. The tensile shear strength of wood veneers was also significantly increased by the incorporation of MS under both dry and wet measuring conditions. The maximum dry shear strength was obtained for the adhesive with Gly polyol and a higher content of MS and was comparable to the control adhesive with pMDI.
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| 6. |
- Hosseinpourpia, Reza, 1983-, et al.
(författare)
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Thermal stability and water vapor sorption of wheat starch modified with isocyanate functional groups
- 2019
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Ingår i: 7th International Conference on Biobased and Biodegradable Polymers (BIOPOL), 17-19th June 2019, Stockholm, Sweden. - : KTH.
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Konferensbidrag (refereegranskat)abstract
- Wheat starch polymer was modified through the unequal reactivity of isocyanate groups in isophorone diisocyanate (IPDI) monomer. Fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR) confirmed the presence of both urethane and isocyanate functionalities in the modified polymer. Thermal stability and water vapor sorption properties of the modified polymer were evaluated by means of thermogravimetric analysis (TGA) and auto-dynamic vapor sorption (AVS) method, respectively. The results indicated that the modified starch polymer showed a better thermal stability (e.g. higher temperature at maximum weight loss) compared to the unmodified one. Water vapor sorption of starch polymer was considerably reduced after modification with IPDI monomer.
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