| 1. |
- Akbari, Samira, et al.
(författare)
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Novel Bio-based Branched Unsaturated Polyester Resins for High-Temperature Applications
- 2023
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Ingår i: Journal of Polymers and the Environment. - 1566-2543 .- 1572-8919.
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Tidskriftsartikel (refereegranskat)abstract
- Unsaturated polyester resins, one of the most important thermosets, are invariably produced from oil-based monomers. Their application is limited in areas where high thermal stability is required due to their low Tg. Besides, these resins contain 30–40% hazardous styrene as a reactive solvent. Therefore, developing bio-based solventless unsaturated polyester resin with medium to high thermomechanical properties compared to petrochemical-based counterparts is important. In order to achieve this, a series of branched bio-based unsaturated polyester resins were synthesized using bulk polymerization method in two steps. In the first step, four different intermediates were prepared by reacting glycerol (as a core molecule) with either isosorbide (diol), 1,3-propanediol (diol), 2,5-furandicarboxylic acid (saturated diacid), or adipic acid (saturated diacid). In the second step, the branched intermediate was end capped with methacrylic anhydride to introduce reactive sites for cross-linking on the branch ends. The chemical structure of the resins was characterized by 13C-NMR. FT-IR confirmed the polycondensation reaction in the first step and the end functionalization of the resins with methacrylic anhydride in the second step. The effect of 2,5-furandicarboxylic acid and isosorbide on thermomechanical and thermal properties was investigated using dynamic mechanical analysis, differential scanning calorimetry, and thermo-gravimetric analysis. Results indicated that 2,5-furandicarboxylic acid based resins had superior thermomechanical properties compared to a commercial reference unsaturated polyester resin, making them promising resins for high-temperature composite applications. For example, the resin based on 2,5-furandicarboxylic acid and isosorbide and the resin based on 2,5-furandicarboxylic acid and 1,3-propanediol gave glass transition temperatures of 173 °C and 148 °C, respectively. Although the synthesized 2,5-furandicarboxylic acid based resins had higher viscosity (22.7 Pas) than conventional unsaturated polyester (0.4–0.5 Pas) at room temperature, preheated resins can be used for making high-temperature-tolerance fiber-reinforced composite.
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| 2. |
- Furgier, Valentin, et al.
(författare)
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Development and Characterisation of Composites Prepared from PHBV Compounded with Organic Waste Reinforcements, and Their Soil Biodegradation
- 2024
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Ingår i: Materials. - 1996-1944. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biobased and biodegradable polymer. This polymer is considered promising, but it is also rather expensive. The objective of this study was to compound PHBV with three different organic fillers considered waste: human hair waste (HHW), sawdust (SD) and chitin from shrimp shells. Thus, the cost of the biopolymer is reduced, and, at the same time, waste materials are valorised into something useful. The composites prepared were characterised by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile strength and scanning electron micrograph (SEM). Tests showed that chitin and HHW did not have a reinforcing effect on tensile strength while the SD increased the tensile strength at break to a certain degree. The biodegradation of the different composites was evaluated by a soil burial test for five months. The gravimetric test showed that neat PHBV was moderately degraded (about 5% weight loss) while reinforcing the polymer with organic waste clearly improved the biodegradation. The strongest biodegradation was achieved when the biopolymer was compounded with HHW (35% weight loss). The strong biodegradation of HHW was further demonstrated by characterisation by Fourier-transform infrared spectroscopy (FTIR) and solid-state nuclear magnetic resonance (NMR). Characterisation by SEM showed that the surfaces of the biodegraded samples were eroded.
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| 3. |
- Jeanson, Amanda L., et al.
(författare)
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Bioenergetic consequences of repeated catch-and-release fisheries interactions on adult steelhead across a range of ecologically relevant water temperatures
- 2023
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Ingår i: Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology. - 1095-6433 .- 1531-4332. ; 284
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Tidskriftsartikel (refereegranskat)abstract
- The biological consequences of catch-and-release angling have been studied for decades, yet little is known about the compounding effects of repeated recreational fisheries recaptures on the physiology and behaviour of angled fish. Using heart rate biologgers and behavioural assays, this study investigated the physiological and behavioural consequences of multiple simulated angling events (i.e., repeated stressors) on female steelhead (Oncorhynchus mykiss), under current (6 °C) and future (11 °C) water temperature scenarios. While steelhead in the warmer water temperature scenario demonstrated alterations in cardiac function (e.g., increases in maximum heart rate and scope of heart rate) and evidence of behavioural impairments (e.g., decreases in chase activity and landing time) over the course of two simulated angling events, cold water treated fish had negligible change. Fish subjected to two simulated angling events under warm water temperature conditions tended to demonstrate an increase in recovery time and scope for heart rate, and a decrease in resting heart rate. A second experiment was conducted to test for sex-specific differences in the heart rate response of steelhead subjected to an increase in water temperature. Females demonstrated a higher scope for heart rate when compared to males during the event and during recovery. More work is needed to better understand the interaction between multiple angling events and recovery from these events at various water temperatures, and the biological basis for sex-specific differences in cardiac function and response to challenges. This study contributes to a growing body of evidence on the effects of repeated stressors on wild fish.
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| 4. |
- Kopf, Sabrina, et al.
(författare)
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Production and Characterization of Melt-Spun Poly(3-hydroxybutyrate)/Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) Blend Monofilaments
- 2024
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Ingår i: ACS Omega. - : American Chemical Society. - 2470-1343.
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the melt-spinning potential of a poly(3-hydroxybutyrate)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blend using a piston spinning machine with two different spinneret diameters (0.2 and 0.5 mm). Results from the differential scanning calorimetry, dynamic mechanical thermal analysis, and tensile testing showed distinct filament properties depending on the monofilaments’ cross-sectional area. Finer filaments possessed different melting behaviors compared to the coarser filaments and the neat polymer, indicating the formation of a different type of polymer crystal. Additionally, the mechanical properties of the finer filament (tensile strength: 21.5 MPa and elongation at break: 341%) differed markedly from the coarser filament (tensile strength: 11.7 MPa, elongation at break: 12.3%). The hydrolytic stability of the filaments was evaluated for 7 weeks in a phosphate-buffered saline solution and showed a considerably reduced elongation at break of the thinner filaments. Overall, the results indicate considerable potential for further filament improvements to facilitate textile processing.
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| 5. |
- Legrand, Sacha, et al.
(författare)
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Preparation, characterization and application of a stationary chromatographic phase from a new (+)-tartaric acid derivative
- 2010
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Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039 .- 1359-8562. ; 51:17, s. 2258-2261
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Tidskriftsartikel (refereegranskat)abstract
- The preparation, characterization and application of a new stationary phase derived from 1,4-cyclohexanedione and diethyl (+)-tartrate are described. A suitable TADDOL for immobilization has been synthesized and grafted to a gamma-mercaptopropylsilylated silica gel. The resulting modified stationary phase has been characterized and its ability to separate enantiomers has been studied. While the free TADDOL in solution was able to resolve a range of enantiomers, the resolving properties were lost on immobilization. Solid state C-13 CPMAS NMR of the new stationary phase was used to explain the lack of stereoselective recognition. (C) 2010 Elsevier Ltd. All rights reserved.
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| 6. |
- Vu, Hoang Danh, et al.
(författare)
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Application of Immersed Membrane Bioreactor for Semi-Continuous Production of Polyhydroxyalkanoates from Organic Waste-Based Volatile Fatty Acids
- 2023
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Ingår i: Membranes. - : MDPI. - 2077-0375. ; 13:6
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Tidskriftsartikel (refereegranskat)abstract
- Volatile fatty acids (VFAs) appear to be an economical carbon feedstock for the cost-effective production of polyhydroxyalkanoates (PHAs). The use of VFAs, however, could impose a drawback of substrate inhibition at high concentrations, resulting in low microbial PHA productivity in batch cultivations. In this regard, retaining high cell density using immersed membrane bioreactor (iMBR) in a (semi-) continuous process could enhance production yields. In this study, an iMBR with a flat-sheet membrane was applied for semi-continuous cultivation and recovery of Cupriavidus necator in a bench-scale bioreactor using VFAs as the sole carbon source. The cultivation was prolonged up to 128 h under an interval feed of 5 g/L VFAs at a dilution rate of 0.15 (d−1), yielding a maximum biomass and PHA production of 6.6 and 2.8 g/L, respectively. Potato liquor and apple pomace-based VFAs with a total concentration of 8.8 g/L were also successfully used in the iMBR, rendering the highest PHA content of 1.3 g/L after 128 h of cultivation. The PHAs obtained from both synthetic and real VFA effluents were affirmed to be poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with a crystallinity degree of 23.8 and 9.6%, respectively. The application of iMBR could open an opportunity for semi-continuous production of PHA, increasing the feasibility of upscaling PHA production using waste-based VFAs.
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| 7. |
- Vu, Hoang Danh, et al.
(författare)
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Thorough Investigation of the Effects of Cultivation Factors on Polyhydroalkanoates (PHAs) Production by Cupriavidus necator from Food Waste-Derived Volatile Fatty Acids
- 2022
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Ingår i: Fermentation. - : MDPI. - 2311-5637. ; 8:11
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Tidskriftsartikel (refereegranskat)abstract
- Volatile fatty acids (VFAs) have become promising candidates for replacing the conventional expensive carbon sources used to produce polyhydroxyalkanoates (PHAs). Considering the inhibitory effect of VFAs at high concentrations and the influence of VFA mixture composition on bacterial growth and PHA production, a thorough investigation of different cultivation parameters such as VFA concentrations and composition (synthetic and waste-derived VFAs) media, pH, aeration, C/N ratio, and type of nitrogen sources was conducted. Besides common VFAs of acetic, butyric and propionic acids, Cupriavidus necator showed good capability for assimilating longer-chained carboxylate compounds of valeric, isovaleric, isobutyric and caproic acids in feasible concentrations of 2.5–5 g/L. A combination of pH control at 7.0, C/N of 6, and aeration of 1 vvm was found to be the optimal condition for the bacterial growth, yielding a maximum PHA accumulation and PHA yield on biomass of 1.5 g/L and 56%, respectively, regardless of the nitrogen sources. The accumulated PHA was found to be poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with the percentage of hydroxybutyrate in the range 91–96%. Any limitation in the cultivation factors was found to enhance the PHA yield, the promotion of which was a consequence of the reduction in biomass production.
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| 8. |
- Wijayarathna, E.R. Kanishka B., et al.
(författare)
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Fungal textile alternatives from bread waste with leather-like properties
- 2022
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Ingår i: Resources, Conservation and Recycling. - : Elsevier. - 0921-3449 .- 1879-0658. ; 179
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Tidskriftsartikel (refereegranskat)abstract
- Food waste and fashion pollution are two of the most prominent global environmental issues. To alleviate the problems associated with food waste, while simultaneously contributing to sustainable fashion, the feasibility of making an alternative textile material with leather-like properties from fungal biomass cultivated on bread waste was investigated. The filamentous fungus, Rhizopus delemar, was successfully grown on waste bread in a submerged cultivation process, and fungal biomass was treated with vegetable tannin of chestnut wood. NMR and FTIR confirmed interactions between tannin and fungal biomass, while OM, SEM and AFM visualised the changes in the hyphae upon the tannin treatment. Thermal stability was assessed using TGA analysis. The wet-laid technique commonly utilised for paper-making was used to prepare sheets of hyphae. Some of the sheets were treated with glycerol and/or a biobased binder as post-treatment. Overall, three of the produced materials exhibited leather-like properties comparable to that of natural leather. Sheets from untreated biomass with only glycerol post-treatment showed a tensile strength of 7.7 MPa and an elongation at break of 5%. Whereas sheets from untreated biomass and tannin treated biomass with both glycerol and binder treatments led to tensile strengths of 7.1 MPa and 6.9 MPa, and the elongation at break of 12% and 17%, respectively. The enhancement of hydrophobicity after the binder treatment, helped to preserve the absorbed glycerol within the sheet and thereby the flexibility was retained when in contact with moisture. These findings demonstrate that bread waste-derived fungal sheets have great potential as environmentally friendly materials with leather-like properties.
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| 9. |
- Åkesson, Dan, 1970-, et al.
(författare)
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Recycling of wood fiber-reinforced HDPE by multiple reprocessing
- 2016
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Ingår i: Journal of Applied Polymer Science. - : John Wiley & Sons. - 0021-8995 .- 1097-4628. ; 133:35
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical recycling of high-density polyethylene (HDPE) reinforced with wood fiber was studied by means of repeated injection moulding. The change in properties during the recycling was monitored by tensile and flexural tests, Charpy impact tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), FTIR spectroscopy, and by measuring the fiber lengths. Tests were also done where injection moulding was combined with subsequent accelerated thermo-oxidative ageing and thereafter repeated numerous times. The results showed that the HDPE composites were relatively stable toward both the ageing conditions and the repeated injection moulding. The change of the mechanical properties was mainly observed as an increased elongation at max. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43877. © 2016 Wiley Periodicals, Inc.
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