| 1. |
- Badía, J. D., et al.
(författare)
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A thermogravimetric approach to study the influence of a biodegradation in soil test to a Poly(lactic acid)
- 2008
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Ingår i: Macromolecular Symposia. - : Wiley. - 1022-1360 .- 1521-3900. ; 272:1, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- An amorphous grade Poly (lactic acid) (PLA) was selected for an accelerated burial in soil test during 450 days. Thermogravimetric analyses were carried out to study the effects of degradation in soil on the thermal stability and the thermal decomposition kinetics. A single stage decomposition process is observed for all degradation times. It is shown that the thermal stability of PLA is slightly affected by degradation in soil. Concerning the study of the thermal decomposition kinetics, Criado master curves were plotted from experimental data to focus the study of the thermodegradation kinetic model.The kinetic methods proposed by Broido and Chang were used to calculate the apparent activation energies (Ea) of the degradation mechanism. These results were compared to the Ea values obtained by the method developed by Coats and Redfern in order to prove the applicability of the former methods to the kinetic study. As expected, non-linear tendency is found out for Ea variation along the degradation times, which can be explained as an evolution by stages. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.
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| 2. |
- Badía, José David, et al.
(författare)
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Thermal analysis applied to the characterization of degradation in soil of polylactide : II. on the thermal stability and thermal decomposition kinetics
- 2010
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Ingår i: Polymer degradation and stability. - : Elsevier. - 0141-3910 .- 1873-2321. ; 95:11, s. 2192-2199
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Tidskriftsartikel (refereegranskat)abstract
- The disposal stage of polylactide (PLA) was assessed by burying it in active soil following an international standard. Degradation in soil promotes physical and chemical changes in the polylactide properties. The characterization of the extent of degradation underwent by PLA was carried out by using Thermal Analysis techniques. In this paper, studies on the thermal stability and the thermal decomposition kinetics were performed in order to assess the degradation process of a commercial PLA submitted to an accelerated soil burial test by means of multi-linear-non-isothermal thermogravimetric analyses. Results have been correlated to changes in molecular weight, showing the same evolution as that described by the parameters of thermal stability temperatures and apparent activation energies. The decomposition reactions can be described by two competitive different mechanisms: Nucleation model (A2) and Reaction Contracting Volume model (R3). The changes in the kinetic parameters and kinetic models are in agreement with the calorimetric and dynamic-mechanical-thermal results, presented in the Part I of the study [1]. © 2010 Elsevier Ltd. All rights reserved.
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| 3. |
- Bishnoi, Shahana, et al.
(författare)
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Adjustable polysaccharides-proteins films made of aqueous wheat proteins and alginate solutions
- 2022
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Ingår i: Food Chemistry. - : Elsevier BV. - 0308-8146 .- 1873-7072. ; 391, s. 133196-
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Tidskriftsartikel (refereegranskat)abstract
- Large amount of wheat proteins by-products are produced during wheat starch manufacture. This work aimed to develop edible films of cast aqueous wheat proteins (WP) and alginate (Al) solutions. The investigation of the microstructure of Al/WP films revealed a more compacted cross-section and homogeneous surface, comparatively to Al films. Those properties could be modified with the increase of WP concentration from 4 to 8 % w/v, as result of electrostatic interactions between WP and Al. Furthermore, the incorporation of WP provided UltraViolet-blocking behaviour (4-fold decrease in the Ultra-Violet-B region). Additionally, the incorporation of WP in the films reduced the water solubility of the Al films. It was also found that by incorporating different amounts of WP the mechanical and Water Vapor Transmission rate (WVTR) properties could also be modified, so the film composition could be adjusted to suit different types of foods and applications (e.g. coatings and packaging).
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| 4. |
- España Giner, Jose Manuel, et al.
(författare)
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Antioxidant effects of natural compounds on green composite materials
- 2012
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Ingår i: Plastics Research Online. - Bethel, United States : Society of Plastics Engineers. ; , s. 1-3
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Naturally-occurring antioxidant compounds can improve the thermal resistance of a bio-composite, increasing the degradation temperature of the material by as much as 130%.
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| 5. |
- España, J. M., et al.
(författare)
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Antioxidant and antibacterial effects of natural phenolic compounds on green composite materials
- 2012
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Ingår i: Polymer Composites. - : Wiley. - 0272-8397 .- 1548-0569. ; 33:8, s. 1288-1294
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to establish the thermal performance of a biocomposite (Arbofill kokos®), stabilized with different natural phenolic additives, to check the antioxidant capacity of the resulting compounds. Different phenolic compounds (thymol, carvacrol, α-tocopherol, and tannic acid) were used as biobased additives and the concentrations ranged between 0.5 wt% and 2 wt%. The results obtained were compared with formulations containing a typical industrial petroleum-based antioxidant agent (octadecyl-3-(3,5-di-tert- butyl-4-hydroxyphenyl) propionate). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the antioxidant performance of the selected natural additives. The antimicrobial effect of these natural phenolic compounds was also studied by analyzing the growth of bacterial colonies. The comparison between the natural phenolic compounds and the petroleum-based antioxidant compound showed good antioxidant action for natural phenolic compounds; in all the mixtures of biocomposite and antioxidant agent the oxidation onset temperature (OOT) increased in a remarkable way, but the highest stabilization effect was achieved with α-tocopherol with provides a % increase on OOT of about 45%. With regard to antibacterial activity of the different natural phenolic compounds, thymol, and carvacrol showed interesting antibacterial properties against Staphylococcus aureus. Copyright © 2012 Society of Plastics Engineers.
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| 6. |
- Ferrero, B., et al.
(författare)
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Green composites based on wheat gluten matrix and posidonia oceanica waste fibers as reinforcements
- 2013
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Ingår i: Polymer Composites. - : Wiley. - 0272-8397 .- 1548-0569. ; 34:10, s. 1663-1669
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Tidskriftsartikel (refereegranskat)abstract
- In this work, green composites from renewable resources were manufactured and characterized. A fibrous material derived from Posidonia oceanica wastes with high cellulose content (close to 90 wt% of the total organic component) was used as reinforcing material. The polymeric matrix to bind the fibers was a protein (wheat gluten) type material. Composites were made by hot-press molding by varying the gluten content on composites in the 10-40 wt% range. Mechanical properties were evaluated by standardized flexural tests. Thermo-mechanical behavior of composites was evaluated with dynamic mechanical analysis (torsion DMA) and determination of heat deflection temperature. Morphology of samples was studied by scanning electronic microscopy and the water uptake in terms of the water submerged time was evaluated to determine the maximum water uptake of the fibers in the composites. Composites with 10-40 wt% gluten show interesting mechanical performance, similar or even higher to many commodity and technical plastics, such as polypropylene. Water resistance of these composites increases with the amount of gluten. Therefore, the sensitiveness to the water of the composites can be tailored with the amount of gluten in their formulation.
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| 7. |
- García-García, Daniel, et al.
(författare)
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Optimizing the yield and physico-chemical properties of pine cone cellulose nanocrystals by different hydrolysis time
- 2018
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Ingår i: Cellulose. - : Springer. - 0969-0239 .- 1572-882X. ; 25:5, s. 2925-2938
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose nanocrystals (CNCs) were isolated for the first time from pine cones (PC) by alkali and bleaching treatments and subsequent sulfuric acid hydrolysis (64%) at 45 degrees C. The influence of the hydrolytic reaction time (30, 45, and 90 min) on the yield, chemical composition and structure, and thermal stability of CNCs was evaluated. The removal of non-cellulosic constituents during the alkaline and bleaching treatment resulted in high pure cellulosic fibres. The isolation of CNCs from these cellulosic fibres at different reaction times was verified by the nano-dimensions of the individual crystals (< 3 and < 335 nm of average diameter and length, respectively). The highest yield (15%) and the optimum CNCs properties in terms of aspect ratio, thermal stability and crystallinity were obtained for an extraction time of 45 min. PC appeared to be a new promising source of cellulose fibres and CNCs with potential to be applied as reinforcement in composites and for food-packaging.
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| 8. |
- García-García, Daniel, et al.
(författare)
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Reinforcing capability of cellulose nanocrystals obtained from pine cones in a biodegradable poly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) thermoplastic blend
- 2018
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Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 104, s. 10-18
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Tidskriftsartikel (refereegranskat)abstract
- In this work, different loads (3, 5 and 7 wt%) of pine cone cellulose nanocrystals (CNCs) were added to films ofpoly(3-hydroxybutyrate)/poly(ε-caprolactone) (PHB/PCL) blends with a composition of 75 wt% PHB and 25 wt% PCL (PHB75/PCL25). The films were obtained after solvent casting followed by melt compounding in anextruder and finally subjected to a thermocompression process. The influence of different CNCs loadings on themechanical, thermal, optical, wettability and disintegration in controlled compost properties of the PHB75/PCL25blend was discussed. Field emission scanning electron microscopy (FESEM) revealed the best dispersion of CNCson the polymeric matrix was at a load of 3 wt%. Over this loading, CNCs aggregates were formed enhancing thefilms fragilization due to stress concentration phenomena. However, the addition of CNCs improved the opticalproperties of the PHB75/PCL25films by increasing their transparency and accelerated the film disintegration incontrolled soil conditions. In general, the blend with 3 wt% CNCs offers the best balanced properties in terms ofmechanical, thermal, optical and wettability
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| 9. |
- Gordobil, O., et al.
(författare)
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Assesment of technical lignins for uses in biofuels and biomaterials : Structure-related properties, proximate analysis and chemical modification
- 2016
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Ingår i: Industrial crops and products (Print). - : Elsevier. - 0926-6690 .- 1872-633X. ; 83, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- The potential of organosolv and kraft eucalyptus and spruce lignin as feedstock for polymeric materials and biofuel applications was assessed. Proximate analysis was used to predict the heating values and char formation. Chemical modification, based on the esterification reaction with methacryloyl chloride, was applied to introduce vinyl groups into the lignin macromolecules for enhanced reactivity. Kraft eucalyptus and spruce lignins had a more condensed structure than organosolv lignins, which resulted in greater thermal stability for these lignins. For different species within the same process, the thermal parameters showed a correlation with certain structural and compositional parameters (ash and sugars content, molecular weight and degree of condensation). Organosolv spruce lignin produced the highest heating value of 24. MJ/Kg, which is suitable for biofuel applications. The content of phenolic OH groups was higher for kraft lignins and especially higher for softwood lignins, both organosolv and kraft. The degree of methacrylation, estimated from the content of vinyl groups per C9 lignin unit, was significantly greater for organosolv lignins than for kraft lignins despite the higher OH-groups content in the latter.
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| 10. |
- Johansson, Mathias, et al.
(författare)
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Effect of starch and fibre on faba bean protein gel characteristics
- 2022
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Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X .- 1873-7137. ; 131
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Tidskriftsartikel (refereegranskat)abstract
- Faba bean is a promising alternative to soybean for production of protein-rich plant-based foods. Increased understanding of the gelling behaviour of non-soy legumes can facilitate development of novel plant-based foods based on other legumes, such as faba bean. A mixture design was used in this study to evaluate the effect of different proportions of protein, starch and fibre fractions extracted from faba beans on gelation properties, texture and microstructure of the resulting gels. Large deformation properties, in terms of fracture stress and fracture strain, decreased as fibre and/or starch replaced protein. In contrast, Young's modulus and storage modulus increased with substitution of the protein. Light microscopy revealed that for all gels, protein remained the continuous phase within the region studied (65–100% protein fraction, 0–35% starch fraction, 0–10% fibre fraction in total flour added). Swollen and deformed starch granules were distributed throughout the mixed gels with added starch. Leaked amylose aggregated on starch and fibre surfaces and in small cavities (<1 μm) throughout the protein network. No clear difference between samples in protein network structure was observed by scanning electron microscopy. The reduction in large deformation properties was tentatively attributed to inhomogeneities created by the added starch and fibre. The increase in small deformation properties was hypothesised to be affected by water adsorption and moisture stability through the starch and fibre, increasing the effective protein concentration in the surrounding matrix and enhancing the protein network, or potentially by starch granules and fibre particles acting as active fillers reinforcing the gel structure.
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