| 1. |
- Marti-Ferrer, F., et al.
(författare)
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Flour rice husk as filler in block copolymer polypropylene : Effect of different coupling agents
- 2006
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 99:4, s. 1823-1831
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Tidskriftsartikel (refereegranskat)abstract
- Flour rice husk (FRH) was employed as a filler in block copolymer polypropylene (PPB) in order to prepare polymer-based reinforced composites. Four coupling agents were selected to modify the surface of the rice husk in the composite materials, including two types of functionalized polymers [PP homopolymer grafted with maleic anhydride (MA-PP) and an elastomer styrene-ethylene-butadiene-styrene triblock copolymer grafted with MA (MA-SEBS)] and two bifunctional organometallic coupling agents (silane and titanate with linear low-density polyethylene as a carrier). The influence of each type of coupling agent on the interfacial bonding strength was studied by dynamic mechanical analysis, scanning electronic microscopy, and rheological tests. The results showed that strong interactions were formed between the coupling agents and the filler surface. The addition of a coupling agent with an elastomeric carrier (MA-SEBS) increased the loss tangent and reduced the storage modulus of the composite. A similar but less intense effect was observed for the titanate coupling agent. However, an antagonistic performance was obtained when MA-PP and silane were employed as coupling agents. In addition, when the percentage of MA-SEBS was increased, the impact properties of FRH/PPB blends were improved and the strength was reduced.
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| 2. |
- 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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| 3. |
- Badia, J. D., et al.
(författare)
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Thermal analysis as a quality tool for assessing the influence of thermo-mechanical degradation on recycled poly(ethylene terephthalate)
- 2009
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Ingår i: Polymer testing. - : Elsevier BV. - 0142-9418 .- 1873-2348. ; 28:2, s. 169-175
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical recycling of poly(ethylene terephthalate) (PET) was simulated by multiple processing to assess the effects of thermo-mechanical degradation, and characterized using rheological and thermal analysis techniques. Thermo-mechanical degradation under repeated extrusion induces chain scission reactions in PET, which result in a dramatic loss in the deformation capabilities and an increase in the fluidity of the polymer under reprocessing, reducing its recycling possibilities after four extrusion cycles. Multiple reprocessing severely affects the storage modulus and the microstructure of recycled PET, both in the amorphous and crystalline regions. Multimodal melting behavior is observed for reprocessed PET, indicating heterogeneous and segregated crystalline regions. A deconvolution procedure has been applied to individually characterize each crystalline population in terms of lamellar thickness distribution and partial crystallinity. Thermal analysis techniques such as differential scanning calorimetry (DSC) and dynamic-mechanical analysis (DMA) have proved to be suitable techniques for the quality assessment of recycled PET, giving unequivocal information about its degree of degradation compared to the common technological measurements of melt-mass flow rate (MFR) or oxidative stability (T-OX).
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| 4. |
- Moriana-Torró, Rosana, et al.
(författare)
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Thermal characterisation of photo-oxidized HDPE/Mater-Bi and LDPE/Mater-Bi blends buried in soil
- 2008
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 109:2, s. 1177-1188
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Tidskriftsartikel (refereegranskat)abstract
- Blends of high and low density polyethylene with a commercial biodegradable material (Mater-Bi) were subjected to an accelerated soil burial test. A set of samples was previously photo-oxidized to evaluate the effects of UV-irradiation on the degradation in soil process of these blends. Thermogravimetric as well as calorimetric analysis were performed to study the biodegradation, photo-degradation and their synergetic effects. Differential scanning calorimetry was carried out to analyze the morphological changes as a consequence of the photo-oxidation process. UV-irradiation slightly modifies the crystalline content of HDPE/Mater-Bi blends, increasing the heterogeneity of this blend. Criado master curves were plotted to analyses the degradation kinetic model. Broido and Coats-Redfern methods have been used for calculating the Ea of the thermal decomposition mechanisms. Thermogravimetric results reveal that noncomplexed starch is more affected by biodegradation than the polyethylene matrix and the starch/EVPH complexes chains from Mater-Bi. However, the effects of both photo-oxidation and biodegradation processes on the thermal decomposition of Mater-Bi is influenced by the polymeric matrix used. Previous photo-oxidation finds to slow down the degradative effects caused by the soil burial test on the HDPE/Mater-Bi blends. © 2008 Wiley Periodicals, Inc.
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| 5. |
- Santonja-Blasco, Laura, et al.
(författare)
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Thermal characterization of polyethylene blends with a biodegradable masterbatch subjected to thermo-oxidative treatment and subsequent soil burial test
- 2007
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Ingår i: Journal of Applied Polymer Science. - : Wiley-Blackwell. - 0021-8995 .- 1097-4628. ; 106:4, s. 2218-2230
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Tidskriftsartikel (refereegranskat)abstract
- The viability of producing environment-friendly blends of HDPE and LDPE with a commercial biodegradable masterbatch containing starch and polyethylene was studied. The service life of these blends was simulated by means of a thermo-oxidative treatment, and their further disposal in landfill was modeled using an accelerated soil burial test. Characterization was carried out in terms of their calorimetric and thermogravimetric properties. Thermo-oxidative treatment causes an increase in the crystalline content of both components of the blends, and promotes a segregation of the crystallite sizes of polyethylene. The soil burial test leads to changes in the crystalline content of the biodegradable material, which is influenced by the polyolefinic matrix used. The kinetics of the thermal decomposition of these blends was studied using the Hirata and the Broido models. Thermogravimetric results reveal that the thermo-oxidative treatment causes a decrease in the activation energy of the thermal decomposition process of both components in the blends, regardless of the type of polyethylene used. The thermooxidative treatment mainly modifies the thermal properties of starch during the degradation process in soil, especially in the LDPE blends. Synergetic degradation of these blends is a complex process that is dependent on the polyolefinic matrix used and mainly causes morphological changes.
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