Search results for "Termoplàstics"
showing 8 items of 28 documents
Water absorption and hydrothermal performance of PHBV/sisal biocomposites
2014
[EN] The performance of biocomposites of poly(hydroxybutyrate-co-valerate) (PHBV) and sisal fibre subjected to hydrothermal tests at different temperatures above the glass transition of PHBV (TH ¿ 26, 36 and 46 C) was evaluated in this study. The influences of both the fibre content and presence of coupling agent were focused. The water absorption capability and water diffusion rate were considered for a statistical factorial analysis. Afterwards, the physico-chemical properties of water-saturated biocomposites were assessed by Fourier-Transform Infrared Analysis, Size Exclusion Chromatography, Differential Scanning Calorimetry and Scanning Electron Microscopy. It was found that the water d…
Thermal analysis applied to the characterization of degradation in soil of polylactide: II. On the thermal stability and thermal decompositon kinetics
2010
[EN] 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 evolutio…
Reprocessed polylactide: Studies of thermo-oxidative decomposition
2012
The combustion process of virgin and reprocessed polylactide (PLA) was simulated by multi-rate linear non-isothermal thermogravimetric experiments under O2. A complete methodology that accounted on the thermal stability and emission of gases was thoroughly developed. A new model, Thermal Decomposition Behavior, and novel parameters, the Zero-Decomposition Temperatures, were used to test the thermal stability of the materials under any linear heating rate. The release of gases was monitored by Evolved Gas Analysis with in-line FT-IR analysis. In addition, a kinetic analysis methodology that accounted for variable activation parameters showed that the decomposition process could be driven by …
Thermal and thermo-oxidative stability of reprocessed poly(ethylene terephthalate)
2013
An exhaustive assessment of the behaviour of virgin and mechanically reprocessed poly(ethylene terephthalate) (PET) facing thermal and thermo-oxidative decomposition processes is presented in this work, as an approach for the energetic valorisation of post-consumer PET goods. Multi-rate linear-non-isothermal thermogravimetric (TGA) experiments under inert (Ar) and reactive (O2) conditions were performed to virgin PET and its recyclates in order to simulate the thermal behaviour of the materials facing pyrolysis and combustion processes. The release of gases was monitored by evolved gas analysis of the fumes of the TGA experiment, by in-line Fourier-transform infrared (IR) analysis, with the…
Tunable Structure and Properties of Segmented Thermoplastic Polyurethanes as a Function of Flexible Segment
2019
Segmented thermoplastic polyurethanes (PUs) were synthetized using macrodiols with different functional groups (carbonate, ester, and /or ether) as a segment with a molar mass of 1000 and 2000 g/mol, and 4,4&rsquo
Electrospun Poly(ethylene-co-vinyl alcohol)/Graphene Nanoplatelets Composites of Interest in Intelligent Food Packaging Applications
2018
Graphene nanoplatelets (GNPs) were synthetized from graphite powder and, thereafter, embedded in poly(ethylene-co-vinyl alcohol) (EVOH) fibers by electrospinning in the 0.1&ndash
Functionalised poly (vinyl alcohol)/graphene oxide as polymer composite electrolyte membranes
2019
[EN] Crosslinked poly(vinyl alcohol) (PVA) based composite films were prepared as polyelectrolyte membranes for low temperature direct ethanol fuel cells (DEFC). The membranes were functionalised by means of the addition of graphene oxide (GO) and sulfonated graphene oxide (SGO) and crosslinked with sulfosuccinic acid (SSA). The chemical structure was corroborated and suitable thermal properties were found. Although the addition of GO and SGO slightly decreased the proton conductivity of the membranes, a significant reduction of the ethanol solution swelling and crossover was encountered, more relevant for those functionalised with SGO. In general, the composite membranes were stable under …
Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites
2017
The decomposition behaviours of composites made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and sisal were assessed in terms of thermal stability and decomposition kinetics, under inert and oxidative conditions, by means of multi-rate linear non-isothermal thermogravimetric experiments. A statistical design of experiments was applied to study the influence of the addition of sisal (0-10-20-30%wt), the presence coupling agent (Yes/No) and the applied conditions of work (inert or oxidative). An improvement of the thermal and thermo-oxidative stability of PHBV with the addition of sisal was observed for all cases. An accurate methodology based on iso-conversional methods was applied…