Title:
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Improvement of the thermal stability of branched poly(lactic acid) obtained by reactive extrusion
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Author:
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Carrasco Alonso, Félix Ángel; Cailloux, Jonathan; Sanchez Jimenez, P.E.; Maspoch Rulduà, Mª Lluïsa
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Other authors:
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Universitat Politècnica de Catalunya. Departament de Ciència dels Materials i Enginyeria Metal·lúrgica; Universitat Politècnica de Catalunya. POLYCOM - Polimers i compòsits: tecnologia |
Abstract:
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One-step reactive extrusion-calendering process (REX-calendering) has been used in order to obtain sheets of 1 mm from poly(lactic acid) modified with a styrene-acrylic multifunctional oligomeric agent. In a preliminary internal mixer study, torque versus time has been monitored in order to ascertain chain extender ratios and reaction time. Once all the parameters were optimized, reactive extrusion experiments have been performed. An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of PLA sheets manufactured by reactive extrusion. This improvement has consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(alpha) = c (1 - alpha)(n) alpha(m) that led to a better adjustment of experimental data and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential methods and n-order reaction kinetics. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function f(alpha) = 2 (alpha(1/2) - alpha), corresponding to a random scission mechanism for L = 2 (as well as other functions for L values up to 8), has been tested. Once optimized the kinetic model, the thermal degradation kinetics of sheets obtained by REX-calendering process was compared to that of conventional sheets and polymer matrix. (C) 2014 Elsevier Ltd. All rights reserved. |
Abstract:
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Peer Reviewed |
Subject(s):
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-Àrees temàtiques de la UPC::Enginyeria dels materials -Polymers--Deterioration -Branched poly(lactic acid) -Kinetics -Thermal degradation -Enhanced general analytical equation -Random scission -Reactive extrusion -COMBINED KINETIC-ANALYSIS -EVA CROSS-LINKING -MECHANICAL-PROPERTIES -THERMOGRAVIMETRIC DATA -POLY(L-LACTIC ACID) -ACTIVATION-ENERGY -DEGRADATION -PARAMETERS -MODEL -EPOXY -Polímers -- Deterioració |
Rights:
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Attribution-NonCommercial-NoDerivs 3.0 Spain
http://creativecommons.org/licenses/by-nc-nd/3.0/es/ |
Document type:
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Article - Published version Article |
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