Kinetics of the Thermal Degradation of Poly(lactic acid) and Polyamide Bioblends.

Félix Carrasco,Maria Maspoch,Orlando Santana Pérez

doi:10.3390/polym13223996

Félix Carrasco, Maria Maspoch + Show 1 more

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https://doi.org/10.3390/polym13223996

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Abstract

Poly(lactic acid) (PLA) and biosourced polyamide (PA) bioblends, with a variable PA weight content of 10–50%, were prepared by melt blending in order to overcome the high brittleness of PLA. During processing, the properties of the melt were stabilized and enhanced by the addition of a styrene-acrylic multi-functional-epoxide oligomeric reactive agent (SAmfE). The general analytical equation (GAE) was used to evaluate the kinetic parameters of the thermal degradation of PLA within bioblends. Various empirical and theoretical solid-state mechanisms were tested to find the best kinetic model. In order to study the effect of PA on the PLA matrix, only the first stage of the thermal degradation was taken into consideration in the kinetic analysis (α < 0.4). On the other hand, standardized conversion functions were evaluated. Given that it is not easy to visualize the best accordance between experimental and theoretical values of standardized conversion functions, an index, based on the integral mean error, was evaluated to quantitatively support our findings relative to the best reaction mechanism. It was demonstrated that the most probable mechanism for the thermal degradation of PLA is the random scission of macromolecular chains. Moreover, y(α) master plots, which are independent of activation energy values, were used to confirm that the selected reaction mechanism was the most adequate. Activation energy values were calculated as a function of PA content. Moreover, the onset thermal stability of PLA was also determined.

Highlights

The generation of polymers derived from renewable sources, called bio-based polymers, is an important field of research due to the role that these ecofriendly polymers play in reducing plastic residues, which are a source of pollution, and carbon dioxide production, which leads to a decrease in the carbon footprint of its lifecycle [1,2]
The goal of this paper was to determine the thermal stability of poly(lactic acid) (PLA)/PA bioblends containing between 50% and 90% rheologically modified PLA
Reactive extrusion was employed, with the addition of 10–50% of biobased PA as a second were prepared by melt blending in order to overcome the extreme brittleness of PLA

Summary

Introduction

The generation of polymers derived from renewable sources, called bio-based polymers, is an important field of research due to the role that these ecofriendly polymers play in reducing plastic residues, which are a source of pollution, and carbon dioxide production, which leads to a decrease in the carbon footprint of its lifecycle [1,2]. Its main features are its biodegradable nature, the decrease in the CO2 footprint associated with the product, and the non-toxic residues released during processing [3,4,5,6]. Blending PLA with other engineering soft polymers represents an industrially relevant strategy for developing bio-based formulations with tailored performances [12]. To overcome the aforementioned issue, Pai et al [14]

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