RESUMEN
This study addresses the fabrication of extruded films using poly(lactic acid) (PLA) and chitosan, with and without maleic anhydride as a compatibilizing agent, for potential applications in disposable food packaging. These films underwent controlled conditions of UV irradiation, water condensation, and temperature variations in an accelerated weathering chamber. The investigation analyzed the effect of different exposure periods on the structural, morphological, mechanical, and thermal properties of the films. It was observed that PLA films exhibited a lower susceptibility to degradation compared to those containing chitosan. Specifically, the pure PLA film showed an increase in elastic modulus and strength during the initial 144 h of exposure, associated with cross-linking induced by UV radiation. On the other hand, film Q2 composed of PLA, chitosan, and maleic anhydride and Q1 without maleic anhydride experienced a tensile strength loss of over 50% after 244 h of exposure. The Q2 film exhibited greater homogeneity, leading to increased resistance to degradation compared to that of Q1. As the degradation time increased, both the Q1 and Q2 films demonstrated a decline in thermal stability. These films also exhibited alterations in crystallinity attributed to the chemo-crystallization process, along with fluctuations in the glass transition temperature and crystallization, particularly at 288 h.
RESUMEN
Conductive polymers, such as polypyrrole and polyaniline, have been extensively studied for their notable intrinsic electronic and ionic conductivities, rendering them suitable for a range of diverse applications. In this study, in situ chemical polymerization was employed to coat extruded PLA films with PPy and PANi. Morphological analysis reveals a uniform and compact deposition of both polyaniline and polypyrrole after polymerization periods of 3 and 1 h, respectively. Furthermore, the PLA-PANi-3h and PLA-PPy-1h composites exhibited the highest electrical conductivity, with values of 0.042 and 0.022 S cm-1, respectively. These findings were in agreement with the XPS results, as the polyaniline-coated film showed a higher proportion of charge carriers compared to the polypyrrole composite. The elastic modulus of the coated films showed an increase compared with that of pure PLA films. Additionally, the inflection temperatures for the PLA-PANi-3h and PLA-PPy-1h composites were 368.7 and 367.2 °C, respectively, while for pure PLA, it reached 341.47 °C. This improvement in mechanical and thermal properties revealed the effective interfacial adhesion between the PLA matrix and the conducting polymer. Therefore, this work demonstrates that coating biopolymeric matrices with PANi or PPy enables the production of functional and environmentally friendly conductive materials suitable for potential use in the removal of heavy metals in water treatment.