Thermal degradation behaviors and biodegradability of novel nanocomposites based on various poly[(butylene succinate)-co-adipate] and modified layered double hydroxides

Synthesized via a polycondensation reaction, three biodegradable poly[(butylene succinate)-co-adipate] (PBSA) containing various succinic acid (SA) and adipic acid (AA) ratios were combined with an organically modified layered double hydroxide (m-LDH) to manufacture PBSA/m-LDH nanocomposites. The structures of these PBSA/m-LDH nanocomposites were studied via wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The WAXD and TEM analyses demonstrated that the various nanocomposites formed with exfoliated LDHs were effectively dispensed in the PBSA matrix. The effects of m-LDH on the biodegradation of PBSA/m-LDH nanocomposites were explored using lipase from Pseudomonas fluorescens. The degradation rates of the neat PBSA copolymers decrease in the order PBSA-25 > PBSA-50 > PBSA-75. The faster degradation rate of PBSA-25 is a consequence of the lower melting temperature and flexibility of its chain backbone. Moreover, weight loss decreases with increasing loading of m-LDH, suggesting that the presence of m-LDH hinders the degradation of the PBSA copolymers. On the basis of the molecular weight and polydispersity index of the remaining PBSA-based specimens, we propose that the degradation behavior of PBSA using P. fluorescens lipase is controlled by exo-type hydrolysis activity wherein PBSA copolymer degradation arises from both ends of the polymer chains. (C) 2017 Taiwan institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.