Reactive extrusion of poly (butylene succinate-co-adipate) and poly (ε-caprolactone) biodegradable blends through titanium-based transesterification catalyst

Abstract

This article addresses the development of biodegradable blends of poly (butylene succinate-co-adipate) (PBSA) and poly (ε-caprolactone) (PCL) processed by reactive extrusion in the presence of titanium butoxide (TiOBu4) (TBT) in twin-screw equipment. The PBSA/PCL concentration was set to 60/40 (wt.%), and 0%, 0.1%, 0.3% and 0.5% of TBT were added to the polymer weight. FTIR analysis revealed slight changes around the carbonyl peak correlated to the generation of copolymers. The results of MFR showed an increase in viscosity for higher TBT concentrations, and tensile tests indicated improved yield stress and yield elongation from up to 0.3% TBT concentration, with similar Young modulus. The storage modulus was similar at room temperature for blends with and without TBT. The thermal properties showed insignificant changes among the formulations. The crystallization behavior seemed to be influenced by a chain scission and copolymer generation competition promoted by transesterification, and altered the microbial susceptibility to a certain extent. PLOM and SEM results showed a blend morphology evolution from a co-continuous-like to a co-continuous-to-dispersed-like when the TBT concentration increased. Overall, TBT was an effective transesterification catalyst for the generation of a cohesive morphology with good mechanical properties, with no loss of microbial susceptibility.