Poly(butylene adipate-co-terephthalate)/thermoplastic starch/zeolite 5A films: Effects of compounding sequence and plasticizer content.

This work investigated the effect of the compounding sequence and the glycerol content on poly(butylene adipate-co-terephthalate)/thermoplastic starch/zeolite 5A (PBAT/TPS/Z5A) composites. The composite pellets and films were prepared by an extrusion process using a PBAT:TPS ratio of 60:40, Z5A loading of 3 wt%, and glycerol contents of 35 and 40 parts per hundred parts of starch (phs). Prior to blown film extrusion, the composite pellets were produced by two compounding sequences: sequence I (SI)-mixing PBAT with Z5A prior to blending with TPS; sequence II (SII)-mixing TPS with Z5A before blending with PBAT. The SII compounding sequence provided improved mixing between PBAT and TPS, leading to increased continuous phase region and a reduced TPS dispersed phase size. Increasing the glycerol content decreased the viscosity and size of the TPS dispersed phase and gave rise to a more uniform dispersion of the TPS domains and Z5A particles. Compounding Z5A via the SII sequence with a glycerol content of 40 phs effectively improved the mixing and the performance of the PBAT/TPS blend.