Compatibilization, processing and characterization of poly(butylene adipate terephthalate)/polylactide (PBAT/PLA) blends

A blend of poly(butylene adipate terephthalate) (PBAT) and polylactide (PLA) is a combination of biodegradable materials. This study aims to prepare compatibilized PBAT/PLA in a cost-effective and timesaving way and to process the material into blown films by fine-tuning the processing parameters. First, a catalyst masterbatch is prepared by transesterification of PBAT and PLA in the presence of tetrabutyl titanate (TBT) as a catalyst. This is followed by the compounding of the two polymer types in combination with the catalyst masterbatch. Third, the compounds are processed into blown films and panels. The processing parameters for film blowing are set to reduce the anisotropy. Finally, the material properties are evaluated such as mechanical tests. The fine-tuning of parameter settings including the blow-up ratio and draw-down ratio results in a higher degree of isotropy of the blown film. By adding the catalyst masterbatch (2 wt%, which corresponds to TBT of approximately 0.002 wt% with copolymers formed) in combination with the fine-tuning of parameter settings, the samples achieved a significant improvement on the material properties. The morphology of the cryogenically fractured panel samples shows a decrease in the diameter of the dispersed phase. In the cross and machine directions, the elongation at break increased by 85 and 93%, and the trouser tear propagation resistance increased by 2.4 and 10 N mm(-1), respectively. Furthermore, both the elongation at break and the trouser tear propagation of the blown films achieved a higher degree of isotropy.