Biobased and Biodegradable Blown Films made of Polyester Blends

This work presents innovative measures for the development of biobased and biodegradable polyester blends. First, the state of the art and science regarding blends of polylactide (PLA) with poly(butylene succinate) (PBS) or poly(butylene adipate-co-terephthalate) (PBAT) was investigated. Second, unmodified PBAT/PLA blends were studied regarding their manufacturability to blown films. In this stage, methods for the comparison of the mechanical characteristics of different film samples were evaluated. Third, the miscibility of PBAT/PLA blends was calculated from solubility parameters using group contribution methods. The influencing parameters were assessed using phase diagram and spinodal curves. Subsequently, the effect of the composition and molecular weight on the miscibility was experimentally determined. Next, to improve the compatibility of PBAT/PLA blends, a catalyst masterbatch was developed based on transesterification reactions using titanium(IV) butoxide (TBT). The panel samples compatibilized in this way showed significant improvement in the morphological and mechanical properties. The fine-tuning of processing parameters in the blown film production process resulted in further significant improvement on the tear propagation resistance and film ductility as well as the degree of isotropy. The biodegradable blown films made of compatibilized PBAT/PLA blends have the potential for use as mulch film.