Blends of poly(butylene adipate--terephthalate) (PBAT) and stereocomplex polylactide with improved rheological and mechanical properties.

Biodegradable blends of poly(butylene adipate--terephthalate) (PBAT) and stereocomplex polylactide (sc-PLA) were prepared herein a melt blending method at various sc-PLA loadings. Wide-angle X-ray diffraction and differential scanning calorimetry results verified that complete stereocomplex polylactide crystallites in the PBAT could be achieved. Scanning electron microscopy observation indicated that sc-PLA was dispersed in the PBAT matrix as spherical particles; the dispersed size of the sc-PLA did not display a pronounced increase once the content of sc-crystallites reached a critical gel point. As solid fillers, sc-PLA could reinforce the PBAT matrix in a relatively wider temperature region and accelerate the non-isothermal crystallization of PBAT. The properties of PBAT were greatly improved after blending with sc-PLA, particularly when a percolation network structure of spherical filler had formed in the blends. In addition, all the blends showed higher yield stresses and moduli than those of the neat PBAT but exhibited reduction in elongations in tensile mechanical tests. These results would be interesting to the industrial polymer materials community, and may be of significant use and importance for the wider practical application of PBAT.