Shear-induced non-isothermal crystallization of poly(butylene adipate-co-terephthalate)

The influence of shear on non-isothermal crystallization of commercial poly(butylene adipate-co-terephthalate) (PBAT) was investigated. PBAT melt was sheared at 130 and 150 °C at rates of 10–100/s, and then cooled. The crystallization was followed by a light depolarization technique, whereas the crystallized specimens were analyzed by DSC, 2D-SAXS, 2D-WAXS, PLM and SALS. Shear flow shifted crystallization to higher temperature, and the effect was augmented by lower temperature of shearing as well as by higher shear rate and strain. Crystallization peak rate temperature of PBAT, sheared at 130 °C for 5 min at 100/s, increased by up to 12 °C. However, no evidence of crystal orientation due to shear was found, indicating that the shear induced the point-like nucleation. Only a small increase of melting peak temperatures, by up to 2–5 °C, was observed for the specimens sheared at the highest rates (≥50/s).