Crystallization of equimolar poly(l-lactide)/poly(d-lactide) blend below the melting point of α crystals under shear

[Display omitted] •The crystallization behavior of 1:1 PLLA/PDLA mixture under shear was investigated.•The nucleation density and crystallization rate increased with shear rate.•The phase content of SC increased with shear rate.•The α content displayed a bell-shaped curve with increasing shear rate. The isothermal crystallization behavior of a 1:1 poly(l-lactide)/poly(d-lactide) (PLLA/PDLA) mixture under pulsed shear was investigated by in-situ polarized light optical microscopy (POM) and wide angle X-ray scattering (WAXS). The effects of shear rate and temperature were studied. The results showed that application of shear flow increased the nucleation density, crystallization rate and degree of orientation for both stereocomplex crystals (SC) and α crystals. Interestingly, when the crystallization temperature was below the melting temperature of α crystals, the phase content of SC increased with shear rate, while the α content displayed a bell-shaped curve with regard to shear rate. The structure formation in this system was closely related to the shear-induced nucleation, phase mixing and chain mobility.