Crystallization of Poly(lactic acid) under continuous shear conditions: On-line x-ray analysis in isothermal conditions

•Synchrotron source was used to study PLA crystallization under different shear rates.•Experimental crystallinity evolutions showed that shear rate enhances kinetics.•A model and its parameters from previous studies was applied to describe kinetics.•The effect of nucleation rate under flow was shown to be determinant. In this work, the effect of shear rate on the isothermal crystallization of a poly(lactic acid), PLA, was analyzed. The crystallinity evolution of PLA during continuous shear was assessed by collecting X-ray diffraction data at short time intervals by adopting a synchrotron source. Shear rates in the range from 0.1 s−1 to 1.5 s−1 were analyzed. It was found that increasing the shear rate induced a dramatic decrease of the half crystallization times, more than one order of magnitude in the analyzed range of shear rates. A model for the description of crystallinity evolution was applied to describe the experimental results. It was found that the nucleation rate needed to describe the data are much larger than what measured in a previous work in the same range of shear rates but adopting a short step shear protocol.