Effect of thermal history on nucleation and kinetics of crystallization of Poly (lactic acid) Amirjalal Jalali1, Michel Huneault1, Saïd Elkoun2 1 Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Canada 2 Department of Mechanical Engineering, Université de Sherbrooke, Canada Abstract – Poly (lactic acid), (PLA), is a biocompatible and biodegradable polymer that can be produced from renewable resources. As a result, it has raised particular attention as a potential replacement for petroleum-based polymers. Nonetheless, PLA suffers from a low kinetics of crystallization. PLA crystallization in the melt state also results in two slightly different crystalline forms known as α and α’. So far, many routes have been explored to enhance crystallinity rate of PLA. In order to evaluate the efficiency of these different methods, in this paper we investigate nucleation and crystallization kinetics by using self-nucleation procedure. Differential Scanning Calorimetry (DSC) and optical microscopy are combined to evaluate crystallization behavior upon cooling for samples previously crystallized at various temperatures and then re-heated to a temperature in the partial melting range of PLA. Effect of thermal history on nucleation, crystallization rate as well as crystalline structure is discussed. Keywords: Self-nucleation, PLA, crystallization,