Influence of blending and blend morphology on the thermal properties and crystallization behaviour of PLA and PCL in PLA/PCL blends

In this paper, we reported on the influence of PCL on the cold crystallization behaviour of PLA in different PLA/PCL blends, and on the influence of blending with PLA on the PCL crystallization behaviour and kinetics. The presence of PCL in the blends had a strong influence on PLA cold crystallization, and the extent of this influence was determined by the blend morphology. Successive self-nucleation and annealing (SSA) analysis of PCL crystallization in the blends showed that the presence and amount of PLA in the blends had a strong influence on the crystal size distribution in the main crystalline fraction of PCL. A kinetic analysis of the crystallization of neat PCL and PCL in the blends showed that the crystallization mechanism of the neat PCL changed from instantaneous/heterogeneous nucleation and two-dimensional growth to sporadic/homogeneous nucleation and two-dimensional growth with decreasing crystallization temperature, while for PCL in the blends, the mechanism over the whole crystallization temperature range was that of instantaneous/heterogeneous nucleation and three-dimensional growth into spherulites. PCL in the blends also crystallized significantly faster than neat PCL, but there was little difference between the crystallization rates of PCL in the different blends.