Crystallization Behavior of Polylactide/Graphene Composites

Polylactide (PLA) composites containing graphene nanosheets were prepared by the approach of solution mixing for a crystallization study. The results revealed that the graphene nanosheets are well distributed in the PLA matrix, leading to an evident viscosity increase despite their dispersion as multilayered structures in stack form. Both the cold and melt crystallization behaviors of PLA were found to depend strongly on the presence of the graphene nanosheets. During cold crystallization, the graphene nanosheets merely act as an inert filler, and the increased viscosity results in a decrease of the overall crystallization rate of the composite relative to neat PLA. However, the graphene nanosheets can act as a heterogeneous nucleating agent, which is their dominant role during melt crystallization. As a result, the composite shows a higher crystallization rate than neat PLA under these conditions.