Non-isothermal crystallization of ethylene-vinyl acetate copolymer containing a high weight fraction of graphene nanosheets and carbon nanotubes

The effect of the different geometrical dimensionality of two dimensional graphene nanosheets (2D GNSs) and one dimensional carbon nanotubes (1D CNTs) on the non-isothermal crystallization of an ethylene-vinyl acetate (EVA) copolymer at high loading (5 wt%) was studied. Transmission electron microscopy indicated a homogeneous dispersion of GNSs and CNTs in EVA obtained by a solution dispersion process. Fourier-transform infrared spectroscopy and differential scanning calorimetry measurements showed that 1D CNTs and 2D GNSs acted as effective nucleating agents, with a noticeably increased onset crystallization temperature of EVA. A high weight fraction of nano-fillers slowed the overall crystallization rate of composites. At the same crystallization temperature, the crystallization behavior of GNS/EVA composites was slowed compared to that of the CNT/EVA ones owing to larger nucleus barrier and activation energy of diffusion. Dynamic mechanical relaxation and rheology behavior of CNT/EVA and GNS/EVA composites demonstrated that the planar structure of the GNSs had an intensively negative effect on EVA chain mobility due to interactions between nanofillers and polymer chains, as well as spatial restriction.