Unusual crystallization behavior of biodegradable poly(ethylene adipate) based nanocomposites induced by graphene oxide

In the present research, we successfully prepared a series of graphene oxide (GO)/biodegradable poly(ethylene adipate) (PEA) nanocomposites through a simple solution and precipitation process. The scanning electron microscopy observation revealed a fine dispersion of GO with a layered structure throughout the PEA matrix. The crystal structure, nonisothermal melt crystallization behavior, overall isothermal melt crystallization kinetics, spherulitic morphology, and spherulitic growth rate of the PEA/GO nanocomposites were investigated in detail and compared with those of neat PEA. Induced by the heterogeneous nucleation of GO, the crystallization processes of the nanocomposites were enhanced, when the samples were nonisothermally crystallized at a cooling rate of 5 degrees C min(-1) or isothermally crystallized at crystallization temperature values ranging from 32 to 40 degrees C; however, the nanocomposites and neat PEA exhibited the same crystallization mechanism and crystal structure. Within the investigated temperature range of 24 to 32 degrees C, banded spherulite morphologies were observed for neat PEA and its nanocomposites. Moreover, it was interesting to find that GO not only enhanced the nucleation density as a nucleating agent but also increased the spherulitic growth rate of the nanocomposites by exhibiting a superstructure templating effect.