Effects of dodecyl amine functionalized graphene oxide on the crystallization behavior of isotactic polypropylene

Dodecyl amine functionalized graphene oxide (DA-GO)/isotactic polypropylene (iPP) nanocomposites were prepared via solution mixing method. Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) verified that the DA was successfully grafted onto the surface of graphene oxide. The crystallization behavior of iPP/DA-GO nanocomposites was investigated by differential scanning calorimetry (DSC) and polarized optical microscope (POM). The DSC results of both isothermal and non-isothermal crystallization process indicated that the addition of DA-GO can decrease the half-time crystallization (t_1/2) and elevate crystallization peak temperature (T_p) of iPP. The results of isothermal crystallization kinetics showed that the overall crystallization rates of iPP/DA-GO nanocomposites, especially with higher DA-GO content, were much faster than that of neat iPP. During the non-isothermal crystallization process, the nucleation ability (Φ) of nanocomposites containing 0.05, and 0.5 wt % DA-GO were 0.83 and 0.69, respectively. And the crystallization activation energy ΔEa of iPP decreased from 348.7 (neat iPP) to 309.2 and 283.1 kJ/m by addition of 0.05 and 0.5 wt % DA-GO, respectively. The decrease of Φ and ln t indicated DA-GO has strong heterogeneous nucleation effect and can promote the crystallization of iPP significantly. Additionally, POM micrographs showed the DA-GO in iPP matrix can form more nucleation sites for the spherulite growth. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40000.