Effect of vapor grown carbon fiber on non-isothermal crystallization kinetics of HDPE/PMMA blend

In this article, the effects of vapor grown carbon fiber (VGCF) and poly(methyl methacrylate) (PMMA) on the non-isothermal crystallization kinetics of high density polyethylene (HDPE) have been investigated by means of Ozawa's equation. It is found that Ozawa's exponent n decreases with decreasing crystallization temperature for all the systems. For both pure HDPE and HDPE/PMMA (50/50) blends, the values of n are reduced by the addition of VGCF. At higher crystallization temperatures, for pure HDPE and its VGCF filled composite, n is near 2, indicating the heterogeneous nucleation followed by two-dimensional crystal growth. However, for unfilled HDPE/PMMA (50/50) blend, n is about 3, implying the heterogeneous nucleation followed by three-dimensional crystal growth. In addition, the values of n for unfilled and 1.5 phr VGCF filled HDPE/PMMA (50/50) blend do not change gradually with the crystallization temperature but exhibit an interruption at a certain temperature. This may suggest that a change of the crystallization mechanism occurs during the cooling process in such systems.