Effect of Clay Dispersion on the Nonisothermal and Isothermal Crystallization Behaviors of Polyethylene Composites

The presence of nanosized clay fillers can greatly influence the crystallization behaviors and crystalline morphologies of polymer composites. In this study, the modified montmorillonite polyethylene nanocomposites have been prepared by melt mixing, followed by injection molding. The morphology and microstructure of the composites were characterized by scanning electron microscopy and Fourier transform infrared spectrometry. The nanosized clay particles act as a nucleating agent in the solidification process of the matrix. The relative crystallinity ratio decreases with the decrement of polymer loading. Nonisothermal and isothermal crystallizations were conducted to characterize the crystallization kinetics of nanocomposites. The effects of clay dispersion on the crystallization of polymer were quantified by Avrami and Hoffman models. The addition of 1 wt% clay into polymer matrix has significantly increased the activation energy. The crystallization rate constants (G) have been determined which are higher for the composites than that for the polymer matrix.