Non-isothermal crystallization kinetics of high density polyethylene/titanium dioxide composites via melt blending

In this study, non-isothermal crystallization of neat high density polyethylene (HDPE) and HDPE/titanium dioxide (TiO₂) composite was studied using differential scanning calorimetry. Non-isothermal kinetic parameters were determined by Jeziorny approach and Mo's method. Polarized optical microscopy and wide angle X-ray diffraction were applied to observe the crystal morphology and investigate the crystal structure, respectively. It was found TiO₂ particles could act as nucleating agent during the crystallization process and accelerate the crystallization rate. The Avrami index indicated nucleating type and growth of spherulite of HDPE was relatively simple. The result of activation energy indicated it was more and more difficult for the polymer chains to crystallize into the crystal lattice as the crystallization progressed. HDPE/TiO₂ composites exhibited lower ΔE values, suggesting TiO₂ particle could make the crystallization of HDPE easier. HDPE/TiO₂ composites had much smaller spherulite size than that of neat HDPE. HDPE formed more perfect crystal when TiO₂ particles were added into its matrix without changing the original crystal structure of HDPE.