Non-isothermal crystallization of HDPE/nano-SiO2 composite

The kinetics of non-isothermal crystallization of high density polyethylene/nano-scale silicon dioxide (HDPE/nano-SiO2) composite was investigated by means of differential scanning calorimetry at various cooling rates. Several theoretical models were applied to describe the process of non-isothermal crystallization. The results showed that the Avrami analysis modified by Jeziorny or by Mo's treatment could describe the non-isothermal crystallization of the composite very well, but the Ozawa analysis did not give an adequate description. The Avrami exponent n of HDPE/nano-SiO2 composite is slightly larger than that of HDPE. The values of half-time t 1/2 and Z c showed that the crystallization rate increased with increasing cooling rates for both HDPE and HDPE/nano-SiO2 composite, but the crystallization rate of HDPE/nano-SiO2 composite was faster than that of HDPE. The activation energies were estimated to be 166.3, 206.2, 251.1 and 266.0 kJ/mol for non-isothermal crystallization of pure HDPE and HDPE/nano-SiO2 composites with different SiO2 loadings of 1%, 3%, and 5% respectively.