Effect of graphene nanoplatelets diameter on non-isothermal crystallization kinetics and melting behavior of high density polyethylene nanocomposites

In the present study the effect of different size of graphene nanoparticles 5, 15 and 25 μm in diameter, on melting behavior and crystallization kinetics of high density polyethylene (HDPE) was investigated. Crystallization of HDPE and its graphene nanocomposites in non-isothermal conditions was studied at several constant cooling rates from 1 to 20 K/min by means of differential scanning calorimetry. The results showed that the Avrami analysis modified by Jeziorny and a method developed by Mo could describe the non-isothermal crystallization of nanocomposites very well. Kinetics data analysis showed that the overall crystallization rate, the activation energy and the fold surface-free energy of the HDPE polymer were apparently changed due to the addition of graphene filler in different diameter size. Particularly, the incorporation of all graphene nanoparticles resulted in a greater crystallization temperature of HDPE, but graphene nanoparticles M5 with the smaller diameter increase more the number of heterogeneous crystallization nuclei and this resulted in a higher crystallization rate.