Non-isothermal crystallization kinetics of recycled PET-Si3N4 nanocomposites

Poly(ethylene terephthalate) (PET) is an important industrial material and has been widely applied in consumer products. Due to its slow crystallization rate, nanoparticles are incorporated into PET to function as heterogeneous nucleating agents. In this study, the non-isothermal crystallization behavior of recycled PET-silicon nitride (Si3N4) nanocomposites was investigated by differential scanning calorimetry (DSC). In the general analysis of the non-isothermal crystallization curves, it was found that the Si3N4 nanoparticles could effectively accelerate the nucleation of PET, but the crystal growth rate was slowed down when the Si3N4 content was more than 1 wt%. This might be attributed to the interaction between the PET chains and the surface-treated Si3N4 nanoparticles. Results obtained from Avrami and Mo treatments agreed well with the general analysis. Application of the Kissinger method and isoconversional method of Flynn-Wall-Ozawa also showed that Si3N4 nanoparticles had a good nucleation effect on the crystallization of PET, and the crystal growth was hindered by Si3N4 when the particle loading is higher than 1 wt%.