Heat Transfer Effects During Solidification of Semicrystalline Polymers

The build-up of the residual stresses in the plastic parts are directly affected by the transient temperature distribution during the solidification stage of the semicrystalline polymers. Hence for crystallizable polymers, it is important to couple the crystallization kinetics with the transport of heat flow to determine the thermal history during solidification. In this paper, an experimental study of solidification of two semi-crystalline polymers under quiescent conditions is carried out to examine the influence of crystallization kinetics on the thermal history. The selected model materials are Nylon-66 and Poly Ethylene Terephalate (PET). The temperature profiles and the location of the solidification front are recorded during the cooling process. The experimental results are compared with the classical heat diffusion model and also with a numerical approach which couples the crystallization kinetics to the heat diffusion equation by modifying the phase change temperature based on the overall cooling rate in the crystalline domain. The front movement and the solidification temperature predictions of the coupled model are in good agreement with the experimental observations.