Thermal analysis of foamed polyethylene rotational molding followed by internal air temperature profiles

In this study, the internal air temperature (IAT) profile was measured to analyze the thermal behavior of a polymer for a complete rotational molding cycle. Foamed and unfoamed linear low density polyethylene parts were produced by biaxial rotational molding using a chemical blowing agent based on azodicarbonamide at different concentrations (0, 0.15, 0.25, 0.50, 0.75, and 1.0% wt) with different oven temperatures (270, 280, and 285 degrees C). The analysis proposed is based on the temperature profiles and their derivatives to better determine the different transitions occurring in a complete molding cycle. The analysis is completed with differential scanning calorimetry (DSC) to get more information related to the dynamics of the different processing stages like polymer melting, exothermic decomposition of the chemical blowing agent, and polymer crystallization. The results obtained show a good agreement between the melting and crystallization temperatures from IAT derivatives and DSC. POLYM. ENG. SCI., 58:E235-E241, 2018. (c) 2017 Society of Plastics Engineers