Experimental and computational analysis of the polymerization overheating in thick glass/Elium® acrylic thermoplastic resin composites

Abstract

The exothermic reaction and overheating during radical polymerization of an Elium® resin and glass fiber reinforced Elium® composites are critically evaluated in this work. The polymerization kinetics of the Elium® resin is obtained by performing differential scanning calorimetry (DSC) scans. The measured data is fit to a temperature and degree of polymerization (DoP) dependent kinetics model. A coupled thermo-chemical process model is developed to predict the temperature evolution and DoP. First, the model is validated with the water bath experiments in which the pure Elium® resin is polymerized at different temperatures (30, 50 and 70 °C). The validated process model is then applied to a vacuum infusion process of glass reinforced Elium® composite laminates with different thicknesses (3.8, 7.5 and 11.3 mm) at room temperature. The produced laminates have the void content lower than 1%. The peak temperature is found to be approximately in the range of 155-160 °C during the water bath experiments. On the other hand, the peak exothermic temperature is approximately 49 °C and 70 °C for 3.8 mm and 11.3 mm thick laminate, respectively. The developed polymerization kinetics model is found to be effective as the predicted temperature evolutions match well with the measured temperatures for different laminates. The effect of laminate thickness and processing teperature on the peak temperature is studied by the developed numerical model. The thermo-chemical process model developed in this work is therefore capable of predicting the polymerization overheating for Elium® composites and can enable the optimization of the manufacturing process to control the thermal and DoP histories.