Comparative study of the use of infrared and microwave heating modes for the thermoforming of wood-plastic composite sheets

This work deals with a numerical study of the potential use of microwave radiation as a heating mode for the thermoforming of wood-plastic composites (WPC). It also shows the comparison between the infrared and microwave heating modes for polypropylene (PP) and PP-based bio-composite sheets. The latter contain PP with 30% wood-based reinforcements. The differentiating parameters between the investigated bio-composite sheets were their thicknesses and the size of their reinforcements. Their thicknesses were 1, 2, 5 and 10 mm, and the size of their reinforcements were 100, 200 and 500 mu m. The target heating temperature is 140 degrees C on the outer surfaces of the sheets. The results indicate that the microwaves generate a closely uniform temperature distribution in the sheets. Meanwhile, the minimum heating time is found for the bio-composites, which is 1 mm thick for the infrared mode, and the bio-composites whose reinforcements are 200 mu m for the microwave mode. (C) 2020 Elsevier Ltd. All rights reserved.