A Review on the Effect of Heat Treatment for Thermoplastic Composites

Thermoplastic composites have recently attracted broad attention in aerospace, transportation, shipping, and other fields for their excellent mechanical properties and high recyclability. However, the properties of thermoplastic composites are unstable because of the problems such as microstructural differences and residual thermal stress after molding processing. Therefore, heat treatment, as a common method to modulate the microstructure and improve the properties of materials, is used to solve the problems. In this paper, the effects of different heat treatment methods were reviewed, including oven heating, microwave heating, and electric heating on the properties of various types of thermoplastic composites. The changes in material properties i.e., phase transformation, residual stress, interface bonding properties, etc. were discussed. Based on these investigations, electric heating experiments were carried out on the damaged samples of short carbon fiber reinforced polyethylene (SCFRPE) composites, and the mechanical properties of the samples before and after electric heating were analyzed. The results showed that the toughness increased, while the strength decreased after electric heating. These phenomena may be related to the changes of crystallinity and interfacial shear strength of the composites. This study can provide a reference for the manufacturing of SCFRPE based structures.