Microwave-Induced Facile Molding of Lightweight and High-Strength Segregated-CNTs/Polycarbonate Foams

Polymer foams have attracted great attention in various fields due to the excellent properties brought by their unique microporous structures. However, the severe thermal stability of commodity thermoplastic polymer and foams hindered them from high-end applications. Polycarbonate (PC) is a widely recognized engineering plastic with an amorphous structure. Herein, a facile technique was proposed for preparing lightweight and high-strength segregated-CNTs/PC foams by microwave-induced selective heating and molding. The microstructures, mechanical properties, thermal properties, and sinter molding behaviors of the CNTs/PC foams were studied by investigating the effects of microwave power, irradiation time, and microwave absorbent contents. Upon in situ molding of the CNTs-coated expandable PC granules inside microwave transparent molds of various geometric shapes, CNTs served as solders to form CNTs/PC foam. By modifying the foaming parameters, CNTs/PC foams with densities ranging from 0.19 to 0.27 g/cm3 and cell sizes of 5–25 μm were successfully obtained. Mechanical testing revealing that the CNTs/PC foam prepared under 2880 W microwave power and a welding time of 25 s exhibited the optimal expansion ratio. Under the ablation test, the CNTs/PC foams showed good heat insulation. This study opens a new direction for the molding of high-performance and engineering thermoplastic foams.