Strong and flame-retardant thermally insulating poly(vinylidene fluoride) foams fabricated by microcellular foaming

Thermally insulating polymer foams are instrumental in conserving energy and reducing peak carbon dioxide emissions owing to their light weight, environmental friendliness, and ease of processing. However, as most polymers are organic and flammable, the fire hazards associated with commonly used polymer foams are significant. Accordingly, intrinsic flame-retardant poly(vinylidene fluoride) (PVDF) is considered ideal for fabricating thermally insulating materials. In this study, lightweight, thermally insulating, flame-retardant, and strong PVDF foams were prepared using microcellular foaming. To analyze the crystallization behavior, various saturation pressures and temperatures were applied to investigate their effects on the foaming behavior of PVDF. PVDF foams with expansion ratios of 5–28.8 and cell sizes of 10–250 μm were prepared using microcellular foaming. Moreover, the crystal forms, thermal insulation, flame retardancy, and compressive performance of the structure-tailored PVDF foams were investigated. The foaming process induces the generation of β-phase crystals, and the PVDF foams exhibit excellent thermal insulating (thermal conductivity of 33 mW⋅m−1⋅K−1), flame-retardant, and compressive properties. High-performance PVDF foams can be potentially used for producing advanced flame-retardant thermally insulating materials via green and cost-efficient microcellular foaming.