Preparation and Characteristics of Flexible Polyurethane Foam Filled with Expanded Vermiculite Powder and Concave-Convex Structural Panel

Abstract We have synthesized a flexible polyurethane foam composite filled with expanded vermiculite powder and covered by concave-convex structural panel in order to improve the compression and cushioning property of PU foam. Concave-convex structural panel is that fabric cubes consisting of three layers of warp-knitted spacer fabrics arranged isometric apart between two layers of low-melting-point PET fabrics and then thermally processed at 180 °C. Effects of particle size and content of expanded vermiculite powders as well as the presence of concave-convex structural panel are examined in terms of foam structure and mechanical properties of composite PU foams. Expanded vermiculite addition decreases the energy required by pore nucleation, and the higher content of expand vermiculite results in pore diameter of foam and greater compression property. Filling of 2% vermiculites makes the compression property improved by 239% at 40% strain. Moreover, the smaller size of expanded vermiculite generates smaller and denser foam pore diameter and thus strengthened compression property. Foam composite with 800-mesh expanded vermiculites show the excellent compression property that 307% higher than neat PU foam at 40% strain. Concave-convex structural panel enhanced compression properties by 852% when fabric cubes arranged 1 cm apart and cushion efficiency by 29 % compared to pure PU foam when fabric cubes arranged 4 cm apart. The resultant flexible polyurethane foam can absorb 97% energy at 12J impact level. This composite can serve as the protective materials in kindergarten and old people's home.