PMI foam is formed by heating and foaming methacrylic acid/methacrylonitrile copolymer board. During the foaming of the copolymerized sheet, the copolymer is converted into polymethacrylimide. The foaming temperature is above 170°C and varies with density and type.
In the linear elastic state, when the foam is made of liquid components (there are many such foams, such as polyurethane foam), the surface tension material can be pulled towards the edge, leaving only a thin film across the surface of the hole, which is easily broken. Thus, although the foam initially has closed cells, its stiffness is entirely due to the cells and ribs, and its modulus is comparable to that of open-cell foams. However, the pore surfaces of PMI foams are composed of real solid parts, and these pore surfaces add to the stiffness of the porous body.
The compression deformation mechanism of closed-cell foam is composed of three parts: cell wall bending, edge shortening and film extension, and the pressure of closed gas. Structural advantages of PMI foam sandwich structures In sandwich structures, PMI foam materials can be used as structural units.
PMI foam adopts unique solid foaming technology, which can guarantee the quality, uniformity and mechanical properties of the foam. PMI foam is a polymer rigid foam material with high specific strength and specific stiffness. After calculation, if PMI foam is used as the structural unit of the sandwich structure, the panel can cut 1-2 layers of carbon fiber laminates. The PMI foam sandwich structure can be used as a structural sandwich structure, and the application field has broken through the traditional views on non-structural sandwich structures such as honeycomb.
