Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. VI. Polyurethane–poly(methyl acrylate‐co‐ethyl acrylate) semi‐1‐interpenetrating polymer networks

Dynamic mechanical and longitudinal sonic velocity measurements have been made on a series of semi‐1‐IPNs in which the network component is a polyurethane and the linear constituent a copolymer of methyl acrylate and ethyl acrylate. Dynamic mechanical analysis reveals phase separation. The shifting of the polyurethane glass transition in both the tan δ− and the E″–temperature plots indicates that some mixing occurs. The longitudinal sonic velocity results indicate that the polyurethane is present as a continuous phase in all the materials investigated.