A Novel Elastic Urea–Melamine–Formaldehyde Foam: Structure and Properties

Abstract

Melamine was chemically introduced into a urea–formaldehyde system via co-condensation reactions during curing and foaming process, and a novel elastic urea–melamine–formaldehyde (UMF) foam with improved thermal stability, insulation property, and flame retardancy was fabricated. It was found that with a decrease of the mass ratio of urea formaldehyde resin and melamine formaldehyde resin (UF/MF), the curing process of UMF was prolonged, and a high curing temperature was necessary. The UMF foam exhibited an interconnected network structure with increasing cell size and size distribution, higher open cell porosity, and lower apparent density compared with pure UF foam. Evident recoverable deformation can be observed for UMF foam during the compression testing, which was resulted from the elasticity and toughness. By addition of melamine, the thermal conductivity decreased, while the decomposition temperature, char yield, and LOI increased, and during burning, the expansion of the flame was suppressed. With increasing content of MF resin, the sound absorption coefficient increased at first and then declined.