Hybrid resins from polyisocyanate,vinyl ester,melamine formaldehyde and water glass: structure and properties

Abstract

Hybrid thermosets were produced from polymeric methylene diphenyl isocyanate (PMDI), styrene cross-linkable vinyl ester (VE) and water glass (WG) using melamine formaldehyde (MF) resin as additional reactive emulsifier. Vinyl ester (VE) was added to the PMDI/MF mixture in which the WG was dispersed next. The content of MF in the resin formulation was varied between 0·5 and 15 wt-%. The resulting water in oil type (W/O) emulsion (water=WG, oil=organic phase composed of PMDI+VE+MF) was cured at room temperature for 24 h followed by post-curing at T=100°C for 4 h. The chemorheology of the hybrid resins was assessed by plate/plate rheometry. Information on the morphology of the cured hybrid resins was received from scanning electron microscope (SEM), atomic force microscopic (AFM) and dynamic mechanical thermal analysis (DMTA) studies. The mechanical and fracture mechanical properties as well as the resistance to thermal degradation of the hybrid thermosets were determined and discussed.