The Curing for Modified Vinyl Ester Resin by Hexamethylene Diisocyanate and Its Influence on Performances

Abstract

The commercial vinyl ester resins (VER) was modified by diphenylmethane diisocyanate (MDI) to enhance its toughness, which is called MVER. Hexamethylene diisocyanate (HDI), a common curing agent for polyurethane (PU), was found to be a reactive agent for MVER and can contribute to the toughness of MVER. Based on present experiment results, the crosslinking mechanism of MVER and HDI system is very similar to that of PU. The FTIR result shows the −NCO of HDI can react with the −OH of MVER. The microstructure of material prepared by MVER and HDI was characterized by NMR, and it was revealed that the unique microstructure leads to the good performances. The different content of HDI has an influence on the microstructure, and the microstructure gradually reduces the toughness and mechanical performances of the MVER cured with increasing concentration of reactive curing agent (HDI). This feature is consistent with a maximum in toughness as a function of the additive (HDI) content, followed by a rapid deterioration in toughness at higher concentrations. The toughness exhibits the maximum at such an HDI concentration (20wt%). Therefore, the special curing agent (HDI) and reactive mode is very important to the microstructure and mechanical properties of material. Furthermore, there should be other reactions which contribute to the curing and microstructure of the material, which needs the further research.

Keywords

modified vinyl ester / hexamethylene diisocyanate / mechanical properties / toughness