HIGH PERFORMANCE FATTY ACID-BASED VINYL ESTER RESIN FOR LIQUID MOLDING

摘要

Liquid resins used for molding composite structures are a significant source of volatile organicrncompounds (VOC) and hazardous air pollutant (HAP) emissions. One effective method ofrnreducing styrene emissions from vinyl ester (VE) resins is to replace some or all of the styrenernwith fatty acid-based monomers. In our investigation, the styrene was reduced to 20-25 wt%rncompared to 40-60 wt% associated with commercial products. In addition, fatty acid-basedrnmonomers can bring about other benefits like higher toughness, lower exothermal heat and lowrnvolume shrinkage. One disadvantage of fatty acid-based VE resins, however, is the reduction inrnglass transition temperature (Tg) which limits their use in high temperature environments.rnTherefore, the specific focus of this work was to design high Tg fatty acid-based VE resins withrnlow viscosities and high fracture properties. These high Tg resins were designed by blendingrnfatty acid monomers with novolac vinyl esters. Various low viscosity formulations werernestablished with Tgs as high as 147℃. Moreover, approaches to further improve the fracturerntoughness of the resin were investigated. Vinyl terminated poly(butadiene-co-acrylonitrile)rn(VTBN) and epoxy terminated poly(butadiene-co-acrylonitrile) (ETBN) were used as modifiersrnto these fatty acid vinyl ester resins. Compared with commercial novolac VE resin, markedrnimprovement in fracture toughness (167 J/m~2 versus 56 J/m~2) was achieved.