Synthesis and Characterization of Vinyl Ester Resins with Thiol- Based Tougheners

Cured vinyl ester resins (VERs) are thermosets that exhibit many desirable properties such as high glass transition temperatures, high mechanical strengths, and chemical stability. However, the current use of VERs is limited by their exhibition of low fracture toughness values.  Cured resins can be toughened utilizing many different techniques, but these methods often have detrimental effects to the aforementioned properties.  In this study, thiol-terminated aliphatic oligomers (TTAOs) were investigated as potential VER toughening agents.  The TTAOs were added to mixtures of bismethacryl glycidyl ether of bisphenol A (Vinyl Ester, VE828) and styrene (St) at various weight percentages and subsequently thermally cured using Trigonox® 239 (45% cumene hydroperoxide) as the radical initiator.  The extent of cure, densities, and thermomechanical properties of the cured TTAO-containing VERs were determined and compared to standard VE828:St resins. These results accompanied by our analyses will be presented.