EFFECT OF ALPHA-METHYL STYRENE ON PROPERTIES OF EPOXY-NOVOLAC BASED VINYL ESTER RESINS

The paper describes the synthesis of vinyl esters using epoxy-novolac resin. The curing behaviour of the resins containing different portion s of styrene and alpha-methyl styrene (alpha-MS) as reactive diluents was studied by gel time determination. Delayed curing was observed in samples containing increasing proportions of alpha-MS. An increase in the alpha-MS content resulted in a decrease in the tensile strength an d increase in heat deflection temperature of the cured sheets. The fle xural strength and flexural modulus of both resin and glass fibre-rein forced composites (resin content approx. 41 wt.-%) increased. Treatmen t with boiling water (12 h) of laminates resulted in a decrease in int erlaminar shear strength with an increase in alpha-MS content.