Recycling of unsaturated polyester resin using propylene glycol

Abstract Cured unsaturated polyester resin was degraded with propylene glycol, and the degraded material was used to make recycled resin by reaction with maleic anhydride. The curing reaction for the recycled resin was faster than that of the neat resin. The mechanical properties of mixtures of neat and recycled resins were measured and, among them the (90 wt% neat/10 wt% recycled) mixture showed the highest impact strength. The addition of 15 wt% of glass fibre to the recycle mixtures further increased the impact strength, with the (90 wt% neat/10 wt% recycle) mixture again exhibiting the highest value.