Suspension copolymerization of unsaturated resins with styrene and acrylonitrile

Investigations are reported on the polymerization kinetics of an unsaturated polyester resin, containing both styrene and acrylonitrile (AN), and on the possibility of making it water-dilutable in order to use it for impregnating organic fibre materials. It is found that the unsaturated polyester resin, containing 31 wt.-% styrene, can be diluted with almost no limits with acrylonitrile, but when the quantity of acrylonitrile is up to 14% the products are homogeneous and mono-phase. After alkalizing with ammonium, the unsaturated polyester resin, containing acrylonitrile, becomes soluble in water in which it forms a fine emulsion. On polymerization of the resin, phase reversal takes place, water remaining dispersely included in the hardened resin. The copolymerization rate as a function of the water quantity is studied.