NEW UNSATURATED POLYESTER RESINS BASED ON TMPD GLYCOL FOR FRP COMPOSITES.

Preparation, properties and applications of an unsaturated polyester resin are described which is based on 2, 2, 4-trimethyl-1,3-pentadiol (TMPD) glycol. The resin, tradenamed GP-1-1T, has been prepared in one-half to 1/3 of the time normally required to prepare conventional poly(propylene maleate) polyesters. Solutions of GP-1-1T in styrene appear to have excellent storage stability with good resistance to gel time drift and no haze formation after 10 to 12 months. This branched-chain, low viscosity polyester has very good glass fiber wetting characteristics; it has been used successfully as a laminating resin, in wet molding processes, and in pigmented and natural SMC and BMC composites. The branched-chain structure of the polymer has been shown to enhance cure characteristics with various commercially used initiators. Physical, curing and mechanical properties of both pure resin and GFRP made of sheet molding compounds and bulk molding compounds are tabulated.