Elastomer toughening of isophthalic polyester resin

Isophthalic unsaturated polyester resins are used as a matrix for high quality, fiber-reinforced plastics. The objective of this investigation is to improve the fracture toughness and impact resistance of cured isophthalic resin by blending with elastomers. The rubbers used for modification of polyester resin are nitrile rubber, styrene butadiene rubber, natural rubber, chloroprene rubber, and butyl rubber. These elastomers are masticated in a two-roll mill, dissolved in styrene, and solution blended with isophthalic resin. The physical properties of the cured blends are compared with those of the neat resin. The performance of nitrile rubber blends with isophthalic resin is found to be far superior to all other rubber blends studied. A considerable enhancement of toughness, impact resistance, and tensile strength has been achieved without seriously affecting any other property.