Development of Rubber Pressure Molding Technique using Butyl Rubber to Fabricate Fiber Reinforced Plastic Components based on Glass Fiber and Polyester Resin

A new technique called rubber pressure molding (RPM), has been developed to fabricate fiber reinforced plastic (FRP) products from glass fiber/polyester resin. The technique is based on the matching die set, where the die is made from mild steel and the punch from a flexible rubber-like material, i.e., butyl rubber, to apply hydrostatic pressure on the various surfaces of a complex shaped product. A split steel die and rubber punch are designed and fabricated to prepare the FRP product. The same split die is also used to cast the rubber punch. Using this new technique, an FRP product called a flanged cone is made from glass fiber. Burn test, coin test, scanning electron microscopy (SEM), and mechanical tests like interlaminar fracture toughness, interlaminar shear test, tension test, etc. were carried out to ascertain the fiber content, void content, presence of delamination, bonding between fiber and resin, microstructure, and mechanical properties. These properties were also compared with FRP components made by the conventional technique to evaluate its performance in the structural applications. It is found that the interlaminar fracture toughness of the specimens made by RPM is 10% higher than the specimens made by the conventional method. The tensile strength of the specimen made by RPM technique is 27% more than the specimen made by the conventional method, whereas tensile modulus and Poisson’s ratio are in agreement. Furthermore, the interlaminar shear strength of the specimen made by RPM technique is 33% higher than the specimens made by the conventional method.