Development of Rubber Pressure Molding Technique using Silicone Rubber to Fabricate Fiber-reinforced Plastic Components Based on Glass Fiber and Epoxy Resin

Abstract

In this study, a rubber pressure molding (RPM) technique is developed to prepare fiber-reinforced plastic components (FRP) using glass fiber and epoxy resin. The technique is based on the matching die set, where the die is made of hard metal-like steel and the punch from flexible rubber-like materials. The use of a flexible rubber punch helps to intensify and uniformly redistribute pressure (both the operating pressure and developed hydrostatic pressure due to the flexible rubber punch) on the surface of the product. A split steel die and rubber punch are designed and fabricated to prepare the FRP components. The same split die is also used to cast the rubber punch. Silicone rubber is used to prepare the rubber punch in this investigation. Burn test, coin test, scanning electron microscopy, and mechanical tests like interlaminar fracture toughness, interlaminar shear test (ILST), tension test, etc. are carried out to know the fiber content, void content, presence of delamination, bonding between fiber and resin, microstructure, and mechanical properties of the composite materials. These properties are also compared with the FRP components made by the conventional technique to evaluate its performances in structural applications.

Pressure distribution analysis of fiber reinforced plastic components made by rubber pressure moulding technique

“…When butyl rubber is replaced by natural rubber, interlaminar fracture toughness and interlaminar shear strength of FRP laminates decrease compared to the FRP specimen prepared by the conventional method without any change of tensile strength 7, 9. Whereas the FRP specimens prepared by RPM using silicone rubber have equal interlaminar fracture toughness and interlaminar shear strength compared to the specimens prepared by the conventional method 7, 10. In tension test, the FRP specimens have slightly higher value (∼ 10%–13%) of tensile strength, modulus of elasticity, and strain% 7, 10.…”

“…Even at higher curing pressure steel mold may not transfer uniform pressure over the complex shaped FRP components. It was found from experiment that the product made by RPM technique had void content less than 3%, free of delamination, and better bonding between fiber and resin 7–16. Mechanical strengths like interlaminar fracture toughness, interlaminar shear strength, and tension test are better in RPM technique using appropriate rubber and hardness of rubber mold 7–16.…”

“…1). 7–16 It is based on the matching die set, where the die is made of hard metal like steel and the punch from the flexible rubber like material. A split steel die and rubber punch were designed and fabricated to prepare the FRP product.…”

“…It was found from experiment that the product made by RPM technique had void content less than 3%, free of delamination, and better bonding between fiber and resin 7–16. Mechanical strengths like interlaminar fracture toughness, interlaminar shear strength, and tension test are better in RPM technique using appropriate rubber and hardness of rubber mold 7–16. Another major advantage of FRP component made by RPM technique is less standard deviation of any properties 7–16.…”

“…Mechanical strengths like interlaminar fracture toughness, interlaminar shear strength, and tension test are better in RPM technique using appropriate rubber and hardness of rubber mold 7–16. Another major advantage of FRP component made by RPM technique is less standard deviation of any properties 7–16. The FRP specimens of glass fiber and epoxy resin prepared by RPM using butyl rubber with 45 phr loading of carbon black (N 330) have equal interlaminar fracture toughness, same or marginally higher (5%) interlaminar shear strength, slightly higher value (∼ 10–13%) of tensile strength, modulus of elasticity, and strain% compared wiht the FRP specimen prepared by the conventional method 7, 8.…”