Fiber Reinforced Polymer - Fabrication Methods and Properties

By Collin Davis

Glass Fiber Reinforced Polymer is a substance composed of a plastic matrix that is embedded with glass fibers to provide strength and reinforcement. Fiber reinforced polymer is used to build architectural elements, car parts, bridges, and consumer products. This article will outline the methods used to fabricate GFRP and the physical properties of fiber reinforced polymer that can help determine its quality.

GFRP Fabrication: How It's Made

Although all types of Glass Fiber Reinforced Plastic are composed of a plastic matrix and glass fibers, there are actually several fiber reinforced polymer manufacturing methods that are commonly used.

The first method of manufacturing Glass Fiber Reinforced Polymer is what is known as the hand lay-up method. Although very precise, this method is also quite labor intensive. In the hand lay-up method, a resin that has been combined with a catalyst is placed inside of a mold. Fiberglass is then packed into the mold with steel rollers. This process may be repeated one or more times. The resin will usually start to cure quite quickly, depending on the exact amount of catalyst used, so the task must be completed relatively fast when this method of GFRP fabrication is used.

Another common method of GFRP fabrication is the spray lay-up process. It is similar to the former method in many respects. The main difference is how the resin and glass fibers are placed into the mold. Instead of being placed into molds by hand, these substances are sprayed in. Not surprisingly, this method of fabricating fiber reinforced polymer is faster than the previous.

One other GFRP fabrication process that may be used is what is known as resin transfer molding. In this method, glass fibers only are added to a mold. The mold is closed, and the resin matrix is injected under pressure. Once the resin cures, the product is removed from the mold.

Properties of GFRP

The quality and strength of architectural fiberglass and other types of GFRP can vary widely depending on the quality of the resin used, the fabrication method employed, and the level of expertise of the individual who made the GFRP. The quality of all types of fiberglass reinforced polymer can be determined by evaluating a number of the material's properties, including:

• Compressive strength: How much stress can be placed on the FRP before it is crushed?
• Tensile strength: How much can the FRP be stretched before it breaks?
• Flexural strength: How far can the Glass Fiber Reinforced Polymer bend before breaking?
• Impact strength: How big of a force, either on its edge or its front surface, can the GFRP withstand before breaking?

Ideally, GFRP will rate well in each of the above categories. Before buying GFRP products, it is always a wise idea to ask about the company's level of experience working with fiber reinforced polymer and their past projects to help ensure the GFRP products being sold are of the highest quality.

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