Applications Using Glass Fiber-Reinforced Polymers

2 APPLICATIONS USING GLASS FIBER-REINFORCED POLYMERS 

Many of these applications require polymers meeting particularly high property standards, for example, stability, tensile strength and impact properties, thermal properties, dimensional stability, and chemical and oil resistance. 

An appreciable amount of work has been carried out on the use of polyamides in engineering applications such as automotive parts, precision engineering applications, and high-strength and -stiffness applications such as fan blades, gears, and bearings. 

Polypropylene 20% talc Stiffness at elevated temperature, automotive under-bonnet application, air ducting channels 

Polypropylene 20% glass fibers Automotive under-bonnet application 

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Components of switches, relays, and connectors use glass fiber reinforced semicrystalline polymers, such as PA, PPS, PBT, and PET. The following requirements are important in these applications dimensional stability and precision, low moisture absorption, strength, resistance to creep, electrical insulating properties, and resistance to high working temperatures ( 85°C). 

Glass fiber-reinforced polymer (GRP) pipe is used for the transport of water and wastewater in pressure and non-pressure systems. This composite is composed of glass fiber and PP, PE, or PVC resins. These pipes are lightweight, corrosion resistant, and straightforward to install and have a long and effective service life and low maintenance costs. These features make GFR POCs, a strong candidate for piping applications in environments with acidic soil [51]. 

The use of fiber-reinforced polymer (FRP) composite materials in the reinforcement of concrete structures has shown important results. These interventions are based on the application of carbon fiber, glass, or aramid impregnated with thermosetting polymers. The effectiveness of these interventions is demonstrated both by extensive research in the laboratory and by applications to existing structures. 

In commercial use a common application of aU of these materials is in the form of glass fiber reinforced polymer composites see Sections 13.7 and 13.8. The glass fiber provides a significant toughening for these materials. For other applications, a variety of fillers are commonly used. 

Printed Circuitry. Printed circuitry, which represents a most intricate structure of polymers and conductors, is frequently made by laminating copper foil onto glass-fiber-reinforced epoxy composites. For certain specialty applications, more expensive fiber-reinforced polyimides are used. 

Fibers are classified as natural or synthetic. Fibers are used as a reinforcement material to increase the mechanical properties of polymer composites [31]. Synthetic fibers have been successfully used as the reinforcing material in composites such as carbon fiber, glass fiber, and Kevlar fiber. Glass fiber is a well-known example of a reinforcement material for polyolefin matrix. Polypropylene is a composite of increasing interest in automotive and other applications [32]. Figure 6.3 illustrates a glass fiber-reinforced polypropylene matrix. 

Other tertiary recycling processes that have been developed include a Freeman Chemical Corp. process to convert PET bottles and film to aromatic polyols used for manufacture of urethane and isocyanurates. Glycolized PET, preferably from film, since it is often lower in cost than bottles, can be reacted with unsaturated dibasic acids or anhydrides to form unsaturated polyesters. These can then be used in applications such as glass-fiber-reinforced bath tubs, shower stalls, and boat huUs. United States companies that have been involved include Ashland Chemical, Alpha Corp., Ruco Polymer Corp., and Plexmar. Unsaturated polyesters have also been used in polymer concrete, where the very fast cure times facilitate repair of concrete structures. Basing polymer concrete materials, for repair or precast applications, on recycled PET reportedly leads to 5 to 10 percent cost savings and comparable properties to polymer concrete based on virgin materials. However, they are still approximately 10 times the cost of portland cement concrete. There appears to be little commercial application of these processes at present. 

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