Glass-fiber-reinforced resins properties

Typical Properties of Glass-Fiber-Reinforced Resins [10]... 

Table 6.14 Some Electrical Properties of Selected Glass-Fiber-Reinforced Resins...

Properties ethylene-propylene resin Poly(vinylidene fluoride) Unfilled Glass-fiber- reinforced ethylene copolymer Cellulose- filled Glass-fiber- reinforced... 

Some of the common types of plastics that ate used ate thermoplastics, such as poly(phenylene sulfide) (PPS) (see Polymers containing sulfur), nylons, Hquid crystal polymer (LCP), the polyesters (qv) such as polyesters that ate 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diaHyl phthalate and phenoHc resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials ate available in several variations which have a range of physical properties. 

Some electrical properties of reinforcing fibers, composite resins, and the resulting composites are given in Tables 6.12, 6.13, and 6.14, respectively. These values should be taken as approximate only, especially for the composites, since fiber orientation, content, and field strengfh have an enormous impacf on fhe dielecfric properties of these materials. Some of the most widespread electrical applications for glass-fiber-reinforced epoxy systems are in printed circuit boards and electrical housing such as junction boxes. 

The glass transition temjierature of PPBT is about 52 C 1125 Fi. Melting point is about 230°C (440°F). Unrcinforccd l BT is obtainable in several molecular weights. Compounded resins are available with numerous types and levels of fillers and reinforcements. Glass fiber reinforcement has a wide spectrum of physical properties. These materials can be made flame-retardant through the use of additives. 

Tetrabromobisphenol A is used in epoxy resins especially for glass fiber reinforced used in printed circuit board. Nonreactive compounds such as tetrabromophatalate ester, bis(tribromophenoxy) ethane, and decabromodiphenyl ether are also used. The use of synergists, such as antimony oxide, reduces the quantity of brominated flame retardant necessary but decreases the electrical properties required. 

This moldable material primarily consists of TS polyester resin, glass fiber reinforcement, and filler. Additional ingredients, such as low-profile additives, cure initiators, thickeners, and mold-release agents are used to enhance the performance or processing of the material. As with any material, such as metallics and plastics, SMC can be formulated in-house or by compounders to meet performance requirements of a particular application such as tensile properties or Class A surface finish. Varying the type and percentage of the composition will result in variations in mechanical properties and processability. 

Glass fiber reinforced polymers and resins have found widespread application as light weight construction materials. In addition, the properties of interfaces and. interphases play a crucial role in determining the ultimate mechanical and other properties in these and related applications. Since the corresponding length scales can be on the far sub-micrometer level, a more detailed insight requires local analysis techniques which provide materials contrast. 

In a recent study, the interphases for different fiber/polymer matrix systems were investigated. By using phase imaging the differences in local mechanical property variation in the interphase of glass fiber reinforced epoxy resin (EP) and glass fiber reinforced polypropylene matrix (PP) composites could be unraveled. As shown in Fig. 3.68, the glass fiber, the interphase and the PP matrix can be differentiated based on their surface mechanical properties as assessed qualitatively by TM phase imaging. 

The electrical SHM of composites refies on the material itself to act as the sensor. Carbon fibers are electrically conductive the epoxy resin is an insulator. The CFRP composite is somehow conductive because the densely packed carbon fibers may touch each other. As damage (e.g., cracks and delamination) takes place in the composite, the electric conductivity is expected to change. The glass fiber-reinforced polymer (GFRP) composite is a nonconductive insulator with certain dielectric properties. Damage in GFRP composites creates microcracks and even... 

Table 3.10 Properties of chopped glass fibers reinforced phenolics and TS polyester resins...

Formulation of SMC/BMC compounds is a very sophisticated balance of many ingredients to enhance specific properties and/or act synergistically with other components. Most SMC/BMC formulations have three main elements binder, filler and fiber reinforcement, from a choice of ingredients such as unsaturated polyester resin, monomer, catalyst, inhibitor, fillers, TP anti-shrinkage additives, flame-retardant, thickener, release agent, and glass fiber reinforcement. 

A new plastic pulley, a cost effective replacement of a cast aluminum counterpart, is now used in all Hotpoint washing machines. The injection molded pulley, made of DuPont glass fiber reinforced Zytel nylon resin offers lower part cost vs. casting, without compromise in mechanical properties. The pulley was designed and manufactured by Rolinx Plastics Co. Ltd., UK, in conjunction with appliance maker Merloni UK... 

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