Glass filling

In Figure 5.24 the predicted direct stress distributions for a glass-filled epoxy resin under unconstrained conditions for both pha.ses are shown. The material parameters used in this calculation are elasticity modulus and Poisson s ratio of (3.01 GPa, 0.35) for the epoxy matrix and (76.0 GPa, 0.21) for glass spheres, respectively. According to this result the position of maximum stress concentration is almost directly above the pole of the spherical particle. Therefore for a... 

Properties Glass-filled Mineral-filled Sheet Molding Sheet... 

Casting resin Thermoplastic elastomer Cast resin, flexible Mineral- and/or glass-filled Epoxy molding and encapsulating compound Polystyrene... 

Glass-filled PPS Glass films Glass frit Glass frits Glass hollow fibers Glassine... 

Because of poor therm oform ability, there are relatively few apphcations for polypropylene sheet. New soHd-phase pressure forming (SPPE) techniques are under development for forming PP sheet. Polypropylene is used in coextmded sheet to some extent for food packaging containers. Glass-filled, wood-filled, or other modified polypropylene sheet materials are used in limited automotive apphcations. 

The water hberated during the cure has no apparent effect on the composite properties. Glass-filled composites prepared in this manner retain mechanical properties at elevated temperatures as well as solvent and flammabiUty resistance (88). PhenoHc-graphite-fiber composites that exhibit superior mechanical properties have also been prepared by this process. 

The higher temperatures ate used for glass-filled or high viscosity materials and the lower temperatures for low viscosity or plasticized resins. 

The market prices for PET molding resins in January 1996 in the United States were 2.90— 3.15/kg for 30% glass-filled PET, 3.26— 3.41/kg for 55% glass-filled, and 3.23— 3.45/kg for 30% glass-filled flame-retardant-grade PET (125). 

Highest thermal performance with PPS compounds requires that parts be molded under conditions leading to a high level of crystallinity. Glass-filled PPS compounds can be molded so that crystalline or amorphous parts are obtained. Mold temperature influences the crystallinity of PPS parts. Mold temperatures below approximately 93°C produce parts with low crystallinity and those above approximately 135°C produce highly crystalline parts. Mold temperatures between 93 and 135°C yield parts with an intermediate level of crystallinity. Part thickness may also influence the level of crystallinity. Thinner parts are more responsive to mold temperature. Thicker parts may have skin-core effects. When thick parts are molded in a cold mold the skin may not develop much crystallinity. The interior of the part, which remains hot for a longer period of time, may develop higher levels of crystallinity. 

Table 4. UL Index of Various Glass-Filled Engineering Materials ...

Eig. 7. GTE of a 40% glass-filled PPS as functions of both temperature and direction. GTE values are measured in micrometers of dimensional change per... 

Pellets for injection-molding, extmsion, and blow-molding appHcations include mineral-filled, glass-filled, pigmented, and flame-retarded grades. 

Polymers used for seat and plug seals and internal static seals include PTFE (polytetrafluoroeth ene) and other fluorocarbons, polyethylene, nylon, polyether-ether-ketone, and acetal. Fluorocarbons are often carbon or glass-filled to improve mechanical properties and heat resistance. Temperature and chemical compatibility with the process fluid are the key selec tion criteria. Polymer-lined bearings and guides are used to decrease fric tion, which lessens dead band and reduces actuator force requirements. See Sec. 28, Materials of Construction, for properties. 

Materials Springs and other metalhc components are available in a wide variety of alloys and are usually selected on the basis of temperature and corrosion conditions. The use of a particular mechanical seal is frequently restricted by the temperature limitations of the organic materials used in the static seals. Most elastomers are hmited to about 121°C (250°F). Teflon will withstand temperatures of 260°C (500°F) but softens appreciably above 204°C (400°F). Glass-filled Teflon is dimensionally stable up to 232 to 260°C (450 to 500°F). 

Slides Microstructures of GFRP, glass-filled polymer, cermet, wood sectioned piece of cord-reinforced automobile tyre. 

Glass-reinforced grades of SAN exhibit a modulus several times that of the unfilled polymer and, as with other glass-filled polymers, a reduced coefficient of thermal expansion and lower moulding shrinkage. The materials are thus of interest on account of their high stiffness and dimensional stability. 

Property ASTM method Units Unfilled 30% glass filled 30% glass filled and impact modified... 

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