Reinforced molding compound

With RTFs, the technical difficulty of mixing the plastic matrix with reinforcement such as glass fiber has made it standard practice for materials suppliers to offer a reinforced molding compound that is ready formulated with all the necessary ingredients, with the possible exception of pigment. A ready-made RTP in sheet form is also available, known as glass mat thermoplastic (GMT). 

Strands of glass, (usually E glass) are mechanically cut into lengths from 0.25 to 2 in. and are used to reinforce molding compounds. The longer lengths are used with thermoset resins whereas the short fibers are used with thermoplastic polymers. 

P13N resin Is an excellent base for the formulation of both particulate and reinforced molding compounds. Three avenues can be employed. 

TS reinforced molding compounds processed in IM require water- or oil-cooled barrels, rather than the electrically heated barrels used for TP. The heat of the TS during screw plastication has to be kept lower than its curing heat. The mold heat is higher than that of the resin, causing the TS finally to react and solidify. If there is excess heat in the barrel, the resin crosslinks and the machine stops operating. A cleanup is required, which can cause machine downtime to be extensive. With a liquid heat control, better control of melt heat is maintained. Also the compression ratio of the screw used to process the TS is one, which helps to keep the heat low and, more important, under control. 

Reinforced molding compound n. A compound containing reinforcing fibers and supplied by the raw-material producer in the form of ready-to-use material, as distinguished from premix. 

QIass/mineral- filled Cellulose- filled Glass fiber-reinforced Molding compounds, phsnol-formaldshyds ... 

In thermoplastics, carbon fiber compounds have been developed with nylon, polysulfone, thermoplastic, polyester, polyphenylene sulfide, polycarbonate, polypropylene, polyamide-imide, and ethylene/tetrafluoroethylene copolymer. Carbon fiber-reinforced molding compounds are available with carbon fiber contents of various levels such as 20, 30, and 40 weight percent. Nylon 66 molding compounds have also been developed with hybrid combinations of carbon and glass fiber reinforcements. 

U s Properties ASTM Test Method Long Glass-reinforced Molding Compound EMI Shielding (Conductive) 30% PAN Carbon Eiber Injection Molding Un- plasticized Plasticized Elexible (Including RTV) Liquid Silicone Rubber... 

Cyglas, Mineral-filled, glass-fiber-reinforced molding compound, Cytec Eiberite Molding Compounds... 

Directionally reinforced molding compound (XMC) continuous fibers crossed in an X pattern. 

Directionally reinforced molding compound (XMC) contains continuous reinforcements (up to 70 wt%) arranged in an X pattern with some chopped fibers and the final product has strong directional properties in the continuous fiber direction. XMC can be made on almost any filament winding machine as shown in Fig. 3.11. 

Properties Unreinforced molding compound 10-20% glass-fiber-reinforced molding compounds Long glass-reinforced molding compound... 

An important application for rubber modified polyester resins is in short-fiber reinforced molding compounds. Specific applications within the automotive industry include grill-opening panels and various car and truck body panels. Rubber modified vinyl ester resins are used as adhesives and as primer coatings for storage tanks. 

Table 14.2 General Processing Conditions for Engineered Rber-Reinforced Molding Compounds...

Fiber-Reinforced Molding Compound Molding Pressure, psi (MPa) Molding Temperature, F (°C) Cycle Time (Exclusive of Any Preheating)... 

Polyurethane 10-20% Glass Fiber Reinforced, Molding Compounds PUR-GFR... 

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