Reinforced-plastic molding fiber shrinkage

To meet fabricated dimensional tolerances different approaches are used. They include use of specific fillers and reinforcements and process control (Chapter 3). Popular filler used is short glass fibers (Chapter 15). Over 50wt% of all types of glass fibers used with different plastics and by different processes are used in injection molding compounds. Table 2.2 shows the shrinkage of different unreinforced plastics ad glass fiber reinforced plastics based on ASTM testing procedures. 

Compared with glass fiber-reinforced plastics, the carbon fiber composites generally feature greatly improved tensile and flexural strengths and moduli. Thermal expansion of the carbon formulations is lower, and mold shrinkage ranges from about one-half to one-fifth that exhibited by the nonreinforced resin. Thermal conductivity of carbon composites is abont twice that of equivalent glass-reinforced formulations. 

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