The effect of pressure on the densification of amorphous polymers in the Injection‐molding process is examined. Density distributions in molded polystyrene slabs were measured for several well‐defined molding histories. In all cases the density of the molded part was spatially inhomogeneous, and its distribution in the slab was closely related to the pressure and temperature histories that prevailed in the molding cavity during the process cycle. The density profile in the gapwise direction followed a characteristic “parabolic” pattern with a minimum at the midplane of the slab. A simple phenomenological model, based on the pressure‐induced densification effect, was constructed to explain the observed density profiles, and close agreement with experimental data was found. Annealing of the molded article at a high temperature (
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Jehuda Greener (1986) studied this question.