Gas-assisted injection molding: Influence of processing conditions and material properties

Experiments were performed using a spiral mold instrumented with pressure transducers and three injection molding grade compounds: polystyrene, polyvinyl chloride, and polycarbonate. Wall thickness along the gas flow path was a strong function of residual time, gas bubble velocity, and material rheology. The shape of the melt viscosity curve provides an indication of the ability to change the wall thickness, as a result of the interaction between the gas bubble velocity and polymer melt rheology.