Bonding strength at solid-melt interface for polystyrene in a sequential two-staged injection molding process

The effects of processing parameters, such as melt temperature, mold temper ature and cooling time, on the bonding strength of the interface in a seque ntial two-staged injection molding process were investigated both theoretic ally and experimentally. A theoretical bonding strength model, which accoun ts for the cooling profile through the thickness of the part and the interp enetration depth of polymer chains across the interface, was proposed. Unde r various mold and melt temperatures, experiments of sequential two-staged injection molding processes for polystyrene (PS) were also conducted to ver ify the validity of the model. Finally, an interrelationship between the av erage extent of reaching an effective interpenetration depth and the degree of bonding has been constructed. The model proposed in this research would be useful in the CAE analysis for a two-staged injection molding process i n which distortions or even fractures might occur at the interface.