抄録
The flow characteristics of foam polystyrene which contains 1.5wt% butane were investigated and compared with those of polystyrene used for general purpose.
The apparent viscosity of foam polystyrene was lower than that of general polystyrene. This may be due to that the Brownian motion of polymer molecules becomes more active by the existence of minute bubbles and reduces the intermolecular force or friction (shearing stress). The non-Newtonian flow index of foam polystyrene was smaller than that of general polystyrene. This may be due to that the random Brownian motion of molecules becomes more active and thus makes harder the imperfect orientation of molecules arising from the increase in shear rate. The activation energy of flow of foam polystyrene was slightly smaller than that of general polystyrene, which may be due to that the molecules of foam polystyrene melt become more movable by the existence of minute bubbles.
Besides, the influences of pressure and temperature upon foaming pattern and foaming ratio were investigated, and it was found that the greatest foaming ratio can be obtained at the optimum temperature (215°C) for extruding general polystyrene, and, at constant temperature, a good skin of extrudate can be obtained only when the extruding pressure exceeds a certain limit value.
