抄録
The theoretical analysis of the tubular film extrusion of amorphous polymer polystyrene (PS) by using a computer simulation presented several interesting results, such as bubble shape, velocity profile, temperature profile, deformation rate and stretching stress. The influence of the process conditions on the film physical properties and the study on the scale-up were discussed. Bubble pressures and bubble tensions predicted theoretically during the tubular film process generally agreed with those observed experimentally. Further, film shrinkage stresses measured experimentally were proportional to the maximum stretching stresses obtained theoretically. The stretching stress and film shrinkage stress decreased with increasing process temperature and decreasing the blow up ratio. It was found that the change of die diameter influenced the stretching stress at a constant out-put rate.
As a result of the experimental comparison of the crystalline polymer with the amorphous polymer as to bubble velocity, deformation rate, bubble shape and bubble temperature, there was big difference between the crystalline polymer and the amorphous one. It was found that the dependence of the temperature on the melt viscosity, crystallinity and crystallization rate profoundly influenced the dynamics of the tubular film extrusion.
