MORE EXPERIMENTS ON THERMOPLASTIC FOAM NUCLEATION

This paper discusses results of polvethylene foam experiments on a counter. rotating twin screw extruder. Various engineering and material parameters were evaluated. Results of nucleation analysis show volatility of the blowing agent, shear force, melt temperature and die pressure gradient to be important parameters, whereas extensional force appears to have limited effect. Nucleator size and its dispersion have similar shear rate dependency upon nucleation. The observation is qualitatively consistent with pre-existing cavity nucleation model.