Evaluation of HFC-245fa as an Alternative Blowing Agent for Extruded Low-Density Polyethylene

HFC-245fa was investigated as a blowing agent in low-density polyethylene (LDPE). Ultrasonic monitoring showed that this blowing agent has degassing pressures systematically lower in LDPE than those reported in polystyrene, in agreement with solubility measurements performed on other polymer-gas systems. Based on these results, HFC-245fa would have solubility properties similar to HCFC-22 both in polyolefins and in polystyrene. Foams were produced in extrusion using gas concentrations ranging from 3 to 7.7 wt.%. Extrusion profiles show that foam growth in LDPE is very slow and that adding a nucleating agent is required to trigger the expansion process. Using an optimal concentration of gas and talc, it was possible to produce foam samples below 100 kg/m ³ .