Increase of open‐cell content by plasticizing soft regions with secondary blowing agent

This article describes the effects of n‐butane mixed with primary CO₂ as a secondary blowing agent on the cell‐population density, the volume expansion ratio, and the open‐cell content of low‐density polyethylene (LDPE) and LDPE/polystyrene (PS) blends in extrusion. With the plasticizing effect of n‐butane, a high open‐cell content (up to 100%) over a wide range of processing temperatures was successfully achieved. POLYM. ENG. SCI., 45:1445–1451, 2005. © 2005 Society of Plastics Engineers