Microcellular Foaming of PP/HDPE Blend Using Supercritical Fluid

Blending was an effective method to improve foamability of polypropylene(PP).Microcellular foams of polypropylene/high-density polyethylene(PP/HDPE) blends were prepared using high-pressure vessel and cellular structures of foams were characterized by scanning electronmicroscope.Experimental results showed that cellular structure was improved by adding HDPE into PP.Compared with saturation temperation 120 ℃,the mean cell diameter decreased,cell density increased,and cell distribution was more uniform at 140 ℃.Cellular structure was greatly improved when stabilization temperature decreased from 179 ℃ to 170 ℃.Perfect cellular structures was always not proportional to pressure drop rate,when the pressure drop rate was too high,microcelluar bubbles frequently were coalesced.