共混改性是改善聚丙烯(PP)发泡性能的一种有效方法。以不同组分比的PP/高密度聚乙烯(HDPE)共混体系为研究对象,用扫描电镜对发泡样品的泡孔结构进行表征,研究加工条件对泡孔结构的影响。结果表明:向PP中加入HDPE可改善泡孔结构,与饱和温度为120℃相比,饱和温度在140℃时,得到泡孔直径更小,泡孔密度更大,泡孔分布更均匀的复合物。稳定温度在170℃时的泡孔结构明显优于稳定温度在179℃时的泡孔结构,并非压降速率越大得到的泡孔结构越理想,当压降速率过大时,泡孔容易合并或塌陷。
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.