Poly(methyl methacrylate)(PMMA)pellets are irradiated using 60Co gamma-ray in air and successfully formed by hot pressing at constant conditions.The irradiated PMMA membranes are prepared by supercritical carbon dioxide(scCO2)as a physical blowing agent using the pressure quench method.Effects of foaming conditions such as adsorbed dose,saturation temperature,pressure on the morphology and cell size of the microcellular PMMA membranes are investigated in detail.The results showed that the irradiated PMMA membranes possess spherically closed-cell structure with uniform cell size.They have a high cell density compared with virgin PMMA.The cell size uniformity becomes poor at dose lower than 10 kGy,but increases with the dose at dose higher than 10 kGy.The mean cell diameter is less than 10μm and the cell density increases with increasing dose.The average cell size of irradiated PMMA membranes decreases and cell density increases with increased saturation temperature and pressure.The changes in morphology of membranes are attributed to the gamma-ray radiation and scCO2synergistic effect.
为了提高直链型聚丙烯(PP)的发泡性能,选用三烯丙基异氰脲酸酯(TAIC)为交联剂与PP共混热压成PP片材,用伽玛射线对PP片材进行辐射改性。采用超临界二氧化碳发泡技术对不同TAIC含量和不同吸收剂量PP片材进行发泡研究。结果表明,TAIC的质量分数为0.5%~2%时,PP较为适宜发泡。当TAIC质量分数为2%(PP2)时,辐射交联增加了PP2的交联度,降低了PP2的熔体流动速率,提高了PP2的发泡性能。PP2片材吸收剂量为10 k Gy时,交联最为充分,此时PP2发泡的性能较好(泡沫的泡孔尺寸分布均匀,体积膨胀率为15)。在相同的发泡条件下,辐照改性PP2的泡孔直径大小随吸收剂量的增加而增大。
