辐射交联聚丙烯的超临界二氧化碳发泡

Foaming of Irradiation Cross-Linked Polypropylene Using Supercritical Carbon Dioxide

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。

Polypropylene sheets were prepared by melting blend using PP and triallyl isocyanurate （TAIC）, and then irradiated by γ- ray with different absorbed dose to improve the foaming behavior of PP. PP sheets with different TAIC content and absorbed dose were foamed by supercritical carbon dioxide technology. The results show that the suitable content of TAIC for foamed PP sample is in the range of 0.5%～2%. When the mass fraction of TAIC is 2% （PP2）, the cross-linked density of PP2 is increased, the melt flow rate of PP2 is decreased and the foamability of PP is improved after irradiation by γ-ray. The absorbed dose of PP2 （the mass fraction of TAIC is 2%） sheet is optimized to 10 kGy, for which PP is cross-linked dramatically and improved the foaming behaviour of PP2, where the cell structure of the resultant foams is uniform, and the foam expansion is 15. It is found that the average cell diameter of irradiation modified PP increases with increasing radiation dose under the same foaming conditions.