过氧化物交联增韧改性PE⁃HD/POE共混物

Toughening Modification of PE⁃HD/POE Blends by Crosslinking with Peroxide

采用过氧化物交联剂对高密度聚乙烯(PE-HD)/乙烯-辛烯共聚物(POE)共混物进行交联。测试了交联PEHD/POE的凝胶含量;通过旋转流变仪和差示扫描量热仪(DSC)分析了交联对PE-HD/POE共混物的流变和结晶的影响;表征了拉伸性能和冲击性能;观察了冲击断面的扫描电子显微镜(SEM)照片。结果表明,交联提高了共混物的复数黏度,抑制了其结晶,导致结晶度下降,晶片变薄;当过氧化物交联剂(BIPB)含量为0.3%(质量分数,下同)时,交联PE-HD/POE的缺口冲击强度达到了61.1 kJ/m^2,断裂伸长率超过900%;交联度低时,交联共混物大部分分子链仍能自由移动,增韧模式为低缠结度产生大变形形成剪切屈服带抵消冲击能量,交联度高时,分子链移动受限,增韧模式为高缠结度产生大量小形变耗散冲击能量,且后者具有更好的增韧效果。

The PE-HD/POE blends were modified by crosslinking with BIPB as a peroxide crosslinking agent.The gel content of the crosslinked PE-HD/POE was analyzed,and the effect of crosslinking modification on the rheology and crystallization of PE-HD/POE blends were investigated by rotary rheometer and DSC.The tensile and impact properties were characterized,and impact fracture surfaces were observed by SEM.The results indicated that the crosslinking modification increased the complex viscosity of the blends and inhibited their crystallization,resulting in a decrease in crystallinity and thinner wafers.When 0.3 wt%of BIPB was added,the notched impact strength of the blends reached 61.1 kJ/m^2,and their elongation at break exceeded 900%.When the crosslinking degree was low,most of the molecular chains in the blends could move freely.The toughening mode was attributed to the low entanglement that produces large deformation to form a shear yield zone to offset the impact energy.With the improvement of crosslinking degree,the toughening mode was converted to the high entanglement that generated a large amount of small deformation to dissipate the impact energy at a high cross-linking degree,leading to a better toughening effect.