HDPE氧化交联与动态流变行为

研究了高密度聚乙烯(HDPE)熔体在200℃的动态流变行为,比较了空气、氮气及加入抗氧剂B215情况下体系动态粘弹行为的差异.研究表明,在空气环境中,HDPE在低频区域出现特征粘弹行为.随着测试前热处理时间的延长,动态储能模量(G')明显增加,在低频率(ω)区域lgG'～lgω关系呈现平台特征.同时损耗角tanδ变小并出现极大值.在氮气环境中,上述特征粘弹行为存在但不明显.在加入抗氧剂的条件下,特征粘弹行为完全消失.这些现象归因于高温下HDPE的氧化导致其发生交联.

Correlation Between Oxidation-induced Crosslinking and Rheological Behavior of HDPE

Studies on the dynamic viscoelastic properties of high-density polyethylene(HDPE) were carried out at 200 ℃ in the atmosphere of air, nitrogen, and in the case of blending with antioxidant B215 respectively. The results revealed that there existed specific character in dynamic rheological behavior corresponding to the conditions above. Especially, in a low frequency range the dynamic storage modulus(G') increased while the dynamic loss tangent(tanδ) decreased obviously in air atmosphere. For the HDPE samples exposed to air, compared with N2 and the condition of blending with B215, the second plateau appeared in G'~ω curves in a low frequency range and the value of peak appeared in tanδ~ω curves decreased simultaneously, together with shifting of the peak in a higher frequency range, were attributed to the change of structure in HDPE because of the oxidation-induced crosslinking of HDPE.