辐照对聚己内酯结构和性能的影响

研究了γ 辐照对不同分子量的聚己内酯 (PCL)的力学性能、热性能、结晶行为的影响 ,在此基础上 ,研究了辐射交联后的PCL的形状记忆行为 .研究结果表明 ,PCL的分子量越大 ,辐射交联所需的凝胶化剂量越低 .溶胶分数S +S1 2 与 1 D的关系很好地符合Charlesby Pinner关系式 ,说明PCL的辐射交联属于无规交联 .剂量对PCL的力学性能影响显著 ,剂量越大 ,抗张强度和断裂伸长率下降越多 ,但分子量较高的PCL的抗张强度受剂量的影响较小 .DMA分析表明 ,聚己内酯辐照交联后的弹性模量和耐热性能显著提高 .交联度较高的PCL表现出高弹态 ,可以拉伸 ,并具有较好的形状记忆行为 .DSC分析表明 ,辐射交联使PCL的结晶度有所增加 ,但也使结晶熔点有所降低

RADIATION EFFECTS ON STRUCTURE AND PROPERTIES OF POLY(ε-CAPROLACTONE)

Poly(ε-caprolactone)s (PCLs) with different molecular weight were cross-linked by γ-radiation.The radiation crosslinking feature was examined by Soxhlet extractor with toluene and analyzed by using the Charlesby-Pinner equation.The crosslinking degree is related to molecular weight and radiation dose,and the relation between the sol fraction and the radiation dose follows the Charlesby-Pinner equation.Radiation may cause a drop of tensile strength and elongation for all the samples d.The DSC diagrams demonstrated that radiation caused an increase of crystallinity and a decrease of melting temperature of PCL crystals.The DMA analysis indicated that radiation crosslinking raised heat deformation temperature of PCL and caused a rubbery state after the melting of PCL crystals.The shape memory results indicated that only those specimens that had a sufficiently high cross-linking degree (gel content is higher than about 15%) were able to show the typical shape memory effect,a large recoverable strain and a high final recovery rate.The response temperature of the recovery effect (about 55℃) was related to the melting point of the samples.The PCL shape memory polymer was characterized by its low recovery temperature and large recovery deformation.