辐照交联SBS／LDPE共混物的形状记忆效应研究

以苯乙烯-丁二烯嵌段共聚物（SBS）热塑性弹性体和低密度聚乙烯（LDPE）为主要原料,使用混炼机将SBS与LDPE按80：20的比例共混并在硫化机上模压制成SBS／LDPE共混物,利用γ射线辐照上述共混物使之交联。通过DSC分析、力学性能和形状记忆性能测试,研究了辐照交联SBS／LDPE共混物材料的结构对形状记忆性能的影响。结果表明,SBS／LDPE共混物随吸收剂量的增加,交联度增大,拉伸强度与断裂伸长率均逐渐降低;此外,适度交联的SBS／LDPE共混物呈现良好的形状记忆效应,形变回复率高于95％。     

辐照聚酰胺1010的后效应

用ＤＳＣ以及凝胶含量测定的方法研究了辐照聚酰胺１０１０的后效应，讨论了晶区分子运动与转变受辐射后效应的影响，也探讨了结晶表面积对后效应的影响，结果表明辐射后效应主要来源于结晶表面内的俘陷自由基。     

聚乙烯的共混－辐射改性

采用共混，辐射，化学后处理的方法，对低密度聚乙烯（ＬＤＰＥ）进行表面改性，并对改性后ＬＤＰＥ片材的表面润湿性（接触角）进行了测量和分析。当ＬＤＰＥ中共混乙烯－乙酸乙烯共聚物（ＥＶＡ）及衣康酸（ＩＡ）时，辐射后用醇碱处理，改性效果较好。     

γ射线辐射交联低密度聚乙烯——乙丙共聚物的结构和性能

文章报道了低密度聚乙烯(LDPE)和三元乙丙共聚物的共混物,经~(60)Co-γ射线辐照后的辐射交联规律以及结构与性能的变化。实验结果表明,这种共混物的辐射交联规律和单独LDPE或EPDM的辐射交联具有类似之处,其交联规律按共混物中占优势的聚合物交联方式进行。经~(60)Co-γ射线辐照后这种共混物的结构和性能发生了变化。结晶度、密度和其它物理性能与共混物中两种聚合物的组成有着密切关系。辐照剂量的改变对同一组成共混物的结晶度和密度影响较小,但是,它对力学性能有显著影响。     

辐射交联对LDPE/CB复合物PTC效应稳定性的影响

研究了低密度聚乙烯（LDPE）／炭黑（CB）复合物在升温、降温循环中的导电性能。利用示差扫描量热分析仪（DSC）研究了复合物的熔融行为，以及应用压力－体积－温度分析仪（PVT）研究了复合在聚合物熔点时的体积膨胀性能。结果表明，辐射交联可以有效地提高复合物正温度系数（PTC）效应的重复性，纯凝胶复合物的PTC强度显著降低，说明溶胶在聚乙烯熔点时的体积膨胀是交联复合物正温度系数（PTC）效应的产生的重要原因。     

The influence of orientation on the radiation-induced crosslinking/oxidative behavior of different PEs

This paper studies the influence of orientation and structural peculiarities on the radiation-induced oxidation/crosslinking changes in different polyethylenes (PEs). For this reason, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) were oriented via solid-state stretching at an elevated temperature. Later on, oriented samples were gamma-irradiated in air to various absorbed doses (up to 700 kGy). In order to investigate orientation- and radiation-induced changes in morphology, surface microstructures were analyzed by optical (OM) and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC), IR spectroscopy and gel measurements were used to determine changes in crystallinity, oxidative degradation and degree of network formation, respectively. Conclusions derived according to these methods were compared. The differences in morphology, crystallinity, oxidation and gel behavior are caused primarily by the structural peculiarities of different types of PEs, the heterogeneous nature of radiation effects in semicrystalline polymers and, in the case of oriented samples, by the molecular orientation as well. The presented results reveal complicate crosslinking behavior with orientation while increase/decrease in crystallinity/oxidation with draw ratio was clearly evident.     

Radiation cross-linking in ultra-high molecular weight polyethylene for orthopaedic applications

The motivation for radiation cross-linking of ultra-high molecular weight polyethylene (UHMWPE) is to increase its wear resistance to be used as bearing surfaces for total joint arthroplasty. However, radiation also leaves behind long-lived residual free radicals in this polymer, the reactions of which can detrimentally affect mechanical properties. In this review, we focus on the radiation cross-linking and oxidative stability of first and second generation highly cross-linked UHMWPEs developed in our laboratory.     

电子束辐照对尼龙610性能的影响

在三烯丙基异氰酸酯多官能团辐照敏化剂存在下,采用电子束辐照尼龙６１０,测度尼龙６１０辐照前后的力学强度、耐温等级、吸水率和吸油率的变化。结果表明：经过电子束辐照７５ｋＧｙ后,提高了ＰＡ６１０的力学强度、耐化学溶剂性能的热变形温度。