中文摘要：

用正电子湮没方法（PALS）和动态力学分析（DMA）方法研究了增韧剂和温度对环氧树脂的自由体积和力学性能的影响．根据正电子素（o-Ps）湮没寿命τ3随温度的变化，玻璃化转变温度Tg和次级转变温度Tβ被确定．实验结果表明，在稀释环氧树脂基体中加入增韧剂会使样品中产生较强界面相互作用，并且明显地改变了材料的结构转变温度Tg和Tβ，使得增韧样品比稀释样品具有更高的玻璃化转变温度Tg．一个很有意义的发现是，低温下力学性能的改变明显地大于室温下力学性能的改变．文中从原子尺度自由体积特性和界面相互作用的角度探讨了温度对样品力学性能影响的机理．

英文摘要：

Effects of toughening agent and temperature on the free volume and mechanical properties were studied by positron annihilation lifetime spectroscopy （PALS） and dynamic mechanical analysis （DMA） for a serious of epoxy resin samples with different toughening agent content（W/W）. According to the variation of ortho-positronium （o-Ps） lifetime as a function of temperature, the glass transition temperature Tg and secondary transition temperature Tβ were determined. The introduction of toughening agent markedly affects the structure transition temperature. An interesting phenomenon was found that the toughened sample D2-10 （epoxy resin/low viscosity live diluents/10% toughening agent） has a higher Tg than that of D2-304 （epoxy resin/low viscosity live diluents）. This fact indicated that the interfacial interaction between toughening agent and epoxy resin was strengthened with increase of toughening agent content, which can restrain segmental motion, bringing about an increase in Tg. On the other hand, it＇s very interested that the module of compression measured at 233 K is much better than that measured at 303 K, and larger difference of mechanical properties between pure sample and D2-10 sample at low temperature was observed compared with that at high temperature. The effect of free volume, interracial properties on the mechanical properties was discussed.