中文摘要：

采用正电子湮没寿命谱技术研究了尼龙6／碳纳米管纳米复合材料的自由体积特性。实验结果发现碳纳米管对纳米复合材料的自由体积孔洞尺寸影响甚微，而自由体积孔洞数目和相对自由体积分数均随碳纳米管含量的增加而明显减小。导致这种减小的原因可能来自两方面，其一是由于碳纳米管和基质聚合物间的相互作用限制了高分子链段运动；其二是碳纳米管填充增强了尼龙6基体结晶性能。此外，力学性能研究表明，碳纳米管在复合材料中较均匀的分散和较好的界面接触可以提高材料的力学强度，而自由体积分数的减小则使材料的韧性变筹。

英文摘要：

Effect of carbon nanotube content on the free volume and mechanical properties of nylon 6/carbon nanotubes （CNTs） nanocomposites have been investigated by positron annihilation lifetime spectroscopy （PALS）. Experimental results found that the variation of free volume hole size is very small, while the concentration of free volume and apparent free volume fraction decrease with increasing the content of CNTs. These decreasing are due to the confining effect on polymer chains in the interfacial layer caused by CNTs, and to the enhancement of crystallinity caused by CNTs filler. The measurements of the mechanical properties revealed that the uniformly dispersion and good interfacial properties between CNTs and polymer matrix can improve the stiffness of material, but the decreasing in free volume fraction will decrease its toughness.