Guadagno Liberata, Naddeo Carlo, Vittoria Vittoria, Sorrentino Andrea, Vertuccio Luigi, Raimondo Marialuigia, Tucci Vincenzo, de Vivo Biagio, Lamberti Patrizia, Lannuzzo Generoso, Calvi Erika, Russo Salvatore
Dipartimento di Ingegneria Chimica e Alimentare, Università di Salerno, Via Ponte Don Melillo-84084 Fisciano (SA), Italy.
J Nanosci Nanotechnol. 2010 Apr;10(4):2686-93. doi: 10.1166/jnn.2010.1417.
Different experimental procedures were investigated for incorporating Multi walled Carbon nanotubes (MWCNT) into epoxy diglycidil-ether bisphenol-A (DGEBA), cured with 4,4' diamine-dibenzyl-sulfone (DDS): (i) mechanical mixing for either 60 or 120 minutes; (ii) high energy ball milling for 30 minutes; (iii) ultrasonication for 20 minutes. The mechanical properties of the obtained samples were monitored and used in order to guide the selection of the most promising composite system. The best results were obtained by using, as method of incorporation of carbon nanotubes in the resin, sonication for 20 minutes. Moreover it was found that the presence of an accelerating agent, BF3, commonly used for the cure reaction, is ineffective in the presence of carbon nanotubes, besides leading to composites with a lower glass transition. Afterwards resins with increasing MWCNT concentration were prepared and the thermal properties analyzed, showing a slight improvement in either the glass transition or the degradation temperature. The electrical conductivity of the selected composite system is characterised by a percolation threshold (lower than 0.1%) comparable to that found for similar systems, but beyond threshold it assumes greater values. The conductivity is characterised by only a slight increase with temperature in the range 30-90 degrees C. The positive temperature coefficient can be related to a decrease of the small gaps separating the CNTs clusters. A simple power law describes the relation between the composite conductivity and CNT concentration near the percolation threshold. A dependence of all the parameters of the power law on the temperature has also been evidenced, and it should be properly considered and indicated when using such a model in describing the behaviour of composites near the percolation threshold.
研究了不同的实验方法，将多壁碳纳米管（MWCNT）加入到用4,4'-二胺-二苄基砜（DDS）固化的双酚A二缩水甘油醚（DGEBA）环氧树脂中：（i）机械搅拌60或120分钟；（ii）高能球磨30分钟；（iii）超声处理20分钟。监测并利用所得样品的机械性能，以指导选择最有前景的复合体系。通过将碳纳米管加入树脂的方法采用20分钟的超声处理，获得了最佳结果。此外，还发现常用于固化反应的促进剂BF3在碳纳米管存在时无效，并且会导致复合材料的玻璃化转变温度降低。随后制备了MWCNT浓度增加的树脂，并对其热性能进行了分析，结果表明玻璃化转变温度或降解温度略有提高。所选复合体系的电导率具有与类似体系相当的渗流阈值（低于0.1%），但超过阈值后其值更大。在30-90摄氏度范围内，电导率仅随温度略有增加。正温度系数可能与碳纳米管簇之间小间隙的减小有关。一个简单的幂律描述了渗流阈值附近复合材料电导率与碳纳米管浓度之间的关系。还证明了幂律的所有参数对温度的依赖性，在使用该模型描述渗流阈值附近复合材料的行为时，应适当考虑并指明这种依赖性。
