【作者】 张晓辉；

【导师】 肖潭；

【作者基本信息】 汕头大学 ， 材料物理与化学， 2008， 硕士

【摘要】 碳纳米管(碳管)具有优异的力学性能、热学性质及化学稳定性,是聚合物结构复合材料的理想增强体.碳管/聚合物复合材料的力学性能主要取决于碳管和基体间界面作用、碳管在基体中的分散性和取向.但是普通(未功能化)碳管易聚集且不溶于大多数溶剂,难于在基体中分散,而且普通碳管与基体之间界面作用较弱.碳管的功能化可以解决碳管分散性差以及界面作用弱的问题.目前,功能化方法有非共价功能化、共价功能化和混杂功能化三类.碳管功能化及其在聚合物复合材料中的应用是近年来的研究热点.本文旨在研究功能化对碳管断裂寿命的影响,以及功能化对碳纳米管/聚合物复合材料弹性模量和拉伸韧性的影响.主要研究内容和结果如下:基于动态断裂模型和分子力学模拟,研究了功能化对碳管拉伸断裂寿命的影响.结果表明:相比未功能化,非共价功能化能有效地增加碳管的断裂寿命,而共价功能化使碳管寿命降低,混杂功能化可以看作是共价功能化和非共价功能化的共同作用,在多数情况下它可以提高碳管的寿命.运用分子动力学方法研究了非共价功能化、共价功能化和混杂功能化碳管/聚合物复合材料的拉伸韧性.发现非共价功能化并不能提高复合材料的拉伸韧性,共价功能化和混杂功能化都可以显著地的提高碳管/聚合物复合材料的韧性.更多还原

【Abstract】 Carbon nanotubes (CNTs) are promising reinforcement material for structural polymer composites due to their extraordinary mechanical and thermal properties. Mechanical properties of CNT/polymer composites depend mainly on the interfacial interactions between CNT and matrix, as well as the dispersion and alignment of CNTs in the matrix. However, pristine CNTs are prone to aggregation, and are insoluble in most solvents, rendering them difficult to be dispersed in the matrix. Moreover, the interfacial interactions between pristine CNT and matrix are rather weak. It was reported that CNT functionalization could be an effective way to improve the dispersion and strengthen the interfacial interactions. There exist three categories of functionalizations: nocovalent, covalent, and hybrid functionalizations. Recently CNT functionalizations and their applications in polymer composites have become a new research interest. The purpose of this thesis is to study the effects of different functionalizations on fracture lifetimes of CNTs, elastic moduli and tenslie toughness of different types of functionalized CNT/polymer composites.Based on a kinetic fracture model and using molecular mechanics (MM) simulations, the influence of different functionalizations on lifetime of single-walled carbon nanotubes (SWCNTs) under tension was studied. Three types of functionalizations, namely, covalent, noncovalent, and hybrid, were studied. Comparing with pristine SWCNTs, our results show that noncovalent functionalization can enhance, while covalent functionalization has detrimental effect, on the lifetime of SWCNTs, Effects from covalent and noncovalent functionalizations superimpose in hybrid functionalization, and in most cases it has positive effect on the lifetime of SWCNTs.Using molecular dynamics (MD) method, tensile toughness of noncovalent, covalent, and hybrid functionalized CNT/polymer composites were studied. Results show that noncovalent functionalization can not enhance the tensile toughness of composites, covalent functionalization and hybrid functionalization can markedly enhance the toughness of CNT/polymer composites.更多还原