Preparation And Performance Of Carbon Nanotubes/Epoxy Resin Composites

Carbon nanotubes(CNTs)have attracted increasingly interest in preparing CNTs/epoxy nanocomposites for improving thermal and mechanical properties.However,the well dispersion of CNTs in epoxy matrix is still a challenge due to the strong interaction among carbon nanotubes and property of self-aggregation.We report a highly efficient approach to functionalize prime CNTs by a thiol-ene click reaction,and obtain different structure of thiol-functionalized CNTs.The thiol-functionalized CNTs show well dispersion in ethyl acetate.Then,the thiol-functionalized CNTs were added into epoxy resin to make CNTs/DGEBA composites.The thiol-functionalized CNTs show a positive effect on reinforcing and toughening of diglycidyl ether of bisphenol-A(DGEBA).Moreover,the performances of CNTs/DGEBA composites and the mechanism of thiol-functionalized CNTs were investigated.The main contents are shown as follows:(1)Synthesis and performance of mercaptans.The mercaptans were prepared by an esterification between hydroxyl-end compounds(Benzyl alcohol,ethylene glycol,trimethylolpropane,hydroxyl-end hyperbranched polyesters)and mercaptopropionic acid.Then a series of mercaptans were obtained with different functionality.The chemical structure of mercaptans were characterized by FT-IR and ~1H NMR,respectively.(2)Synthesis and performance of thiol-functionalized CNTs.The five kinds of mercaptans(PMMP,EMP,TMMP,THBP-1,THBP-2)were used to functionalize CNTs by thiol-ene reaction,forming thiols modified CNTs with photoinitiator(DMPA),named P-CNTs,E-CNTs T-CNTs,H1-CNTs and H2-CNTs),respectively.The chemical structure of thiol-functionalized CNTs were characterized by FT-IR,Raman,TGA,XPS and TEM.The thiol-functionalized CNTs with different chemical chains show well dispersion and stability in ethyl acetate.(3)Synthesis and performance of CNTs/DGEBA composites.We have used different functionalized CNTs as filler to prepare CNTs/DGEBA composites with different content.Six kinds of CNTs/DGEBA composites were synthesized and named CNTs/DGEBA,P-CNTs/DGEBA,E-CNTs/DGEBA,T-CNTs/DGEBA,H1-CNTs/DGEBA and H2-CNTs/DGEBA.From the result of rheological properties of CNTs/DGEBA blends,the viscosity of CNTs/DGEBA blends increased at room temperature with the same CNTs content,and the viscosity of thiol-functionalized CNTs/DGEBA blends are lower than that prime CNTs/DGEBA blend.It is improved that the functionalized CNTs have a stronger interaction between CNTs and DGEBA,and the functionalized CNTs have a better compatibility with DGEBA.From the performances,thiol-functionalized CNTs show a positive effect on reinforcing and toughening of DGEBA.The mechanical performance of CNTs/DGEBA composites first increased and then decreased with the increase of content of CNTs.With the content of 2.0wt%of CNTs,H2-CNTs/DGEBA composite showed the maximum tensile strength and flexural strength,the maximum improvements were 63.1%and26.7%compared with neat DGEBA.The maximum improvements of impact strength and thermal conductivity were 196.4%and 33.8%with 2.0wt%E-CNTs loads of CNTs/DGEBA composite compared with neat DGEBA.However,the Tg of CNTs/DGEBA decreased with adding CNTs.The reinforced and toughed mechanism of CNTs/DGEBA composites could well investigated by SEM technologies.The improved dispersion and compatibility of thiol-functionalized CNTs in DGEBA and the increasing crosslink of CNTs/DGEBA composites are the main reasons of reinforced and toughed mechanism.