Research On The Enhancement Mechanism And Properties Of Carbon Nanotube Sponge Reinforced Polymer Matrix Com Posites

The area of Carbon Nanotube (CNT)-polymer composites has been progressingextremely rapidly in recent years, because of CNT has remarkable mechanical,thermal, and electrical properties. However, due to their small diameter, large aspectratio, CNTs are normally curled and aggregation, this has been found todramatically hamper the dispersion and content of CNT in polymer matrix. To solvethis problem, we propose to synthesis three dimensional macroscopic---carbonnanotube sponge by self-assemble method, then using it as filler, thus, we canobtain uniformly disperse, content controllable Carbon Nanotube-polymercomposites. In view of interface strength, the carbon nanotube sponges arechemically modified by a dentrimer named polypropylenimine (PPI) and used asreinforcement to prepare composites in order to establish a strong chemical affinitywith the surrounding polymer matrix，thus improve the interface strength andprovide value experimental results for the future works.In this dissertation, CNT sponges are directly synthesized by chemical vapordeposition (CVD), using dichlorobenzene and ferrocene as carbon source andcatalyst precursor, respectively. Its macroscopic morphology is similar to traditionalsponge and possess excellent elasticity. The CNT sponges consist of randomlyoverlapped multi-walled CNTs with diameter about30-50nm, which self-assembledinto a porous framework, the diameter of the porous rage from a few nanometers tomicrons. These carbon nanotube sponges have outstanding electrical properties, ofwhich conductivity is about1.63S·cm-1. The microscopic morphology of CNTsponges can be controlled by modulating CVD process parameters.The CNT sponge reinforced PMMA composites are prepared by directlyinfiltration method and in-situ polymerization. The CNTs are distributed uniformlyin the polymer matrix, which effectively solve the dispersion problem. The insulatedmatrix is given certain electrical conductivity that is about0.13S·cm-1due to theaddition of CNTs. The flexural strength of the composites showed an increased of23%compared with PMMA. The tensile strength increased47%and the elasticmodulus improved27%.In view of the interface strength, the enhacement mechanism of the composites was investigated. The carbon nanutube sponges were chemically midified then uesdas filler to prepare composites, in order to establish covalent bond with thesurronding polymer matrix. After this modification, the flexural strengh of thecomposites increased32%compared with unmodified CNT sponge/PMMAcomposites and a63%enhacement compared with PMMA. The tensile strenghincresed11%in comparison to unmodified CNT sponge/PMMA composites and64%higher than the neat resin. The elastic modulus improved46%.