The Preparation And Property Of Carbon Nanotubes/Elastomeric Composites

Carbon nanotubes(CNTs) have attracted a great deal of interest sincethey were discovered in1991, which have unique structure consisted ofsp2carbon hybridization type, forming the strongest C-C bond and thewhole tube scale delocalized bond as well as a large ratio aspect,leading to high strength, excellent electrical properties, thermalconductivity, etc. Using carbon nanotubes as the fillers for elastomericmaterials, one can expect not only the reinforcement of mechanicalproperties but also the improvement of thermal and electric properties,which will find application in thermal interface materials, thermalconductive tires and electromagnetic shielding materials, etc. The mainwork and results are described as follows1. Using ball milling processing to produce the short CNTs with aseries of decreased length by controlling the ball milling time. The ballmilling times were15min,60min, and5h,10h,16h, respectively. Allsamples including pristine carbon nanotubes were observed on SEM andTEM based which the length distributions of short CNTs were obtained.Also BET specific surface area and Raman spectra were characterized. The results reveal that with the ball milling time increasing, the meanlength of the sample decreases; the specific surface area climbes slowly;no remarkable change can be seen in Raman spectra.2. The CNTs/NR composites with different ball milling time (2h,5h,10h,16h) in the same filler loading(10phr) were prepared. The effect ofincreasing ball milling time on the mechanical properties and thermalconductivity was investigated. The results suggest that the stress at100%and300%are reduced gradually with the decreasing length, while thethermal conductivities remain stable at a moderate length. Differentloadings (10phr,20phr,30phr) of pristine and short carbon nanotubesmilled for16h were applied to prepare CNTs/NR composites. Themechanical properties and thermal conductivity were investigated.Increasing loading of pristine CNTs enhances the improvement oftensile strength and thermal conductivity, but the elongation at breakdrops less than200%. The short CNTs filled NR composites have amoderate conductivity and an acceptable tensile property, which is stillbetter than CB/NR composites. When the loading of pristine CNTs, shortCNTs and carbon black is15phr30phr60phr, the hardness and stress at300%elongation of the three composites are in the same level, and thecompression fatigue, cut resistance and Akron abrasion were determined.The relationship between structure and property of the three compositeswere discussed. 3. The CNTs/SBR composites with different ball milling time(15min,60min,5h) in different filler loadings (5phr,10phr,20phr) were prepared.The mechanical properties, electric properties, thermal conductivities andcompression fatigue properties were characterized. The results suggestthat when the ball milling time is increasing (0h,15min,60min), thestress at100%and300%elongation decrease, the elongation at break andtensile strength increase, thermal conductivities remain stable; when theball milling time is5h, the mechanical properties worsen, and the thermalconductivities decrease remarkably; the heat build-up in the compressfatigue test is prone to decrease. When the filler loading is increasing, themechanical properties, thermal and electric conductivities improves.Compared to CB composites, CNTs exhibit better reinforcement in tensileproperty, electric and thermal conductivity, worse performance incompression fatigue properties.