Mechanical properties of carbon nanoparticle-reinforced elastomers

Silicone based elastomers have been mixed with single-wall carbon nanotubes or larger carbon nanofibrils. Tensile tests show a dramatic enhancement of the initial modulus of the resulting specimens as a function of filler load, accompanied by a reduction of the ultimate properties. We show that the unique properties of the carbon nanoparticles are important and effective in the reinforcement. The modulus enhancement of the composites initially increases as a function of applied strain, and then at around 10–20% strain the enhancement effect is lost in all of the samples. This "pseudo-yield" in elastomeric (or rubber) composites is generally believed to be due to trapping and release of rubber within filler clusters. However, in-situ Raman spectroscopy experiments show a loss of stress transfer to the nanotubes suggesting that instead, the "pseudo yield" is due to break-down of the effective interface between the phases. The reorientation of nanotubes under strain in the samples may be responsible for the initial increase in modulus enhancement under strain and this is quantified in the Raman experiments.