The effect of carbon nanotubes on viscoelastic behaviour of biomedical grade ultra-high molecular weight polyethylene

Nanocomposites of ultra-high molecular weight polyethylene reinforced with multiwalled carbon nanotubes (UHMWPE/MWCNT) have been prepared with different volume fractions of MWCNTs: 0.2, 0.4, 0.6, 0.8 and 1.0%. DMTA experiments were carried out using a TA Instruments Q800 equipment and the samples were cut from the compressed sheets of polymer and composites. The experiments were conducted on each sample at 12 different frequencies varying from 0.1 Hz to 100 Hz over the temperature range of 22-82 degrees C at an interval of 5 degrees C where the reference temperature was kept at 37 degrees C. It was verified that both horizontal and vertical shifts are necessary to superimpose the dynamic modulus/frequency curves of all cases. The MWCNT did not seem to change the viscoelastic nature of the UHMWPE, i.e. incorporation of up to I wt.% of MWCNTs has negligible influence on the viscoelastic behaviour of the UHMWPE. Hence the same analytical model is applicable for the viscoelastic description of the nanocomposites.