Carbon nanotubes (CNTs) are potentially the ultimate filler for high-performance composite materials due to their exceptional intrinsic properties such as Young's modulus up to 1TPa, tensile strengths of up to 300 GPa and high electrical and thermal conductivity. Recently, biobased cellulose nanowhiskers (CNWs) have attracted lots of interest due to their mechanical properties, such as elastic modulus up to 220GPa and tensile strengths up to 17GPa, as well as the abundance and renewable resource for the raw material. In this study, we explore the potential of partially or totally replacing CNTs with CNWs in advanced composite materials. Specifically, CNTs and CNWs are compared in terms of their mechanical reinforcing capacity for epoxy composites. CNWs, prepared via TEMPO oxidation, were dispersed in the epoxy by a solvent exchange method and a similar procedure was employed for dispersing CNTs in the resin. We determined the percolation threshold for these fillers in the epoxy resin using small amplitude oscillatory rheology. Due to the difference in the aspect ratio (~160 for CNTs versus ~50 for CNWs), the percolation threshold for CNTs at 0.1-0.2 vol. % is lower than that for CNWs at 0.3-0.4 vol. %. Interestingly, DMA measurements show higher storage modulus at temperatures beyond the glass transition temperature for the epoxy composites with CNWs at concentrations around the percolation threshold by comparison with the composites containing CNTs around the percolation threshold (Figure 1). 

Can cellulose nanowhiskers replace carbon nanotubes in advanced composite materials?

248th National Meeting (2014)

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