Understanding the polymer type and CNT orientation effect on the dynamic mechanical properties of high volume fraction CNT polymer nanocomposites

Dispersion and distribution of CNTs in polymers without applying any functionalization and using traditional processes such as mixing, sonication do not exhibit the full potential of CNTs due to agglomeration and limits the use of weight fractions when bulk CNTs is considered. In this work, vertically aligned CNTs (VACNT) and randomly oriented CNTs (RCNT) are used to fabricate vertically aligned CNT polymer nanocomposites and randomly oriented polymer nanocomposites with an elastomer and epoxy as two distinctive polymer types. The comparison of alignment effect is investigated by using both vertically aligned and randomly oriented CNTs. These CNTs were also studied at different volume fractions (up to 10% volume fraction) with a mechanical densification process. Dynamic mechanical analysis of both vertically aligned and randomly oriented CNT polymer nanocomposites were performed with single cantilever clamp and the results showed that longitudinal storage modulus of high volume fraction vertically aligned CNT polymer nanocomposites is higher than randomly oriented polymer nanocomposites due to the alignment effect of CNTs. However, the transverse direction mechanical properties showed an opposite affect that within high volume fractions of CNTs in vertically aligned CNT polymer nanocomposites. Also, due to the nature of elastomer, the reinforcing capability of CNTs showed a higher enhancement on the modulus of PNCs compared to the thermoset resin.