Multi-walled carbon nanotubes (CNTs) exhibit excellent electrical, mechanical and thermal properties. A key challenge is to translate these properties to a polymer matrix. Poly(ethylene terephthalate) (PET) – CNT composites show enhanced electrical and mechanical properties with low CNT loading (%wt). The mechanical properties are vastly improved (Young’s modulus of increased by 79%) and electrical conductivity increased by 14 orders of magnitude, compared to neat PET. However, these properties depend on the dispersion and distribution of the CNT in the PET matrix where the formation of random conductive networks for electron transfer is achieved when the CNT content reaches a critical volume fraction or <i>percolation threshold</i>. Secondary processing can alter the random networks of CNTs, for example, uniaxial stretching disrupts the CNT network, but subsequent annealing increases the CNT-CNT contacts. Here, the structure development during uniaxial deformation and annealing is investigated with respect to 1 and 2% wt loading of CNTs in PET. In-situ small-and wide-angle X-ray scattering, thermal and mechanical techniques have been combined to follow the structure development in PET-CNT composites at different draw rates and ratios. Results showed that although the CNTs increase the rate of crystallization, they reduce the bulk crystallinity and disrupt the lamellar macrostructure usually seen in pure PET (Figure 1). The results have allowed us to correlate the macromolecular structure with the enhanced mechanical and electrical properties of these materials.

Polymer-carbon nanotube composites: Enhancing structure-property relationships

251st National Meeting (2016)

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