Relationship between microstructure evolution and properties enhancement of carbon nanotubes-filled polybutylene terephthalate/polypropylene blends induced by thermal annealing

Thermal annealing induced microstructure evolution and properties enhancement of polybutylene terephthalate/polypropylene/carbon nanotubes (PBT/PP/CNTs) nanocomposites was methodically investigated. The electrical conductive PBT/PP/CNTs nanocomposites with a low percolation threshold were obtained by simple melt blending due to the selective location of the CNTs in PBT phase and the formation of the double percolation structure. Thermal annealing further remarkably decreased the volume resistivity of the nanocomposites, with the maximum reduction of seven orders of magnitude. Scanning electron microscope observation and rheology tests demonstrated that the relatively large CNTs agglomerates were redistributed to build more homogeneous CNTs networks after annealing. The phase coalescence during annealing promoted the formation of the more perfect co-continuous structure. These phenomena helped to enhance the electrical conductivity of the nanocomposites. Flexural properties of the nanocomposites were also enhanced after annealing, which might be due to the more effective stress transfer between the polymer and CNTs induced by the reconstructed CNTs networks. The nanocomposites obtained in this study possess excellent electrical and mechanical properties, which can be applied to the fields of sensors, electromagnetic interference shielding, anti-static materials, and so forth.

Automated summary

Thermal annealing was found to induce microstructure evolution and enhance properties of PBT/PP/CNTs nanocomposites. The volume resistivity was significantly reduced by seven orders of magnitude after annealing, leading to improved electrical conductivity. Additionally, the reconstructed CNTs networks during annealing contributed to enhanced flexural properties of the nanocomposites.