Recycled polyethylene terephthalate/carbon nanotube composites with improved processability and performance

Recycled poly(ethylene terephthalate) (PET) nanocomposites containing multiwalled carbon nanotubes (CNTs) were prepared through melt compounding via masterbatch dilution method. The masterbatch and the nanocomposites were processed in a twin-screw extruder. The rheological, morphological, thermal and mechanical properties of the PET-CNT nanocomposites have been investigated. Incorporation of CNTs into recycled PET at low concentration (0.25 wt%) significantly increases the viscosity. The storage modulus and loss modulus of nanocomposites were also increased with increasing amount of CNTs. This effect was more pronounced at lower frequencies. The incorporated CNTs in recycled PET increase the degree of crystallinity and crystallization temperature through heterogenous nucleation. Thermal stability and glass transition temperature of PET-CNT nanocomposites were slightly higher than the reference recycled PET. The tensile strength and modulus of PET-CNT nanocomposites increased even at low concentrations of CNTs. Morphological investigation through scanning electron microscopy indicated homogeneous dispersion of CNTs at lower concentrations. At higher concentrations, the CNTs tend to agglomerate due to nanotube-nanotube interactions.