The multi-walled carbon nanotubes (MWCNT) were modified using sodium dodecyl sulfate(SDS) as the aid and the SDS treated MWCNT was named as SCNT.We successfully prepared the multi-walled carbon nanotubes/poly(ethylene terephthalate)(MWCNT/PET) composites and SCNT/PET composites with the desired filler content.The effects of the SDS on the MWCNT/PET composites were investigated from several aspects such as microstructure

electrical conductivity

crystallization behavior and mechanical properties.The results showed that SDS treatment can effectively improve the dispersion of MWCNT in the PET matrix

accelerate the construction of the electrical conducting networks.The percolation threshold of the composites can be dramatically decreased from 2.35 wt% to 0.18 wt%.At the 1 wt% filler content

MWCNT cannot increase the electrical conductivity of the PET composites

but SCNT induced a dramatic increase of about 10 orders of magnitude in the electrical conductivity of the PET composites.SCNT not only increased the electrical conductivity of the PET composites

but also more effectively improved the mechanical properties of the PET composites compared with MWCNT.At the 1 wt% SDS treated MWCNT content

SDS treated MWCNTs increase the tensile strength of PET matrix by about 31% and the tensile modulus of PET matrix by about 58%.Not like MWCNT/PET composites

SCNT/PET composites increase the tensile strength with increasing filler content after 1 wt% loading.Being similar to MWCNT

SCNT could act as a nucleating agent to shift the crystallization temperature of PET matrix to higher temperatures but decrease crystallinity of PET matrix with increasing filler content.The role of SDS in these MWCNT/PET composites has been explored in detail.