Plasma treatment-induced fluorine-functionalized multi-walled carbon nanotubes to modify poly(ethylene terephthalate) obtained via in situ polymerization

摘要

The introduction of carbon nanotubes in a polymer matrix can markedly improve its mechanical properties and electrical conductivity, and much effort has been devoted to achieve homogeneous dispersions of carbon nanotubes in various polymers. Our group previously performed successfully fluorine-grafted modification on the sidewalls of multi-walled carbon nanotubes (MWCNTs), using homemade equipment for CF4 plasma irradiation. As a continuation of our previous work, in the present study CF4 plasma-treated MWCNTs (F-MWCNTs) were used as a nanofiller with polyethylene terephthalate) (PET), which is a practical example of the application of such F-MWCNTs to prepare polyester/MWCNTs nanocomposites with ideal nanoscale structure and excellent properties. As confirmed from scanning electron microscopy observations, the F-MWCNTs could easily be homogeneously dispersed in the PET matrix during the in situ polymerization preparation process. It was found that a very low content of F-MWCNTs dramatically altered the crystallization behavior and mechanical properties of the nanocomposites. For example, a 15°C increase in crystallization temperature was achieved by adding only 0.01 wt% F-MWCNTs, implying that the well-dispersed F-MWCNTs act as highly effective nucleating agents to initiate PET crystallization at high temperature. Meanwhile, an abnormal phenomenon was found in that the melt point of the nanocomposites is lower than that of the pure PET. The mechanism of the tailoring of the properties of PET resin by incorporation of F-MWCNTs is discussed, based on structure-property relationships. The good dispersion of the F-MWCNTs and strong interfacial interaction between matrix and nanofiller are responsible for the improvement in mechanical properties and high nucleating efficiency. The abnormal melting behavior is attributed to the recrystallization transition of PET occurring at the early stage of crystal melting being retarded on incorporation of F-MWCNTs.