In situ grafting of polybutylene terephthalate onto multi-walled carbon nanotubes by melt extrusion, and characteristics of their composites with polybutylene terephthalate

Multi-walled carbon nanotubes (MWCNTs) functionalized with hydroxyl groups were explored as effective fillers for polybutylene terephthalate (PBT) composites with expected in situ transesterification between hydroxyl groups in MWCNTs and ester groups in the PBT during melt extrusion. The interfacial adhesion energy between PBT and PBT-grafted MWCNTs (PBT-g-MWCNTs) calculated by using drop-on-fiber method was higher than that between PBT and pristine MWCNTs. As a result of higher interfacial adhesion energy, the dispersion of MWCNTs in the PBT matrix and interfacial adhesion between the MWCNTs and PBT matrix were better in the case of the PBT/PBT-g-MWCNT composite than in the case of the PBT composite with pristine MWCNTs. The former also exhibited better mechanical properties and electrical conductivity than the latter at the same MWCNT content.