N-Epoxypropyl poly(p-phenylene terephthalamide) covalently and non-covalently coated multi-walled carbon nanotubes for PVC reinforcement

Poly(p-phenylene terephthalamide) (PPTA) coated multi-walled carbon nanotubes (PPTA-MWNTs) showed an enhancement effect on the yield strength and Young's modulus of PVC composite films, but no improvement in toughness. In this paper, MWNTs were covalently and non-covalently coated by N-epoxypropyl PPTA (PPTA-ECH) to prepare PPTA-ECH-MWNTs-NH2-x and PPTA-ECH-MWNTs-x, which were used as additives to reinforce PVC composite films. It was found that the maximum yield strength, Young's modulus, and toughness of PPTA-ECH-MWNTs-NH2-x/PVC composite films increased by 227.84%, 201.56%, and 589.96%, respectively, in comparison to pure PVC, while those of PPTA-ECH-MWNTs-x/PVC composite films increased by 215.08%, 153.13%, and 540.81%, respectively. The maximum yield strength, maximum Young's modulus, and maximum toughness of both PPTA-ECH-MWNTs-NH2-x/PVC and PPTA-ECH-MWNTs-x/PVC showed significant improvement as compared to PPTA-MWNTs/PVC composite film and PPTA-MWNTs-NH2/PVC. This indicates that N-epoxypropyl PPTA covalently and non-covalently coated MWNTs are promising additives for reinforcing PVC.