A Study On PMIA Modified Multi-walled Carbon Nanotubes And Their Polymer Composites

Carbon nanotubes have received extensive attention due to their unique structural characteristics and excellent properties,since they are discoveried.They are light in weight,hexagonal structures are perfectly connected,and there are many fabulous mechanical,electrical and chemical properties.The extremely excellent properties of CNTs make it an ideal material enhancer.Many studies have shown that the mechanical properties of composites are significantly improved with very low additive.However,CNTs also have its disadvantages.Its surface lacks active groups and there is a strong interaction between the one and the other carbon nanotube,which make CNTs impossible to achieve better dispersion in polymer materials,so that CNTs cannot be fully utilized as a reinforcing agent.Therefore,we expect to find a way to solve the agglomeration problem of carbon nanotubes.In this paper,CNTs are modified by meta-aramid（PMIA）with similar structure to CNTs,which enhances the surface activity of CNTs and weakens the interaction between tubes and tubes,and finally enhanced the dispersion of CNTs.At the same time,PMIA itself has very good performance,so we hope to get a better material through the synergy.In this paper,a series of oligo-meta-aramid（o-PMIA）chemically modified multi-walled carbon nanotubes（MWNTs-o-P-x:y）are prepared via the condensation reaction of carboxylic multiwall carbon nanotube（MWNTs-COOH）with amino-terminal o-PMIA in the presence of condensation agent.A series of epoxidized PMIA solutions are reacted with aminocarbon nanotubes to obtain a multi-walled carbon nanotube MWNTs-P-G-x chemically modified by PMIA epoxidation solution.The structures of MWNTs-o-P-x:y and MWNTs-P-G-x are characterized and observed by FTIR,TGA,TEM,SEM and Raman spectroscopy.MWNTs-o-P-x:y and MWNTs-P-G-x are used as additives to reinforce two kinds of PVC composite films.From the results of tensile strength test,it is found that the maximum values of Tensile modulus,yield strength,and toughness of MWNTs-o-P-x:y/PVC-L increased by 70.54%,117.46%,and 195.34%,respectively,in comparison to pure PVC-L film,while those of MWNTs-o-P-x:y/PVC-H increased by138.41%,126.44%,and 83.66%,respectively,in comparison to pure PVC-H film.It is also found that the maximum values of Tensile modulus,yield strength,and toughness of MWNTs-P-G-x/PVC-L increased by 86.71%,105.99%,and 141.31%,respectively,in comparison to pure PVC-L film,while those of MWNTs-o-P-x:y/PVC-H increase by 154.40%,150.21%,and 77.46%,respectively,in comparison to pure PVC-H film.As the above values are compared with MWNTs-COOH and MWNTs-NH₂ as PVC additives,the mechanical properties have been significantly improved.This shows that the modified carbon nanotubes can exert the ideal additive effect of the composite.In addition,the results show low dosage of MWNTs-o-P-x:y and MWNTs-P-G-x can make the mechanical properties of PVC with lower molecular weight reach or exceed those of Pure PVC with higher molecular weight.So MWNTs-o-P-x:y and MWNTs-P-G-x are expected to have broad prospects in widening the application of universal polymer material such as PVC.