The Study Of Surface Modification For Carbon Nanotubes, Carbon Fibers And Properties For Mwnts/P(VDF-TrFE) Composites

Because of their noticeable mechanical, chemical and physical properties, carbon nanotubes (CNT) and carbon fibers (CF) are attracted wide attention as reinforcement for composites. However, both of them have poor wettability and absorption with most polymers because their surface is non-polar and compound of highly crystallized graphitic basal planes with inert structures. In order to improve the performance of composites, we use chemical methods to modify CNT and CF surface. And after that, the composites'performances were studied.In order to obtain higher dielectric constant and higher energy storage material, we modified MWNTs with ultrasonic acid treatment and prepared MWNTs/P(VDF-TrFE) films. SEM results showed that the dispersibility in polymer matrix was improved after treatment. The dielectric properties of these films obey the percolation theory. The dielectric constant of MWNTs/P(VDF-TrfE) reaches 497 at 100 Hz near its percolation threshod, while a-MWNTs/P(VDF-TrFE) is 705, 50 times higher than P(VDF-TrFE).The interfacial bonding strength between fibers and polymer matrices is low, therefore, good mechanical performance of composites cannot be ensured. We use ultrasonic oxidation to modify the CF surface. Surface analyses of carbon fibers before and after treatment were performed by SEM, Raman spectroscopy and contract angle was also tested. The results showed that, after the treatment, the surface of carbon fibers was functioned and the wetting properties were improved. The testing results of Interfacial Shear Strength showed that, after the treatment, the strength increased by 33%. But the strength of carbon fibers declined.Grafting Epichlorohydrin onto fiber surface was also used to improve IFSS. Results showed that IFSS increase while the strength carbon fiber increased.