Preparation And Properties Of PPTA Coated Carboxyl Carbon Nanotube Composites

As one dimensional nanomaterials,carbon nanotubes have high strength,high modulus and low density.They can be used as polymer enhanced filler.At the same time,the agglomeration of carbon nanotubes has become one of the most urgent problems.PPTA is a high performance polymer with high strength,stiffness and thermal stability.It has many important applications in lots of fields.If the carbon nanotubes and PPTA are both combined,not only the dispersion of carbon nanotubes can be improved,but also strong high-performance nanocomposites can be obtained.In this paper,a series of new composite materials of aramid-modified carbon nanotubes?PPTA-MWNTs-COOH-x?were prepared by physically coating para-aramid on three kinds of CNTs with different carboxyl groups?3.86%,2.00%,1.23%?.It can be seen by IR spectroscopy that the PPTA-MWNTs-COOH-x not only shows the infrared peak of the original carboxyl-CNTs at 3433 and 1630 cm^-1,but also appears at1540,1318 and 1018 cm^-11 corresponding to PPTA New absorption peak,which can prove that PPTA is successfully adsorbed on the surface of carboxyl carbon nanotubes.The analysis of transmission electron microscopy showed that the tube wall of carboxyl carbon nanotube modified by PPTA was thickened and roughened,indicating the existence of PPTA on the surface of carboxyl carbon nanotubes.Thermogravimetricanalysisshowedthatthethermalstabilityof PPTA-MWNTs-COOH-x was worse than that of the original carboxyl carbon nanotubes,and the weight of PPTA in carboxyl carbon nanotubes could be roughly estimated by weight loss ratio.The dispersive experiment can prove that the modification of PPTA improves the dispersibility of carboxyl carbon nanotubes significantly.The effect of PPTA-MWNTs-COOH-x on mechanical properties of polymer polyvinyl chloride?PVC?was studied.The prepared PPTA-MWNTs-COOH-x was filledintoPVCwithdifferentfillingamounttocastinto PPTA-MWNTs-COOH-x/PVC composite film and tested for tensile strength.It can be found through the tensile test data,PPTA-MWNTs-COOH-x has certain enhancement effect on PVC yield strength,Young's modulus and toughness,and with different filled amount of composite materials,different PPTA loading and different content of carboxyl carboxyl of carbon nanotubes on the same,its effect on PVC is different.At the same time,it was concluded that among the three kinds of carbon nanotubes with different carboxyl contents,the enhancement effect of PVC with 3.86%carboxyl content of carbon nanotubes modified with PPTA?3.86%PPTA-MWNTs-COOH-x?is the best.The maximum enhancement value of yield strength,Young's modulus and toughness of 3.86%PPTA-MWNs-COOH-x increased by 114.76%,108.22%and101.99%respectively compared with PVC;The maximum yield strength,Young's modulus and toughness of 2.00%PPTA-MWNs-COOH-x increased by 107.66%,107.78%,85.97%respectively compared with PVC;The maximum enhancement value of yield strength,Young's modulus and toughness of 1.23%PPTA-MWNs-COOH-x increased by 105.35%,106.61%and 64.48%respectively compared with PVC.