Preparation And Properties Of PPTA Coated Carboxyl Carbon Nanotube Composites

Carbon nanotubes?CNTs?are the preferred filler for composite reinforcement due to their superior modulus and strength.However,the poor compatibility of carbon nanotubes with matrices limits their widespread use in composites.PPTA has excellent mechanical properties and thermal stability.If it is compounded with CNTs,a new composite reinforcement with better performance can be prepared by the combination of strong and strong.In this paper,two series of PPTA oligomer chemically modified carbon nanotube composites were prepared by grafting oligomer PPTA directly onto multi-walled carbon nanotubes by chemical bonding.The enhancement properties of PVC were studied and the enhancement mechanism was discussed.In this paper,p-phenylenediamine?PDA?and terephthaloyl chloride?TPC?were dissolved in different molar ratios?n[PDA/TPC]=x,x are 1.1,1.2,1.4,1.6,1.8 and 2.0respectively?.In N-methylpyrrolidone?NMP?,six different molecular weight terminal amino oligomeric PPTA(o-PPTA-NH_2-x):o-PPTA-NH₂-1.1,o-PPTA-NH₂-1.2,o-PPTA-NH₂-1.4,o-PPTA-NH₂-1.6,o-PPTA-NH₂-1.8 and o-PPTA-NH₂-2.0.The molecular weights were determined by flight mass spectrometry to be 5106,2726,1536,1139,941 and 822 g/mol,respectively.18 kinds of o-PPTA chemically modified carbon nanotubes(o-PPTA-NH_2-x@MWNTs)with different PPTA chain lengths and different grafting rates)were prepared by reacting them with carbon nanotubes with carboxyl content of 3.86%,2.00%and 1.23%,respectively.The products were characterized by infrared spectroscopy,transmission electron microscopy,thermogravimetric analysis and X-ray photoelectron spectroscopy.The dispersibility in solvents such as DMF,DMSO,NMP,acetone and absolute ethanol was studied.The results showed that o-PPTA-NH_2-x@MWNTs can be well dispersed in DMF solvent.Subsequently,using DMF as solvent,the above o-PPTA-NH_2-x@MWNTs were filled into PVC with different addition amounts by solution mixing method,and 126composite membranes(o-PPTA-NH_2-x@MWNTs/PVC)were prepared,and the mechanical properties of the composite membrane were tested.The test results showed that the Young's modulus,toughness and yield strength of the composite film were significantly improved compared with the pure PVC film;the composite material with a carboxyl content of 3.86%is stronger than 2.00%and 1.23%;the Young's modulus of the composite film The amount,toughness and yield strength can be increased by up to 129.15%,262.82%and 126.31%.In addition,six different molecular weight terminal acid chloride oligomeric PPTA?o-PPTA-COCl-x?were synthesized by a similar synthesis method,and reacted with amino carbon nanotubes to prepare six kinds of o-PPTA chemically modified carbon nanotubes?o-PPTA-COCl-x@MWNTs?were prepared by reacting them with aminocarbonnanotubes.Dispersiontestexperimentsshowedthat o-PPTA-COCl-x@MWNTs can also be well dispersed in DMF solvent.Similarly,DMF was used as the solvent,and the above o-PPTA-COCl-x@MWNTs were filled into PVC with different addition amounts by solution mixing method,and 42composite membranes o-PPTA-COCl-x@MWNTs/PVC were prepared.The mechanical properties test showed that the Young's modulus,toughness and yield strength of the composite film were significantly improved compared with the pure PVC film,and the maximum increase was 126.43%,179.34%,144.89%.Comparing the enhanced performance of the above two series of products on PVC,overall,o-PPTA-NH_2-x@MWNTs was superior to o-PPTA-COCl-x@MWNTs in enhancing the performance of PVC,which was a kind of nanometer with potential.Reinforcement material.