The Study On The Preparation And Properties Of The PA6/PP/CNTs Composites

The PP-g-(MAH-co-St), PP-g-(MMA-co-St), PP-g-(GMA-co-St), PP-g-(ITA-co-St) are processed by muti-monomer melting grafting and thegrafting ratios are 1.52, 1.86, 2.52 and 2.19 (wt%) respectively. CNTs isfirstly dissolved in diluted nitric acid for purification, then treated withaquaregia, nitric acid and caprolactam grafting, as the result of whichchange the surface states of CNTs. The polyamide 6(PA6)/polypropylene(PP), PA6/PP/compatilizers and PA6/PP/compatilizers/Carbon nanotubes(CNTs) are prepared by melt blending. The influences of PP,compatilizers and CNTs on the thermal property, friction and wearproperty, process property, structure, mophology of the composites areinvestigated by Fourier Transform Infrared Spectrum (FTIR), RamanSpectrum, Differential Scanning Calorimetry (DSC), TransmissionElectron Microscopy (TEM) and Scanning Electron Microscopy (SEM)and Torque Rheolometer.The above treated CNTs are used to prepare PA6/CNTs compositesthrough melt blending. It is indicated that the CNTs acts as effectivenucleating agents, the crystallization rate of PA6 in the composites is thusincreased. The friction and wear performance of PA6 reinforced by CNTsare carry out on the tribology tester, and show that the addition of theCNTs effectively lower the friction coefficient and wear loss. CNTs withdifferent -COOH groups have different modifying effects on the PA6matrix. Shorter CNTs with more-COOH groups are helpful to disperse inthe matrix evenly. The composites with stronger interface cohesion canrelease the friction force in the sliding process by appropriateplastic-deform, which can reduce the weariness of materials. The Dynamic Mechanical Analysis (DMA) of the PA6/CNTs compositesshow that with the addition of CNTs, the storage modulus E' and Lossmodulus E" are increased, the storage modulus E' and loss modulus E"change as follows PA6/CNTs3^#＞PA6/CNTs1^#＞PA6/CNTs2^#＞PA6.The results show that the grafted chains play the nucleus roles in thecrystal process and make the crystal temperature of the PP rise. Theexotherm peak width (AW) shows a reduce tendency which means thecrystallite size distribution of grafted PP is narrower than that of the neatPP for thinner crystal particles. A few ofβ-crystal come into being forgrafted chain. The compatilizer reduces the absorption of water of the PA6/PP composites.The studies on the PA6/PP/compatilizers and PA6/PP/compatilizers/CNTs show that the compatilizer can make PP evenly disperse in the PA6matrix, and CNTs and YWCNTs can evenly disperse in the PA6/PP/compatilizers. The treated states of the CNTs can make the interfacecohesion of PA6 and PP reinforced, and influence the friction and wearproperty of the PA6/PP/CNTs (YWCNTs) composites. The-COOHgroups on the CNTs react with-NH₂ on the molecular chain of PA6, asthe result of which the CNTs only dispersed in PA6. The-NH₂ on theYWCNTs reacts with -COOH from the PP-g-(ITA-co-St) that makeYWCNTs can disperse in the PP. The PA6/PP/PP-g-(ITA-co-St)/YWCNTs composites can produce more uniform transform film on thecounterface during sliding process, so the weight loss of thePA6/PP/PP-g-(ITA-co-St)/YWCNTs composites is lowest.