Research On The Effect Of Organic Copper Salt Antioxidants On Aging Resistance Of Nylon 6

Nylon 6?PA6?,as one of the most widely used engineering plastics,has excellent properties such as high strength,wear resistance and corrosion resistance.However,in the progress of production,processing and use,the molecular chains are susceptible to heat,oxygen,ultraviolet light,water vapor and other factors,which lead to the decline in mechanical performances and the change of color.Therefore,it is great significance work to research and develop the thermal stability of Nylon 6.In this thesis,two organic copper salts?A and B?were synthesized by oxidation-reduction method based on triphenylphosphine?PPh₃?,cupric nitrate and cupric bromide as raw materials in methanol and ethanol solvents respectively,and structures and properties of which were characterized.The heat resistant PA6 was prepared by melt extrusion with organic copper salts A and B,composite antioxidants 1098/168,1098/A and1098/B used as additives,and the effect of these antioxidants on the thermos-oxidative stability of nylon 6 was studied.The heat resistant PA6 was characterized by the test of X-ray diffraction?XRD?,Infrared Spectroscopy?FTIR?,Ultraviolet Spectroscopy,Scanning Electron Microscopy?SEM?,Differential Scanning Calorimetry?DSC?,Mechanical Properties,Heat Deflection Temperature?HDT?,Molecular Weight,Termination group and Thermogravimetric Analysis?TG?.The main contents and conclusions of this study are as follows:The organic copper salts A and B were prepared by the methods of single factor variable and orthogonal experiment.The optimum synthesis conditions of organic copper salts were determined by the analysis of yield,copper content and melting range of the products.The yields of organic copper salts A and B were 53.38%and 78.17%,respectively.The results showed that triphenylphosphine was the ligand of organic copper salts A and B.Organic copper salt A is copper compounds with two triphenylphosphine ligands,and organic copper salt B is copper compounds with three triphenylphosphine ligands.The effect of organic copper salts A and B on thermo-oxidative stability of PA6 showed that the crystallinity of Nylon 6 was increased by organic copper salt A,and organic copper salt A increased the apparent viscosity of Nylon 6 melt.The sample of Nylon 6 was dyed obviously by organic copper salt A.The crystallinity of nylon 6 containing copper A was decreased after aging treatment.On the other hand,the crystallinity of Nylon 6 was reduced by organic copper salt B,but it was improved after aging 144 h.The tensile strength and elongation at break of Nylon 6 were improved more significantly by organic copper salt B,and the number of carbonyl of Nylon 6 was reduced by organic copper salt B.The surface of Nylon 6 containing organic copper salt B was crack-free after accelerated aging.It suggested that organic copper salt B had a prominent effect on improving aging resistance of Nylon 6.The effect of composite antioxidants on thermo-oxidative stability of PA6 showed that the compound of antioxidant 1098 with organic copper salts A and B displayed excellent synergistic effect on thermo-oxidative stability of Nylon 6.The melting temperature and crystallization temperature of Nylon 6 were decreased by antioxidant 1098 combined with organic copper salts,indicating that the composite antioxidants reduced the wafer thickness of Nylon 6.The composite antioxidants 1098/A were more effective in inhibiting increase of the end carboxyl group and decrease of end amine group of Nylon 6.The aging of Nylon6 was accelerated by oxygen,and the decomposition temperature of Nylon 6 was improved by composite antioxidants 1098/organic copper salt A and 1098/organic copper salt B under N₂ and O₂ atmosphere,indicating that Nylon 6 containing composite antioxidants1098/organic copper salt A and 1098/organic copper salt B had the excellent thermal-oxidative stability.The Nylon 6 containing with composite antioxidants 1098/A was intact and ductile fracture,indicating that composite antioxidants 1098/organic copper salt A had better effect on thermo-oxidative stability of Nylon 6.