Effect Of Compound Stabilizer On Resistance To Aging Of Nylon 6

Nylon 6(PA6)has excellent thermal stability,wear resistance,excellent mechanical properties,chemical resistance and easy processing.However,due to the presence of amide groups,in light and thermal oxygen conditions,PA6 is extremely susceptible to aging yellowing,With the wide application of PA6 products,the requirements of its appearance have been paid more and more attention by the academic community.Therefore,the improvement of the resistance to yellowing of nylon 6 is also an important direction of research and development.In this paper,stabilizer made of different antioxidants and light stabilizers is added to PA6,and samples are made by extrusion and injection molding.Thermal oxygen oven was used to simulate the thermal oxygen aging of PA6 samples.The artificial accelerated aging test box(QUV)was used to simulate the aging of light oxygen.The changes of color difference(?E)?yellowing index(YI)and tensile strength before and after aging were evaluated,and the best formula was selected.At the same time,the infra-red spectrum(FTIR)of the samples before and after aging were also carried out.Dynamic mechanical analysis(DMA),differential scanning calorimetry(DSC),scanning electron microscopy(SEM),X ray diffraction(XRD)and other analytical tests were conducted,and the principle of PA6 photoaging was explored.The experimental results showed that in the anti oxygen system used in this experiment,the anti oxidant effect of the antioxidant 1098 and the phosphite antioxidant 126 was the best,and the sample could be reduced to ?E<6.2 and YI<0.1 after the thermal oxygen aging of 4h.After adding different light stabilizers to the preferred oxygen resistant system,the samples prepared by the thermal oxygen aging test showed that the ?E,YI and mechanical properties of the samples decreased with the addition of light stabilizers.Only the UV absorbents 326 and the hindered amine light stabilizer 770 were added at the same time,the thermal oxygen performance of the sample is slightly improved.When the samples were heated at 150? for 4h,AE<4.2,YI<5,and the retention rate of tensile strength increased to 95%after 120? 1000h aging.The UV absorbents 326 and the hindered amine light stabilizer 770 showed excellent photooxidation resistance.After 1000h UV aging,?E<4.3,YI<6.5,and the tensile strength retention rate reached 63%.In this paper,infrared,DSC,DMA,XRD,SEM and other characterization methods were used to study the thermal oxygen and weatherability of PA6 and SPA6 samples before and after the long-term aging of 120 ? and UVA-340nm.The results showed that adding compound stabilizer can reduce the group produced by aging and protect the main chain of nylon well.Comparison of samples before and after aging,it can be seen from the infrared that adding compound stabilizer can reduce the aging group and have a certain protective effect on the main chain of nylon.The melting temperature of PA6 is reduced by hot oxygen aging and photoaging,while the melting temperature of the stabilizer is almost unchanged.The aging makes the crystallization starting temperature(Tonset),the crystallization peak temperature(Tc)and the crystallinity(Xc)increase.In the same thermal history,the storage modulus of the stable nylon 6 is higher than that of nylon 6.The peak area and strength of the loss modulus after aging are lower than that before aging,and the loss angle tangent tan?decreases obviously after aging;the XRD test,two were dominated by y crystal.These tests indicate that nylon 6 with compound stabilizer can reduce the degree of thermal oxidative aging and photooxidative aging.