The Study On Anti-Aging Property Of High-Temperature Nylon

The whitening and anti-aging effects of the rutile titanium dioxide, antioxidants, ultramarine blue, coupling agent, on the polyphtalamide (PPA) were studied in this paper. Both titanium dioxide R104/PPA mixtures and titanium dioxide RCL-69/PPA mixtures with different additives were prepared in the twin-screw extruder and and the mechanical properties,Blu-ray whiteness (R457), yellowness index (YI) were investigated. The changes of PPA structure occured in the aging process were analyzed with the infrared spectroscopy. The Arrhenius equation was used to predict the useful life of the PPA with14%titanium dioxide R105in150℃.The TGA test showed that a relatively small weight loss appears from290℃to350℃. This area was caused by the Thermal-oxidative aging in the process of PPA. And the range of processing and useing temperature was at280-400℃. The Solvay PPA which was named as A-4000had a better thermal stability than A-1000.The ranking for initial decomposition temperature of TG curve of antioxidants sample and blank sample is:H3373>KBG779>H10>blank. In the machining process, the antioxidant effect of H3373was better than the others.The antioxidants had an important influence on the mechanical properties of the PPA mixtures. The antioxidant H3373and the anti-yellowing agent KBG779had good performance in retarding the decline of the mechanical properties caused by thermal oxidation.The H3373samples without artificial aging had the highest tensile strength, flexural strength,respectively55.7MPa,111.7MPa.After aging12h at180℃,the tensile strength can keep47.4MPa, bending strength can reach97.3MPa, iMPact strength is18.3MPa.The antioxidants also had an important influence on the Blu-ray whiteness and yellowness index of the PPA mixtures. H10is one kind of inorganic phosphates containing metal ions, making PPA show gray-blue.The H3373had the best performance in the whitening and whiteness maintenance of PPA.However.for the anti-yellowing ofPPA, both KBG779and H3373were available.Titanium dioxide can affect the mechanical properties of the PPA mixtures. Without antioxidants, the tensile strength of the R104sample was slightly higher than the RCL-69sample. After aging for12h at180℃, the tensile strength could keep at about40MPa. In addition, when Run used with H3373, the mechanical properties were better. With the increase of the content of titanium dioxide, the ten.sile strength of PPA mixtures, before and after aging,also increased.The addition of titanium dioxide could improve the process stability of PPA mixtures. For different titanium dioxide samples, the main reason for the mechanical property gap was the coMPatibility between titanium dioxide and plastic. The titanium dioxide used in experiment was covered by silicon and aluminum surface-treatment.The influence of Titanium dioxide on the Blu-ray whiteness and yellowness index of the PPA mixtures.The addition of titanium dioxide could increase R157obviously. With the increase of the content of R104, the R457of PPA mixtures increased rapidly.After the content of titanium dioxide increased to10%, the R4.17of PPA sample could reach80, the basic requirements, since the increase trend of Bin-ray whiteness was slowing down.When these titanium dioxide used with KBG779, the whitening effect on the PPA was similar. When R104used with H3373, there existed an excellent synergistic effect on the whitening of PPA mixtures.However, with the increase of the content of titanium dioxide Rioi, the yellow index of PPA mixtures decreased first and then increased. When used with anti-yellowing agent KBG779, the yellow index of RCL-69sample was lower. The anti-yellowing of Rioi sample performed excellently when use with KBG779or H3373Besides, the subject researched the whitening and yellow covering of PPA biends when ultramarine were used with the rutile-type titanium dioxide. The results showed that: After adding ultramarine, the YI reduces significantly. When the titanium dioxide’s content increased to11%, the YI was only13.94smaller than the YI of samples without ultramarine. The aging of PPA is unavoidable. Infrared analysis showed that, The long-term using temperature of PPA can research170℃. The thermal oxidation process of PPA is similar to the process of ordinary nylon.The yellowing of PPA is caused by some chromophores, for example, carboxyl group, aldehyde or ketone, etc. Finally, there was a research about the working life prediction of high-temperature nylon mixtures whose thermal oxidation was accelerated.In the Arrhenius equation, the decrease of tensile strength by25%concerned as the threshold. The results showed that:the working life of the PPA sample containing1%of antioxidant H3373and14%titanium dioxide R104in150℃can reach15135.61h.