The Synthesis Of Reactive Antioxidant NAPM And Application In NR

Rubber antioxidant N-(4-Anilinophenyl)-methacrylamide (NAPM) was successfullysynthesized from intermediate product methacryloyl chloride (MAC) and objective product4-aminodiphenylamine. Effects of the reaction time, the molar ratio of materials, the reactiontemperature and hydrogen chloride acceptors on the yields of MAC and NAPM wereinvestigated respectively. It was found that the optimum reaction conditions of MAC are:SOCl₂: MAA=1.5 (molar ratio), the reaction temperature ranging from 10 to 60℃, thereaction time 6 hours, yield: 88.59%; the optimum conditions of NAPM are: MAC:4-aminodiphenylamine=1.5 (molar ratio), the reaction temperature ranging from 0 to 20℃,the reaction time 2.5h, yield 76.53%. Infrared spectrum (IR), ¹H-NMR and element analysiswere carried out to identify structures of MAC and NAPM. Moreover, thermogravimetricanalysis (TGA) was performed to investigate thermal stability of NAPM. It can be concluedthat the degradation started at about 160℃for 4010NA, 4020 and it was 240℃for NAPM.These results indicate that the thermal stability and antiaging property of NAPM are higherthan those of 4010NA and 4020.The age resistant and mechanical properties of rubber antioxidant NAPM in naturalrubber (NR) were investigated and compared with those of conventional antioxidants N-(1,3- dimethyl butyl)-N'-phenyl-p-phenylene diamide (4010NA) andN-isopropyl-N'-phenyl-p-phenylene diamide (4020). The results showed that the ratio of K(4020)/K (4010NA) increases merely by 3.09%, whereas an increase of 14.21% in the ratio ofK (NAPM)/K (4010NA) was obtained as the aging time was extended from 48h to 72h. Thegained aging coefficient (K) of NR vulcanizates containing NAPM is slightly lower than thatof 4010NA, 4020 after 70℃×48h aging; nevertheless, it is markedly higher than that of4010NA and 4020 after 70℃×72h aging. Thus, NAPM has stronger antiaging property thanantioxidant 4010NA and 4020.Moreover, Unsaturation level of NR vulcanizates containing different antioxidants wasmeasured by iodometry. Unsaturation level of NR latex containing NAPM is 7.975, and it is3.375 for the corresponding vulcanizates with a decrease of 4.6; for 4010NA they are 7.425and 4.25, respectively, with a decrease of 3.175, indicating that not only NAPM is distributedto NR, but potentially reacts with NR causing the decrease of unsaturation level of NRcontaining NAPM. A reaction between NAPM and cis-1, 4-polyisoprene in NR is proposed to explain betterproperties of NAPM, which was indentified by IR and IR differential spectra analysis. FromSEM and TEM images a network structure was observed on the surface of NR vulcanizates,giving a microcosmic evidence for the reactivity of antioxidant NAPM.