| The structural parameters of domestic Nd-IR were analyzed by means of Gel Permeation Chromatography (GPC), Differential Scanning Calorimeter (DSC) and Nuclear Magnetic Resonance( NMR), and the morphological structure of carbon black Gel was studied through the use of SEM, and compared parallelly with NR and Ti-IR which produced in Russia (denoted by SKI-3-IR). After the aforementioned researches, the effect of raw rubber and the carbon black (CB) Gel structure in Nd-IR on stress-strain properties were studied, and then the basic properties and application in tire tread were investigated.The investigation showed that Mooney viscosity, molecular weight, molecular weight distribution, and glass transition temperature (Tg) of masticated NR (denoted by NR-2), Nd-IR and SKI-3-IR were similar respectively, although 1,4-structure content of three types of raw rubber was not different, cis1,4-structure content of NR was higher than IR. By comparison, the Gel content in un-masticated NR (denoted by NR-1) was the highest, and that in NR-2 was higher, but there was almost no Gel in raw isoprene rubber. The CB filled compounds of NR-2 contained the most bound rubber, while the Nd-IR contained the lowest. So the most obvious Payne effects appeared in Nd-IR compounds. SEM images showed that the carbon black surface of NR-2 compounds joined the most rubber and more and longer rubber wire-drawing appeared in section gap of NR-2 compounds. The result that the interaction between carbon black and natural rubber was stronger than that of IR was concluded.The research of stress-strain curve showed that NR-1 and CB filled NR-2 compounds had strain hardening phenomenon which didn't appear in NR-2 rubber. Neither raw rubber nor CB filled isoprene rubber compounds displayed strain hardening phenomenon. The strength of raw rubber and CB filled compounds of IR was lower than that of NR. But the stress-strain curves of vulcanized NR-2, Nd-IR and SKI-3-IR showed the similar trend.Compared with the ASTM standard formula, JIS standard formula was more suitable for Nd-IR. Through optimization of JIS standard formula, the basic formula of Nd-IR was obtained. On the basis of JIS standard un-filled NR formula, the un-filled formula of Nd-IR can be gotten by adding 0.2phr accelerator. On the basis of JIS standard carbon black filled NR formula, the carbon black filled formula of Nd-IR can be obtained by adding 0.1phr accelerator. The function of accelerated vulcanization of accelerator NS and alkalescent carbon black on IR was more obvious than NR.The study on application of Nd-IR in tire tread obtained the following results.In pure NR tread rubber formula, Nd-IR can substitute NR at the ratio of 20% without affecting the performance. The curing rate can be accelerated by adjusting the curing system, so Nd-IR can replace NR at the ratio of 50%. N375 was suitable for Nd-IR in the pure Nd-IR compound during the study on the effect of carbon black species on properties.In truck tire tread rubber(NR/ SBR/BR blends)formula, Nd-IR can substitute NR at the ratio of 80% without affecting the performance, so Nd-IR possessed good blending with other rubber. Contrasting with basic formula, the dispersion of carbon black in Nd-IR was similar to NR as a result of adding processing agent containing polar groups.In engineering tire tread rubber(NR/SBR blends)formula, Nd-IR can substitute NR at the ratio of 20% without affecting the performance. Because of white CB in formula, the dispersion of filler in Nd-IR was worse than NR, so the Payne effect was stronger than NR. If Nd-IR substitutes NR in the greater proportion, on the one hand, curing rate and crosslink density has to be raised by adding accelerator content. On the other hand, the dispersion of filler in Nd-IR should be improved by adding processing agent. |
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