Effect Of Filler And Processing Aids On The Creep Properties Of NR

Railway is a vital means of transport, along with our country railway leap-forward development, especially the development of high-speed and light railway, the demand on the rail line is higher and higher. In high-speed railway construction project,the rubber damping products is one of the most effective way to reduce the track vibration and noise. Because the rubber cushionings are buried under the road bed, bearing the double weight from road bed and vehicular traffic at long times,the creep of rubber cushioning occurs,leading to shortened life, so further study of the creep law of rubber is very necessary.This topic select nature rubber which commonly used as isolation pads as experimental materials, mixtured with different fillers and processing AIDS, testing the creep property of the vulcanized rubber by the high temperature creep and stress velaxation test machine, researching the effects of formulation such as the types and rates of fillers, dispersants and plasticizers and test temperature on the creep properties of the nature rubber. The results show that:(1) When the dosage of carbon black is the same, with the increase of carbon black particle size, the slow variables of NR vulcanizates decreases, and creep resistance. At the same level of the particle size, can gift lower creep to NR which filled with high structure carbon black.(2)With the amount of N660 carbon black increase, creep variable had a tendency to reduce, but the gap is very small. The creep variable of 20 PHR and 30 PHR are similar,50 PHR and 60 PHR are similar too. Creep variable has a decreasing trend with the decrease of N330 and the increase of N660, but this trend does not look so obvious.(3) In test time, the creep variable of NR vulcanizates increases gradually, creep curve flattens, and creep variable tends to an equilibrium value in the end with the extension of time. When the test temperature become higher, the initial shape of NR vulcanizates variables increase, creep variable decrease, the performance of creep resistance gets better.(4) the research shows that the rubber filled with light calcium carbonate has the similar compression permanent deformation and creep properties with the rubber filled with carbon black N660. The rubber filled with white carbon black and coupling agent has the similar creep curve with which filled with white carbon black without coupling agent, but the creep variable of former is reduced greatly, because the former’s compatibility with rubber matrix is better than the latter, show the relationship between NR creep and filler network. In the process of creep, the deformation of relative slip appears between the fillers and polymer chains, this deformation will become more apparent with temperature increases, and the worse the compatibility of filler and rubber, the easier the relative sliding.(5) the addition of dispersant makes the creep variable of natural rubber down, and the different dispersants have the different influences on the creep deformation under the different temperatures. Little effect on the other properties of natural rubber and also can reduce the creep variable of natural rubber when the content of the dispersant is 2 PHR.(6) when the amount of plasticizer is 5 PHR, the addition of plasticizer make the creep variable of natural rubber increases. Oil plasticizer effect is obvious at the room temperature, when coumarone resin plasticizing effect is obvious at high temperature of 80℃.