Study On The Application Of Nitrile Rubber In The Airtight Layer Of All-steel Radial Tire

Nitrile rubber(NBR)is famous for its excellent oil resistance,but also belongs to the air tightness good,excellent heat resistance rubber,and is expected to become ideal raw rubber material of the all-steel radial tire inner liner formula.The formulations of traditional heavy-duty tire airtight layer are mainly composed of halogenated butyl rubber,which is mainly due to its excellent air tightness,ozone resistance and fatigue resistance.But due to the difficulty to store its masterbatch which is easy to occur early curing,and expensive cost causes long-term dependence on imports,many domestic tire enterprises eager to looking for a good alternative to reduce its usage.Nitrile rubber is one of the few rubber materials with high air tightness,and its air tightness is far superior to halogenated butyl rubber at higher acrylonitrile(AN)content.However,the high molecular chain polarity makes it difficult to mix with traditional tire rubber such as natural rubber,and it has the defects such as high hysteresis loss and bad aging properties.So far,few studies have reported on its use in tires.In this study,we are committed to mixing nitrile rubber and brominated butyl rubber(BIIR),combining the advantages of the two rubbers,to prepare the high performance airtight layer material.In order to improve the compatibility of BIIR/NBR blends,this paper first studied the effects of different compatibilizers(CJ-100/epoxy natural rubber ENR)and their dosage on the properties of blends.The results show that the CJ-100 has a better cmpatibilizing effect,which can greatly improve the fatigue performance and ozone aging performance of the blend,but excessive usage leads to a high hysteresis loss.The phase structure was characterized by AFM and SEM,and the size of the two-phase dispersed phase of CJ-100 was the smallest one,which proved its good effect from the microscopic perspective.In order to further improve the fatigue resistance of the blend,this paper use the polarizing small molecule plasticizer DOP to plasticize the rubber material and reduce its hardness,thereby improving its fatigue resistance.The results show that DOP can effectively block the interaction between the molecular chains of NBR and increase the flexural fatigue times of the blend.In addition,the addition of DOP can improve the aging performance of the blend and reduce the hysteresis loss.In addition,the influence of NBR with different AN contents on the performance of the blend was investigated.The results showed that the NBR blends with low AN content have better ozone resistance and fatigue performance,but the air tightness was relatively bad.With the increase of acrylonitrile content and amount of NBR,material's hysteresis loss increases notably.Through the compatibilizing/plasticizing modification and formulation optimization,BIIR/NBR blends with excellent comprehensive properties are prepared in this study.The study broadens the application of NBR in the tire industry and provides a new design idea for higher performance load tire inner layer formula.It is pointed out that zinc oxide is a crack source of flexural fatigue and has great influence on flexural fatigue performance.In last section,different zinc oxide is used as vulcanization activator to discuss its effect on the properties of pure natural rubber formula.It is the best to choose CaZ type zinc oxide with 3phr,and different zinc oxide has little effect on the mechanical properties of the airtight layer material.