Preparation Of Maleic Anhydride Grafted Natural Rubber And Its Application In Tread Compound

With the development of tire industry,green tire has been widely attention.As the main material of tires,natural rubber has excellent physical properties,such as high elasticity,high strength,and low heat fatigue life.However,natural rubber also has some undesirable properties,such as sensitive to heat,low abrasion performance,aging resistance,oil resistance and flame retardant etc.Therefore,modification of NR has been the hot topic.At the same time,there are problems of hard scattered and strong interaction among SiO₂ fillers in NR matrix.Maleic anhydride grafted natural rubber was synthesized based on natural rubber graft modification by mechanical force and heat.And the effect of NR-g-MAH on SiO₂ filled NR vulcanizates were investigated.At the same time,this paper discussed the grafted product as tread rubber and adhesive with polyester fiber cloth.Via FT-IR,SEM,DMA,mechanical properties etc.,the relationship between the structure and properties of materials were investigated.By melt grafting without initiator,maleic anhydride can be grafted on macromolecular chain of natural rubber using mixer with St as a comonomer.Under the conditions of 5 phr MAH and St,110?of temperature,50 r/min of speed,and 3min of plasticizing and mixing time,the obtained NR-g-MAH have 1.23%graft degree and a lower gel rate than 2%.NR/SiO₂/NR-g-MAH compounds were prepared by mixing on open mill,and were vulcanized on vulkameter,using SiO₂ as reinforcing filler and NR-g-MAH as compatilizer.The effects of NR-g-MAH on properties of the vulcanizates were investigated,and compared with that of the silane coupling agent Si69 in-situ modification.By adding the NR-g-MAH,interaction between NR and SiO₂increases,scorch time extends,curing speed increases,curing time reduces and crosslinking density of the vulcanizates increases.With 20 phr NR-g-MAH,the scorch time and curing speed are better than that of the Si69 modification.NR-g-MAH can enhance the mechanical properties of vulcanizates.With 20 phr NR-g-MAH,the tensile strength increases by 36%,hardness increases by 21.9%,and tear strength increases by 476%.And the tensile and tear strength are superior to that of the Si69 modification.NR-g-MAH can decreased the rolling resistance of vulcanizate,and the low rolling resistance decreases significantly,which shows that fuel consumption is reduced.With 20phr content of NR-g-MAH,the rolling resistance of vulcanizate is dropped by 20.9%than that of Si69 modification,and it indicates that fuel consumption is lower.NR-g-MAH can improve the thermo-oxidative aging resistance of vulcanizates.With the 20 phr NR-g-MAH,loss rate of tensile property reaches 8.8%.The polyester fiber cloth was immersed in NR-g-MAH glue with different concentrations,then vulcanized with NR/SiO₂/NR-g-MAH compounds.Finally,the vulcanizate/polyester fiber cloth composites were synthesized.It shows that the peel strength of composites is 2.92 MPa/m,which increases by 124%than that of the blank group,after the fiber cloth is treated by 3%NR-g-MAH glue.After thermo-oxidative ageing,the peel strength decreases 16.5%,as well as after oil test,the peel strength decreases 20.1%.It provides a new method for the polyester to replace nylon applying in tire crowned layer.