Selection Of Compatibilizers In The Process Of Preparing NR/SiO₂ Composites By Wet Compounding Method

Silica is often used as a reinforcing agent in the preparation of green tires,and the prepared tires are more excellent in moisture resistance and rolling resistance.Since a large amount of hydroxyl groups are present on the surface of the silica,hydrogen bonds are easily formed,so that the silica exhibits a strong self-aggregation phenomenon.The poor compatibility between the polar silanol and the non-polar natural rubber results in poor dispersibility of the silica in the natural rubber matrix,and the natural rubber/silica composite has lower mechanical properties.The main purpose of this thesis is to compare and analyze the compatibilizing effect ot different comoatibilizers on silica/natural rubber,find suitable compatibilizers,improve the compatibility between natural rubber and silica,and prepare excellent comprehensive pertormance composite material.In this paper,the silica reinforced natural rubber composite material is prepared by wet mixing process.The NR/SiO2 composites was prepared by wet mixing technology with grevertex(MG)and five dfferet silane coupling agent(Bis[3-(triethoxysilyl)propylltetrasulfide(Si69),3-Thocyanatopropyltr,ethoxysilane(Si264),3-(Trimethoxysilyl)propanethool(A189),EthyltriMethoxysilane(11-100),S-3-(triethoxysilyl)propyl octanethioate(NXT))as co,,patibilizer.The effects of different compatibilizers on the comprehensive performance of NR/SiO2 composites were investigated.The effects of six different kinds of compatibilizers on the dispersing,vulcanization and mechanical properties of silica-reinforced natural rubber composites in silica were compared and analyzed,which provided a basis for the preparation of high performance NR/SiO2 composites.The results show that(1)the interaction between MG and silica significantly reduces the surface polarity of silica and improves the dispersibility of silica in NR/SiO2 composites.When the amount of silica 1s 10 phr,the average particle size of silica in the NR/SiO2 composite is 7.6 ?m and the dispersion grade is 9.9.During the vulcanization process,the positive vulcanization time of the rubber compound decreased significantly due to the better network structure of the MG.When the silica was 40 phr,the T90 decreased from 17.2 min to 13.9 min.MG as a compatibilizer significantly improved the mechanical properties of NR/SiO2.When the silica was 40 phr,the tensile strength ot NR/SiO2 increased from 15.03MPa to 17.97 MPa,and the tear strength was from 36.06 KN.m.-1.Raised to 42.7 KN.m-1.(2)Si69 is used as a compatibilizer,and the dispersibility of silica is not effectively improved.During the vulcanization process,Si69 can significantly promote the vulcanization process.When the silica 1s 40 Phr,the vulcanization time of the rubber is reduced from 17.26 min to 11.51 min.When Si69 is used as a compatibilizer,the mechanical properties of NR/SiO2 are obviously improved.When the silica is 40 phr,the tensile strength of NR/SiO2 is increased from 15.03 MPa to 20.04 MPa,and the tear strength is from 36.06 KN.m-1.Up to 50.98 KN.m-1;the dynamic mechanical properties of NR/SiO2-Si69 are significantly improved,the wet skid resistance is higher,and the rolling resistance is significantly lower.(3)When A-189 is used as compatibilizer and the silica is 30 phr,the dispersion grade of silica in NR/SiO2 is increased from 6.1 to 9.6.A-189 can significantly improve the dispersibility of silica.In the vulcanization process,the addition of A189 has a certain negative impact on the cross-linking process of the composite.(4)Using Si264 as a compatibilizer,the dispersion grade of silica in NR/SiO2 is not significantly improved,and its self-aggregation effect is not lowered,and the dispersibility is hard to be improved.During the vulcanization process,Si264 can significantly reduce the positive vulcanization time of the rubber compound.When the silica is 40 phr,the T90 decreases from 17.2 min to 1 3.2 min.However,the network structure of NR/SiO2 is poor.The vuleanization cross-linking of NR/SiO2 is affected,so its mechanical properties are reduced.(5)Using 11-100 as a compatibilizer,the addition of 11-100 significantly improved the dispersion performance of SiO2.When the silica was 30 phr,the dispersion grade of silica in NR/SiO2 increased from 6.1 to 9.1.100 as a compatlbilizer,significantly improve the mechanical properties of NR/SiO2,when the silica is 40 phr,the tensile strength of NR/SiO2 increased from 15.03 MPa to 20.76 MPa,tear strength from 36.06 KN.m-1 liter Up to 90.21 KN.n-1;11-100 improves the wet skid resistance of the vulcanizate and maintains low rolling resistance.(6)Using NXT as a compatibilizer,NR/SiO2 has a higher dispersion grade,and the average dispersion grade of NR/SiO2 is 9.05.NXT can significantly reduce the positive vulcanization time of the rubber compound and promote the vulcanization cross-linking process.When the silica is 40 phr,the T90 decreases fron 17.2 min to 12.1 min.NXT can effectively improve the mechanical properties of NR/SiO2 vulcanizate.When the silica is 40 phr,the tensile strength of NR/SiO2 increases from 15.03 MPa to 26.90 MPa,and the tear strength increases from 36.06 KN.m-1.122.90 KN.m-1;NR/SiO2 has higher wet skid resistance and lower rolling resistance.