The Application Of Environmentally Friendly Fatty Acid Ester Plasticizer In Silica-filled SSBR/BR Composites

Petroleum-based aromatic oils generally used as plasticizers in rubber products such as tires,but they are restricted because they contain polycyclic aromatic hydrocarbon carcinogens.Compared with aromatic oils,plant-based plasticizers have the advantages of easy availability,renewable,low-carbon environmental protection,and adapt to the requirements of the society for environmental protection and energy conservation in the rubber industry.In this study,several fatty acids which from vegetable oil were esterificated with alcohol and then the fatty acid esters are used as rubber plasticizers in silica-filled SSBR/BR rubber composites to explore the effects of fatty acid esters of different structures and their amounts on the plasticizing effect,processing properties,physical and mechanical properties of SSBR/BR compounds.In this paper,esterification was carried out to obtain several plant-based fatty acid ester plasticizers: Benzyl laurate,Benzyl myristate,Benzyl palmitate,Benzyl stearate,a mixture of benzyl oleate and benzyl linoleate,Heptyl laurate and Diphenylmethyl laurate.The synthesized products were analyzed and characterized by FT-IR,1H NMR,GC,TGA,DSC and other testing methods.The reaction yields reach more than 95%.Firstly,the fatty acid benzyl ester plasticizers were added to the SSBR/BR composite and the properties of SSBR/BR composite were characterized by RPA,DSC,DMA and SEM.It was found that compared with TDAE,different structures of fatty acid benzyl esters reduced the mixing torque,Mooney viscosity and Payne effect of SSBR/BR compound,improved the dispersion of silica in SSBR/BR compound.As the alkane chain length of the saturated fatty acid benzyl ester becomes shorter,the filler dispered better,the crosslink density and the tensile stress of vulcanized rubber increase,the tensile strength and elongation at break decrease.The mixed benzyl oleate and benzyl laurate do not crystallize in SSBR/BR,so they have good compatibility with rubber,can reduce the glass transition temperature of vulcanizate and have superior plasticizing effect than TDAE.The mixed benzyl oleate is superior to benzyl dodecanoate.The effect of laurate plasticizer on the properties of SSBR/BR composites was then investigated.The results show that compared with diphenylmethanol laurate and heptyl laurate,benzyl laurate reduces the mixing torque and Mooney viscosity of SSBR/BR compound,improves the dispersion of silica and wear resistance of SSBR/BR vulcanized.Benzyl laurate has good compatibility with SSBR/BR due to its proper content of benzene ring and alkane chain structure.It prrovides the best plasticizing effect and the lowest glass transition temperature of SSBR/BR vulcanized.Finally,the effect of the amount of benzyl oleate on the properties of SSBR/BR composites was studied.The results showed that with the increase of the amount of benzyl oleate,the mixing torque and Mooney viscosity of SSBR/BR compound decreased gradually,the vulcanization time increased,the crosslink density of vulcanizate,300% modulus and tensile stress The tensile strength is gradually lowered,and the elongation at break is increased,and the glass transition temperature is gradually lowered.