Technology Study Of Natural Rubber/silica Composite Prepared By Ultrasonic Dispersion

Traditional natural rubber(NR)products have disadvantages such as low strength and lack of wear resistance,which cannot meet daily needs.The introduction of reinforcing agents such as silica can improve the performance of NR.Due to its large surface energy,silica can appear to aggregate in the NR matrix,which seriously affects the performance of the composite material.Improving the dispersion of the filler can directly affect the performance of the composite material in use.Silicon dioxide is easily agglomerated in the dry blending process of NR,consumes a lot of energy,and causes dust pollution.Wet compounding in the form of emulsion compounding can solve the shortcomings of dry compounding to a certain extent.In the wet blending latex mixing stage,in addition to the introduction of silane coupling agent and other chemical modification of the filler surface,the main use of physical stirring and ultrasonic dispersion process,but the optimal process parameters for ultrasound has not yet been clearly studied.Therefore,the process exploration and optimization of ultrasonic treatment in the wet mixing process is beneficial to improve the dispersion of the reinforcing filler in rubber,thus further improving the comprehensive performance of the rubber and providing a technical reference for industrial application.In this paper,Si O₂ was selected as filler,and the optimal ultrasonic parameters in wet mixing were investigated,and NR/MXene composites were prepared with these ultrasonic optimal parameters.The research contents and results are as follows.(1)To study the effect of ultrasonic treatment on NR/SiO₂ composites.Scanning electron microscopy was used to observe the tensile section and to analyze the filler dispersion in combination with the rubber content test,and the results showed that the filler dispersion was continuously improved with the increase of power and amplitude.The rubber processing analyzer was used to test the filler network and processing performance of the blends,and the results showed that ultrasonic treatment could reduce the payne effect of the blends and improve the processing performance.The results of the vulcanization characteristics test,crosslink density test and static mechanical properties test all show that increasing power and amplitude leads to a gradual improvement in filler dispersion and improved performance.Using dynamic thermo-mechanical analysis tests to characterize the wet-slip resistance and roll resistance of the composite,it was found that the wet-slip resistance was improved,the roll resistance did not change much,and the wear resistance was significantly improved.When the power was 900 W and the amplitude was 80 um,the ultrasonic treatment improved the dispersion,processing performance,anti-slip performance and abrasion of the filler significantly.(2)To study the effect of SiO₂ contents on NR/SiO₂ composites.The effects of filler addition on the composite properties were characterized using scanning electron microscopy and bonded rubber content to characterize the filler dispersion,the rheological properties of the blends to characterize the filler network and processing properties,and the static mechanical properties,wet slip resistance and roll resistance.The results showed that when the filler addition increased above 60 per hundred-part rubber(phr),the cross-section was flat,the change of bonding glue content was not obvious,and the filler dispersion was not good.The high degree of filler network,processing performance and static mechanical properties appear to be substantially reduced,wear resistance,anti-slip performance and roll resistance changes are not obvious.The 60 phr sample showed more anti-slip performance and wear resistance compared with the low addition sample.Therefore,when the addition amount is 60 phr,the ultrasonic treatment has the most obvious improvement on the filler dispersion and composite properties.(3)To investigate the long-term heat and oxygen resistance aging performance of NR/Mxene elastomers prepared by ultrasonic.The NR/MXene composites were prepared by ultrasonic dispersion method,and the thermal and oxygen aging resistance was studied by analyzing the change pattern of network structure and the retention of mechanical properties before and after thermal and oxygen aging.The results showed that the tensile strength retention rate of NR/MXene was 63%after thermal oxygen aging for 72 hours,which was improved by 47%compared with the conventional antioxidant 4010NA.X-ray photoelectron spectroscopy(XPS)and electron paramagnetic resonance spectroscopy(EPR)were used to analyze the ability of MXene to absorb oxygen and free radicals,and the results showed that the anti-thermo-oxidative aging mechanism of MXene is as follows:MXene has strong absorption of oxygen and free radicals in the rubber matrix under the hot oxygen environment;meanwhile,the layered structure composed by MXene can prevent oxygen from attacking the rubber molecular chains,and MXene can adsorb molecular chains and inhibit the migration of MXene to the sample surface,which makes it have long-term thermo-oxidative resistance.