Preparation And Tear Resistance Of Natural Rubber Composite Materials

Natural rubber（NR）,as the most widely used general rubber,which was widely used in aerospace,transportation,medical instruments and other fields due to its unique self-reinforcing properties and viscoelastic properties.In the tire rubber,because of its special working environment,the rubber products were often used under the condition of high strength impact or periodic load change,which made the rubber products easy to tear and damage cracks,or even failure,which will cause huge safety risks and economic losses.In order to solve the problems such as crack generation and fatigue failure of rubber products,improve the durability and safety of rubber products,it is urgent to develop tear resistant and fatigue resistant tire rubber,which is of great significance to extend the service life of rubber and expand the application field of rubber.This paper explores and reveals the effects of crosslinked network structure,filler network structure,filler treatment and preparation method on the mechanical strength and tear resistance of rubber composite materials,and provides a new method and strategy for the design and preparation of high strength and tear resistance rubber composite materials.The research content of this paper is as follows:（1）First,three vulcanization systems,Conventional Vulcanization（CV）,semi-effective（SEV）and effective（EV）,were prepared by adjusting the ratio of sulfur（S）and accelerator（CZ）.The mechanical properties of NR/GO/CB composites prepared by different vulcanization systems were investigated from the perspective of cross-linking network analysis of rubber composites.The effect of tear resistance.CV system has a well-developed cross-linking network with a cross-linking density of 3.72×10^-4mol/cm3.Compared with EV system with lower crosslinking density,the tensile strength of CV system reaches the maximum value of27.5 MPa and the tear strength of 71.6 N/mm,which are increased by 11.0%and 31.4%,respectively.CV system has improved tear resistance.Under the tearing energy of 2000 J/m²,the crack growth rate of CV system is 64.1 nm/cycle,which is 30.6%and 57.6%lower than that of SEV system and EV system,respectively.（2）Adjust the particle size of carbon black filler and prepare rubber composite with different filler network structure by latex co-sedimentation method.The effect of carbon black filler network difference on the properties of rubber composites was studied.The minimum average particle size of N110 carbon black was 253.8 nm,and the maximum average particle size of N765 carbon black was 477.2 nm.The results revealed that the smaller the carbon black particle size was,the more perfect the filler network was formed and the stronger the interfacial force between the carbon black and the rubber molecular chain was.The N110 carbon black has the strongest rubber internal filler network,giving the composite excellent mechanical properties.The tear strength and tensile strength of N110 carbon black rubber composite were77.9 N/mm and 29.4 MPa respectively,which were 119.4%and 39.3%higher than that of N765 carbon black,which were 35.5 N/mm and 21.1 MPa respectively.In addition,the developed packing network can inhibit crack propagation.The crack propagation rate of N110carbon black rubber composite was 52.7 nm/cycle,which was 216.3%lower than that of N765carbon black rubber composite.（3）First,the surface modifier sodium methylene dinaphthalene sulfonate（NF）was used to treat CB,and the physical binding NF-CB was obtained.NR/GO/NF-CB rubber composite was prepared by latex co-precipitation method.Secondly,NR/GO/S-CB and NR/GO/CB rubber composites were prepared by emulsion co-deposition and mechanical blending respectively.The experimental results revealed that the particle size of NF-CB prepared by surface modification was reduced and evenly dispersed in the rubber matrix,and the mechanical properties and tear resistance of NR/GO/NF-CB were improved.The tear strength of NR/GO/NF-CB（89.9 N/mm）was 6.5%and 15.4%higher than that of NR/GO/S-CB（83.5N/mm）and NR/GO/CB（77.9 N/mm）.In addition,the number of carbon black agglomeration and the number of defects causing microcracks decreased significantly in NR/GO/NF-CB composites,and the crack growth rate of NR/GO/NF-CB composites was the lowest（47.7nm/cycle）.NR/GO/NF-CB prepared by surface treated latex co-sedimentation method has the best tear resistance.