Preparation Of Nano-Se And Its Influence On The Crosslinking Structure And Properties Of SBR

In the modern rubber industry,sulfur is widely used in vulcanization reactions to crosslink rubber molecular chains.The crosslinking network has a great influence on the performance of rubber products.Sulfur,as the most important vulcanizing agent,forms a good cross-linking network with the rubber segment.However,when sulfur alone is used as a vulcanizing agent,it is melted and dispersed in the rubber matrix before participating in vulcanization,which makes it difficult to design and functionalize the cross-linking network structure based on active sulfur,and also limits the activity of the vulcanization reaction and the physical machinery of the material.performance.As a homogenous element of sulfur,selenium has similar properties to sulfur,and has its unique characteristics,and the use of nanotechnology can make elemental selenium have higher reactivity.In addition,in traditional sulfur vulcanization systems,the use of zinc compounds is essential and the amount used is large.The overflow of a large amount of zinc will cause serious ecological problems due to water pollution.Based on this background,this thesis applied nano-Se to styrene-butadiene rubber vulcanization system,designed and prepared nano-Se vulcanized rubber with a new cross-linked network structure,and sulfur/nano-Se composite vulcanized rubber,and discussed the nanometer in zinc-free vulcanization system.Activation of selenium.The main contents are as follows:?1?Tubular nano-selenium?nano-Se?was prepared by ascorbic acid reduction of selenium dioxide?Se O₂?.The study found that nano-Se alone can participate in the formation of cross-linked networks.Compared with sulfur?S?,because the chemical bond energy is lower than S-S,Se-Se is more likely to break into active selenium when participating in the vulcanization reaction,resulting in a lower activation energy of nano-Se vulcanization system.At the same time,the high melting point of selenium causes its dispersibility to be less than that of melt-vulcanizable sulfur,so the cross-linking network density of selenium vulcanized rubber is low.However,the nano-Se existing in a solid structure forms a tube-network cross-linked structure with rubber segments.Among them,the cross-linked micro-domains formed based on nano-Se make the cross-linked network oriented under stress,which greatly improves the physical and mechanical properties of styrene-butadiene rubber material.In addition,due to the semiconductor properties of selenium,nano-Se improves the thermal conductivity of the styrene-butadiene rubber cross-linked network.?2?Designed S/nano-Se composite vulcanization system of styrene-butadiene rubber crosslinking network.The study found that nano-Se provides a higher vulcanization activity for the composite vulcanization system than a single vulcanizing agent system in equimolar amounts.At the same time,nano-Se-based high-density cross-linked micro-regions are interspersed in the network structure based on active S to form a dense cross-linked network,which further increases the density of the overall cross-linked network and improves the compression fatigue heat generation of rubber materials.In addition,different ratios of S and nano-Se have effects on the degree of restriction and strain morphology of the rubber crosslinking network.When the molar ratio of S:Se is 1:1,the mechanical properties of SBR/carbon black materials are relatively superior.Compared with S single vulcanizing agent system,the tensile strength,100%fixed tensile stress and 200%fixed tensile stress were increased by 7.6%,93.1%and 94.3%,respectively,and the wear volume was reduced by 9.3%.?3?Compared with the conventional zinc-containing vulcanization systems of zinc stearate?Zn St?and zinc oxide?Zn O?,we studied the vulcanization characteristics,vulcanization kinetics and physics of SBR/silica materials based on nano-Se zinc-free vulcanization system Characteristics of mechanical properties and dynamic thermomechanical properties.The study found that a small amount of nano-Se can produce excellent activation effect.Under the combined effect of nano-Se-based activation reaction and cross-linking reaction,compared to the conventional amount of Zn O?5phr?,only adding 0.25phr of nano-Se can lead to a significant increase in the vulcanization rate and cross-linking degree of SBR/silica.In addition,with the help of nano-Se to participate in the vulcanization of SBR molecular movement capacity and cross-linking network reinforcement,nano-Se zinc-free vulcanization system makes SBR/silica materials have more excellent physical and mechanical properties.Dynamic mechanical performance analysis shows that the SBR/silica prepared by this system has lower rolling resistance,and its wet skid resistance gradually increases with the increase of nano-Se.The nano-Se zinc-free vulcanization system provides reference for the study of"green"environmentally friendly rubber materials while reducing zinc pollution.