Study On Modification,Structure And Properties Of Chloroprene Rubber

Chloroprene rubber(CR)is a kind of universal synthetic rubber,with excellent mechanical properties,aging resistance and chemical corrosion resistance,so it has become one of the rubber varieties widely used in various sectors of the national economy.However,neoprene has strong polarity,poor workability,fatigue resistance and low temperature resistance,which limit its application scope.The current rubber formulations and types alone cannot completely solve these problems.Therefore,this work around to solve problems such as extrusion distortion,poor fatigue resistance and,put forward the new type of synthetic rubber high trans-1,4-butadiene-isoprene copolymer rubber(TBIR)modified CR,excellent use of TBIR extrusion processability and excellent fatigue performance,improve the processing performance and fatigue performance of neoprene,The results provided a basis for the preparation of high-performance neoprene matrix composites.The main contents of this work are as follows:The influences of TBIR component on the rheological behaviors,crystalline morphology and crystalline behavior,phase morphology and properties of CR/TBIR blends are studied.When compared with CR,the viscosity of CR/TBIR blends decreases,while the initial vulcanization induction time and the stress relaxation rate increase significantly with increasing TBIR addition,which reflects the improved fluidity,plasticity and processing safety of CR/TBIR compounds.In addition,the surface morphologies of the CR-based extrudates improve with TBIR addition.The CR/TBIR blends with improved tensile strength and superb fatigue resistance exhibit microphase separation morphology with TBIR domain size in the range of several-hundred nanometers and nano lamellar fibrils from TPI segments penetrating both TBIR and CR domains.Based on the polarity difference between CR and TBIR,and the different curing systems and curing mechanisms,the effect of master rubber blending method on CR/TBIR blends was studied.In this paper,CR/TBIR blends with different blending ratios were prepared,and the phase structure,crosslinking structure and mechanical properties of CR/TBIR blends were systematically studied.It was found that TBIR island-phases with dimensions of less than 300 nm were uniformly distributed in CR matrix.With the increasing of TBIR dosage,the crosslinking density of CR/TBIR vulcanizates increased gradually:the crosslinking density of CR/TBIR vulcanizates containing 10?20 TBIR increased by about 20-30%.Due to the changes in the crosslinked structure and phase structure above,the tensile strength,elongation at break and compression permanent deformation of CR/TBIR were improved compared with CR vulcanizate.Particularly,the fatigue performance of CR/TBIR adhesive was improved.The 1st flexural fatigue lifetime of the CR/TBIR vulcanizate was 1.5?2.2times of that of the CR vulcanizate,and 6nd flexural fatigue lifetime of the CR/TBIR vulcanizate was 2?4.6 times of that of the CR vulcanizate.The crosslinking network of TBIR phase was changed by changing the amount of sulfur,and the relationship between the structure and properties of the adhesive crosslinking was studied.It was found that with the increase of sulfur content,the scorching time of CR/TBIR decreased(t₁₀),the process positive curing time increased(t₉₀),and the curing rate slowed down.With the increase of sulfur content,the cross-linking density of CR/TBIR vulcanizates increased,the content of multi-sulfur cross-linking bonds increased,and the content of single and double sulfur cross-linking bonds decreased,which was beneficial to the improvement of dynamic properties of vulcanizates.With the increase of sulfur content,the density of TBIR intersections increased gradually,the crystallization of vulcanized adhesive decreased,and the glass transition temperature gradually moved to high temperature direction.With the increase of sulfur content,the tensile strength,tear strength and elongation fatigue property of vulcanized rubber firstly increased and then decreased,while the heat generation,wear,compressive permanent deformation and dynamic and static stiffness of vulcanized rubber firstly decreased and increased.When the sulfur content was 0.6-1 parts,CR/TBIR vulcanized rubber had excellent comprehensive properties.