Study On The Effect Of Fillers On The Properties Of Dehydroabietic Acid Modified Room Temperature Vulcanized Silicone Rubber

Silicone rubber is widely used in national economy,medicine,light industry,metallurgy and many other fields because of its excellent properties such as high temperature resistance,low temperature resistance,moistureproof,insulation and unique structure.However,because silicone rubber has long flexible segments and weak intermolecular forces,its mechanical properties are poor,which limits its practical application.In this study,dehydroabietic acid,a natural biomass resource,was used to modify silicone rubber,and 3-glycidyl ether oxypropyl triethoxysilane modified by dehydroabietic acid was prepared.Dehydroabietic acid modified silicone rubber with high thermal stability was prepared by using dehydroabietic acid as cross-linking agent However,because silicone rubber has long flexible segments and weak intermolecular forces,its mechanical properties are poor,which limits its practical application.The mechanical properties of silicone rubber were further improved by using silica and titanium dioxide,and the effect of fillers on the structure and properties of modified silicone rubber was discussed.The specific research contents and results are as follows:1.A new silicone rubber cross-linking agent was prepared from dehydroabietic acid and 3-glycidyl ether oxypropyl triethoxysilane,and its structure was identified.Dehydroabietic acid modified 3-glycidyl ether oxypropyl triethoxysilane was compounded with tetraethyl silicate according to different proportions to prepare dehydroabietic acid-based room temperature vulcanized silicone rubber,and its optimum ratio was explored.The mechanical properties,thermal stability and micromorphology of the samples were characterized by means of universal tension machine,scanning electron microscope,thermogravimetric analyzer,dynamic mechanical property test and hardness test.the effect of the structure of dehydroabietic acid-based silicone rubber on its properties was discussed.The rigid structure of rosin is introduced into silicone rubber,the interaction force between polysiloxane chains is increased,the intermolecular winding of silicone rubber is increased,and the cross-linking density is increased,so as to improve the mechanical properties and thermal stability of silicone rubber materials.The experimental results show that the mechanical properties,thermal stability and hardness of modified silicone rubber are improved in varying degrees,the tensile strength is increased by 44% from 0.45 MPa to 0.65 MPa,the elongation at break is increased from 150% to 250%,by 66%;the maximum thermal weight loss temperature is increased from 553 ? to 560 ?;Shore hardness is increased from 18 A to 25 A.2.Titanium dioxide modified silicone rubber was prepared with titanium dioxide as filler and 3-glycidyl ether oxypropyl triethoxysilane modified by dehydroabietic acid as cross-linking agent.The mechanical properties,thermal stability,micro-morphology and hardness of modified silicone rubber were characterized by means of universal tension machine,scanning electron microscope,thermogravimetric analyzer,dynamic mechanical properties test and hardness measurement.The results show that the maximum addition of titanium dioxide is 9%,and the mechanical properties of dehydroabietic acid-based silicone rubber have been improved during the process of adding titanium dioxide from 1% to 7%.The tensile strength increased from 0.71 MPa to 0.91 MPa,and the elongation at break increased from 266% to 350%,while the mechanical properties decreased when the addition of titanium dioxide was 9%.The silicone rubber with the addition of 7% titanium dioxide has the best performance,the tensile strength is 0.91 MPa;and the elongation at break is 371%.Compared with dehydroabietic acid silicone rubber,the tensile strength increased by 0.35 MPa.The elongation at break increased by 151%.The Shaw hardness(A)increased from 25 A to 35 A,the maximum thermogravimetric temperature increased from 560 ? to 673.8 ?.3.Nano-silica modified silicone rubber was prepared with nano-silica as filler,dehydroabietic acid modified 3-glycidyl ether oxypropyl triethoxysilane as crosslinking agent and tetraethyl silicate in different proportions.The mechanical properties,micro-morphology,thermal stability and water resistance of the samples were characterized by universal tension machine,scanning electron microscope,thermogravimetric analyzer,dynamic mechanical properties test and hardness measurement.The maximum addition of silicon dioxide is 25%,and the addition of silicon dioxide from 5% to 20%,the mechanical properties of dehydroabietic acidbased silicone rubber and pure silicone rubber have been improved,the tensile strength of dehydroabietic acid-based silicone rubber increased from 1.43 MPa to 4.39 MPa,and the elongation at break increased from 427% to 587%;Shore hardness(A)increased from 38 A to 50.5 A;The tensile strength of pure silicone rubber increased from 1.21 MPa to 3.88 MPa,the elongation at break increased from 404% to 560%,the Shore hardness increased from 37 A to 50 A,and the mechanical properties decreased when the addition was 25%.When the addition of silicon dioxide is 20%,dehydroabietic acid silicone rubber and pure silicone rubber have the best performance.The tensile strength of pure silicone rubber is 3.75 MPa,the tensile strength of dehydroabietic acid-based silicone rubber is 4.39 MPa,the elongation at break of pure silicone rubber is 554%,and the elongation at break of dehydroabietic acid-based silicone rubber is 587%.The hardness of pure silicone rubber is 50 A and that of dehydroabietic acid silicone rubber is 50.5 A.It is further verified that the introduction of dehydroabietic acid containing hydrogenated phenanthrene ring structure into silicone rubber will increase the cross-linking density and chain winding of silicone rubber,which plays a key role in improving the mechanical properties and thermal stability of silicone rubber.