Study On Preparation Of Highly Aging Resistant Rubber By Antioxidant Sustained Release From One-Dimensional Inorganic Nanotubes

Mechanical properties of the elastomer materials always progressive deteriorate even lose the value in application due to the aging process.In order to slow down the aging,antioxidants are added into the rubber composites.However,antioxidants often diffuse toward the surface of rubber products through the elastomer cross-linked networks in a phenomenon called"blooming".Carbon nanotubes(CNTs)have become the ideal filler for the fabrication of high-performance rubbers due to their unique tubular structure and its excellent performance.Halloysite nanotubes(HNTs)which are inexpensive and green have widely used in ceramic materials,adsorption,sustain release,catalyst and microcapsule encapsulation and targeted transport of drug macromolecules,ect.In this study,the highly aging resistant rubber fabricated with antioxidants sustained release from carbon nanotubes and halloysite nanotubes.The sustained release of antioxidants from nanotubes extends its action time in rubber matrix.The details are as following:(1)The anti-aging styrene-butadiene rubber composite was prepared by using the filler of 4020 loaded into the carbon nanotubes by solution filling method.The sustained release of antioxidant 4020 from carbon nanotubes extends its service life in the rubber matrix and it will take 10 months for the antioxidant release of 50%.The amount of antioxidant in the rubber composites allows for a concentration of 2.0 wt.%without causing blooming.A fifteen-day thermal-oxidative aging test at 100℃ and twenty four-hour ozone aging test show preservation of mechanical properties due to the antioxidant sustained release from rubber matrix.Furthermore,due to the present of thermal and electrical conductive carbon nanotubes,the rubber composites emerge thermal conductivity of 0.303 W/m·K and electrical conductivity of 4.74×107 Ω·cm which performs antistatic properties.(2)In this study,the impurities in halloysite were removed successfully by the way of centrifugal separation according to the different physical and chemical properties.The experimental devices of antioxidant loaded into halloysite have built successfully and the bulk production of halloysite filling with 4010NA,4020 and RD was realized by this devices.The yield can reach to 2～3 kg one time.The loading efficiency can be controlled by the system viscosity and feed ratio.The use of antioxidant recovery liquid can save the production cost and has little effect in loading efficiency.The loading efficiency can be stabilized at around 30%when the weight ratio was 1:1.Compared to the composites filled with the same amount of free antioxidant,the mechanical properties of EPDM composites prepared by using the antioxidant 4010NA loaded into halloysite keep better in 7-day thermal-oxidative aging test at 100℃.