Study On Structure And Properties Of Graphene/Acrylonitrile-butadiene Rubber (Ethylenen-propylene-diene Rubber) Composites

Graphene is under the spotlight in the nanoworld due to itsexceptional mechanical, thermal and eletrical properties, which makes itan ideal filler to prepare polymer composites. It is critical to improve thedispersion of graphene in polymer and to optimize the interfacialinteractions between graphene and matrices. Aiming to address theseproblems, this dissertation focuses on the functionalization of graphene,and studies on the structuctre and properties of graphene/rubbercomposites.Graphene oxide （G-O） was prepared by modified Hummer’s methodby using graphite. Ethylenen–propylene–diene rubber （EPDM）/petroleumresin （PR）/G-O composites were prepared by the combination of solutionblending and two-roll mill mixing. G-O nanosheets were dispersedhomogenously in EPDM and EPDM/PR blends, possibly due to thematched surface energy as well as low interfacial energy of EPDM andG-O, which were determined by contact angle tests. The addition of0.5wt%G-O nanosheets increased the tensile modulus, tensile strength andelongation at break of EPDM by more than130%,50%and30%,respectively. G-O nanosheets containing composites were novel inimproving the damping properties of EPDM and EPDM/PR blends.By taking advantage of the good coordination ability of copper ion(Cu²⁺), a novel and simple strategy for bonding G-O nanosheets to acrylonitrile–butadiene rubber （NBR） via coordination was developed.Cu²⁺could also serve as a bridge among individual G-O nanosheets byinterconnecting oxygen-containing functional groups, as well as acrosslinking agent for NBR by coupling nitrile groups. The bondingnature of NBR/G-O/CuSO₄composites was studied by Fourier transforminfrared and electron spin resonance spectra. The activation energy ofcoordination crosslinking of NBR cured by CuSO₄was lower than that ofcovalent crosslinking of NBR cured by dicumyl peroxide. IntroducingCu²⁺led to a more than4-fold improvement of the tensile strength ofNBR/G-O composites. The crosslinking reaction of NBR/G-O/CuSO₄composites was reversible and the recrosslinked composites had goodmechanical properties.G-O nanosheets were functionalized with octadecylamine （ODA）and then reduced by L-ascorbic acid （L-AA）. The octadecylaminefunctionalized graphene （G-ODA） was characterized by atomic forcemicroscope, X-ray diffraction, Fourier transform infrared spectroscopy,which corroborates the modification and reduction of G-O. NBR/G-ODAcomposites with different acrylonitrile contents （AN=19%,29%and41%）were prepared by solution blending. The stability of NBR/G-ODAsuspensions was better than that of NBR/G-O suspensions. G-ODAnanosheets were dispersed homogenously in NBR matrices. Thereinforcement of G-ODA on NBR （19%and41%AN） were moresignificant than that on NBR （29%AN）.Graphene oxide nanoribbon （GONR） was prepared bysolution-based oxidative process via longitudinally unzipping carbonnanotubes （CNT）. The addition of GONR improved the mechanicalproperties of polar rubbers including carboxylated styrene–butadiene rubber latex （XSBRL）, hydrogenated carboxyl acrylonitrile–butadienerubber and ethylene–vinyl acetate rubber. XSBRL/G-O/GONRcomposites were in situ reduced by L-AA to obtain XSBRL/graphenenanosheet （GNS）/graphene nanoribbon （GNR） composites. The electricalconductivity of XSBRL was significantly improved by9orders ofmagnitude after adding3wt%GNS, with percolation threshold of1³wt%. XSBRL/GNS （100/5） composites had high permittivity as well asdielectric loss, and showed high microwave absorbing capacity with aminimum reflection loss of-39.7dB. The incorporation of10wt%GNSexhibited a93%improvement on the thermal conductivity of XSBRL,which was more significant than that of CNT，GNR and their hybridfillers with GNS at the same content.