Preparation And Properties Of Graphene-Based Rubber Composites

Acrylonitrile butadiene rubber(NBR),as a synthetic elastomer,has been widely used in many fields due to its excellent physical and chemical properties(good processability,mechanical properties,gas impermeability and excellent resistance to oil and solvents,etc.).However,NBR is sensitive to heat and oxygen due to unsaturated double bonds in butadiene units.NBR tends to harden and brittle during aging due to oxidation and cross-linking reactions.Thus,the thermo-oxidative aging resistance of rubbers is of great significance to ensure the normal service life of the product.Furthermore,because NBR is a non-crystalline rubber,it has poor self-reinforcing properties and weak tensile strength,which limit its application in real life.Therefore,fillers need to be added to NBR to improve the properties of rubber.In this paper,the effect of modified graphene as filler of NBR on the properties of rubber was investigated.There are three different ways to modify graphene.The first way is to modify GO with silane coupling agents KH550,KH560,KH570 and KH590.After hydrolysis reaction and dehydration condensation reaction,silane coupling agent was successfully grafted onto GO surface to prepare silane coupling agent modified graphene(G-SCA),including G-550,G-560,G-570 and G-590.The second modification method is to use KH590 as a bridge agent to graft uridine onto GO surface.Firstly,KH590 was grafted onto GO surface to prepare G-590,and then G-590 reacted with uridine to prepare functional graphene(FGO).The third modification method is to use KH570 as a bridge agent to graft 2-mercaptobenzimidazole(MB)onto GO surface.Firstly,KH570 was grafted onto GO surface to make graphene surface contain double bonds and prepare intermediate product(m GO).Then MB was successfully grafted onto graphene through the click reaction between m GO and MB,and functionalized graphene oxide sheets(FGS)were prepared.NBR-G-SCA composites,NBR-FGO composites and NBR-FGS composites were prepared by dispersing modified graphene evenly in NBR rubber through emulsion blending and mechanical blending.The structure and properties of NBR composites were characterized and analyzed by means of scanning electron microscope(SEM),thermo gravimetric analyzer(TGA),modulated differential scanning calorimetry(MDSC),oscillating-die rheometer(ODR)and universal testing machine,respectively.The results showed that the mechanical properties of NBR-G-SCA composites were improved best by G-590.Compared with pure NBR,the tensile strength and elongation at break of the composites increased by 4.6% and 19.8% respectively when the addition of G-590 was 1phr.The test results of compression set properties show that NBR-G-560 and NBR-G-590 have better compression set properties,which are 71.4% and 68.3% of pure NBR rubber,respectively.In NBR-FGO composites,the addition of FGO can increase the crosslinking density of NBR,so the tensile strength of NBR-FGO composites is improved obviously.Compared with pure NBR,the crosslink density and tensile strength of sample NBR-FGO-1 increased by 51.3% and 46%,respectively.Furthermore,NBR-FGS nanocomposites have good thermal oxidative aging resistance,high tensile strength and fast curing rate index.Compared with neat NBR,the tensile strength,curing rate index and OIT value of NBR-FGS samples containing 2 phr FGS increased by 1.1,1.9 and 4times,respectively.