Study On (oxidized) Graphene Modified Nitrile Rubber

Nitrile rubber(NBR)is an important bulk rubber often used to prepare materials for seal.However,the more and more complex usage occasion requires NBR composites of higher performance.Carbon black and silicon dioxide are used for reinforcement of rubber,and they have advantages of low price and good processability.However,adding too much carbon black is harmful for rubber’s elasticity.So,a new kind of high-perforcemance and functional filler need be discovered.Graphene has been widely used as a functional filler to improve thermal,mechanical and electrical properties of rubbers.The mechanical properties of natural rubbers or butadiene styrene rubber are apparently improved by introducing with 3%or less contents graphene.However,graphene tends to aggregate,which heavily influence properties of graphene.In this study,graphene and graphene oxide were modified via physical hybridization and chemical grafting.Then rubber composites were prepared via mechanical and solution blending.According to FTIR and XRD,it was demonstrated that graphene/Fe3O4,GO/SiO2 and GO-PPD were successfully synthesized.Results of Raman and TGA show GO/SiO2 and GO-PPD own better thermostability and structure regularity,but thermostability and structure regularity of graphene/Fe3O4 are poor than graphene.Universal tensile testing machine was used to test tensile properties of NBR composites.The results showed the tensile strength and elongation at break were improved when the content of graphene/Fe3O4 and GO/SiO2 increased and those of NBR/GO-PPD increased first and then decreased when the content of GO-PPD.The functional graphehe gives rise to a significant increase in the tensile strength and elongation of the composites,especially when the content of graphene/Fe3O4 and GO/SiO2 was 3 phr,a 90%and 61%of increase in tensile strength are achieved.It is worth to note that the 4phr of Fe3O4 and GO/SiO2 only respectively contain 5%of graphene and 66.7%of GO,i.e.,there is merely about 0.2 phr of graphene and 2.67 phr GO in these composites.Although the tensile strength of NBR was only improved 11%,the tensile strength of NBR still remain 94%of it after aging for 90 ℃,96 hour.It was worth note that the tensile strength of pure NBR only remain 83.7%of it after aging for 90℃,96 hour.Then SEM images show graphene/Fe3O4 and GO/SiO2 disperses well in NBR,but GO-PPD obviously aggregates,which verify it is the dispersion status of fillers influence the properties of NBR composites.Dynamic mechanical analysis was used to test dynamic mechanical properties of NBR composites.Tg of NBR increased with adding graphene/Fe3O4 and GO/SiO2 into NBR sheets and that of NBR decreased when adding GO-PPD via mechanical blending.It is worth noting that Tg of/NBR/graphene/Fe3O4 increased when content of graphene/Fe3O4 increased,but Tg of NBR/GO/SiO2 first increased and then decreased when content of graphene/Fe3O4 increased.Tg of NBR decreased with adding GO-PPD into NBR sheets.