The Preparation And Performance Of Graphene/Polypropylene Composites

Graphene is a typical two-dimensional nano-material with excellent comprehensive performance.Polypropylene is a common general plastic,and using nano-filler modified polypropylene is a commonly used method at present.The paper mainly focuses on the surface functionalization and reduction of graphene,and modified polypropylene using the functionalization graphenes,which have a better mechanical and thermal performance.The functional graphene was prepared with ethylenediamine as functional monomers,and then was reduced by soluble thermal reduction method.The composites with different contents of functional graphene were prepared by solution method.Tensile tests showed that the tensile strength of composites increased firstly and then decreased with increasing content of functional graphene.When 0.5 wt.%GS-EDA was added,the tensile strength of composites reached 39.6 MPa,which increased by 24.7%compared with that of pure PP/PP-g-MAH?31.8 MPa?and by 17.5%compared with that of pure PP?33.7 MPa?.SEM observations showed that GS-EDA could be dispersed homogenerously in the matrix when a small amount of GS-EDA was added,but aggregation took place when too much GS-EDA was added.In this paper,the graphene oxide was selective reduced firstly by environmentally friendly solvent-water,and then ODA?Octadecylamine?was grafted onto the surface of the selective reducted graphene oxide,which was suffered reducing again.FTIR and XRD tests showed that the carboxyl groups located on the edge of graphene oxide could be reduced selectively by water and under re-flow conditions at high temperature.FTIR?XRD and XPS tests showed that ODA grafted successfully to the surface of graphene oxide and the selective reduced graphene oxide,and G-ODA contained more octadecylamine than the rG-ODA.Dispersion research in different solvents showed that G-ODA and rG-ODA would disperse stablely in non-polar solvents such as benzenes,and precipitated fastly in the polar solvent such as water.The composites with different contents of G-ODA and rG-ODA were prepared by solution-melting method and their mechanical and thermal properties were studied.Tensile tests showed that rG-ODA could improve the tensile strength and elastic modulus of composites more effectively than G-ODA.But G-ODA was more effectively in improving the toughness of polypropylene than rG-ODA,as indicated by impact tests.DSC tests showed that the existence of r G-ODA and G-ODA enhanced crystallization temperatures and melting temperatures of polypropylene.TG tests showed that the addition of rG-ODA and G-ODA reduced the initial decomposition temperature and improved the termination decomposition temperature of the polypropylene.In order to study the effects of different dimensional fillers?zero dimensional and two-dimensional?on the properties of polypropylene,the graphene-silica/polypropylene composites and silica/polypropylene composites were prepared by melting blending.Mechanical performance tests showed that the tensile strength,elastic modulus and impact strength of graphene-silica/polypropylene composites increased with increasing GO-g-SiO₂content.When a small amount of GO-g-SiO₂ was incorporated,tensile strength,elastic modulus and impact strength rose fastly,but the growth was slowed down when more GO-g-SiO₂ and SiO₂ was added?higher than 0.5 wt.%?.At the same filler contents,GO-g-SiO₂ was more effective than SiO₂ in improving the mechanical properties of composites.When 2 wt.%GO-g-SiO₂ was added,the tensile and impact strength of composites increased by 21.4%and 21.4%,respectively,compared wich those of pure PP.DSC test showed that the crystallization and melting temperature of composites containing GO-g-SiO₂ were higher than composites containing SiO₂.In summary,the GO-g-SiO₂ was more effective than SiO₂ to modify the mechanical and thermal performance of polypropylene.