Research On The Preparation And Properties Of Graphene/Polypropylene Composites

Graphene(GE),which has unique two-dimensional structure of carbon atoms,large specific surface area,high modulus,high strength,good gas barrier property and high thermal conductivity,can be used as a strengthening agent to improve the mechanical properties,thermal stability and thermal conductivity of the polymer materials.In this paper,three kinds of GE(GESB,GEHH and GEAA)were prepared by reduction of graphene oxide(GO)using different reducing agents sodium borohydride(SB),hydrazine hydrate(HH)and ascorbic acid(AA),respectively.The various kinds of prepared graphene through chemical reduction method were characterized.GO was modified by ionic liquids,followed by a reduction with hydrazine hydrate.Finally,the ionic liquids modified graphene(m-GEHH)was prepared.Graphene oxide/polypropylene(GO/PP)and graphene/polypropylene(GE/PP)composites were prepared by melt blending method.The effects of graphene structure,various contents of graphene and modification of graphene on the crystallization properties,thermal stability,mechanical properties,dynamic mechanical properties and thermal conductivity of PP were investigated.The results showed that the addition of 1.0wt%GE(GO)could improve the thermal stability,the tensile strength,the storage modulus and thermal conductivity of PP matrix.The effect of various fillers on the tensile strength of PP was in the order of GEHH>GESB>GEAA>unfilled>GO.While the storage modulus at room temperature(E')was in the order of GESB>GEHH>GO>GEAA>unfilled.The thermal stability was in the order of GEHH>GESB>GEAA>GO>unfilled.And the thermal conductivity was in the order of GEHH>GEAA>GO>GESB>unfilled.Compared with pure PP,the comprehensive performance of GEHH/PP composites(1.0wt%)was optimum:the maximum thermal decomposition temperature(Tmax)(nitrogen atmosphere,10 ?/min)value was 441.5 ?;the tensile strength was 65.9 MPa and the elongation at break was 23%;the E '(25 ?)value was 2350 MPa;the thermal conductivity was 0.238 W·m-1·K-1.When the graphene content was within the scope of Owt%?2.Owt%,the thermal stability and tensile strength of PP composites were increased with the graphene content.After incorporation of 2.0wt%GESB and GEHH,the Tmax values of PP were increased by 35.1? and 48.9 ? and the tensile strength could be increased by 23.6%and 24.5%,respectively.The modification of GEHH with ionic liquids improved the dispersion of GEHH in PP matrix,the dynamic mechanical properties and thermal conductivity of GEHH/PP composites.The Tmax value of PP with 2.0wt%m-GEHH was increased by 53.6 ? and the thermal conductivity of PP with 1.0wt%m-GEHH could be increased by 102.3%.