Preparation And Properties Of Graphene Oxides/Polymer Composites

Since the graphene was found in 2004,the nano material has become a research hotspot in chemistry,physics and other fields,due to its unique two-dimensional structure and excellent performance.The graphene and graphene/polymer nano-materials show great scientific significance and application value in both theory and experimental research.However,in order to realize the industrialization application of graphene and the composite,there exist still a lot of problems and challenges.In this paper,the graphene oxides/polymer composite materials with excellent mechanical and thermal properties were prepared and the relationship between the interfacial morphology and properties of graphene oxides/polymer composite materials were discused.The main research contents are following:(1)Functionalization of graphene oxides.In order to overcome the dispersion of the graphene in the polymer matrix,the isocyanate-treated graphene oxides(iGO)has been successfully fabricated by grafting octadecyl isocyanate onto the suface of the graphene oxides(GO)with isocyanicacid octadecyl ester.The iGO was characterized by FT-IR,Raman,TEM,TGA,element analysis.The results show that 18 carbon atoms in the alkyl chain are successfully covalently bonded to the surface of the GO,and one alkyl chain unit is incorporated for every 4 graphene carbons.Compared with the GO,the iGO shows the better dispersion in organic solvents.(2)Preparation and properties of graphene oxides / polypropylene nanocomposites.The graphene oxide/polypropylene(GO/PP)and the functional graphene oxide /polypropylene(iGO/PP)composite materials were prepared by solution blending method.The structure,the dynamic mechanical properties,thermal stability,tensile mechanical properties and the crystallization behavior of the composite materials were analyzed and discussed.As a result,compared with PP,the glass transition temperature of GO/PP increases slightly and iGO/PP composite materials decreases by 2 ?.The thermal stability property of these composites also increases.The thermal decomposition of 5 % weight temperature of the GO/PP and the iGO/PP are 27 ? and 42 ? higher than that of PP,respectively.Based on XRD data,the crystal morphology of GO/PP and iGO/PP composites are dominated by the a spherulite.The crystallization kinetics of iGO/PP and GO/PP is investigated by means of several methods.The isothermal crystallization kinetics of iGO/PP and GO/PP composite are analyzed by Avrami model based on the differential scanning calorimetry data.The results show that the well dispersed graphene nanosheets acts as a heterogeneous nucleating agent and decreases the activation energies,leading to an acceleration of crystallization during the PP isothermal crystallization process.The non-isothermal crystallizing data are analyzed with the Ozawa and Mo et al.models,and it is demonstrated that both two models are successful to describe the non-isothermal crystallization process for GO/PP and iGO/PP composite.(3)Preparation and properties of graphene oxides / PP / PS blends.The graphene oxides/PP/PS blends materials were prepared by melt blending method.The impact of the phase morphology and related properties of PP/PS blends materials with the modified graphene oxides were analyzed,and the effect of processing order on the phase structures and properties of the polymer blends were discussed.As a result,the compatibilization of GO for PP/PS blends materials is not obvious,but iGO can significantly promote the compatibility between two phases of the PP/PS blends.The aggeragation of iGO results in the poor compatibility of PP/PS blends with a high content of iGO.GO has a little effect on dynamic mechanical properties of PP/PS blends,while iGO performs more impact,which induces the Tg of PP and PS,were significantly migrate to the higher temperatures.Both of GO and iGO can increase crystallization rate of PP in PP/PS blends,leading to the low crystallinity,and the influence of iGO is more obvious.The enhancement of GO in the mechanical properties of PP/PS blends is limited,and iGO enhances the tensile mechanical properties of PP/PS blends.The tensile strength increases by 35 % compared with PP/PS blends with a loading of 0.2 wt% GO.What's more,GO and iGO can promote to improve the thermal stability of the PP/PS blends,in which iGO exhibits a greater performance.When weightlessness is 10 %,the decomposition temperature of iGO/PP/PS blends improved nearly 30 ? than PP/PS composites and GO/PP/PS composites 25 ?,respectively.In addition,the blending order of iGO,PP and PS has a great influence on interface structure,phase morphology and related performance of PP/PS blends in the fabrication process.When melt-blend all the ingredients to prepare iGO/ PP/PS blends at the same time,the iGO concentrates on the phase interface and adjacent areas,and form a "transition zone" in the phase interface to improve the compatibilization effect and enhance the corresponding mechanical properties.When firstly melt iGO with PS following with mixing of PP,the iGO concentrates on the PS phase and the phase interface adjacent areas in the prepared(PS/iGO)/PP blends.And,a "transition zone" between the phase interface forms to facilitate the improved compatibilization effect between PP and PS phases and mechanical properties has been raised.However,when firstly melt iGO with PP following with mixing of PS,the iGO exists mainly in the PP phase of the prepared(PP/iGO)/PS blends,which induce the phase separation and the decrease of corresponding mechanical properties.(4)Preparation and properties of graphene oxides / polyimide composites.We have successfully prepared graphene oxides/polyimide composite films,functionalized graphene oxides/polyimide composite films and functionalized graphene oxides/polyimide composite fibers.As a result,functionalized graphene oxides provides a induced action for cyclizing the polyamic acid(PAA)to polyimide(PI).The interface between PI and iGO is much better than the GO/PI.Dynamic mechanical analysis exhibits that the glass transition temperature(Tg)of GO/PI composite is slightly higher than that of the PI,while the Tg of the iGO/PI composite is significantly lower than that of the PI at the loading of 1 wt% iGO.The iGO effectively improves the mechanical properties of the PI compared with GO.The tensile strength of iGO/PP composite films with a laoding of 1 wt% iGO increases by 80% than that of PI films,while the tensile strength of iGO/PP composite fibers increases by 93 % and tensile modulus increases by 192 % compared with PI fibers with a laoding of 0.5 wt% iGO.