Modified Multiwall Carbon Nanptubes And Graphene Nanosheets-reinforced Polyarylene Ether Nitrile Composites

Poly (arylene ether nitrile)(PEN) is the main polymer of interest since it is a highperformance thermoplastic for special uses such as aerospace, military and electronicareas. PEN exhibits excellent mechanical strength, high radiation resistance and strongchemical inertia. The polar and potential cross-linking nitrile groups on the aromaticring in PEN promote adhesion of the polymer to many substrates and PEN can easily beprocessed into shaped forms. Thus it is the good polymer matrix which can be used toprepare advanced materials. Herein, we adopt bisphenol A-based PEN as the mainpolymer matrix, carbon nanotube (CNT) and graphene nanosheet (GN) as fillers toexplore various advantages and applications of PEN materials, especially in the fieldsrequired for high performances in dielectric, mechanical and thermal properties. Toachieve good dispersion states of nanofillers, PEN nanocomposites containing variouscontents of CNT-nitrile and GN-nitrile were prepared by a facile solution-castingmethod and investigated for their morphological, mechanical properties. And the resultswere compared with PEN/pure CNT and PEN/pure GN composites to discover effect ofCNT-nitrile and GN-nitrile on the properties of PEN. Then, different filler effect ofCNT-nitrile and GN-nitrile in the poly (arylene ether nitrile) matrix was compared in theterms of the thermal and rheological properties. In addition, we also investigatedsynergetic effect of CNT-nitrile and GN-nitrile on the mechanical and thermalproperties of poly (arylene ether nitrile).First, CNT-nitrile and GN-nitrile was prepared by (1) CNT-oxide and GN-oxidepreparation by means of modified Smalley method,(2) CNT-chloride and GN-chloridefabrication by reacting GN-oxide with SOCl2through substitution reaction.(3) Graftingof APN to the GN surface with condensation reaction. Then, CNT-nitrile and GN-nitrilewere incorperated into PEN matrix by solution-casting method and thusPEN/CNT-nitrile PEN/GN-nitrile composites were obtained. Consequent, after nitrile fuctionlization, the dispersion states and the ahension of CNT-nitrile and GN-nitrile inPEN matrix were improved in comparasion of these of pure CNT and GN. ThusPEN/CNT-nitrile PEN/GN-nitrile composites showed better dielectric mechanical andthermal properties compared with PEN/pure CNT and PEN/pure GN composites.Second, the different filler effect of identical CNT-nitrile and GN-nitrile in thePEN matrix was investigated. PEN/CNT-nitrile and PEN/GN-nitrile composites wereprepared by a facile solution-casting method and systematically investigated for theirdifferences of morphological, thermal and rheological properties. In the PEN matrix GNcontacts each other by the means of plane-to-plane while CNT is quite separated.Compared with PEN/CNT composites, PEN/GN composites below2wt%filler contentexhibited higher thermal stabilities. Rheological properties of resulted compositesindicated that PEEN/GN composites were more sensitive to the strain, and exhibitedhigher η*, G′, and G″than PEN/CNT composites. The rheological percolation for CNTis over2wt%, higher than that for GN (around1wt%). All these differences areoriginated from the different dimension and structure between CNT and GN: GN withflake-like structure and larger surface area can have stronger physical and interfacialinteractions with polymer matrix. This work gives a comparative view of the differentfiller effect that functionalized CNT and GN can have in the polymer host. With theidentical processing technology, GN can show stronger filler effect than CNT in thepolymer host.Third, nitrile functionalized CNT and GN/PEN (CNT-CN/GN-CN/PEN)nanocomposites were systhensized and the weight ratio of CNT-CN/GN-CN was variedfrom CNT-dominated to GN-dominated for the purpose of investigating their synergeticinfluence on the mechanical and thermal performances of PEN-based composites.Consequently, GN-CN/PEN composites demonstrated better mechanical and thermalproperties than CNT-CN/PEN composites due to larger contact area between GN-CN and PEN matrix. Nevertheless, all CNT-CN/GN-CN/PEN composites exhibit enhancedmechanical properties than those of GN-only nanocomposites. With the increasing ofCNT-CN/GN-CN weight ratio, mechanical performances of PEN/CNT-CN/GN-CNcomposite films increase, then decrease, and reach their maximums whenCNT-CN/GN-CN weight ratio is around4/4. From scanning electron microscopeimages, it is found that around that point GN-CN is flatly dispersed and CNT-CN ispenetrated into GN-CN, capable of transferring stress load and thus decreasing interfaceloss. Thermal properties of CNT-CN/GN-CN/PEN composites once again confirmed thejoint effect of CNT-CN and GN-CN, leading to improved thermal properties. In short, asynergistic effect between one-dimensional (1-D) CNT and two-dimensional (2-D) GNon the mechanical and thermal performances of nanocomposite films have beendemonstrated in these systems. This can provide some references on the issues ofmaterial design.