Functionalized graphene sheet—Poly(vinylidene fluoride) conductive nanocomposites

PVDF nanocomposites based on functionalized graphene sheets, FGS prepared from graphite oxide, and exfoliated graphite, EG, were prepared by solution processing and compression molding. FGS remains well dispersed in the PVDF composites as evidenced by the lack of the characteristic graphite reflection in the composites. Although the α-phase of PVDF is seen in the EG-based composites, a mixture of α- and β-phases is present in the FGS analogs. SEM and TEM imaging show smooth fractured surfaces with oriented platelets of graphite stacks and obvious debonding from the matrix in the EG-PVDF composites. In contrast, the FGS-PVDF composites show a wrinkled topography of relatively thin graphene sheets bonded well to the matrix. Storage modulus of the composites was increased with FGS and EG concentration. A lower percolation threshold (2 wt %) was obtained for FGS-PVDF composites compared to EG-PVDF composites (above 5 wt %). Lastly, the FGS-PVDF composites show an unusual resistance/temperature behavior. The resistance decreases with temperature, indicating an NTC behavior, whereas EG-PVDF composites show a PTC behavior (e.g., the resistance increases with temperature). We attribute the NTC behavior of the FGS based composites to the higher aspect ratio of FGS which leads to contact resistance predominating over tunneling resistance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 888–897, 2009

[1]  R. Car,et al.  Single Sheet Functionalized Graphene by Oxidation and Thermal Expansion of Graphite , 2007 .

[2]  S. Stankovich,et al.  Graphene-based composite materials , 2006, Nature.

[3]  R. Bissessur,et al.  Intercalation of solid polymer electrolytes into graphite oxide , 2007 .

[4]  Guohua Chen,et al.  PMMA/graphite nanosheets composite and its conducting properties , 2003 .

[5]  Z. Dang,et al.  Enhanced dielectric properties and positive temperature coefficient effect in the binary polymer composites with surface modified carbon black , 2008 .

[6]  V. Djoković,et al.  Temperature dependence of the electrical conductivity of epoxy/expanded graphite nanosheet composites , 2008 .

[7]  Y. Mai,et al.  New Method To Prepare Graphite Nanocomposites , 2008 .

[8]  S. Wong,et al.  Electrical and mechanical properties of expanded graphite‐reinforced high‐density polyethylene , 2004 .

[9]  S. Wong,et al.  TRANSPORT BEHAVIOR OF PMMA/EXPANDED GRAPHITE NANOCOMPOSITES , 2002 .

[10]  L. Drzal,et al.  Dynamic Mechanical and Thermal Properties of Phenylethynyl‐Terminated Polyimide Composites Reinforced With Expanded Graphite Nanoplatelets , 2005 .

[11]  Shing Chung Josh Wong,et al.  Electrical conductivity and dielectric properties of PMMA/expanded graphite composites , 2003 .

[12]  V. Causin,et al.  Morphological and structural characterization of polypropylene/conductive graphite nanocomposites , 2006 .

[13]  L. Brinson,et al.  Functionalized graphene sheets for polymer nanocomposites. , 2008, Nature nanotechnology.

[14]  M. Xiao,et al.  Facile synthesis of highly conductive polyaniline/graphite nanocomposites , 2004 .

[15]  Guo-Hua Hu,et al.  A new process of fabricating electrically conducting nylon 6/graphite nanocomposites via intercalation polymerization , 2000 .

[16]  H. X. Yang,et al.  A positive-temperature-coefficient electrode with thermal cut-off mechanism for use in rechargeable lithium batteries , 2004 .

[17]  Wengui Weng,et al.  Nonlinear conduction in nylon-6/foliated graphite nanocomposites above the percolation threshold , 2004 .

[18]  Tianxi Liu,et al.  Crystal transformation and thermomechanical properties of poly(vinylidene fluoride)/clay nanocomposites , 2005 .

[19]  Shoko Yoshikawa,et al.  Resistivities of conductive composites , 1992 .

[20]  Lawrence T. Drzal,et al.  A new compounding method for exfoliated graphite–polypropylene nanocomposites with enhanced flexural properties and lower percolation threshold , 2007 .

[21]  J. Mano,et al.  Characterization of poled and non-poled β-PVDF films using thermal analysis techniques , 2004 .

[22]  C. Macosko,et al.  Morphology and Properties of Polyester/Exfoliated Graphite Nanocomposites , 2008 .

[23]  Lawrence T. Drzal,et al.  Thermal conductivity of exfoliated graphite nanocomposites , 2006 .

[24]  Rodney S. Ruoff,et al.  Polymer−Graphite Nanocomposites:  Effective Dispersion and Major Property Enhancement via Solid-State Shear Pulverization , 2008 .

[25]  Guohua Chen,et al.  Preparation of polymer/graphite conducting nanocomposite by intercalation polymerization , 2001 .

[26]  D.D.L. Chung,et al.  Electrical applications of carbon materials , 2004 .

[27]  X. Yi,et al.  Thermal volume expansion in polymeric PTC composites: a theoretical approach , 2001 .

[28]  Badr Eddine El Mohajir,et al.  Changes in structural and mechanical behaviour of PVDF with processing and thermomechanical treatments. 1. Change in structure , 2001 .

[29]  Wengui Weng,et al.  Preparation of polystyrene/graphite nanosheet composite , 2003 .

[30]  M. Itkis,et al.  Graphite Nanoplatelet−Epoxy Composite Thermal Interface Materials , 2007 .

[31]  M. Rodríguez-Pérez,et al.  Functionalized graphene sheet filled silicone foam nanocomposites , 2008 .

[32]  Dajun Wu,et al.  Dispersion of graphite nanosheets in polymer resins via masterbatch technique , 2007 .

[33]  Guohua Chen,et al.  Preparation of polymer/oriented graphite nanosheet composite by electric field-inducement , 2008 .

[34]  M. Xiao,et al.  Synthesis and characterization of polyaniline/graphite conducting nanocomposites , 2004 .

[35]  K. Lafdi,et al.  Use of exfoliated graphite filler to enhance polymer physical properties , 2007 .

[36]  Z. Yu,et al.  Conductive mechanism of polymer/graphite conducting composites with low percolation threshold , 2002 .

[37]  H. Shen,et al.  Graphitic nanofillers in PMMA nanocomposites—An investigation of particle size and dispersion and their influence on nanocomposite properties , 2007 .

[38]  P. Salagnac,et al.  Conductive polymer composites with double percolated architecture of carbon nanoparticles and ceramic microparticles for high heat dissipation and sharp PTC switching , 2008 .

[39]  W. Huang,et al.  Structure and electrical properties of grafted polypropylene/graphite nanocomposites prepared by solution intercalation , 2003 .

[40]  L. Drzal,et al.  Mechanical properties and morphological characterization of exfoliated graphite–polypropylene nanocomposites , 2007 .

[41]  L. Drzal,et al.  Multifunctional polypropylene composites produced by incorporation of exfoliated graphite nanoplatelets , 2007 .

[42]  F. Kang,et al.  Preparation and structure analysis of carbon/carbon composite made from phenolic resin impregnation into exfoliated graphite , 2006 .

[43]  Roberto Car,et al.  Functionalized single graphene sheets derived from splitting graphite oxide. , 2006, The journal of physical chemistry. B.