Piezoresistive Materials from Directed Shear-Induced Assembly of Graphite Nanosheets in Polyethylene

Abstract

A three‐dimensional conductive nanocomposite with an ordered conductive network and low percolation threshold has been successfully prepared by blending graphite nanosheets (GNs) with polyethylene on a two‐roll mill. The conductive nanosheets orient intensively in the composite, leading to highly anisotropic properties. The nanocomposite with the fraction of conductive nanosheets closest to the percolation threshold possesses a sharp positive pressure coefficient of resistivity, in which the abrupt transition can be attributed to compressive‐stress‐induced deformation of the conductive network. Such piezoresistive effects depend strongly on filler morphology, filler spatial arrangement, and filler concentration.

Anisotropic alignment of non-modified BN nanosheets in polysiloxane matrix under nano pulse width electricity

“…4) Aligning nanosheets by reorienting in polymer matrix is critical techniques; electric field, 5),6) magnetic force 7), 8) and sheer force 9) are widely used to reorient nanosheets in polymer matrix. In these cases the nanosheets surface should be modified by metallic nanopowders, such as iron nanoparticle to enhance the orientation of nanosheets in electric field.…”

Densely Packed Linear Assembles of Carbon Nanotube Bundles in Polysiloxane‐Based Nanocomposite Films

“…This implies that applying a switching DC field increases the CNT population in LACNTs. When an electric field is applied, polarized 1D or 2D dielectric fillers tend to orient their longitudinal directions parallel to the electric flux to minimize the electrostatic energy [16]. The polarized ends of CNTs become interconnected through Coulomb attraction forming a side-by-side attachment of CNTs due to self-assembly and generating a dendritic structure of CNTs [37].…”

“…The thermal conductivities of such composites are strongly affected by the dispersion, orientation, and linear alignment of inorganic fillers aligned to parallel to the thermal flux [12][13][14] in polymer matrices [15]. The orientation and formation of network structures containing small quantities of nanofillers in a polymer matrix can be controlled by applying a shear force [16], a magnetic field [17], or an electric field [18][19][20], or by mechanical stretching [21,22]. Of these methods, orienting conducting or dielectric nanofillers by applying an electric field has the advantage that the fillers form self-assembled linear structures due to Coulombic attraction during electrophoretic movement in a polymer with a controlled viscosity [23,24].…”

“…Assembly of fillers with end-to-end attachment can also reduce the thermal boundary resistance. This cannot be achieved in composites with random filler orientation or using other torque sources, such as shear or a magnetic field, which can only change the orientations of 1D or 2D fillers [16,17,25].…”

Temperature Dependence of Electrical Transport in a Pressure-Sensitive Nanocomposite

“…In bulk form, these materials typically consist of electrically conducting filler particles dispersed in an insulating matrix. Filler particle 2 materials are diverse and commonly include graphite 4 , carbon black, and metal powders of varying size and shape 5 , and more recently carbon nanotubes 6 and graphene 7,8 . The insulating matrix materials are equally varied, with a range of polymeric materials 9,10,11 and even cement 12 utilized.…”