Laser Treatments for Improving Electrical Conductivity and Piezoresistive Behavior of Polymer–Carbon Nanofiller Composites

Abstract

The effect of carbon nanotubes, graphene-like platelets, and another carbonaceous fillers of natural origin on the electrical conductivity of polymeric materials was studied. With the aim of keeping the filler content and the material cost as low as possible, the effect of laser surface treatments on the conductivity of polymer composites with filler load below the percolation threshold was also investigated. These treatments allowed processing in situ conductive tracks on the surface of insulating polymer-based materials. The importance of the kinds of fillers and matrices, and of the laser process parameters was studied. Carbon nanotubes were also used to obtain piezoresistive composites. The electrical response of these materials to a mechanical load was investigated in view of their exploitation for the production of pressure sensors and switches based on the piezoresistive effect. It was found that the piezoresistive behavior of composites with very low filler concentration can be improved with proper laser treatments.

Multifunctional Conductive Paths Obtained by Laser Processing of Non-Conductive Carbon Nanotube/Polypropylene Composites

“…The effect of the laser in increasing electrical conductivity by several orders of magnitude is associated with the local increment of the MWCNT concentration and the resulting resistance per length of conductive path is as low as about 1 kΩ/cm. To the best of our knowledge this value is among the best that has been achieved by the laser treatment considering the mixture of MWCNTs with other polymer matrices, including SEBS, PP, HDPE, ABS, PC, EPDM, epoxy resin, PP/PC and PC/ABS blends, and GO/PET [8,33,35,[37][38][39][40]. Although the use of these technologies applied to conventional and unconventional carbon-based polymer composites may enable new applications and functionalities, the resistance values are still too high and represent a limitation for most applications due to the random distribution of CNTs as obtained by laser activation processes.…”

“…Principles, basic results, and applications about the laser processing of graphite-, graphene-and MWCNT-based composites with the aim of increasing locally the electrical properties on the outer surface of non-conductive polymers are reported in [8,33,35,[37][38][39][40]. In these works, a variety of polymers, including styrene-b-ethylene-co-butylene-b-styrene triblock copolymers (SEBS), PP, high-density polyethylene (HDPE), acrylonitrile-butadienestyrene (ABS), polycarbonate (PC), ethylene-propylene-diene monomer (EPDM) rubber, epoxy resin, PP/PC and PC/ABS blends, and graphene oxide/polyethylene terephthalate (GO/PET) with MWCNTs were contemplated.…”

Piezoresistive and mechanical Behavior of CNT based polyurethane foam

“…The polymer composites containing CNT, or carbon nanoparticles, or both also showed piezoresistive behavior. Therefore, they were investigated for fabrication of stress, strain or pressure sensors [12][13][14][17][18][19].…”

Editorial for the Special Issue on Carbon Based Electronic Devices

“…A wide spectra of carbon materials and a wide range of applications are described in the present issue. As per material type, papers deal with graphene and graphene-oxide [1][2][3][4], carbon nanotubes [2,5,6] and with other forms of carbon, such as porous carbon [7] and nanofibers [8,9]. A plethora of devices are witnessing the versatility of carbon materials: supercapacitors [1,9], non-volatile memories [8], pressure sensors [2,7], field-effect transistors [10], white-light photosensors [3], cold cathode electron emitters [5], gas and humidity detectors [6,11], MEMS and NEMS [12], carbon based inks for 3D microfluidic MEMS [13], transparent conductive electrodes [4].…”

“…Bondavalli et al [8] focus on the fabrication of Resistive Random Access Memory (ReRAM) on flexible substrates based on oxidized carbon nanofibres (CNFs) showing that two different resistance states (ON, OFF) reversibly switchable can be obtained. Caradonna et al [2] discuss the use of various carbon nanofillers to promote piezoresistivity in polymers by means of laser scribing treatment able to produce conductive tracks in an otherwise low conductive material. Porous carbon electrodes and their interesting piezoresistive properties are discussed by Dai et al [7].…”