Carbon-based piezoresistive polymer composites: Structure and electrical properties

• Published in: Carbon (New York) Vol. 62; pp. 270 - 277
• Main Authors: Cravanzola, Sara, Haznedar, Galip, Scarano, Domenica, Zecchina, Adriano, Cesano, Federico
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2013; Elsevier
• Subjects: Carbon; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Devices; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Extrusion; Fibers; Fibres; Fullerenes and related materials; diamonds, graphite; General equipment and techniques; Hot pressing; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Materials science; Melts; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Physics; Piezoelectricity and electromechanical effects; Polymer matrix composites; Polypropylenes; Sensors; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Specific materials; Piezoresistive devices; Electrical properties; Carbon nanotubes; Carbon; Fibers; Hot pressing; Composite materials; Multiwalled nanotube; Polypropylene; Graphite; Displacement rates; Piezoelectricity; Extrusion; Microstructure; Polymers; Structure; Polymer structure; Diameter; Melts
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2013.05.064

Piezoresistive polymeric composites were prepared by melt mixing of polypropylene (PP) with expanded graphite (EG) (10–15wt%) and/or multiwalled carbon nanotubes (MWCNTs) (1–2wt%). The composites were extruded at a temperature of 185°C, by adopting 2.5–10rpm screw speeds, and fibres with diameters of 0.2, 1.5 and 3mm, were obtained. An integrated piezoresistive sensor device was obtained by hot pressing the extruded fibres into two sandwiched PP panels. Structure and morphology of the carbon fillers (EG and MWCNTs) and of the fibres, were investigated by means of X-ray diffraction, optical microscopy, scanning electron microscopy (conventional and conductive SEM) and atomic force microscopy. Piezoelectric properties of fibres and sensor devices were detected through a set up made by a dynamometer, a potentiometer and a digital multimeter. It was shown, that mechanical deformations, due to the applied loads, affect remarkably the resistivity of the materials.