Time and temperature dependent piezoresistance of carbon nanofiller/polymer composites under dynamic load

• Published in: Journal of materials science Vol. 47; no. 6; pp. 2648 - 2657
• Main Authors: de la Vega, Alejandra, Sumfleth, Jan, Wittich, Hans, Schulte, Karl
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.03.2012; Springer; Springer Nature B.V
• Subjects: Analysis; Carbon black; Carbon nanotubes; Carbon-epoxy composites; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Direct current; Dynamic loads; Electric properties; Electrical conductivity; Electrical resistance; Electrical resistivity; Elongation; Epoxy resins; Glass; Glass transition; Loads (forces); Materials Science; Nanocomposites; Nanostructure; Phase shift; Piezoresistivity; Polymer matrix composites; Polymer Sciences; Solid Mechanics; Temperature dependence; Thermal analysis; Time dependence; Interparticle Distance; Percolation Threshold; Dynamic Mechanical Thermal Analysis; Electrical Resistance Change; Resistance Change
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-011-6090-7

In this study, the behaviour of carbon nanotube/epoxy and carbon black/epoxy composites under dynamic load is studied via dynamic mechanical thermal analysis (DMTA) in combination with DC electrical resistivity measurements. DMTA measurements are carried out at fixed temperature whilst the dynamic loading frequency is varied. With this procedure, a loading frequency-dependence of the phase shift between DC electrical resistance and mechanical elongation (δ R –ε ) is observed, although the force and elongation of the sample are still in phase. Moreover, the magnitude of this phase shift, as well as the amplitude of the DC electrical resistance change shows a clear dependence on the initial electrical conductivity of the samples. In addition, temperature sweeps are carried out to investigate the temperature dependency of the piezoresistance of the samples. An abrupt change in their sensitivity is observed as soon as the glass transition of the polymer is reached. However, the trend of the resistance change beyond the glass transition is substantially different between the nanocomposites containing carbon black and carbon nanotubes, revealing a strong influence of the network characteristics on the piezoresistive behaviour of these novel materials.