Piezoresistive Behavior of Carbon/Carbon Composite Based on Expanded Graphite and Polyfurfuryl Alcohol

The aim of the study was to investigate the effect of polyfurfuryl alcohol (PFA) and the carbonization process on the mechanical properties of a carbon-carbon composite based on expanded graphite. Four types of samples were obtained and tested for their mechanical features: GE -compressed expanded graphite not subjected to any modification; GEFA - compressed expanded graphite mixed with polyfurfuryl alcohol subjected to the cross-linking process; GE8000 - compressed expanded graphite subjected to the carbonization process at the temperature of 800 ℃; GEFA800 - compressed expanded graphite mixed with polyfurfuryl alcohol subjected to the carbonization process at the temperature of 800 ℃. This paper presents preliminary results of the characterization of the true density, bulk porosity, elasticity and resistivity of the studied composites. Our results indicate that changes in the resistivity of the obtained composites depend on the pressure force. The electrical resistivity decreases with time under mechanical stress. Samples with the small amount of PFA added and subjected to the carbonization process are characterized by the lowest values of resistance, the highest values of elastic modulus E, but lower true density and bulk porosity. Small amount of PFA allows to change the properties of the composite samples, what can be potentially applied to the enzyme support obtaining.