Effect of pressure and temperature on properties of carbon-carbon composites prepared from renewable material

This paper presents the preparation of carbon-carbon composites (CCC) from jute fibre - phenol formaldehyde (PF) resin by programmed carbonisation process. Jute/PF resin composite was prepared using hand layup technique followed by curing in compression press at 160°C under pressure of 460 bar. Carbonisation cycle was designed using TGA studies carried out up to 800°C at different heating rates in the range of 3-20 °C / min. Carbonisation experiments were carried out in both tubular furnace and hot press. Carbonisation of the composite was performed at a programmed heating rate in a hot press with application of pressure from room temperature to 800°C, the partially carbonized composite was further carbonized in the tubular furnace without application of pressure from room temperature to 1000°C in argon atmosphere under programmed heating rate. The resulting composites were characterized for density, functional groups, extent of carbonisation, graphitization, porosity and conductivity. The results show that the density of the composite before carbonisation was 1.30 g/cc which was reduced to 0.78 g/cc and 0.97 g/cc after carbonisation without and with pressure respectively indicating the weight loss due to the escape of the volatiles. The transformation of functional groups such as CH, C-OH etc to aromatic C=C, C≡C in carbonized composite was evident from FTIR studies. Raman spectra shows the evidence of graphitic structure in the carbonized composites. Surface pores in the range of 82 to 312 μm were noticed in the composite carbonised without pressure and the pore sizes were reduced to 42 to 93 μm when carbonized under pressure. Electrical conductivity also increases from 4.7 × 10^-12 S/cm to 1.429 × 10^-2 S/cm and 6.777 × 10^-2 S/cm for the composite carbonised without and with pressure during carbonisation.