| Carbon foam is a material with many unique characteristics and proposed applications. Demanding processing requirements make many of the applications uneconomical. In this study, the possibility of impressing external physical blowing agents (PBA) into pitch is investigated to form pitch foam, a precursor to carbon foam. This would reduce processing pressure and temperature requirements and decrease the cost of manufacturing. Two pitches have been characterized and have thermoplastic character similar to organic polymers. Several physical properties were measured for 110°C and 180°C softening point pitch which were supplied by Koppers Inc. and compared to select common polymers. PBAs are frequently used in industrial polymeric foam to produce cells within the melt. Introduction of PBAs into pitch melts, coupled with an induced thermodynamic instability, successfully yielded foams.;Variations of three polymeric foam process parameters, temperature, saturation pressure, and pressure release rate, in a batch process were examined to determine if the parameters qualitatively yield similar trends for pitch foam as for polymer foam. Results showed parallel trends of the variables with pressure release rate being the prominent variable. It is believed that ambient moisture present in the pitch coupled with CO2 and N2 PBAs may have a significant factor in cell formation. A simple extrusion setup was constructed in which pitch foam was successfully extruded. This investigation could lead to a novel and inexpensive route for the production of carbon foam. |
