Vitreous carbon

Abstract

The vitreous carbon disclosed herein is prepared from the molded product of a moldable composition produced from co-reacted mixtrues of powder or otherwise blendable form of 20-80% by weight of a phenolic-furfuraldehyde Novolac resin and of 20-80% by weight of a phenolic-aldehyde resol resin dispersed in water, either in solution or suspension, the percentages being based on the combined weight of the Novolac and resol resins, and the aldehyde in said Novolac resin comprising at least 50 molar percent, preferably substantially 100 percent, furfuraldehyde. The composition advantageously contains an amine such as hexamethylenetetramine ('hexa') in an amount equivalent to 1-15%, preferably 2-10% of hexamethylenetetramine based on the total amount of phenolic component. The composition is made by adding the preformed phenol-furfuraldehyde Novolac to the resol resin prior to dehydration of the resol resin to produce a grafted polymerization product of improved properties. This composition is particularly useful in admixture with a carbonaceous filler, preferably graphite in a proportion as high as 76% by weight based on the total composition. Generally in such admixtures the graphite may comprise 30-76%, advantageously 35-65% and preferably 40-60% of the molding composition. The vitreous carbon is improved in electrical properties and in the capability of being suitably molded, carbonized and graphitized into large shapes, particularly thin plates which are much more stress-free and crack or pore-free than otherwise produced.