EFFECT OF SURFACE-ACTIVE AGENTS ON AGEING BEHAVIOUR OF IMPREGNATING PITCH

摘要

Efficiency of impregnation of carbon artefacts by a liquid pitch is a function of accessibility of porous system, impregnant properties and process conditions. A minimum radius of pores r which can be penetrated by an impregnating pitch at a given pressure p can be evaluated using Washburn equation r≥ 2σ@ cos θ/p (1) where: σ- surface tension θ- contact angle It has been therefore anticipated that modification of impregnating pitch with a surface-active agent can result in enhanced penetration ability into porous system of artefacts. The suitable additive in addition to improvement of pitch viscosity and wettability should not have a harmful effect on thermal stability under impregnation conditions. The present study is intended to assess the effect of additive of surf ace-active agents of polyglycol and ester type on thermal stability of commercial impregnating pitch.