Effect of charcoal on formaldehyde emission, mechanical, thermal and dynamic properties of resol resin

Abstract

The effect of charcoal (CH), on reducing the emission of free formaldehyde from phenol–formaldehyde resol resins and the properties of the modified resins were investigated. The reduction of free formaldehyde content (FFC) of the resol resin was monitored by Waker’s titration method. The charcoal was found to be very effective in reducing the FFC of the resin due to its high porosity and large surface area. With the incorporation of charcoal the free formaldehyde content of resol resin was almost reduced to zero. The mechanical properties of the PF resin were improved by modification with charcoal. SEM micrographs of tensile fractured surfaces were in agreement with improved mechanical properties. Modified samples exhibited improvements in elastic modulus, loss modulus and tan delta as indicated by dynamic mechanical analysis. The activation energy for the relaxation process in the glass transition region increased with the increase in the amount of charcoal. The thermogravimetric analysis showed that the charcoal had only marginal influence on the thermal stability of the resin.