Abstract

Phenolic (PF) resol resins contains unreacted free formaldehyde which continues to be released from the
products after manufacturing process is completed. Formaldehyde is incredibly volatile, has an unpleasant
odour which irritates the eyes and nasal passages and may cause other health problems. Hence an efficient
method is necessary to decrease the amount of free formaldehyde in PF resol resin. In this study we have
investigated the synthesis of resol resin using sodium sulphite (SS) and hydroxylammine hydrochloride (HH) as
formaldehyde scavengers. These scavengers form reversible adducts with formaldehyde. The effect of these
scavengers on the free formaldehyde content (FFC) of the new modified resol resin was analyzed by Walkers
titration method. With the incorporation of sodium sulphite and hydroxylammine hydrochloride, the free
formaldehyde content was reduced to zero. The scanning electron micrographs of tensile fractured surfaces
were used to investigate the morphological changes on scavenger addition. The physical, mechanical and
thermal properties of the PF resins were improved on modification with these scavengers.