PHOTOSTABILIZATION OF MECHANICAL PULPS BY POLYVINYLPYRROLIDONE

Free phenolic hydroxyl groups in lignin are largely responsible for th e formation of colored structures in mechanical pulps. Polyvinylpyrrol idone (PVP) has been reported to interact with the phenolic hydroxyl g roups in lignin via hydrogen bonds. Results presented here show that m echanical spruce pulps were stabilized against photoyellowing by treat ment with PVP The most efficient PVP compounds were the monomer (n-vin yl-2-pyrrolidone) and the lowest-molecular-weight (10, 000) polymer Th e polymers increased initial brightness and functioned as stabilizers against photoyellowing.