Effects of poly(vinyl alcohol) on the strength of kraft paper crosslinked by a polycarboxylic acid

Fully hydrolyzed poly(vinyl alcohol) (PVA) was applied as a co-additive of poly(maleic acid) (PMA) to improve the mechanical properties of kraft paper Although PUA brings abort significant improvement in wet strength, it caus es embrittlement and severe loss of folding endurance of treated paper. PVA is able to minimize the negative impact on dry properties of paper treated by PMA. When applied as a co-additive. PVA improves wet strength. dry stre ngth, as well as folding endurance of the paper crosslinked by PMA. Thermal analysis data indicate that PMA reacts with PVA under the curing condition s. The improvement in mechanical properties may be attributed to the improv ed fibre-fibre bonding and consequently alleviation of stress concentration .