The effect of degradation on the strength of hardwood kraft pulp fibres

In order to study the effect of degradation on the strength of hardwood kraft pulp fibres, a hardwood kraft pulp was subjected to oxidative and hydrolytic degradation in alkali for various periods of time. The two series obtained, were characterized by viscosity and by size exclusion chromatography. Strength and deformation of the degraded pulp fibres were measured as zero-span tensile strength and shape factor. The results show that, at given viscosity and molecular weight of the carbohydrate polymers, the oxygen/alkaline degraded pulp fibres are less deformed and stronger than those treated by alkali at a high temperature. Temperature and chemical modification during treatment may thus be of greater importance for fibre strength than the size of the carbohydrate polymers.