Effect Of Main Composition Of Dissolving Pulp On Its Reactivity

Dissolving pulp is a high-grade cellulose pulp, with high content of cellulose and low content of hemicellulose. Dissolving pulp is usually used to manufacture viscose or cellulose derivatives. In recent years, people pay more and more attention to dissolving pulp as demand rises. When dissolving pulp is used to prepare viscose or cellulose derivatives, the key properties of the pulp is its reactivity.Pentosans are the important components in pulp. Pentosan content has great effect on the pulp and paper performance. There are many methods for determining pentosans in pulp. Volumetric method and spectrophotometry are commonly used in industry for determining pentosans. Compare with volumetric method, coloration spectrophotometry by orcinol reagent has more exact determining results; hydroxymethyl-furfural formed from hexoses does not interfere in this determinationWe took four different dissolving pulps as material to find the main factor which influence the reactivity. The results showed that the pulp with high reactivity has low hemicellulose content and low viscosity, cellulose content, acetone-extractable compounds content and ash content did not show obvious influence to reactivity.Fock’s method was introduced to determine the reactivity of dissolving pulps in this paper. Dissolving pulp with poor reactivity was treated with a cellulase and hydrochloric acid. The results showed that the reactivity of the dissolving pulp was improved significantly after both treatments. The cellulose was slightly degraded after cellulase treatment, the pulp viscosity, yield and alkali solubility changed little, on the contrary, the cellulose was strongly degraded and the pulp viscosity and yield decreased rapidly, and the alkali solubility increased significantly.More analyses have been done through Fourier transform infrared spectroscopy(FTIR), Scanning electron microscope(SEM) and X-ray diffraction(XRD). Analyses conclude that no new group was introduced during the cellulase treatment, but damages had been found on the fiber cell wall. The cellulase degrades amorphous cellulose and cleaves the cellulose randomly within the chain. Cellulase treatment may lead to a swelling of the cell wall and thus an increase in accessibility to solvents and reagents and thereby increase the reactivity. Cellulase treatment also leads to increase the crystallinity of pulp.