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Swelling Performance of Cotton Waste Dissolving Pulp During Mercerization in the Viscose Process
- Elise Meurs
- Regeneration of cellulose through the viscose process has been optimized for dissolving-pulp sources from special grade wood pulp or cotton linters. More recently, the undeniable environmental impact of the textile-industry has caused a growing urge for developing ways to tackle that pollution, for example by reusing waste-cotton as input for the viscose process. However, previous experiences in industry and research have indicated that waste-cotton pulp performs differently due to differences in chemical and physical properties and morphology. This study focused on the first step of the viscose process (‘mercerization’) with the purpose of activating the cellulose-chains generally densely packed within crystalline formation through hydrogen-bonds, causing cellulose in its natural form to have poor accessibility and reactivity towards chemicals. Hereby, cellulose pulp is steeped in concentrated lye-solution (17-19 wt%) for 20-30 minutes at elevated temperature (45-55°C), creating a swollen alkoxide derivative.The behaviour during mercerization is critical for sufficient reactivity in further process steps and removal of undesirable components in the pulp. However, excessive swelling can complicate following process steps such as pressing out excess lye, necessary for obtaining optimal cellulose-content in further steps. Therefore, different input materials including dissolving pulp from softwood, cotton linters and cotton waste were investigated regarding swelling-properties and the ease of pressing after mercerization. The analysis indicates cotton pulp to swell more than dissolving wood pulp, but also lead to more difficult pressing afterwards. These findings give more insight on the performance of different sources during mercerization, and consequently, in the viscose process.
