COTTON STALK APMP PROPERTIES AND THE CHANGES OF CHEMICAL COMPOSTIONS OF COTTON STALK IN THE COURSE OF CHEMIMECHANICAL PROCESSING

摘要

APMP pulping conditions of cotton stalk were discussed in this paper, also the changes of main chemical compositions of cotton stalk in the course of chemimechanical processing were systematically investigated. It was concluded that under the moderate chemical impregnation conditions as follows: The first stage pretreatment: H2O2 1.0 %, NaOH 3.0 %, Na2SiO3 1.0 %, 95°C, 30 min, liquor-to-fiber ratio 6∶1; the second stage pretreatment: H2O2 4.0 %, NaOH 3.0 %, Na2SiO3 1.0%, EDTA 0.05%, MgSO4 0.1%, 90 °C , 30min, liquor-to-fiber ratio 5∶1, cotton stalk APMP pulp with yield 79.20%, brightness 50.5%ISO, breaking length 4.85km and tear index 3.95 mN·m2/g can be obtained. In addition, it was found that main chemical compositions of cotton stalk had been changed significantly in the course of APMP pulping. 1% NaOH significantly in the course of APMP pulping. 1% NaOH extractives from30.78 % in the raw material decreased to 18.14 % in the resultant pulp after chemimechanical pulping, correspondingly, lignin content from 25.13% to 22.65%, and pentosan content from 19.89 % to 16.12 %, respectively.