كليدواژه :
الفاسلولوز , Poplar Sawdust , مهندسي , Alpha Cellulose , خمير , خاك اره صنوبر , درجه پليمرشدن
چكيده لاتين :
Alpha cellulose pulps contain 90-98% alpha cellulose. Alpha cellulose is an important raw material for cellulose derivatives production. Wood and its residues are main sources of alpha cellulose. In order to prepare alpha cellulose from poplar sawdust, the following steps were carried out: three types of prehydrolysis including: water, 5% sulfuric acid and 20% potassium hydroxide for pentosan removal, then, three types of cooking liquor including: Kraft liquor, 50% aqueous-ethanol with 4% NaOH and a liquor compound of acetic acid, hydrochloric acid and acetone for delig-nification (pulping), and finally three types of bleaching sequences including: CEH, HEHEP and CEHEP for residual lignin removal and enhancement of alpha cellulose purity. In prehydrolysis with water and cooking with liquor compounds of acetic acid, acetone and hydrochloric acid and bleaching sequence of HEHEP, the lowest percentage amount of alpha cellulose was gained. In prehydrolysis with potassium hydroxide and cooking with Kraft liquor and bleaching sequence of CEHEP the highest value of alpha cellulose was gained. Cellulose chains length (degree of polymerization) was in contrast to those of alpha cellulose values.
