Dissolving pulp from eucalyptus sawdust and its application in cellulosic beads and films

OLMOS G.V. ; EHMAN, NANCI VANESA; VALLEJOS, MARÍA EVANGELINA; TALEB M.C. ; PERESIN, SOLEDAD; MAXIMINO, MIRTA; FELISSIA, FERNANDO ESTEBAN; AREA, MARIA CRISTINA

Sao Paulo

Congreso; 51st ABTCP International Pulp and Paper Congress and X IberoAmerican Congress on Pulp and Paper Research; 2018

ABTCP - CIADICYP 2018

The aim of this study was to evaluate the capability of eucalyptus sawdust dissolving pulp (EP) to obtain regenerated cellulose products (beads and films). A commercial dissolving pulp (CP) was used as a reference. Eucalyptus sawdust pulp was obtained by a soda pulping followed by a short TCF sequential bleaching process (OOpZ), followed by a cold soda extraction. EP and CP were characterized by alpha-, beta and gamma-cellulose, alkali solubility with 10 wt% (S10) and 18 wt% NaOH (S18) aqueous solutions, and degree of polymerization. The Fock´s method was used to measure the cellulose reactivity. Pulp solubility in alkali (9 wt% NaOH at -5°C) was used to determine the soluble material of the pulps. Two methods (viscose and direct dissolution in NaOH/urea) were tested to evaluate the pulps dissolving capacity. The quality of the obtained viscose was evaluated by cellulose content, total carbon disulfide, and carbon disulfide as byproducts, gamma number, and the intrinsic viscosity of the film of regenerated cellulose. The direct dissolution of cellulose in NaOH/urea was evaluated by solubility and cellulose content. The obtained cellulose solutions were used to produce beads and films as regenerated products. Both dissolving pulps presented high and similar cellulose content (96.7% in EP and 95.3% in CP, expressed as -cellulose) and high molecular weight (1385 in EP and 993 in CP). S10 and S18 values for EP pulps were within the range specified for the different grades of dissolving pulps. Both pulps showed a very similar reactivity about 69%), but CP solubility was higher. The sequential mechanical and enzymatic pretreatment of pulps favored the decrease of the polymerization degree, which decreased about 50% for EP and 35% for CP, with viscosities of 290 and 271 mL g-1, respectively. Films of both pulps with a thickness between 38 and 44 μm were obtained from the direct solutions. The films showed approximately the same breaking stress, but films from CP were more ductile. EP presented a response comparable to CP in both, dissolving pulp quality and regenerated products characteristics.