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

OLMOS, G.V.; TALEB, M.C.; FELISSIA, F.E.; EHMAN, N.; PERESIN, M.S.; AREA, M.C.; VALLEJOS, M.E.; MAXIMINO, M.G.

São Paulo

Congreso; ABTCP - CIADICYP 2018 51º ABTCP Congresso Internacional de Celulose e Papel e X Congresso Ibero-Americano de Pesquisa em Celulose e Papel; 2018

ABTCP - CIADICYP

The aim ofthis study was to evaluate the capability of eucalyptus sawdust dissolving pulp(EP) to obtain regenerated cellulose products (beads and films). A commercialdissolving pulp (CP) was used as a reference. Eucalyptus sawdust pulp wasobtained by soda pulping followed by a short TCF sequential bleaching process(OOpZ), followed by cold soda extraction. EP and CP were characterized byalpha-, beta and gamma-cellulose, alkali solubility with 10 wt% (S10) and 18wt% NaOH (S18) aqueous solutions, and degree of polymerization. The Fock´smethod 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 toevaluate the pulps dissolving capacity. The quality of the obtained viscose wasevaluated by cellulose content, total carbon disulfide, and carbon disulfide asbyproducts, gamma number, and the intrinsic viscosity of the film ofregenerated cellulose. The direct dissolution of cellulose in NaOH/urea wasevaluated by solubility and cellulose content. The obtained cellulose solutionswere used to produce beads and films as regenerated products. Both dissolvingpulps presented high and similar cellulose content (96.7% in EP and 95.3% inCP, expressed as alfa-cellulose) and high molecular weight (1385 in EP and 993in CP). S10 and S18 values for EP pulps were within the range specified for thedifferent grades of dissolving pulps. Both pulps showed a very similarreactivity (about 69%), but CP solubility was higher. The sequential mechanicaland enzymatic pretreatment of pulps favored the decrease of the polymerizationdegree, which decreased about 50% for EP and 35% for CP, with viscosities of290 and 271 mL g-1, respectively. Films of both pulps with a thickness between38 and 44 μm were obtained from the direct solutions. The films showedapproximately the same breaking stress, but films from CP were more ductile. EPpresented a response comparable to CP in both, dissolving pulp quality andregenerated products characteristics.