Comparative characterization of eucalyptus fibers and softwood fibers for tissue papers applications

Significative growth and demanding for premium tissue products, in which softness and absorbency are key consumer requests, pointed out the need for the establishment of relations between fiber properties and tissue paper properties. For this purpose, an experimental plan was designed using a representative group of pulp fibers, six hardwood, and six softwood, for the production and characterization of low basis weight paper structures (20 g/m2). The pulp fibers morphology and chemical content were evaluated, and hardwoods showed lower fiber length (0.70–0.84 vs 1.57–1.96 mm), coarseness (6.71–9.56 vs 16.77–19.66 mg/100 m) and higher pentosan content (6.3–21.1 vs 7.6–10.3%). Even though the paper structures were produced with the same basis weight, they presented a broad range for bulk (3.46–8.04 cm3/g), tensile index (2.00–11.45 N.m/g), softness (65.7–86.9) and absorption capacity (8.08–9.48 g/g). The results indicated that softness was directly influenced by structural properties, increasing with bulk, while tensile strength correlated inversely. Therefore, the correlations obtained were used to identify the most suitable pulp fibers properties for each type of tissue paper. Keywords: Absorption, Cellulose fiber materials, Pulp fiber morphology, Softness, Tissue papers