Blended paper: physical, optical, structural, and interfiber bonding analysis

Abstract

Background: Blended paper can present suitable mechanical properties due to sirnergetic effect. However, regarded to physical properties, few studies are conducted. This study aimed to evaluate optical, structural, interfiber bonding, and other physical properties from blended paper and try to understand how these properties can affect applications. The eucalyptus, sisal, and pine pulp were used for handsheet forming. Pulps were disintegrated, refined, and blended two by two in 5/95%, 25/75%, and 45/55% ratios. Also, virgin pulps (100% of each pulp) were used for handsheet forming. Handsheets were formed and evaluated by bond strength, cobb test, air permeance, roughness, optical, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Results: Treatments differed statistically in bond strength, cobb test, optical, air permeance, and roughness. Generally, treatments with eucalyptus presented higher bond strength, brightness, and air permeance. Treatments with sisal presented the highest opacity and roughness. Spectra of virgin handsheets presented differences in 2170-2000 and 2360 cm-¹ bands, probably related to residual lignin content. SEM images revealed structural differences between blended and virgin pulps. Conclusion: Treatment T15 (45S 55P) presented the best results, suggesting better physical-mechanical properties. Blended handsheets presented better properties than virgin handsheets on most properties, evidencing a synergetic effect.