Sustainable high-yield lignocellulosic fibers and modification technologies educing softness and strength for tissues and hygiene products for global health

Abstract

Unbleached hardwood kraft pulp was treated with a non-ionic surfactant to decrease the concentration of a hydration shell by dislodging hard-to-remove water through a targeted reduction in surface tension. Energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry techniques were used to investigate and evaluate these fiber-surfactant interactions. Scanning electron microscopeimages were taken to observe the change in the morphology from the surfactant treatment. The surface tension was measured by using pendant drop tests, which reduced from 71.46 mN/m to ∼ 49–51 mN/m for different pretreatment techniques and hence, reduced the pulling force exerted by the liquid bridge water on the fibers by 28–31%. This consequently led to reduced fiber collapse, and the surfactant-treated fibers showed higher bulk and softness without a concomitant sacrifice of mechanical properties. The scanning electron microscopeimages confirmed a more cylindrical fiber structure and showed an unaffected fiber–fiber interaction because of which the tensile strength was not compromised with the increase of bulk. The surfactant-treated fibers showed better recovery or spring back, i.e. a return to their original form after compression relative to the untreated fibers. Therefore, it was possible to make tissue papers with higher bulk, softer hand-feel, and a higher absorbing capacity, without reducing the tensile strength by simple and green processes involving chemical and mechanical modifications.