Ultrasonic treatment for enhancing the accessibility and reactivity of softwood rayon-grade kraft-based dissolving pulp

The cellulose reactivity is a critical parameter in the manufacturing process of viscose rayon with dissolving pulp. In this study, an ultrasonic treatment, which is considered as an environmentally friendly pretreatment technology, was applied to a softwood prehydrolysis kraft-based dissolving pulp for enhancement of accessibility/reactivity in terms of viscose rayon production through cavitation of ultrasound. Results show that the ultrasonic treatment can lead to the decrease of cellulose crystallinity, the increase of specific surface area and average pore diameter in fibers, and the increase of water retention value due to the release of energy induced by the collapse of the gas/vapor bubbles. As a consequence, the Fock reactivity and viscose filterability of dissolving pulp is enhanced significantly after ultrasonic treatment. Other parameters, such as intrinsic viscosity and fiber morphology were also determined.