Novel CED-based rheological test to evaluate pulp reactivity

Reactivity is an important quality parameter for some grades of pulp,
but its estimation is usually complex and time demanding. The study
verified the possibility to utilize an alternative rheological approach to
investigate pulp reactivity rapidly and with limited effort. 12.5 ml of
pulp at 1.5% consistency was dissolved in 12.5 ml bis(ethylenediamine)
copper(II) hydroxide solution (CED) 1 M. The reaction was moni-
tored by a torque rheogram and its two indices: the optimal dissolution
time (ODT) and the initial dissolution rate (IDR). The method used to
assess pulps either hornified to different extents or subjected to enzy-
matic hydrolysis. ODT was shown to decrease with increasing pulp
swelling, while IDR reported the opposite trend. Both the indices were
shown to be sensitive to pulp treatments. However, the ODT showed
larger differences between hardwood and softwood pulps. The method
had reasonable statistical reliability and required only 1.5 h per
measurement.