Quantification of the microdeformation degree of fast-growing poplar wood during prehydrolysis and its relationship with subsequent pulping

Prehydrolysis is a typical pretreatment in dissolving pulp preparation to remove hemicellulose prior to pulping. In this study, we employed the combined severity factor (CSF) as a reaction parameter to control the pretreatment intensity during prehydrolysis of fast-growing poplar wood, and we investigated the influence of the pretreatment intensity on the components and morphology of wood chips. To assess the microstructural changes in the cell wall, we introduced a mathematical model named the microdeformation coefficient (MDC) to quantitatively evaluate the degree of microstructural deformation and verified its validity and reliability under different CSFs. The results indicated that the MDC could precisely describe the significance of the effect of prehydrolysis on microstructural changes in wood chips. Furthermore, the relationship between the MDC and the physicochemical properties of pulp fibers and handsheets was explored. A moderate MDC of approximately 0.0050 is suggested to attain good hemicellulose removal and produce pulp with good properties (accept pulp content = 47.21 %, permanganate numbers = 18.23, degree of polymerization (DP) = 1774.40) after prehydrolysis. Moreover, the produced handsheets exhibited excellent properties (brightness = 29.50 %, fold resistance = 5.11 times, tensile index = 81.43 N mg, and tear index = 6.36 mN.m(2)/g).