Hasanjanzadeh, H., Hedjazi, S., Ashori, A., Mahdavi, S., & Yousefi, H.

International Journal of Biological Macromolecules 68: 198–204.

2014

The aim of this study was to evaluate the influence of mild alkaline pre-extraction on the hemicel-luloses removal of rice straw. In addition, the performance of cellulose nanofibers (CNFs) addition onsome physico-mechanical properties obtained from extracted and un-extracted (control) samples wereinvestigated. An optimum compromise was found as operating conditions (10% soda, 50◦C, and 90 min)that provided moderate hemicelluloses removal (48.1%). The residual extracted rice straw particles weresubjected to soda–anthraquinone pulping at 160◦C for 30–60 min with 6 to 18% active alkali charge.Compared with the control samples, the screened yield and Kappa number for extracted pulps decreasedslightly. Extracted samples showed better air resistance compared with the un-extracted (control) pulps.However, pre-extraction was found to negatively impact on some mechanical properties such as decreasein burst and tensile indices while addition of CNFs and refining of fibers could improve the strength prop-erties considerably. In general, the addition of CNFs in any concentrations considerably enhanced tensileand burst indices of the sheets in extracted and un-extracted conditions, compared with the unfilledones. The improvement in mechanical properties was considered one of the key benefits brought byCNFs reinforcement. On the other hand, the stretch properties of the beaten pulps are higher than thoseof control samples. SEM observations showed that CNFs were deposited on the voids between the ricestraw fibers.