title: Effects of hemicellulose pre-extraction and cellulose nanofiber on the properties of rice straw pulp.
abstract: The aim of this study was to evaluate the influence of mild alkaline pre-extraction on the hemicelluloses removal of rice straw. In addition, the performance of cellulose nanofibers (CNFs) addition on some physico-mechanical properties obtained from extracted and un-extracted (control) samples were investigated. An optimum compromise was found as operating conditions (10% soda, 50°C, and 90min) that provided moderate hemicelluloses removal (48.1%). The residual extracted rice straw particles were subjected to soda-anthraquinone pulping at 160°C for 30-60min with 6 to 18% active alkali charge. Compared with the control samples, the screened yield and Kappa number for extracted pulps decreased slightly. 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 decrease in burst and tensile indices while addition of CNFs and refining of fibers could improve the strength properties considerably. In general, the addition of CNFs in any concentrations considerably enhanced tensile and burst indices of the sheets in extracted and un-extracted conditions, compared with the unfilled ones. The improvement in mechanical properties was considered one of the key benefits brought by CNFs reinforcement. On the other hand, the stretch properties of the beaten pulps are higher than those of control samples. SEM observations showed that CNFs were deposited on the voids between the rice straw fibers.
authors.affiliation: Department of Wood and Paper Science and Technology, Faculty of Natural Resources, University of Tehran, Karaj, Iran.
authors.forename: Hadi
authors.initials: H
authors.lastname: Hasanjanzadeh
authors.affiliation: Department of Wood and Paper Science and Technology, Faculty of Natural Resources, University of Tehran, Karaj, Iran.
authors.forename: Sahab
authors.initials: S
authors.lastname: Hedjazi
authors.affiliation: Department of Chemical Technologies, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran. Electronic address: ashori@irost.org.
authors.forename: Alireza
authors.initials: A
authors.lastname: Ashori
authors.affiliation: Department of Wood and Paper Science, Research Institute of Forests and Rangelands (RIFR), Tehran, Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Mahdavi
authors.affiliation: Department of Wood Engineering & Technology, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences &Natural Resources, Gorgan, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Yousefi
mesh_terms: D000468:Alkalies / Q000494:pharmacology; D000704:Analysis of Variance; D000880:Anthraquinones / Q000494:pharmacology; D002482:Cellulose / Q000737:chemistry*; D057139:Nanofibers / Q000737:chemistry*; D012275:Oryza / Q000737:chemistry* / Q000187:drug effects; D011134:Polysaccharides / Q000302:isolation & purification*; D013499:Surface Properties; D014866:Waste Products
chemical_list: D000468:Alkalies; D000880:Anthraquinones; D011134:Polysaccharides; D014866:Waste Products; C007916:hemicellulose; D002482:Cellulose
keywords: Cellulose nanofiber; Hemicelluloses; Pre-extraction; Rice straw; Soda–anthraquinone