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    The effect of different enzymatic pretreatment processes on the production of nanocellulose from wheat straw
    (Gazi Universitesi, 2023) Sertkaya, S.; Arslan, R.; Tozluoğlu, A.; Fidan, H.; Erol, Ö.; Ünal, H.İ.; Candan, Z.
    Nanocellulose is an important material in the field of forest products with its application potential which can be obtained from lignocellulosic raw materials such as roots, stems, straw, leaves and bark. It emerges as a result of agricultural activities and gives positive effects on the final products obtained due to its physical, chemical, and morphological properties. Compared to the alkaline or acidic production method, which is frequently used as a nanocellulose production method in the literature, the enzymatic hydrolysis method has been less studied. In general, cellulose nanofibrils (CNF) are produced by nanocellulose production processes via enzymatic hydrolysis, while crystalline nanocelluloses (CNC) are produced by non-enzymatic processes. In this study, CNF was obtained by two different enzymatic pretreatments (hemicellulase Pulpzyme HC 2500 and cellulase Celluclast 1.5 L commercial enzymes) followed by homogenization on soda-NaBH4 bleached pulp fibers obtained from wheat straw for the first time and the changes in chemical, morphological, thermal, and rheological properties the CNF obtained after the homogenization process were investigated. HPLC analyses performed after enzymatic pretreatment showed that more carbohydrates were removed from the structure at increasing enzyme concentrations, and SEM images taken after homogenization under high pressure showed that the fibers were homogeneously reduced to nano size (average fiber diameter of 20-50 nm) in CNF production. © 2023 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.
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    Effect of Size Press Coating of Cationic Starch/ Nanofibrillated Cellulose on Physical and Mechanical Properties of Recycled Papersheets
    (North Carolina State University, 2023) Tozluoğlu, A.; Fidan, H.
    This study aimed to evaluate the effect of size press coating on two types of recycled papers using different types of nanofibrillated cellulose (NFC) and cationic starch (CS) on physical and mechanical properties. Wheat straw was used as a cellulose source, and NFC was obtained through oxidative and enzymatic pretreatments. Recycled fluting and coreboard papers were coated with cationic starch/NFC blends at various concentrations of NFC (0.5%, 1%, 2%, 3%, and 4%) using a three-time repetitive size press application, followed by one-time drying section, and compared to uncoated papers. The application of a coating suspension containing 4% periodate-oxidized NFC on both paper surfaces resulted in a significant improvement in the tensile index, burst index, and internal bond strength of the papersheets, with increases of up to 60.6%, 96.3%, and 119.9%, respectively. Furthermore, significant decreases in air permeability were also observed with reductions of 75% and 81.6% for coreboard and fluting papers, respectively. Compared to other pretreatment methods, periodate oxidation resulted in higher viscosity values in NFC samples. Therefore, the application of periodate-oxidized NFC with a size press resulted in a significant improvement in the mechanical and barrier properties of papers made from recycled pulps. © 2023, North Carolina State University. All rights reserved.