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    Application of modified cellulose nanofibrils as coating suspension on recycled paper using size press
    (Walter De Gruyter Gmbh, 2021) Fidan, Hakan; Tortuoglu, Ayhan; Tutus, Ahmet; Poyraz, Bayram; Arslan, Recai; Sertkaya, Selva; Killi, Ufuk
    Cellulose based nanomaterials have the great potential to be applied to paper as bulk additive or coating material to improve overall final properties, especially in secondary fiber. In the present work, the effect of applying different kinds of cellulose nanofibrils (CNF) to papers obtained from recycled fibers using size press on physical, mechanical and barrier properties was investigated and compared with the sole use of starch as coating material. The coating process of CNF was carried out by the addition of size press grade starch to coating suspension. As a cellulose source, wheat straw was evaluated and CNF was obtained through oxidative and enzymatic pretreatments. Results indicate that starch/CNF suspension improves the overall paper properties. As a result of the deposition of coating suspension contains of 4 % wt. periodate-oxidized CNF onto paper surface, tensile and burst indices of papersheets increased as 52.2 % and 194.4 %. Significant decreases were observed in air permeability as 69.8 %. Compression tests also have been conducted to evaluate papersheets end-use properties. In comparison to the other pretreated CNF, due to is lower viscosity, applying periodate-oxidized CNF as size press significantly increased the mechanical properties of the papers fabricated from the recycled pulps.
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    Developing Wallpaper/Dodecyl alcohol composite phase change materials as new kind of wall covering elements for building interior thermoregulation
    (Elsevier, 2023) Gencel, Osman; Ustaoglu, Abid; Sari, Ahmet; Hekimoglu, Gokhan; Sutcu, Mucahit; Tozluoglu, Ayhan; Tutus, Ahmet
    This study introduces a novel wall-covering element consisting of wallpapers (WP) impregnated with Phase Change Material (PCM), with the aim of enhancing thermal properties and providing effective thermal regulation performance in interior spaces. The study conducts practical investigations into the thermal attributes of wall-papers (WPs) impregnated with Dodecyl alcohol (DDA) as the chosen PCM, culminating in a leakage-free WP/ DDA wall covering element. The process of impregnating involved applying liquid DDA to the back side of the WP using a manual coating apparatus. Four distinct DDA ratios, ranging from 0% to 20% by mass of WP, were applied. The chemical compatibility of the developed WP/DDA composite was explored using Fourier Infrared Spectroscopy (FTIR). The thermal energy storage (TES) properties were assessed through Differential Scanning Calorimeter (DSC) analysis, and the thermo-regulative performance of the WP/DDA composite was evaluated in laboratory-scale test rooms under real weather conditions. The DSCoutcomesexposed that melting temperature and latent heat capacity of WP/DDA were 21.78 degrees C and 26.9 J/g, respectively.The thermoregulation tests showed that the prepared WP/DDAsignificantly reduce interior room temperature fluctuation and can maintain indoor temperature longer in comfortable temperature ranges. The largest difference between the reference room and test room was observed to be about 2celcius. The room temperature was cooler for about 9 h 53 min during day times for the DDA case.The results designated that the developed WP/DDA composite could be evaluated as a promising new kind of building wall covering element for reducing the cooling load of room.
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    Printability of variative nanocellulose derived papers
    (Springer, 2021) Ozcan, Arif; Tozluoglu, Ayhan; Arman Kandirmaz, Emine; Tutus, Ahmet; Fidan, Hakan
    The printability properties of the paper can be increased by some processes applied to the surface. The use of non-recyclable materials derived from petroleum is decreasing day by day, and the demand for recyclable materials obtained from renewable sources is increasing. These materials include cellulose derivatives, starch types and polyvinyl alcohol. The materials ratios, sizes, physical and chemical properties of these materials used in the processes applied to the paper and the content of the paper will affect the strength of the paper as well as change the surface properties and significantly affect the printability. The aim of this study is to obtain better printability properties by improving the paper surface with CNF/CNF-OX coating. In this study, fluting and core board papers coated with different amounts of cellulose nanofiber (CNF)/cellulose nanofiber-oxidized (CNF-OX) were produced. Surface properties, contact angle, surface energy, color and gloss of the produced papers were measured by optical microscope, goniometer, spectrophotometer and glossmeter. The papers were printed with the IGT C1 offset printability tester. As a result, in terms of printability, it was determined that CNF/CNF-OX coated papers have smoother surfaces and give better results in terms of both gloss properties and printability. [GRAPHICS] .
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    Reinforcement Potential of Modified Nanofibrillated Cellulose in Recycled Paper Production
    (North Carolina State Univ Dept Wood & Paper Sci, 2021) Tozluoglu, Ayhan; Fidan, Hakan; Tutus, Ahmet; Arslan, Recai; Sertkaya, Selva; Poyraz, Bayram; Gucus, Mehmet Onurhan
    The influence of nanofibrillated cellulose (NFC) was investigated as a reinforcing agent to improve strength properties of papersheets fabricated from recycled pulp fibers of mixtures of old newspapers, old magazines, and old corrugated cardboards. To determine the effects of the NFC on the mechanical and physical properties of the recycled pulp papers, cellulose nanofibrils (NFC) were isolated from wheat straw, pretreated chemically and enzymatically (NFC-OX), and then added to the bulk suspensions of papermaking pulp slurries at various percentages. The electrokinetic and drainage properties of the pulps and the mechanical and physical properties of the papersheets were analyzed and compared. As expected, the addition of NFC/NFC-OX significantly increased the strength properties of papers. Papers containing 4% of NFC-OX (periodate pretreated) presented higher increases in tensile index (43%) and burst index (59.3%) than other papers. However, a high addition of NFC/NFC-OX increased the water retention, which is undesirable for papermaking. Hence, with optimum selection of NFC/NFC-OX and process conditions, higher mechanical properties could be acquired without increasing drainage rate. Compared to the other pretreated NFC/NFC-OX types, sodium-periodate-oxidized NFC-OX samples significantly increased the mechanical properties of the papers fabricated from the recycled pulps.