In this study, the use of modified calcite as a filler in fluting paper production was investigated and its effects on retention and some mechanical properties of the papers were determined. Ground calcium carbonate (GCC/calcite) and cationic starch were used for modification. Filler modification with alum effect of CPAM resulted in starch-calcite encapsulation. Produced modified calcite (MC) was used in fluting paper production at certain dosages as filler. Simultaneously, paper was made with unmodified calcite (UC), and the effects of modified calcite on the paper properties and filler retention were studied. The results of this study indicated that the use of 10% MC improved filler retention and provided approximately 23% more retention than the use of 10% UC. In addition, mechanical properties and air permeability values of MC-filled papers were higher than those of UC-filled papers. With the use of MC in fluting papers production, better filler retention was achieved, while the reduction in mechanical properties caused by the addition of filler can be minimized. Besides, impurities in white water can be minimized by reducing the filler dosage given during paper production.

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.

This study aims to investigate the impact of coating with ground calcium carbonate (GCC) on the optical properties and filler content of white top testliner (WTT) papers. The paper properties investigated include brightness, whiteness, opacity, color coordinates, and yellowness. The results showed that the amount of filler mineral used in the coating process significantly affected the optical properties of the paper. The use of 15% total solids of GCC in the coating suspension resulted in the highest level of whiteness and improved the brightness value by 6.8%. The use of 7% total solids of starch and 15% total solids of GCC reduced the yellowness index by 85%. However, the use of only 7 and 10% total solids of starch had an adverse effect on the yellowness values. The surface treatment led to a significant increase in the filler content of the papers, with a maximum of 23.8% achieved using a coating suspension with 10% total solids of starch solution, 15% total solids of GCC suspension, and 1% dispersant. The starch and GCC in the coating suspension were found to have a direct impact on the filler content of the WTT papers. The addition of a dispersant improved the uniform distribution of the filler minerals and increased the filler content of the WTT. The water resistance of WTT papers increases due to the use of GCC, while their surface strength remains at an acceptable level. The study demonstrates the potential benefits of the surface treatment in terms of cost savings and provides valuable information on the impact of the treatment on the properties of WTT papers.

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.

Bu çalışmada, soymuk lifleri alınmış kenevir (Cannabis sativa L.) saplarının kağıt hamuru ve kağıt üretiminde kullanımı ve üretilen kağıtların bazı mekanik ve optik özellikleri araştırılmıştır. Soymuk liflerinden arındırılmış kenevir saplarının kimyasal bileşenleri ve lif morfolojik özellikleri belirlenerek kağıt hamuru ve kağıt üretimine uygunluğu tespit edilmiştir. Kenevir saplarının holoselüloz, selüloz ve lignin içerikleri sırasıyla %79.7, %52.0 ve %22.2, lif uzunluğu, lif genişliği ve lümen çapı ise sırasıyla 0.60 mm, 28.8 µm ve 13.4 µm bulunmuştur. Bu veriler doğrultusunda, kenevir saplarından Kraft yöntemi ile pişirme yapılarak kağıt hamuru üretimi gerçekleştirilmiştir. Kenevir saplarından elde edilen kağıt hamurunun verimi, kappa numarası ve viskozite değerleri sırasıyla %48.2, 39 ve 1400 cm 3 /gr olarak tespit edilmiştir. Bu hamurlardan üretilen kağıtların kopma uzunluğu ve parlaklık değerleri ise sırasıyla 6.87 km ve 33.34 %ISO olarak ölçülmüştür. Sonuç olarak, soymuk liflerinden arındırılmış kenevir saplarından yüksek verimde ve mukavemette kağıt hamuru üretimi gerçekleştirilebilmektedir. Aynı zamanda, kağıt hamurları düşük kappa numarasına ve yüksek viskozite değerine sahip olduğundan ağartılması kolay olmaktadır.