Reinforcement potential of modified nanofibrillated cellulose in recycled paper production

Abstract

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.

Improving Recycled Paper Materials through the Incorporation of Hemp, Wood Virgin Cellulose Fibers, and Nanofibers

“…Regarding natural ones, cellulose fibers, including micro and nanofibers, from different sources are used in most cases. The mechanical properties of recycled paper have been significantly improved by the addition of nanocellulose varying the sources, such as oil palm empty fruit bunches [25], corn stalks [26], wheat straw [27], wood [9], recycled pulp [28], hemp [29], and others. The addition of wood virgin pulp to recycled pulp to improve mechanical performance has been investigated [30], as well as the addition to different agro-waste, for example, rice straw [31].…”

Effect of size press coating of cationic starch/ nanofibrillated cellulose on physical and mechanical properties of recycled papersheets

“…Mazhari Mousavi et al (2017) indicated that incorporating CMC as an additive to alter the rheological properties of NFC suspension, by decreasing the fiber-fiber interactions of NFC fibrils, thus reduces flocculation tendency of NFC suspensions; therefore, it enables uniform spreading of NFC at moderate solids content. The rheological behaviours of the evaluated nanofibrillated celluloses in this work were given in the authors' previous study (Tozluoğlu et al 2021). The periodate-oxidated samples exhibited lower viscosity than TEMPO and PINO oxidated samples, therefore the formulation was able to penetrate and uniformly spread on the substrate surface under high pressure.…”

“…For instance, González et al (2012) reported that the bulk addition of 3% NFC to bleached eucalyptus pulp suspension increased °SR as 61.1%. Furthermore, 23.3% increase in °SR was reported by Tozluoğlu et al (2021) after the bulk addition of 4% NFC to recycled pulp suspensions. The use of retention agents not only increases retention but also has positive effects on the mechanical properties by enhancing fiber-fiber bonding, thus proper selection and optimization of retention agents would be required.…”

“…For this purpose, 2 wt% aqueous suspensions of fibers were prepared and then passed through Z-shaped chambers by pressure following the next sequences: 1 time through a chamber with 200 μm diameter at 14000 psi, subsequently 5 times through a chamber with a 100 μm diameter at 24000 psi. The rheological properties of obtained NFC suspensions were studied in the authors' previous study (Tozluoğlu et al 2021). The viscosity of NFC samples was determined with RST-CPS Rheometer (Brookfield Corp., Toronto, Canada) at room temperature.…”