Abstract
Recycling cycles cause a decrease in mechanical paper properties due to cellulose fiber degradation. The use of cellulose micro/nanofibers (CMF/CNF) to reinforce paper strength has been well studied, although it has been found to have negative effects on drainage. However, the application of CMF/CNF as paper reinforcement is affected by the nanocellulose type. Thus in this study mechanical and chemical treatments in CNF production were compared. Old corrugated container (OCC) pulp used to produce recycled cartonboard was reinforced with 1) CMF from never-dried northern bleached softwood kraft pulp (NBSK) highly refined in a 16-inch low consistency refiner at 1200 rpm and 25 kW of net power; and 2) CNF from NBSK pulp treated by TEMPO-mediated oxidation and homogenization at 600 bars. CMF/CNF and OCC were pulped at the same time and handsheets formed with cationic starch (CS) as retention system. Mechanical, drainage and flocculation properties were evaluated and compared. Data were also compared with other sources of TEMPO CNF. Results show an improvement in mechanical properties, drainage and flocculation when OCC is reinforced with CMF obtained with LCR. Therefore, high fibrillation was not necessary to improve mechanical paper or cardboard properties.
Highlights
Several strategies have been used to improve mechanical and physical properties of recycled products, such as fiber refining[8,9], or the addition of strength additives, for instance, cationic starch or synthetic polymers such as polyacrylamides, polyvinylamines or polyvinyl alcohols[10,11,12,13]
Other researchers have studied refining as the main mechanical defibrillation treatment to prepare cellulose microfibers (CMF) or cellulose nanofibers (CNF) without additional treatments or using a low concentration of NaOH in the fibers soak. These CMF/CNF were obtained in high consistency refiners (HCR), where the heterogeneous furnish formed by fibres and fines, water and steam is at a concentration in the range of 10–40%41,42; or in low consistency refiners (LCR) at a concentration of 2–6%26,43
The properties of CMF produced by LCR and with 2 or 4 homogenization passes barely affect the CMF characteristics
Summary
Several strategies have been used to improve mechanical and physical properties of recycled products, such as fiber refining[8,9], or the addition of strength additives, for instance, cationic starch or synthetic polymers such as polyacrylamides, polyvinylamines or polyvinyl alcohols[10,11,12,13]. The pulp is more homogeneous and, the refining treatment more uniform than in HCR26,36 Among these studies, only some of them use CMF/CNF as an additive to reinforce strength properties in paper or board. CNF from LCR with different fines content were used by Johnson et al.[26] to improve paper mechanical and surface properties, drainage properties were adversely affected Pretreatments such as enzymatic hydrolysis before LCR defibrillation has been studied by Bharimilla et al.[14] to prepare unbleached kraft paper handsheets reinforced with 5 and 10% of CMF and the mechanical properties were improved
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
