Grafting nanocellulose with diethylenetriaminepentaacetic acid and chitosan as additive for enhancing recycled OCC pulp fibres

This paper develops a novel paper additive for effectively recycling old corrugated container (OCC) by functionalizing nanocellulose (NC) with diethylenetriaminepentaacetic acid (DTPA) and chitosan (CS), and investigate the reinforcing mechanisms and effect of the developed additive on the physical properties of recycled OCC pulp handsheets. The tensile, tear and burst index, air permeability, tensile energy absorption (TEA), and drainage performance of the recycled OCC handsheets are examined. Fourier transform infrared FTIR) spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM) are used for the chemical and microstructure characterization of both NC based additives and paper from recycled OCC pulp. The results show that functional groups on the NC based additive, such as carboxyl, amino and hydroxyl groups, can bond with the hydroxyl groups on the recycled OCC fibres to generate a chemical bond. This leads to an increase in the crosslinks and bonding area between the fibres, which increases their tensile strength and improves their recycling rate. SEM shows that the paper with NC based additives had tighter inter-fibre bonds and smaller paper pore structure. Addition of 0.3% NC-DTPA-CS additive results in optimal properties of the recycled OCC paper with an increase by 31.64%, 22.28% and 36.6% of tensile index, tear index, burst index respectively, and the air permeability decreases by 36.92%. Graphical Abstract

Locust bean gum adsorption onto softwood kraft pulp fibres: isotherms, kinetics and paper strength

The adsorption of locust bean gum (LBG) onto Northern Bleached Softwood Kraft (NBSK) pulp improved paper tensile and burst strength and lowered refining energy by strengthening inter-fibre bonding. Adsorption kinetics and isotherms were investigated to develop a fundamental understanding of the adsorption mechanism. The adsorption rate followed pseudo-second-order kinetics and the activation energy was 99.34 kJ·mol−1, suggesting chemisorption. The adsorption rate constant increased rapidly with temperature from 25 to 45 °C (k = 1.93 to 24.03 g·mg−1·min−1), but the amount adsorbed at equilibrium decreased (qe = 1.91 to 0.48 mg·g−1 o.d. fibre). LBG adsorption to NBSK at 25 °C was consistent with the Langmuir adsorption model for LBG < 2.1 wt% of o.d. fibre, suggesting reversible, homogenous adsorption to a finite number of sites on the fibre surface. Refining to 3000 rev increased the heterogeneity of the NBSK pulp surface leading to multi-layer Freundlich adsorption with adsorption constant n = 5.00, and the equilibrium constant Kf = 2.57 mg·g−1·(mg·L−1)−1/n at 25 °C. Favorable adsorption conditions for negatively charged LBG were identified: 25 °C for 10 min, low dosage level (< 2 wt%), lightly refined (< 3000 rev) NBSK pulp at low fibre consistency (< 0.5 wt%), high agitation rate (> 150 r.p.m.), acidic or neutral conditions (pH 2–7) without salt addition. Graphic abstract

Grafting Nanocellulose With Diethylenetriaminepentaacetic Acid and Chitosan As Additive for Enhancing Recycled OCC Pulp Fibres

This paper is to develop a novel paper additive for effectively recycling old corrugated container (OCC) by functionalizing nanocellulose (NC) with diethylenetriaminepentaacetic acid (DTPA) and chitosan (CS), and investigate the reinforcing mechanisms and effect of the developed additive on the physical properties of recycled OCC pulp handsheets. The tensile, tear and bursting strength, whiteness, air permeability, tensile energy absorption of the recycled OCC handsheets are examined. Fourier transform infrared FTIR) spectroscopy, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM) are used for the chemical and microstructure characterization of both NC based additives and recycled OCC pulp paper. The results show that the functional groups, such as carboxyl, amino and hydroxyl groups on the NC based additives, can combine with the hydroxyl groups on the recycled OCC fibres to generate chemical bonds, which increase the crosslinks between fibres as well as the bonding area, thus enhancing their tensile strength and improving their recycling rate. SEM shows that the paper with NC based additives had tighter inter-fibre bonds and smaller paper pore structure. Addition of 0.2% NC-DTPA-CS additive results in optimal properties of the recycled OCC paper with an increase by 32%, 188%, 19% and 35% of tensile strength, tearing degree, breaking resistance and air permeability respectively.

Tear Resistance and Morphology Study of Tree Pruning Waste Papers: Effect of Soda Pulping Concentration

With the aim to explore the use of tree pruning waste as replacement material in papermaking, a study was conducted to investigate the effect of soda pulping concentration on the tear resistance and surface morphology of the fabricated papers. By varying the sodium hydroxide concentration from 5% to 25%, tree pruning waste papers with different tear resistance and surface morphology were fabricated. The tree pruning waste papers with the optimum tear resistance (73049.68 mN) was produced when the pulping medium was prepared at 20% sodium hydroxide concentration. As confirmed by the morphology study, the pulp fibres with improved interlocking surface morphology was produced at 20% sodium hydroxide concentration. Beyond that, fibre fibrillation had took place and exerted negative impact on the tear resistance of the papers. The present study confirms the use of tree pruning waste as an alternative in papermaking. Nonetheless, the soda pulping concentration must be properly regulated in order to maximize the performance of the fabricated paper products.

Sound absorption properties of wood-based pulp fibre foams

In this study, sound absorbing materials were produced through foam forming technique using hardwood and softwood pulps with varying chemical composition, ultrastructural, and morphological properties as raw materials. The sound absorption properties of the produced foams were measured and related to the ultrastructure and the morphology of the pulp fibres. All the fibre foams provided sound absorption properties comparable to those of conventional porous materials used for acoustic purposes. In general, further processing, as well as smaller fibre dimensions contribute to improve the sound absorption properties of the pulp fibre foams. The results provide valuable insight on the optimization of wood-based sound absorbing materials. Graphic abstract

How Flushable Wet Wipes Are Causing Sewer Blockages – and An Approach to Prevent That

Scientific publications and newsfeeds recently focused on flushable wet wipes and their role in sewage system blockages. It is stated that although products are marked as flushable, they do not disintegrate after being disposed of via the toilet. In this work it is shown that wetlaid hydroentangled wet wipes lose their initially good dispersive properties during their storage in wet condition. This behaviour is found for both, wet wipes from industrial production and wipes produced on pilot facilities. It is demonstrated that the deterioration of the wipe’s ability to disintegrate during wet storage is linked to the type of cellulosic fibres used. Only wipes made from a combination of band-shaped viscose fibres and unbleached softwood pulp fibres were preserving good disintegration during wet storage. The results are also suggesting to add tests after defined times of wet storage when assessing the flushability of wet wipes.

Modification of softwood kraft pulp fibres using hydrogen peroxide at acidic conditions

The aim of this work was to provide softwood kraft pulp fibres with new functionalities by the introduction of carbonyl groups. Carbonyl groups are known to affect properties such as wet strength through the formation of covalent bonds, i.e. hemiacetals. The method developed involves oxidation using hydrogen peroxide at mildly acidic conditions. It was found that the carbonyl group content increased with both increasing temperature and residence time when oxidized at acidic conditions. The number of carboxylic groups, however, remained approximately constant. There was virtually no increase in carbonyl groups when oxidation was performed at alkaline conditions. The maximum increase in carbonyl groups was found at a residence time of 90 min, a reaction temperature of 85 °C and a pH of 4. These conditions resulted in an increase in carbonyl groups from 30 to 122 µmol/g. When formed into a sheet, the pulp oxidized at acidic conditions proved to maintain its structural integrity at aqueous conditions. This indicates the formation of hemiacetal bonds between the introduced carbonyl groups and the hydroxyl groups on the carbohydrate chains. Thus, a possible application for the method could be fibre modification during the final bleaching stage of softwood kraft pulp, where the wet strength of the pulp could be increased.