PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 8, Number 2, 2022
the external core has no considerable effect on the panel behavior. Next, the effect of orientation for the corrugated cores is studied for two 0/90/0 and 90/0/90 layups. The results show that bending rigidity of 90/0/90 is greater than other case due to more bending rigidity of the external cores. To design an optimum sandwich panel, genetic algorithm is utilized by constraining the mass and height of the panel. For optimization purpose, an analytical formulations that is validated by presented experimental and numerical results are used. Based on optimization results, optimized sandwich panel is constructed and exposed to TPB test. Good agreement is observed between all the numerical, analytical and experimental methods. The results indicate that the optimized configuration can achieve notable higher bending resistance in the same weight especially for the 90/0/90 case. Finally, an isotropic multilayered sandwich panel is introduced and optimized to overcome the drastic anisotropic properties of corrugated cores. The optimized isotropic panel have equal bending rigidity in two principal axes of the panel. TISSUE “ Enhanced water absorption of tissue paper by cross-linking cellulose with poly(vinyl alcohol) ”, A. Cláudia S. Ferreira, Roberto Aguado, Raquel Bértolo, Ana M. M. S. Carta, Dina Murtinho & Artur J. M. Valente, Chemical Papers , Vol.76, pp.4497- 4507 (2022). Tissue paper was the only paper grade whose consumption increased during 2020 in Europe. In a highly competitive context, this work explores a strategy based on bisacrylamide cross-linkers and poly(vinyl alcohol) (PVA), seeking to enhance the water uptake of pulps for tissue paper and the key properties of the resulting tissue sheets: water absorption capacity, capillarity, softness, porosity, and strength. For that, α -cellulose from cotton and a kraft hardwood pulp, in parallel, were reacted with N,N’ - methylenebisacrylamide, both in the absence and in the presence of PVA. The water desorption rate of the modified polymers was monitored. Pulp blends were then mixed with a conventional softwood pulp (30%) to prepare laboratory tissue paper sheets (20g m – 2 ). For cotton cellulose, cross-linking with PVA more than doubled the water uptake, up to 7.3g/g. A significant enhancement was also obtained in the case of pulps, up to 9.6g/g, and in the case of paper, to 11.9g/g. This improvement was consistent with a drastic increase in porosity, and it was not detrimental to paper strength. “Insights into Gum Arabic interactions with cellulose: Strengthening effects on tissue paper”, A. Cláudia S.Ferreira, Roberto Aguado, Ana M.M.S. Carta, Raquel Bértolo, Dina Murtinho & Artur J.M. Valente, Materials Today Communications , Vol.31, 103706 (June 2022). Competitiveness in the market for tissue paper, the only paper grade whose consumption increased during 2020 in Europe, requires seeking viable options to continuously improve its properties. This work explores the combination of gum Arabic, which is a naturally found, biodegradable, cheap and versatile heteropolymer, with bleached cellulosic pulps. Blends of pulps and alkaline gum Arabic (GAb) were analyzed in terms of their thermal degradation behavior, morphology, water absorptivity and drying rate. It was found that water uptake increased by 23% for the maximum proportion of GAb tested (30%, w/w) and that water desorption followed quasi-zero-order kinetics. Furthermore, these blends were used to prepare light-weight paper handsheets by bulk addition, in which small proportions of GAb (3%) were enough to significantly improve tensile strength. Remarkably, the most unexpected result came from the surface addition of alkaline GAb by spray coating, as the tensile index was increased from 7 to 18N m g – 1 . Overall, even though it was not possible to improve and enhance simultaneously all properties, the use of pre-blended GAb in papermaking revealed significant potential when it comes to increasing strength, a key property in different tissue products, such as multipurpose and kitchen rolls, or even in handtowels.
Technical Abstracts
Page 6 of 9
Made with FlippingBook - Online magazine maker