Reinforcing potential of wood pulp-derived microfibres in a PVA matrix

Abstract In this study, the reinforcing potential of cellulose “microfibres” obtained from bleached softwood kraft pulp was demonstrated in a matrix of polyvinyl alcohol (PVA). Microfibres are defined as fibres of cellulose of 0.1–1 μm in diameter, with a corresponding minimum length of 5–50 μm. Films cast with these microfibres in PVA showed a doubling of tensile strength and a 2.5-fold increase in stiffness with 5% microfibre loading. The theoretical stiffness of a microfibre was calculated as 69 GPa. The study also demonstrated that the strength of the composite was greater at 5% microfibre loading compared to 10% loading. Comparative studies with microcrystalline cellulose showed that the minimum aspect ratio of the reinforcing agent is more criticalthan its crystallinity in providing reinforcement in the composite.

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Effect of machine speed on formation and strength efficiency in twin-wire roll forming of never-dried unbleached softwood kraft pulp

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2018-3038 ◽

2018 ◽

Vol 33 (2) ◽

pp. 271-278

Author(s):

Bengt Nordström ◽

Lennart Hermansson

Keyword(s):

Tensile Strength ◽

Kraft Pulp ◽

Roll Forming ◽

Favorable Effect ◽

Paper Properties ◽

Difference Curve ◽

Insignificant Effect ◽

Wide Range ◽

Softwood Kraft Pulp ◽

Machine Speed

Abstract There is a constant drive to increase machine speed in the production of kraftliner and most other major paper grades, but the separate effect of the machine speed on the paper properties has been unclear. The effect of machine speed in twin-wire roll forming of never-dried unbleached softwood kraft pulp was evaluated here in a pilot machine investigation by examining three machine speed levels (500, 750, and 1000 m/min) over a series of jet-to-wire speed differences. Similar headbox consistency and draw from wire section to winding were employed at the different machine speed levels. An increase in the machine speed had a favorable effect on formation and Z-strength efficiency over a wide range of jet-to-wire speed differences, whereas the machine speed had an insignificant effect on tensile strength efficiency and tensile stiffness efficiency. For all properties, the overall shape of the jet-to-wire speed difference curve remained similar when changing the machine speed.

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Processing and Mechanical Properties of Starch and PVA Composite Reinforced by Nano-SiO2

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.557-559.201 ◽

2012 ◽

Vol 557-559 ◽

pp. 201-204 ◽

Cited By ~ 2

Author(s):

Wen Yong Liu ◽

Yi Chen ◽

Xi Tu ◽

Yue Jun Liu ◽

Xi Hai Hao

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Composite Materials ◽

Polyvinyl Alcohol ◽

Weight Ratio ◽

Weight Percent ◽

Nano Silica ◽

Glycerol Content ◽

Rheological Measurements ◽

Reinforcing Agent

The thermoplastic processing and mechanical properties of starch and polyvinyl alcohol (PVA) composites were studied. Glycerol was chosen as the plasticizer and nano-silica (nano-SiO2) as the reinforcing agent of the starch/PVA composites. The results showed that the mechanical properties of the obtained starch/PVA blend were best when the glycerol content was 30% of starch and 20% of PVA, and the weight ratio of PVA and starch was 0.8 (wPVA/ wstarch= 0.8/1). After the addition of nano-SiO2, the mechanical properties of the starch/PVA blends were improved. When the weight percent of nano-SiO2was 2%, the mechanical properties of the SiO2/starch/PVA composite were most excellent. It was shown that the tensile strength was increased by 16% and the elongation increased by 72%. Moreover, it was confirmed by rheological measurements that nano-SiO2could interact with the composite materials, which results in the improvement of the mechanical strength of the starch/PVA composites.

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Softwood kraft pulp fines: application and impact on specific refining energy and strength properties

Cellulose ◽

10.1007/s10570-020-03467-1 ◽

2020 ◽

Vol 27 (17) ◽

pp. 10359-10367

Author(s):

Daniel Mandlez ◽

Lukas Zangl-Jagiello ◽

Rene Eckhart ◽

Wolfgang Bauer

Keyword(s):

Tensile Strength ◽

Linear Relationship ◽

Apparent Density ◽

Kraft Pulp ◽

Strength Properties ◽

Air Permeability ◽

Research Interest ◽

Paper Properties ◽

Softwood Kraft Pulp ◽

Breaking Length

AbstractAlong with the emergence of micro and nanofibrillated celluloses and their application in papermaking, the influence of the so called fines fraction of pulps on both process and product properties has received increasing research interest in recent years. Several researchers have experimented with primary and/or secondary pulp fines to assess their effects on paper properties with not always consistent results. Our work focuses on the targeted application of the primary fines fraction of an unbleached softwood kraft pulp. The primary fines are separated from the pulp to be subsequently added to achieve blends of $$5\%, 9\%$$ 5 % , 9 % and $$12\%$$ 12 % primary fines content. These blends were then refined in a PFI mill to evaluate the effect of the primary fines on refining as well as on paper properties of hand sheets prepared from these pulps. It is shown that the addition of primary fines enhances tensile strength in the unrefined and slightly refined state, while the maximum tensile strength of the highly refined reference pulp is not increased. A slightly increased dewatering resistance (Schopper Riegler) at comparable air permeability (Gurley) for a given tensile strength was also observed. The linear relationship between tensile index and apparent sheet density seems to be affected in the unrefined and slightly refined state where the breaking length of the fines enriched samples is higher for a given apparent density.

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Densification by wet pressing versus refining of neverdried high-yield softwood kraft pulp – effects on compression strength, tensile stiffness, and tensile strength

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-2016-31-03-p422-431 ◽

2016 ◽

Vol 31 (3) ◽

pp. 422-431 ◽

Cited By ~ 2

Author(s):

Bengt Nordström

Keyword(s):

Tensile Strength ◽

Compression Strength ◽

Kraft Pulp ◽

High Yield ◽

Tensile Stiffness ◽

Wet Pressing ◽

Softwood Kraft Pulp

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Optimization of elemental chlorine-free bleaching for a softwood kraft pulp • part 2: economic analysis of chemical and steam consumption

TAPPI Journal ◽

10.32964/tj9.9.47 ◽

2010 ◽

Vol 9 (9) ◽

pp. 47-53 ◽

Cited By ~ 2

Author(s):

BRIAN N. BROGDON

Keyword(s):

Chlorine Dioxide ◽

Previous Investigation ◽

Kraft Pulp ◽

Energy Costs ◽

Alkaline Extraction ◽

Stage Versus ◽

Kraft Pulps ◽

Steam Consumption ◽

Elemental Chlorine ◽

Softwood Kraft Pulp

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U.S. Southern softwood kraft pulp. The economic advantages of ~0.35% to 0.65% H2O2 peroxide reinforcement in a 70°C (EOP)-stage versus 90°C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90°C (EO) is employed in D0(EO)D1 bleaching, whereas a 70°C (EOP) is economically advantageous for D0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.

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An effective method for determining the retention and distribution of cellulose nanofibrils in paper handsheets by dye labeling

TAPPI Journal ◽

10.32964/tj17.03.157 ◽

2018 ◽

Vol 17 (03) ◽

pp. 157-164 ◽

Cited By ~ 3

Author(s):

Shengdan Wang ◽

Wenhua Gao ◽

Kefu Chen ◽

Jinsong Zeng ◽

Jun Xu ◽

...

Keyword(s):

Correlation Coefficient ◽

Congo Red ◽

Kraft Pulp ◽

Cellulose Nanofibrils ◽

Standard Curve ◽

Congo Red Dye ◽

Mechanical Disintegration ◽

Softwood Kraft Pulp ◽

White Water ◽

Red Dye

Cellulose nanofibrils (CNF) were prepared by cellulase in conjunction with mechanical disintegration from the bleached softwood kraft pulp and labelled by Congo red dye. The labelled CNF were used to investigate the retention and distribution of CNF in paper handsheets. The retention of the labelled CNF was obtained by measuring the absorbance of white water using an ultraviolet-visible spectrophotometer. The results showed that this method for measuring the retention was rapid, feasible, and sensitive, owing to the high correlation coefficient R2 (0.9993) of the standard curve. The labelled CNF showed even distribution in paper handsheets. The colorimetric values of paper handsheets were explored with a residual ink analyzer.

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