Using cationic polyvinyl alcohol (C-PVA) to improve the strength of wood-free papers containing high-yield pulp (HYP)

AbstractHigh-yield pulp (HYP) is gaining increasing interest in wood-free papers, because it can improve the bulk, formation, and opacity of papers. However, one of the challenges for the papermakers is the strength of papers when a large amount of HYP is replaced with hardwood kraft pulp. In this work, we explored the potential of using cationic-modified polyvinyl alcohol (C-PVA) in increasing the strength properties of HYP. Also, C-PVA was applied to the paper-sheets made of softwood/hardwood bleached kraft pulps (SBKP/HBKP) and HYP under various conditions, and the corresponding paper properties were evaluated. It was observed that C-PVA increased the strength properties of these paper-sheets, and the results obtained from using C-PVA were only slightly less effective than those obtained from using cationic starch (C-starch). Furthermore, the addition of C-PVA to HYP, and subsequently mixing with the blend of SBKP/HBKP (option no. 1) improved the tensile and burst indices, light scattering coefficient and apparent density of paper-sheets more significantly than did the addition of C-PVA directly to the mixed furnish of SBKP/HBKP/HYP (option no. 2). Additionally, atomic force microscope (AFM) analysis showed that the attraction force, developed between the AFM-tip and the fiber surface, was changed by the C-PVA modification. The tensile and burst indices of paper-sheets were improved by adding 10 mg g-1C-PVA and substituting 30% of HYP for HBKP, whereas the tear index, apparent density, PPS-roughness, and brightness decreased.

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Influence of cellulose supramolecular structure on strength properties of chemical pulp

Holzforschung ◽

10.1515/hf-2013-0226 ◽

2014 ◽

Vol 68 (8) ◽

pp. 861-866 ◽

Cited By ~ 3

Author(s):

Per Tomas Larsson ◽

Lennart Salmén

Keyword(s):

Supramolecular Structure ◽

Strength Properties ◽

Cellulose Microfibrils ◽

Kraft Pulps ◽

Chemical Pulp ◽

Chemical Pulps ◽

Fiber Wall ◽

Tear Index ◽

Pulp Strength ◽

Selective Increase

Abstract The industrially produced chemical pulps have lower strength properties than those obtained under laboratory conditions, and this difference is referred to as the strength delivery (SD) problem. In this study, the hypothesis was put forward that the SD could, at least in part, be accounted for by the supramolecular structure of the cellulose microfibrils of the fiber wall. To test the hypothesis, two bleached softwood kraft pulps (BSKP) were manufactured from the same starting material with different degrees of cellulose aggregation, but the pulps were otherwise as similar as possible in other controllable respects. The chemical and physical properties, including the pulp strength, were tested. A selective increase of the degree of cellulose microfibril aggregation resulted in a pulp with a decreased tear index (TI) at a specified tensile index, and this decrease was similar in magnitude to what is typically encountered in SD. Accordingly, the current experimental study succeeded in mimicking the SD problem. The lateral fibril aggregate dimensions (LFAD) seem to play a pivotal role and it can be safely concluded in general that the supramolecular structure of cellulose in the fibers may be an important factor contributing to the SD problem.

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Influences of Bleached Softwood Pulp Pretreated with Endo-Cellulase on Fiber Surface Properties and Aggregation Structure

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.391-392.692 ◽

2011 ◽

Vol 391-392 ◽

pp. 692-696

Author(s):

Min Du ◽

Xin Ping Li ◽

Wu Guang Li

Keyword(s):

Energy Consumption ◽

Fiber Surface ◽

Paper Sheet ◽

Paper Properties ◽

Enzymatic Pretreatment ◽

Wetting Properties ◽

Tear Index ◽

Softwood Pulp ◽

Aggregation Structure ◽

Refining Performance

The influences of endo-cellulase pretreatment of bleached softwood pulp before refining was investigated in this paper. Refining energy consumption, paper properties, wetting properties, electric charge and aggregation structure of fiber were investigated. The results showed that pretreated with endo-cellulase at the dosage of 0.4ECG/g before refining could increase the refining degree by 53.09%, and it would reduce refining energy consumption significantly. At this dosage, the tensile index of the paper sheet increased while the tear index of paper sheet decreased slightly. Additionally, enzymatic pretreatment could raise fiber surface wettability, lower the absolute value of Zeta potential and decrease the crystallinity of fiber, which was help to improve refining performance.

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Effects of Mixing Ratio of Heavily Beaten Pinus merkusii Pulp on Physical Properties of Kraft Acacia nilotica Pulp Sheets

Wood Research Journal ◽

10.51850/wrj.2019.10.2.53-60 ◽

2020 ◽

Vol 10 (2) ◽

pp. 53-60

Author(s):

Ganis Lukmandaru ◽

Fajar Setiaji ◽

M. Rena Siagian

Keyword(s):

Physical Properties ◽

Strength Properties ◽

Microscopic Investigation ◽

Acacia Nilotica ◽

Kraft Pulps ◽

Clear Trend ◽

Mixing Ratios ◽

Essential Step ◽

Tear Index ◽

Pinus Merkusii

Paper industries commonly produce pulp sourced from a mixture of pulps, rather than from a single pulp, to obtain desired properties. In addition, the beating process is an essential step with respect to physical properties of pulp. Kraft pine (Pinus merkusii/PM) pulps were beaten to different degrees, i.e 200~300 CSF (heavy-beating) and 300~400 CSF (moderatebeating), paper sheets then were formed from each beaten sample. It was found that the strength properties of prepared paper sheets decreased the longer they were beaten, particularly as seen by the tear index and fold number. By microscopic investigation, it was found that cut or shortened fibers occurred very frequently in the pine pulps. Furthermore, the effects of heavily beaten pine pulp additions on handsheet properties of kraft pulps of Acacia nilotica (AN) were investigated. Four different mixing ratios by weight of AN/PM from 100:0, 90:10, 80:20, and 70:30 during beating, as well as four different kappa numbers of AN pulps (32.5, 34.0, 34.2, and 35.9) were applied. In general, the decrease in strength properties (3~25%) that occurred with increasing pine pulp ratio was more evident between pulp without pine and a 30% ratio of pine pulps. Fold number was reduced considerably (2.8~24.7%) by the blend composition but less pronounced in tear index (3.0~8.9%) from the initial values. However, the 10% or 20% ratio of PM pulps could increase opacity, brightness, and strength properties in some cases. No clear trend was found with increasing kappa number.

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Treatment of NBKP with Cellulase to Reduce the Refining Energy Consumption in Production of Grease Proof Paper

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.236-238.1379 ◽

2011 ◽

Vol 236-238 ◽

pp. 1379-1384

Author(s):

Jun Liu ◽

Hui Ren Hu

Keyword(s):

Energy Consumption ◽

Energy Requirement ◽

Fiber Surface ◽

Orthogonal Test ◽

Manufacturing Cost ◽

Fiber Morphology ◽

Paper Properties ◽

Binding Domains ◽

Tear Index ◽

Cellulose Binding

Refining is an energy-intensive papermaking process where energy consumption contributes about 18% of the total manufacturing cost. Through the application of cellulases before refining, mills can reduce their energy requirement for refining of pulps and realize the aim of energy consumption. In the present study, two kinds of cellulase within or wothout the cellulose binding domains (CBDs) were used to treat the pulp aimed at reducing the refining energy consumption in production of grease proof paper. In order to compare and evaluate these effects on reducing the pulp refining energy consumption, these two cellulases were compared based on their effects on Schopper-Riegler freeness (°SR), fiber morphology and paper properties ( tensile index, tear index). Orthogonal test was used to examine the interaction of enzyme dosages and contact time on the beatability of the pulp. Results showed that the cellulase of Refinase M (within the CBDs) was excellent in reducing the refining energy consumption, when pretreated with 0.02% of Refinase M about 18.5% of the refining energy can be saved, and the properties of paper were not affected obviously. Moreover, results showed that the existence of CBDs in cellulases play a significant role in reducing the energy consumption. Examination of the fiber surface by SEM show notable improvement in fibrillation.

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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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Improving paper wet strength via increased lignin content and hot-pressing temperature

TAPPI Journal ◽

10.32964/tj19.10.487 ◽

2020 ◽

Vol 19 (10) ◽

pp. 487-497

Author(s):

TOVE JOELSSON ◽

GUNILLA PETTERSSON ◽

SVEN NORGREN ◽

ANNA SVEDBERG ◽

HANS HOGLUND ◽

...

Keyword(s):

Hot Pressing ◽

Lignin Content ◽

Pilot Scale ◽

Strength Properties ◽

High Yield ◽

Kraft Pulps ◽

Pressing Temperature ◽

Wet Strength ◽

Tensile Index ◽

Reference Samples

It is known that the strength properties of wood-based paper materials can be enhanced via hot-pressing techniques. Today, there is a desire not only for a change from fossil-based packaging materials to new sustainable bio-based materials, but also for more effective and eco-friendly solutions for improving the dry and wet strength of paper and board. Against this background, hot pressing of paper made from high yield pulp (HYP), rich in lignin, becomes highly interesting. This study investigated the influence of pressing temperature and native lignin content on the properties of paper produced by means of hot pressing. Kraft pulps of varied lignin content (kappa numbers: 25, 50, 80) were produced at pilot scale from the same batch by varying the cooking time. We then studied the effect of lignin content by evaluating the physical properties of Rapid Köthen sheets after hot pressing in the temperature range of 20°C–200°C with a constant nip pressure of 7 MPa. The pilot-scale cooked pulps were compared with reference samples of mill-produced northern bleached soft-wood kraft (NBSK) pulp and mill-produced chemithermomechanical pulp (CTMP). Generally, the results demonstrated that lignin content had a significant effect on both dry and wet tensile index. All of the pilot cooked pulps with increased lignin content had a higher tensile index than the reference NBSK pulp. To obtain high tensile index, both dry and wet, the pressing temperature should be set high, preferably at least 200°C; that is, well above the glass transition temperature (Tg) for lignin. Moreover, the lignin content should preferably also be high. All kraft pulps investigated in this study showed a linear relationship between wet strength and lignin content.

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Recycling of Waste MDF by Steam Refining: Evaluation of Fiber and Paper Strength Properties

Waste and Biomass Valorization ◽

10.1007/s12649-021-01391-4 ◽

2021 ◽

Author(s):

Sebastian Hagel ◽

Jesan Joy ◽

Gianluca Cicala ◽

Bodo Saake

Keyword(s):

Strength Properties ◽

Steam Treatment ◽

High Yield ◽

Medium Density ◽

Paper Strength ◽

Fiber Morphology ◽

Steam Refining ◽

Paper Test ◽

Paper Properties ◽

Intimate Knowledge

AbstractCurrently, most of the collected waste medium-density fiberboards (MDF) is incinerated or landfilled, as economically viable recycling methods are yet to be developed. By steam refining waste medium-density fiberboards (MDF), it is possible to hydrolyze the incorporated resins and isolate a high yield fiber fraction. Further refining of the steam treated fibers might enable the fibers to be utilized in applications such as paper packaging, facilitating a cascading use of the waste material stream. To this end, intimate knowledge of the material is needed. In this study, the steam refined fibers of two waste MDF samples containing differing amounts of softwood and hardwood underwent refining and beating. The resulting fibers were characterized regarding their morphology and paper test sheets were produced to evaluate their strength (compression-, tensile- and tear-strength). Distinct differences in response to refining between the MDF samples were apparent. For the sample with the higher hardwood share an increase in strength properties with increasing steam treatment severities could be observed and it was possible to produce test sheets with comparable compression strength to recycled pulp for industrial corrugated paperboard. For the sample with a higher share of softwood, the steam treatment severity did not show any influence on fiber morphology or paper properties, and the resulting paper strength was low in comparison to the other steam refined waste MDF sample. Graphic Abstract

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SEM Study of Tension Wood Fiber Morphology and its Effect on Paper Properties

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079061 ◽

1977 ◽

Vol 35 ◽

pp. 308-309

Author(s):

K. W. Robinson

Keyword(s):

Tension Wood ◽

Wood Fiber ◽

Strength Properties ◽

Fiber Morphology ◽

Paper Properties ◽

Pure Cellulose ◽

Short Rotation ◽

Hardwood Trees ◽

Sem Study

Tension wood (TW) is an abnormal tissue of hardwood trees; although it has been isolated from most parts of the tree, it is frequently found on the upper side of branches and leaning stems. TW has been classically associated with geotropic alignment, but more recently it has been associated with fast growth. Paper made from TW is generally lower in strength properties. Consequently, the paper industries' growing dependence on fast growing, short- rotation trees will result in higher amounts of TW in the final product and a corresponding reduction in strength.Relatively few studies have dealt with the role of TW in the structure of paper. It was suggested that the lower strength properties of TW were due to a combination of factors, namely, its unique morphology, compression failures in the cell wall, and lower hemicellulose content. Central to the unique morphology of the TW fiber is the thick gelatinous layer (G-layer) composed almost entirely of pure cellulose.

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Does kraft hardwood and softwood pulp viscosity correlate to paper properties?

TAPPI Journal ◽

10.32964/tj15.10.643 ◽

2016 ◽

Vol 15 (10) ◽

pp. 643-651 ◽

Cited By ~ 1

Author(s):

ROBERT J. OGLESBY ◽

HUMPHREY J. MOYNIHAN ◽

RICARDO B. SANTOS ◽

ASHOK GHOSH ◽

PETER W. HART

Keyword(s):

Physical Properties ◽

Strength Loss ◽

Strength Properties ◽

Clear Correlation ◽

Paper Properties ◽

Physical Strength ◽

Pulp Viscosity ◽

Softwood Pulp ◽

The Impact ◽

Multiple recycling of paperboard: Paperboard characteristics and maximum number of recycling cycles— Part I: Multiple recycling of corrugated base paper

TAPPI Journal ◽

10.32964/tj18.11.631 ◽

2019 ◽

Vol 18 (11) ◽

pp. 631-638

Author(s):

FREDERIC KREPLIN ◽

HANS-JOACHIM PUTZ ◽

SAMUEL SCHABEL

Keyword(s):

Compression Test ◽

Production Capacity ◽

Strength Properties ◽

Paper Properties ◽

Corrugated Board ◽

Laboratory Conditions ◽

Base Paper ◽

Study Results ◽

Short Span ◽

Multiple Recycling

Paper for recycling is an important fiber source for the production of corrugated base paper. The change in production capacity toward more and more packaging papers affects the composition of paper for recycling and influences the paper quality. This research project investigated the influence of the multiple recycling of five different corrugated base papers (kraftliner, neutral sulfite semichemical [NSSC] fluting, corrugating medium, testliner 2, and testliner 3) on suspension and strength properties under laboratory conditions. The corrugated board base papers were repulped in a low consistency pulper and processed into Rapid-Köthen laboratory sheets. The sheets were then recycled up to 15 times in the same process. In each cycle, the suspension and the paper properties were recorded. In particular, the focus was on corrugated board-specific parameters, such as short-span compression test, ring crush test, corrugating medium test, and burst. The study results indicate how multiple recycling under laboratory conditions affects fiber and paper properties.

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