Study of the mechanical behavior of recycled fibers. Applications to papers and paperboards.

Mapping Intimacies ◽

10.31237/osf.io/46w8m ◽

2018 ◽

Author(s):

Imtiaz Ali

Keyword(s):

Surface Friction ◽

Strength Properties ◽

Size Exclusion ◽

Ultrastructural Changes ◽

X Rays ◽

Paper Strength ◽

Electron Microscopic ◽

Paper Properties ◽

Recycled Pulp ◽

Fibre Width

Incorporation of recycled fibres in high value paper products can reduce cost and environmental loads. Papermaking potential of cellulosic fibres decreases with recycling. The phenomenon of fibre hornification during pressing and drying is normally held responsible for the loss in strength. To study the impacts of recycling on pulp, fibre and paper properties some non conventional characterisation techniques like fibre saturation point, X-rays microtomography, environmental scanning electron microscopic observations, atomic forcemicroscope (PeakForce QNM mode) and inverse size exclusion chromatography(ISEC) were used. In order to achieve good reproducibility of ISEC measurements,a semi-automatic column fabrication pilot system was built. The techniques were first validated on refining process before being applied to the recycling process. In this study, it was found that fibre hornification alone cannot fully explain loss in strength during recycling. The loss in strength is much more complex and it is required to understand the morphological and ultrastructural changes associated with recycling. Fibre width, cell wall thickness,curl, kink, irregularities decreased during recycling. Fibre became hard and brittle in dry state. Number of weak points in the fibre wall were increased initially and in the later recyclings. The increase in wet breaking length indicates increased surface friction and capillary forces with recycling. Decrease in bonded area during first recycle may be caused by the loss of fines and fibre flexibility whereas the increase afterwards may be linked to the lumen collapse.The strength of fibres did not decrease with recycling as shown by zero-span breaking lengths therefore the quality of bond may be deteriorated. It was thought that the partially delaminated P/S1 layers may be responsible for the loss of paper strength. It is suggested since the significant change is associated with the pressing and drying of never dried pulp therefore the drying process needs to be revisited. The delaminated layer should be restored so as to increase the recyclability of the recovered fibres for high value paper. Influence of recycled pulp blends on physical properties of paper was also studied. It was revealed that small quantity of recycled pulp can be used without significantly affecting the mechanical strength properties.

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Improvement of paper properties of recycled unbleached softwood kraft pulps by poly(allylamine hydrochloride)

BioResources ◽

10.15376/biores.6.1.570-583 ◽

2011 ◽

Vol 6 (1) ◽

pp. 570-583

Author(s):

Paulina Mocchiutti ◽

María V. Galván ◽

María C. Inalbon ◽

Miguel A. Zanuttini

Keyword(s):

Kraft Pulps ◽

Paper Strength ◽

Acid Media ◽

Paper Properties ◽

Cellulosic Fibers ◽

Recycled Pulp ◽

Bonding Area ◽

Neutral Media ◽

Allylamine Hydrochloride ◽

Page Equation

Polyelectrolytes containing amine functional groups such as PAH (poly(allylamine hydrochloride)) can be useful, under certain conditions, for improving paper strength. In this work, the charge density of PAH was determined at different pH and ionic strengths; PAH adsorption onto the cellulosic fibers was characterized, and the effects of low PAH dosage on the papermaking properties were evaluated. It was found that the ionization of PAH is complete in acid media, but it is partial and depends on the ionic strength in neutral media. The adsorption isotherms of PAH on a recycled pulp from kraft liner allowed us to determine the amount needed to saturate the adsorption capacity of the fibers. For the three ionic strengths analyzed, the swelling of the fibers decreased when PAH was added in an amount corresponding to saturation (0.23% PAH on dried pulp). Nevertheless, the swelling was recovered when the amount of PAH was the double the saturation level (0.46% PAH on dried pulp). At these levels of addition, the papermaking properties were clearly improved, especially compressive strengths SCT (short compressive test) and CMT (concora medium test). The Page equation of tensile strength showed that PAH improved the shear bond strength, while the relative bonding area slightly decreased.

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Composite filler by pre-flocculation of fiber fines and PCC and its effect on paper properties

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2019-0061 ◽

2020 ◽

Vol 35 (2) ◽

pp. 251-260

Author(s):

Hyun Kang ◽

Jong Myoung Won ◽

Byoung-Uk Cho

Keyword(s):

Strength Properties ◽

Ash Content ◽

Paper Strength ◽

Precipitated Calcium Carbonate ◽

Paper Properties ◽

Loading Method ◽

Retention Aids ◽

Composite Filler ◽

Filler Retention ◽

Better Than

AbstractA composite filler was developed by pre-flocculation of fiber fines and precipitated calcium carbonate (PCC) particles with flocculants such as cationic polyacrylamide (cPAM) and bentonite. The composite filler was compared with a conventional loading method in terms of physical properties of handsheet and filler retention. The handsheets using the composite filler showed higher strength properties than that using a conventional loading at a similar paper ash content level, implying that paper ash content can be increased maintaining same level of paper strength. Optical properties such as opacity and brightness of the paper with the composite were quite similar with the paper with the conventional loading. Filler retention of the composite filler was slightly higher than that of the conventional loading even though retention aids were not used for the composite filler. Paper formation of the composite filler was better than the case of the conventional loading. However, the sheet with the composite filler showed lower bulk than that with the conventional loading. Conclusively, the composite filler technology by pre-flocculation of fines and filler has a potential to be utilized to produce a high loaded paper.

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Effects of Recycled Fiber Fines on Hand Sheet Properties of Different Unbeaten and Beaten Pulps

Drvna industrija ◽

10.5552/drvind.2020.1904 ◽

2020 ◽

Vol 71 (4) ◽

pp. 327-337

Author(s):

Sezgin Koray Gülsoy ◽

Saffet Uysal

Keyword(s):

Kraft Pulp ◽

Strength Properties ◽

Populus Tremula ◽

The Other ◽

Paper Strength ◽

Pinus Brutia ◽

Recycled Pulp ◽

European Aspen ◽

Calabrian Pine ◽

Recycled Fiber

In this study, 5, 10, and 15 % secondary fines of recycled pulp were added to unbeaten and beaten (28 ºSR) samples of recycled pulp, Turkish Calabrian pine (Pinus brutia Ten.) kraft pulp, and European aspen (Populus tremula L.) kraft pulp. The effects of the addition of fiber fines on hand sheets properties were evaluated. The addition of fiber fines to the unbeaten pulps improved the strength properties of hand sheets. The roughness of hand sheets was also decreased with the addition of fines. When fiber fines were added to the beaten pulps, the type of pulp strongly affected the paper strength properties. The strength properties of beaten pulps of Turkish Calabrian pine and European aspen were decreased with the addition of fiber fines, while the strength properties of beaten pulps of recycled pulp were increased. On the other hand, the air permeance of unbeaten and beaten samples was decreased with the addition of fiber fines. Consequently, the addition of fines to unbeaten and beaten pulps had a more pronounced effect on European aspen kraft pulp and recycled pulp than on Turkish Calabrian pine kraft pulp. Also, the strength of paper made of unbeaten recycled pulp with the addition of 15 % fines was higher than that of fines-free beaten recycled pulp.

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The Use of Oil Palm Empty Fruit Bunches (OPEFB) Fibers as Partial Replacement for Imported Recycled Fibers

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.737.335 ◽

2017 ◽

Vol 737 ◽

pp. 335-340 ◽

Cited By ~ 1

Author(s):

A.B. Khairul Hafizuddin ◽

Roslan Rohaizu ◽

W.D. Wan Rosli

Keyword(s):

Oil Palm ◽

Paper Industry ◽

Strength Properties ◽

Partial Replacement ◽

Paper Strength ◽

Empty Fruit Bunches ◽

Recycled Pulp ◽

Recycled Fibers ◽

The Cost

Papermaking in Malaysia is basically based on recycled (secondary) fibers which are sourced from various parts of the world with prices depending on the quality of the fibers procured. The costs of paper production could possibly be reduced by using local fibers as partial replacement provided that the strength requirements are not compromised; and one such type is the oil palm fibers which are obtained as the by-product of the palm oil industry. This paper reports the use of the oil palm empty fruit bunch (OPEFB) fiber as a partial substitute in the production of corrugating medium. Both unbleached and totally chlorine free (TCF) bleached OPEFB pulps were mixed in different ratios with high quality recycled pulps which had been mechanically and chemically treated. Burst strength results indicate as high as 70% recycled pulp can be replaced by OPEFB pulps yet still having strength properties that are comparable with the industrial produced corrugating medium. Although the effect of bleached pulp is significant at high addition levels of more than 70%, the cost-energy balance will not be effective to use these bleached fibers, and furthermore the utilization of unbleached pulps also gave the same desired results. The use of the underutilized OPEFB fibers for replacement of imported recycled fibers without compromising the paper strength qualities could help the Malaysian paper industry in their quest for finding fiber alternatives.

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Filler modified by a sequential encapsulation and preflocculation method and its effect on paper properties

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2019-0047 ◽

2020 ◽

Vol 35 (1) ◽

pp. 89-95

Author(s):

Nannan Chen ◽

Lijun Wang ◽

Junchao Wen ◽

Xianping Yao ◽

Wenyan Zhao

Keyword(s):

Filler Content ◽

Strength Properties ◽

Paper Strength ◽

Cationic Starch ◽

Paper Properties ◽

Polyelectrolyte Complexes ◽

New Methods ◽

Charge Potential ◽

Filler Retention ◽

Anionic Polyacrylamide

AbstractIncreasing the filler content of sheet tends to decrease filler retention and paper strength properties. To overcome this problem and make better use of fillers, development of new methods on filler modification has never been stopped. In this study, filler modification was carried out by sequentially adding an anionic polyacrylamide, a cationic starch and a cationic polyacrylamide. It is believed that in this process, multiple polyelectrolyte complexes are formed which can not only encapsulate filler particles but also preflocculate the particles. The results showed that, compared to the single preflocculation treatment, the sequential encapsulation and preflocculation (SEP) treatment brought significantly larger particle size and higher surface charge potential of the filler, thus higher filler retention was achieved. When the modified fillers were used for papermaking and paper ash contents were controlled at the same level, the SEP modification was better in improving the tensile index, internal bond strength and tearing index of paper than the single preflocculation method, in addition, it maintained better paper formation, caused insignificant change on opacity of paper. It is believed that this newly developed SEP method is worthy of being applied to industrial scales in making various grades of filled paper.

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Fractionation of epidermal cells from wheat straw pulp by flotation

TAPPI Journal ◽

10.32964/tj14.4.229 ◽

2015 ◽

Vol 14 (4) ◽

pp. 229-235

Author(s):

MIKKO KARJALAINEN ◽

ARI ÄMMÄLÄ ◽

PÄIVI ROUSU ◽

JOUKO NIINIMÄKI

Keyword(s):

Wheat Straw ◽

Cell Types ◽

Strength Properties ◽

Epidermal Cells ◽

Raw Material ◽

Paper Strength ◽

Paper Properties ◽

Vessel Elements ◽

Wide Availability ◽

Wheat Straw Pulp

The wide availability of wheat straw makes it a promising raw material for various fiber products, but its heterogeneity makes it a challenging material to use. In addition to reducing paper properties, some cell types cause processing problems such as silicate deposition and poor dewatering. The aims of this work were to examine the fractionation tendency of wheat straw pulp cells in flotation and to determine the effect of fractionation on paper strength properties. A cell type categorization based on automatic optical fiber analysis was used to assess fractionation. The results showed that epidermal cells can be selectively enriched from unbleached wheat straw pulp by flotation and other short cells had a tendency to become enriched in the overflow fraction. The underflow fraction consisted mostly of fibrous material, as well as vessel elements and long parenchyma cells. Removal of the epidermal cells from pulp will reduce its silicate content and improve the strength properties of the paper.

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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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Morphologic alteration in the muscles of patients with hypokalemic periodic paralysis or myopathy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158650 ◽

1990 ◽

Vol 48 (3) ◽

pp. 222-223

Author(s):

T. Shimizu ◽

Y. Muranaka ◽

I. Ohta ◽

N. Honda

Keyword(s):

Clinical Manifestations ◽

Quadriceps Muscle ◽

Honeycomb Structure ◽

Periodic Paralysis ◽

Ultrastructural Changes ◽

Hypokalemic Periodic Paralysis ◽

Electron Microscopic ◽

Tubular Aggregates ◽

Hypokalemic Myopathy ◽

Transmission Electron

There have been many reports on ultrastructural alterations in muscles of hypokalemic periodic paralysis (hpp) and hypokalemic myopathy(hm). It is stressed in those reports that tubular structures such as tubular aggregates are usually to be found in hpp as a characteristic feature, but not in hm. We analyzed the histological differences between hpp and hm, comparing their clinical manifestations and morphologic changes in muscles. Materials analyzed were biopsied muscles from 18 patients which showed muscular symptoms due to hypokalemia. The muscle specimens were obtained by means of biopsy from quadriceps muscle and fixed with 2% glutaraldehyde (pH 7.4) and analyzed by ordinary method and modified Golgimethod. The ultrathin section were examined in JEOL 200CX transmission electron microscopy.Electron microscopic examinations disclosed dilated t-system and terminal cistern of sarcoplasmic reticulum (SR)(Fig 1), and an unique structure like “sixad” was occasionally observed in some specimens (Fig 2). Tubular aggregates (Fig 3) and honeycomb structure (Fig 4) were also common characteristic structures in all cases. These ultrastructural changes were common in both the hypokalemic periodic paralysis and the hypokalemic myopathy, regardless of the time of biopsy or the duration of hypokalemia suffered.

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