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

BioResources ◽  
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.

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

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.

Complex formation of modified chitosan and carboxymethyl cellulose and its effect on paper properties

TAPPI Journal ◽  
2009 ◽  
Vol 8 (6) ◽  
pp. 29-35 ◽  
Author(s):  
PEDRAM FATEHI ◽  
LIYING QIAN ◽  
RATTANA KITITERAKUN ◽  
THIRASAK RIRKSOMBOON ◽  
HUINING XIAO
Keyword(s):  
Carboxymethyl Cellulose ◽  
Polymer System ◽  
Layer By Layer ◽  
Paper Strength ◽  
Anionic Polymer ◽  
Paper Properties ◽  
Modified Chitosan ◽  
Layer By Layer Assembly ◽  
Polyelectrolyte Titration ◽  
Layer Assembly

The application of an oppositely charged dual polymer system is a promising approach to enhance paper strength. In this work, modified chitosan (MCN), a cationic polymer, and carboxymethyl cellulose (CMC), an anionic polymer, were used sequentially to improve paper strength. The adsorption of MCN on cellulose fibers was analyzed via polyelectrolyte titration. The formation of MCN/CMC complex in water and the deposition of this complex on silicon wafers were investigated by means of atomic force microscope and quasi-elastic light scattering techniques. The results showed that paper strength was enhanced slightly with a layer-by-layer assembly of the polymers. However, if the washing stage, which was required for layer-by-layer assembly, was eliminated, the MCN/CMC complex was deposited on fibers more efficiently, and the paper strength was improved more significantly. The significant improvement was attributed to the extra development of fiber bonding, confirmed further by scanning electron microscope observation of the bonding area of fibers treated with or without washing. However, the brightness of papers was somewhat decreased by the deposition of the complex on fibers. Higher paper strength also was achieved using rapid drying rather than air drying.

scholarly journals DUAL-POLYELECTROLYTE ADSORPTION OF POLY(ALLYLAMINE HYDROCHLORIDE) AND XYLAN ONTO RECYCLED UNBLEACHED KRAFT PULPS

BioResources ◽  
2012 ◽  
Vol 7 (2) ◽  
Author(s):  
María Verónica Galván ◽  
Paulina Mocchiutti ◽  
Laura María Cornaglia ◽  
Miguel Ángel Zanuttini
Keyword(s):  
Kraft Pulps ◽  
Polyelectrolyte Adsorption ◽  
Allylamine Hydrochloride

Role of particle size and preflocculation of talc in improvement of paper properties

TAPPI Journal ◽  
2014 ◽  
Vol 13 (4) ◽  
pp. 17-26 ◽  
Author(s):  
VIPUL SINGH CHAUHAN ◽  
NISHI KANT BHARDWAJ
Keyword(s):  
Particle Size ◽  
Strength Loss ◽  
Filler Loading ◽  
Paper Strength ◽  
Paper Properties ◽  
Viable Solution ◽  
Filler Retention ◽  
Mineral Fillers ◽  
Different Doses

Mineral fillers are added during papermaking to improve the optical and printing properties of paper and decrease energy costs. Filler loading using conventional approaches has some disadvantages, such as reduction in paper strength. The finer filler, the more the strength loss. Several methods and materials have been reported to overcome or alleviate the same, but with higher costs. Our approach provides an economically viable solution to the problem, using conventional papermaking materials. Talc filler of different particle sizes, preflocculated using different doses of cooked amphoteric starch, were used for papermaking. Relatively higher filler retention, paper strength, and hydrophobicity of paper were obtained with preflocculated talc compared to native talc. The optical properties of paper were unchanged on the loading of similar talc after preflocculation. The preflocculated talc of finer particle size provided higher opacity at similar ash, as well as paper strength, than the native talc of coarser size.

scholarly journals EFFECT OF CHITOSAN ADDITION DURING PAPER-MAKING ON AGEING STABILITY OF DOCUMENT PAPER

2021 ◽  
Vol 55 (9-10) ◽  
pp. 1083-1094
Author(s):  
DIMITRINA TODOROVA ◽  
◽  
VESKA LASHEVA ◽  
Keyword(s):  
Chitosan Solution ◽  
Thermal Ageing ◽  
Paper Strength ◽  
Aluminium Sulphate ◽  
Paper Properties ◽  
Hygroscopic Properties ◽  
Complex Evaluation ◽  
Softwood Pulp ◽  
Negative Effect ◽  
Hardwood Pulp

The aim of the present work has been to study the influence of chitosan addition into the composition of paper intended for documents on its ageing stability, with a view of enhancing the resistance of paper strength and optical properties over time. The chitosan solution was added during the formation of the paper sheets in various amounts: 0.2%, 1% and 2% o.d.f. Paper samples of different fibrous compositions were prepared from bleached sulphate softwood pulp (BSWP) and bleached sulphate hardwood pulp (BHWP) in the following ratios: 50% BSWP:50% BHWP, 80% BSWP:20% BHWP, 100% BSWP and 100% BHWP. Then, paper samples were subjected to accelerated thermal ageing for 24 hours at 105 °C. It was found that the use of chitosan as additive in the composition of bleached cellulose paper samples led to improved strength and hygroscopic properties. The study showed that chitosan could be used in the production of kraft document papers comprising aluminium sulphate, as the presence of aluminium sulphate had no negative effect on the action of the biopolymer. Regarding the complex evaluation of the properties of the obtained papers, it could be summarized that, for the studied fibrous compositions, the optimum amount of the additive was 1% chitosan for a fibrous composition of 50% bleached softwood pulp and 50% bleached hardwood cellulose. Therefore, preparing document paper with the addition of chitosan is a convenient procedure to enhance a number of paper properties, even after the ageing process.

The influence of screening process parameters on paper properties produced from wastepaper

2020 ◽  
Vol 110 ◽  
pp. 16-24
Author(s):  
Anhelina Nikalaichyk ◽  
Edyta Małachowska
Keyword(s):  
Surface Properties ◽  
Process Parameters ◽  
Raw Material ◽  
Paper Strength ◽  
Recycled Paper ◽  
Cellulose Fibres ◽  
Screening Process ◽  
Paper Properties ◽  
Paper Surface ◽  
The Impact

The influence of screening process parameters on paper properties produced from wastepaper. Wastepaper processing is of pivotal importance for environmental protection; it is also crucial for the economy and the management of raw materials. Not only does recycling save space at landfills, it also saves an extremely valuable raw material used for paper production, i.e. wood. Unlike primary pulps, however, wastepaper contains much more than just cellulose fibres and fillers. The fact that recycled paper contains many contaminants, such as metal staples, paper clips, plastic film, glass fragments, and others, makes it necessary to develop a much more complex pulp preparation systems compared to the ones used for primary pulps. Contaminants affect not only the usable quality of paper made of wastepaper, but also cause the wear and tear of paper processing equipment. Thus, the purifying and screening of secondary pulps for further processing is very important. Considering the above, the authors’ objective was to study the impact of the width of screen slots on paper properties if produced from screened wastepaper pulp. Paper strength and paper surface properties were used as the main evaluation criteria. White and mixed wastepaper was used as research material. Based on the tests, the screen slot width was found not to have any significant impact on either paper mechanical strength or paper surface properties.

Absence of unwinding of double-helical DNA in the surface of mercury electrode charged to DNA reduction potentials at neutral pH

1979 ◽  
Vol 44 (2) ◽  
pp. 448-455 ◽  
Author(s):  
Emil Paleček ◽  
Sianette Kwee
Keyword(s):  
Conformational Changes ◽  
Electrode Surface ◽  
Mercury Electrode ◽  
Linear Sweep Voltammetry ◽  
Reduction Product ◽  
Potential Range ◽  
Acid Media ◽  
Reduction Potentials ◽  
Dropping Mercury Electrode ◽  
Neutral Media

The influence of adsorption of DNA on its double-stranded (ds) structure was studied with the aid of hanging mercury drop electrode (HMDE) in neutral media. Changes in DNA reducibility followed by linear sweep voltammetry served as an indication of the DNA conformational changes in the electrode surface. It has been shown that, due to contact of ds DNA with the electrode for periods many times longer than those which can be reached at the dropping mercury electrode, extensive surface denaturation of DNA can be detected only in a narrow potential range around -1.2 V. At potentials more negative than this region neither surface denaturation nor blocking of the electrode by the reduction product were observed. On the other hand, interaction of the denatured DNA with the mercury surface under the same conditions, resulted in blocking of the electrode surface by the reduction product. In agreement with the previous studies in acid media similar blocking of the surface was observed at pH 5 both with thermally denatured and ds DNAs. On the basis of the experimental data the following conclusions have been drawn: i) in neutral media the course of interfacial events of DNA is strongly dependent on DNA conformation and differs from the course suggested for acid media; ii) the deduction concerning the behavior of ds DNA on the electrode in neutral media made by other authors on the basis of their measurements in acid media is not justified.

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

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.

Paper dry strength improvement by xyloglucan addition: Wet-end application, spray coating and synergism with borate

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Lage Ahrenstedt ◽  
Antti Oksanen ◽  
Kristian Salminen ◽  
Harry Brumer
Keyword(s):  
Kraft Pulp ◽  
Spray Coating ◽  
Fibre Surface ◽  
Thermomechanical Pulp ◽  
Paper Strength ◽  
Paper Properties ◽  
Chemical Pulps ◽  
Spray Solution ◽  
Cross Links ◽  
Strength Improvement

Abstract The polysaccharide xyloglucan as a wet-end additive improves paper properties. In the present study, paper strength improvement was analysed for dry handsheets made from chemical, mechanical and recycled pulps coated with xyloglucan in a spray application. Results are compared with sheets made from the same pulps treated with xyloglucan in the wet-end. Kraft pulp handsheets of bleached hardwood and softwood showed significant improvements of tensile, tear and Z-strength by xyloglucan spray treatment versus wet-end application, whereas handsheets of de-inked and thermomechanical pulp were improved only slightly. In both wet-end and spray applications, the effect of xyloglucan addition was intimately related to the presence of non-cellulosic components on the fibre surface. Further strength improvements were obtained for chemical pulps by addition of borax to the spray solution, which were likely to be due to the formation of borate-mediated xyloglucan cross-links. Spray coating of xyloglucan, with or without borax, thus represents a potential new application of this polysaccharide to increase paper dry strength.

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