bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging of Macromolecular Events Occurring During the Manufacture of Paper
Authors:   Institute of Paper Science and Technology at Georgia Institute of Technology, 500 10th Street NW, Atlanta, Georgia 30332–0620 USA, McNeal Michelyn R. , Nanko Hiroki ,   Institute of Paper Science and Technology at Georgia Institute of Technology, 500 10th Street NW, Atlanta, Georgia 30332–0620 USA, Hubbe Martin A. ,   North Carolina State University, Dept. of Wood & Paper Science, Box 8005, Raleigh, NC 29695–8005
Published: February 2024

A novel transmission electron microscopy (TEM) technique, developed to observe the nano-scale interactions of polymeric additives and cellulosic fibrils under idealized laboratory conditions, was applied for the first time in a comprehensive study of the colloidal interactions within a mill producing light-weight coated publication paper. The technique allows the observation of incremental changes in the nano-scale appearance of the paper-making slurry as successive additives are introduced to the system. Such changes include the coagulation of colloidal and dissolved substances present in thermomechanical (TMP) pulp after the addition of a low molecular weight, high charge density polymer, and the subsequent flocculation of the coagulated matter, hydrophobic materials, and fines following the introduction of talc, aluminum sulfate, a high mass cationic polyelectrolyte, and silica nanoparticles. The new results demonstrate that the TEM technique can be applied even in systems as complex as commercial papermaking, leading to a more accurate understanding of what happens on a macromolecular level.
Mechanisms of Flocculation of Microcrystalline Cellulose by Poly(ethylene oxide) and Cofactor Corilagin
Authors:   Department of chemistry, McGill University, 801 Sherbrooke St. W, Montreal, QC, Canada, H3A 2K6, Gaudreault Roger ,   Cascades inc., Recherche et Développement, 471 Marie-Victorin boul., Kingsey Falls, QC, Canada, J0A 1B0, Whitehead M. A. ,   Department of chemistry, McGill University, 801 Sherbrooke St. W, Montreal, QC, Canada, H3A 2K6, van de Ven Theo G.M. ,   Department of chemistry, McGill University, 801 Sherbrooke St. W, Montreal, QC, Canada, H3A 2K6;Pulp & Paper Research Centre, McGill University, 3420 University St., Montreal, QC, Canada, H3A 2A7
Published: February 2024

Poly(ethylene oxide) (PEO), a widely known flocculation agent used primarily as a fines retention aid in mechanical grade papers, has its efficiency enhanced by various compounds, known as cofactors. These cofactors form a complex with PEO, which acts as an efficient bridging agent for fines flocculation. The nature of the PEO/cofactor complex is mainly unknown, and it was originally believed that the association was driven by hydrogen bonding. Therefore it was decided to investigate the complex formation in more detail. As a model system we studied PEO and a model cofactor, corilagin, a precursor of tannic acid, a known cofactor for PEO. We performed both Semi-Empirical Molecular Orbital (PM3) gas phase calculations and Molecular Dynamics (MD) calculations in the presence of water. Both methods lead to the same surprising conclusion: no association between PEO and corilagin occurs at room temperature. The reason is that the gain of association enthalpy is not large enough to overcome the loss in entropy. No correlation was found between the association enthalpy and the number of hydrogen bonds between PEO and corilagin. The absence of PEO/corilagin complexation was confirmed by NMR, isothermal titration calorimetry and the inability of PEO/corilagin to flocculate MCC (microcrystalline cellulose). In the presence of low concentrations of salt, complexation and MCC flocculation was observed.
The Mechanism of Polyvinylamine Wet-strengthening
Authors:   Department of Chemical Engineering, McMaster University, Hamilton, Ontario, Canada, L8S 4L7, DiFlavio John-Louis , Bertoia Robert ,   Department of Chemical Engineering, McMaster University, Hamilton, Ontario, Canada, L8S 4L7, Pelton Robert ,   Department of Chemical Engineering, McMaster University, Hamilton, Ontario, Canada, L8S 4L7, Leduc Marc ,   BASF Aktiengesellschaft, 67056 Ludwigshafen, Germany
Published: February 2024

Regenerated cellulose films were laminated with polyvinylamine, PVAm, and the wet peel delamination forces were used to explore the mechanism by which PVAm increases the wet strength of paper. Conventional wet strength resins contain highly reactive chemical groups which can crosslink the resin and graft it to fibre surfaces. By contrast, it is not obvious how PVAm provides wet strength. The delamination experiments revealed that PVAm gives strong adhesion which was approximately independent of drying temperature (23 to 110°C), pH 3 to 9, PVAm molecular weight (34,000 to 1,500,000Da), and PVAm coverage (monolayer to 70mg/m2 ). By contrast the adhesion increased with the amine content of PVAm and with the degree of oxidation of the cellulose films. It is proposed that the PVAm adhesion is a combination of electrostatic and covalent bonding. The electrostatic bonding is between protonated amines, which are positively charged, and carboxyl groups on the cellulose. Whereas the covalent bonds, aminal and imine linkages, are formed between amines and aldehyde groups on the oxidized films.
The Effect of Ketene Dimer Melting Point on the Rate of Sizing Development
Authors:   Hercules Incorporated, Pulp and Paper Division, Wilmington, Delaware 19808, Brungardt C. L. , Varnell D. F. ,   Hercules Incorporated, Pulp and Paper Division, Wilmington, Delaware 19808
Published: February 2024

Two studies were carried out in an effort to gain a better understanding of how ketene dimers develop sizing. In the first study, eight ketene dimers with a range of melting points, vapor pressures, and molecular weights were evaluated for rate of sizing development. Ketene dimer melting point had a clear effect on the rate of sizing development. High melting ketene dimers initiated sizing at higher sheet moistures than low melting dimers. High melting dimers also developed their ultimate level of sizing faster than low melting ketene dimers. These results suggest that solid and liquid ketene dimers have different mechanisms of sizing development. Ketene dimer vapor pressure and molecular weight had no consistent effects on the rate of sizing development. Pseudo first order rate constants for sizing development were then measured for a high melting solid ketene dimer and a liquid ketene dimer over dryer temperatures ranging from 55 °C to 85 °C. The rate constants measured for the liquid ketene dimer increased steadily as dryer temperature increased. An Arrhenius plot of the rate constants obtained for the liquid ketene dimer yielded an activation energy of 11 kcal per mole for sizing development. These results are consistent with the hypothesis that the chemical reaction of the lactone ring is the rate determining step in sizing development for liquid ketene dimers. The high melting solid ketene dimer followed more complex kinetics and probably developed sizing by a combination of mechanisms. It is likely that the differing sizing responses measured for the solid and liquid ketene dimers are due to differing sizing contributions from the unreacted and hydrolyzed ketene dimers.
Direct Measurement of Attractive van der Waals Forces and Repulsive Electrostatic Forces between Regenerated Cellulose Surfaces in an Aqueous Environment
Authors:   Department of Applied Mathematics, Research School of Physical Sciences and Engineering, Australian National University. Canberra 0200 ACT, Australia, Notley Shannon M. , Wågberg Lars ,   Department of Fibre and Polymer Technology, Royal Institute of Technology (KTH), SE-10044 Stockholm, Sweden
Published: February 2024

Using the colloidal probe technique, the interaction between carboxymethylated cellulose films and a cellulose sphere was studied. At low pH (pH 3.5), the interaction was dominated by dispersion forces. This was due to the low dissociation of carboxyl groups within the film at pH 3.5. However, at pH greater than 5, the interaction was dominated by an electrostatic repulsion. The increase in pH had the two-fold effect of completely dissociating the charged groups as well as causing appreciable swelling of the film leading to a decrease in the van der Waals component of the interaction. From these results it can be concluded that these cellulose films are suitable for a range of surface forces measurements including electrostatic, van der Waals’, steric and adhesion forces. Furthermore, the measurement of forces using the colloidal probe technique can be extended to inorganic particles as well as for interactions between surfaces in the presence of for example wet and dry strength agents and other materials relevant to the paper-making industry.
On the Origins of Adhesion in Papermaking Systems
Authors:   Department of Wood and Paper Science, North Carolina State University, Campus Box 8005, Raleigh, NC, 27695–8005, USA, Rojas Orlando J. , Dedinaite Andra ,   Department of Chemistry, Surface Chemistry, Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden and Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden, Byrd Medwick V. ,   Department of Wood and Paper Science, North Carolina State University, Campus Box 8005, Raleigh, NC, 27695–8005, USA, Hubbe Martin A. ,   Department of Wood and Paper Science, North Carolina State University, Campus Box 8005, Raleigh, NC, 27695–8005, USA, Claesson Per M. ,   Department of Chemistry, Surface Chemistry, Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden and Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden
Published: February 2024

The purpose of this study was to investigate the effect of polyelectrolytes on the adhesion forces between polyelectrolyte-coated surfaces and to relate the observed phenomena to the performance of dry strength additives in papermaking systems. The adhesive properties (pull-off forces) between polyelectrolyte-coated surfaces in air were determined as a function of the polymer charge density and the number of contacts. We found strong adhesion energy for model systems coated with polymers of the highest (cationic) charge density, which suggests that electrostatic surface-polyelectrolyte-surface bridges are the main cause of the adhesion. At low charge density another force contribution due to entanglement of polymer chains gives rise to a significant contribution to the adhesion forces. The disruption of the contact leads to irreversible changes in the adsorbed layers when either the number of electrostatic bridges formed is large or when entanglement effects are important for polymers with a relatively low binding strength to the surface. These results are discussed in terms of our current understanding of development of dry strength in fiber systems.
Molecular Interactions between Model Cellulose Surfaces and Ink – Influence of Surface Energy and Surface Structure on Adhesion
Authors:   TetraPak R&D AB, Ruben Rausings gata, SE-22186 Lund, Sweden, Forsström Jennie , Eriksson Malin ,   Department of Fibre and Polymer Technology, Royal Institute of Technology, (KTH), SE-10044 Stockholm, Sweden, Wågberg Lars ,   Department of Fibre and Polymer Technology, Royal Institute of Technology, (KTH), SE-10044 Stockholm, Sweden
Published: February 2024

The influence of surface roughness and surface hydrophobicity on ink detachment of water-based flexographic ink was studied. It was shown that increased surface roughness and an increased surface hydrophobicity both had a negative effect on ink detachment. The increased surface roughness was suggested to increase the molecular contact area between ink and cellulose and thereby also to decrease ink detachment. Ink cellulose interaction was evaluated from interfacial energies and contact angle measurements. A new technique in which the adhesion properties between ink and the model cellulose surface were directly measured using a Micro Adhesion Measurement Apparatus (MAMA) was also used. Upon increasing the hydrophobicity of the model cellulose surface it was shown that the work of adhesion between ink and model cellulose surfaces decreased. At the same time the interfacial energy between cellulose and ink increased, as did the interfacial energy between cellulose and water resulting in a lower degree of ink detachment.
Characterisation of the 3D Paper Structure with X-ray Synchrotron Radiation Microtomography
Authors:   Laboratoire Génie des Procédés Papetiers (LGP2/EFPG/CTP/CNRS UMR 5518), BP 65, 38402 Saint-Martin-d’Hères Cedex, France, Rolland du Roscoat S. ,   European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, Polygone Scientifique, BP220, 38 043 Grenoble, France, Bloch J.-F. ,   Laboratoire Génie des Procédés Papetiers (LGP2/EFPG/CTP/CNRS UMR 5518), BP 65, 38402 Saint-Martin-d’Hères Cedex, France, Thibault X. ,   European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, Polygone Scientifique, BP220, 38 043 Grenoble, France
Published: February 2024

Paper is a complex three-dimensional network of fibres, pores and often fillers. The main goal of this study is to characterise its structure in a non invasive and non destructive way. In order to overcome the limitations of 2D measurements, Synchrotron Radiation microtomography is used to visualise the samples. Coupled with appropriate processing tools, it allows a quantifica- tion of some structural characteristics on the samples. This is the main aim of this paper. Different articles relate the feasibility of such a study for paper samples: imaging at the European Synchrotron Radiation Facility (ESRF, France) in phase contrast [1] or in absorption mode [2] gives the opportunity to reach a pixel size smaller than a micron which can not be obtained with classical tomographs [3]. A first step is to visualise the structure then, structural parameters are extracted from these 3D data [4]. However, this requires a segmentation technique adapted for application to typical paper samples that are constituted of three phases. The first step consists in the segmentation of the different phases, namely, air, fibres and fillers. The amount of each component may be evaluated. This was validated for both the porosity and the filler content. Furthermore, structural parameters were calculated from the binarised volumes. The comparison with the published results validates the calculation.
Imaging Fibre Deformations
Authors:   Georgia Institute of Technology, Institute of Paper Science and Technology, 500 10th Street, NW, Atlanta, GA 30332–0620, United States, Lowe Rob , Ragauskas Art ,   Georgia Institute of Technology, Institute of Paper Science and Technology, 500 10th Street, NW, Atlanta, GA 30332–0620, United States, Page Derek H. ,   6 Apple Hill, Baie D’Urfe, QC, H9X 3G6, Canada
Published: February 2024

A new experimental technique is presented that allows the direct observation of fibre deformation during wet pressing. Pulp fibres were wet pressed onto a glass slide and the region where two fibres crossed was examined microscopically through the glass. While the underlying fibre was in contact with the glass slide down its length, the overlying fibre must span from the top of the fibre to the glass slide. The geometry of the intersection is controlled by both the local conformability of the overlying fibre and the deformability of the underlying fibre. It is not primarily controlled by the longitudinal flexibility of a fibre. The method provides new opportunities to investigate the effect of mechanical and chemical treatment on the papermaking properties of pulp fibres in both the dry and wet state.
Effect of Correlated Free Fibre Lengths on Pore Size Distribution in Fibrous Mats
Authors:   School of Mathematics, University of Manchester, PO Box 88, Manchester, M60 1QD, UK, Dodson C.T.J. , Sampson W.W. ,   School of Materials, University of Manchester, PO Box 88, Manchester, M60 1QD, UK
Published: February 2024

We provide a simulator for a range of bivariate stochastic processes of various application in the physics of stochastic fibrous networks. We illustrate the effects of local correlation on the statistics of voids in the bulk and the surface of fibre mats in general and paper in particular. The reference case of random isotropy has an inherent ‘ground-state’ correlation of adjacent free-fibre-lengths; this explains the classical observation of Corte that pores seem mainly ‘roundish’ in real paper samples. In the isotropic case, the mean pore radius can be reduced from that in a random network by 20% through structural changes associated with increased flocculation. The mean eccentricity of pores seems to give a measure of the variability in free-fibre-length distributions that is not due to local correlation. We find a uniform effect of local correlation on mean pore eccentricity over a range of stochastic network structures; at a given correlation, increased flocculation increases mean eccentricity slightly.
Applications of Thickness and Apparent Density Mapping by Laser Profilometry
Authors:   Empire State Paper Research Institute, Faculty of Paper Science and Engineering, SUNY College of Environmental Science and Forestry, Syracuse, New York, USA 13210, Sung Y.J. ,   KT & G Corporation, Central Research Institute, Yuseong, Daejeon, South Korea, Ham C.H. ,   Empire State Paper Research Institute, Faculty of Paper Science and Engineering, SUNY College of Environmental Science and Forestry, Syracuse, New York, USA 13210; Department of Forest Products, Seoul National University, Seoul, South Korea, Kwon O. ,   Empire State Paper Research Institute, Faculty of Paper Science and Engineering, SUNY College of Environmental Science and Forestry, Syracuse, New York, USA 13210, Lee H.L. ,   Department of Forest Products, Seoul National University, Seoul, South Korea, Keller D.S. ,   Empire State Paper Research Institute, Faculty of Paper Science and Engineering, SUNY College of Environmental Science and Forestry, Syracuse, New York, USA 13210
Published: February 2024

This paper describes the development of a method for mapping the apparent density of paper, nonwovens and other fibrous webs based on non-contact laser profilometry and β-transmission radiographic imaging. The method is applied in three complimentary studies that examine the in-plane non-uniformity of thickness, grammage and apparent density in printing papers. The first section focuses on the development and verification of the analytical method for mapping thickness. Through simultaneous scanning of the topography of both sides of the specimen by opposing range sensors, the surface contour of each side, the local thickness, and the out of plane deformation were measured. It was demonstrated that the laser based method provides results that closely approximate the intrinsic thickness that is independent of paper formation. The method was then used to examine the structural differences in laboratory sheets pressed by soft and hard nip calenders. The well known difference in web densification mechanisms of the two was reaffirmed by mapping discrete changes in thickness and statistically comparing these with corresponding points on grammage maps. Densification was shown to be dependent on grammage for the hard calender, and independent of grammage for the soft calender. The final study used the thickness mapping method to monitor the hygroexpansivity of representative printing papers as equilibrium humidity was varied between 9% and 80%. Thickness maps were obtained for newsprint, SC-A (calendered and uncalendered), bulk offset and office copy. Differential thickness maps were used to compare the in-plane non-uniformity of hygroexpansion. The inplane hygroexpansion was characterized and corrected for using a recently developed algorithm known as Enhanced Digital Image Correlation (EDIC). Thickness change did not appear to correspond to grammage maps. The results suggest that a significant irreversible increase in thickness occurs for papers that are heavily calendered.
On the Mechanisms of Mechano-sorptive Creep Reduction by Chemical Cross-linking
Authors:   Department of Fibre and Polymer Technology, Royal Institute of Technology, KTH, SE-100 44 Stockholm, Sweden, Gimåker Magnus , Olsson Anne-Mari ,   INNVENTIA AB, Box 5604, SE-114 86 Stockholm, Sweden, Salmén Lennart ,   INNVENTIA AB, Box 5604, SE-114 86 Stockholm, Sweden, Wågberg Lars ,   Department of Fibre and Polymer Technology, Royal Institute of Technology, KTH, SE-100 44 Stockholm, Sweden
Published: February 2024

Despite the technical importance of mechano-sorptive creep in paper, the exact mechanism behind this phenomenon is still not fully understood. In this study it was shown that the mechanosorptive creep of paper sheets can be signiﬁcantly reduced by chemical cross-linking through periodate oxidation. The mechanism behind this reduction has been examined through creep measurements of both sheets and individual ﬁbres. For sheets the creep acceleration due to varying humidity was signiﬁcantly reduced by the chemical cross-linking. For single ﬁbres, however, the creep acceleration was not affected by the chemical crosslinking. In fact the absolute creep rate for the periodate oxidised ﬁbres were higher than that of the reference ﬁbres. This clearly showed that the improvement in mechano-sorptive creep found on a sheet level does not originate from an improved creep resistance for individual ﬁbres but rather from mechanisms operating at the ﬁbre network level. Hygroexpansion and moisture sorption of the sheets during the humidity cycling used for creep testing have also been measured, and the results showed that both was reduced by the periodate oxidation. Reduced moisture sorptivity and hygroexpansion probably minimises stress concentrations at the ﬁbre network level and thereby also the creep acceleration.
Prediction of Fibre Orientation and Stiffness Distributions in Paper – An Engineering Approach
Authors:   Stora Enso AB, Publication Paper R&D, Box 9090, 650 09 Karlstad, Sweden, Wahlström Torbjörn
Published: February 2024

The orientation of the ﬁbres in a paper directly inﬂuences many of its properties. The focus of this work was to predict the ﬁbre orientation distribution and tensile stiffness distribution of a paper. The predictions were based on a proposed link between the two distributions and physical parameters measurable on the paper, no ﬁtting parameters. The ﬁbre orientation distribution in paper was approximated by a probability density function. Both curve ﬁtting type of distribution functions earlier used in paper physics and physical based functions derived from Fluid mechanics, Orthotropic analysis and a simple Stress/strain analysis were evaluated. The physical based functions used one measurable physical parameter, the ﬁbre orientation anisotropy. The tensile stiffness distribution was predicted with a distribution function from the literature and functions derived from the Fluid mechanics and Orthotropic analysis approach. The predictions needed two measurable physical parameters, the MD and CD tensile stiffness. Predictions of ﬁbre orientation distribution and tensile stiffness distribution for restrained dried papers were compared with experimental data from restrained dried oriented handsheets with varying ﬁbre orientation anisotropy. General approaches valid for all papers were compared with experimental data from pilot made papers with different drying restraint history. Both the predicted results for ﬁbre orientation distribution and tensile stiffness distribution showed good agreement with experimental data.
Bioactive Enzymatic Papers
Authors:   Australian Pulp and Paper Institute (APPI), Department of Chemical Engineering, Monash University, Clayton, VIC 31800, Australia, Khan Mohidus Samad , Tian Junfei ,   Australian Pulp and Paper Institute (APPI), Department of Chemical Engineering, Monash University, Clayton, VIC 31800, Australia, Xu Li ,   Australian Pulp and Paper Institute (APPI), Department of Chemical Engineering, Monash University, Clayton, VIC 31800, Australia, Shen Wei ,   Australian Pulp and Paper Institute (APPI), Department of Chemical Engineering, Monash University, Clayton, VIC 31800, Australia, Garnier Gil ,   Australian Pulp and Paper Institute (APPI), Department of Chemical Engineering, Monash University, Clayton, VIC 31800, Australia
Published: February 2024

The thermal stability of Alkaline phosphatase enzyme (ALP) adsorbed on paper was measured using a colorimetric technique quantifying the intensity of the product complex. ALP adsorbed on paper retains its functionality and selectivity. Adsorption of ALP on paper increased the enzyme thermal stability by 2 to 4 orders of magnitude compared to the same enzyme in solution. Complex patterns of enzyme were also printed using a thermal inkjet printer on paper. Microﬂuidic channels were printed on paper to demonstrate the concept of paper-based bioassays as diagnostic devices. Paper is an ideal material for functional materials for functional bioactive surfaces.
On Fundamentals and Applications of Superhydrophobicity in Papermaking and Packaging
Authors:   YKI, Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden, Swerin Agne , Wåhlander Martin ,   YKI, Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden
Published: February 2024

Fundamental material science investigations of superhydrophobicity in recent years has evolved toward industrial applications and recently to papermaking and packaging. The present study concerns both fundamental and applied aspects of superhydrophobicity. An industrially viable process for a one-step waterborne superhydrophobic coating was developed. It is shown that different measures of the degree of superhydrophobicity are needed depending on the ﬁnal application whether this may be self-cleaning or stain repellent action. Fundamental aspects of superhydrophobicity were investigated using silica wafers roughened by a particulate formulation containing nanosize silica particles, which were ﬁxed to the substrate by calcination. After hydrophobization by silylation, the forces between a colloidal superhydrophobized silica probe, made according to a similar procedure, and these surfaces were measured by Atomic Force Colloidal Probe Microscopy. The results show an extremely long range interaction force and a large inﬂuence of surfactant and surfactant concentration. The results would prove useful in designing robust superhydrophobic application in the papermaking and packaging industry and also imply that coating and printing technique could be used for controlled deposition of superhydrophobized layers or areas.
A Structural Analysis of the Thermal Conductivity of Paper Coatings: Application of Particle Deposition Simulation to a Lumped Parameter Model
Authors:   Helsinki University of Technology, Faculty of Chemistry and Materials Science, Department of Forest Products Technology, Gerstner Philip , Ridgway Cathy J. ,   Omya Development AG, CH-4665 Oftringen, Switzerland, Paltakari Jouni ,   Helsinki University of Technology, Faculty of Chemistry and Materials Science, Department of Forest Products Technology, Gane Patrick A. C. ,   Helsinki University of Technology, Faculty of Chemistry and Materials Science, Department of Forest Products Technology; Omya Development AG, CH-4665 Oftringen, Switzerland
Published: February 2024

Thermal conductivity of paper coating structures can be regarded as an important property for many processes involving the application of thermal energy on coated papers. This work analyses the thermal conductivity of coatings in terms of their structure. A Monte Carlo simulation-based particle deposition was used to create idealised two-dimensional coating structures. They acted as a master template for the superimposed parameters of a Lumped Parameter Model for the calculation of thermal conductivity, in which pigment and binder are treated as separate solid phases within a ﬂuid (air). Binder alone was initially assumed to provide the necessary thermal connectivity. Comparison of the numerically calculated conductivities with corresponding experimental results, obtained from ground calcium carbonate pigment structures, showed generally lower calculated conductivities and clear differences in the change of conductivity when increasing latex binder content. Two different mechanisms are suggested as the cause of this lack of correlation. Firstly, it is shown that both the simulation and the current Lumped Parameter Model do not account sufﬁciently for pigment connectivity. This is the reason for the underestimation, especially evident when no binder is present. The nature of pigment connectivity is related to polymer dispersant on the pigment surface and the surface crystallite planar structures, if present, mostly related to larger particles. Secondly, it is conﬁrmed that surface and colloid chemistry factors cause binder to accumulate ﬁrst at pigment nodal points, which causes a disruption of the pigment packing already at 6 w/w% binder. This creates in homogeneity in the real coating structure which is not accounted for by the homogeneous assumption of the model. It could be shown that an introduced parameter of pigment connectivity becomes lower for the binder concentrations for which pigment disruption occurs. It is shown that the method is sensitive enough in respect to reﬁnement of both pigment and latex connectivity factors to allow identiﬁcation and parameterisation of the subtleties occurring in real colloidally interactive particulate systems that are reﬂected in the thermal conductivity response of the dried coating structure.
Probabilistic analysis of small-scale print defects with aligned 2D measurements
Authors:   Department of Automation Science and Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland, Mettänen Marja , Hirn Ulrich ,   Institute of Paper, Pulp and Fibre Technology, Graz University of Technology, Kopernikusgasse 24, 8010 Graz, Austria, Lauri Mikko ,   Department of Automation Science and Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland, Ritala Risto ,   Department of Automation Science and Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland
Published: February 2024

We present an analysis of the pointwise relationship between the reﬂectance of print and the surface topography of the paper before printing. We have measured the surface topography and reﬂectance of paper before and after printing in a sheet-fed pilot offset printing press. The 2D measurement maps have been aligned to obtain local print reﬂectance and surface topography values for every spatial position on the samples. In contrast to the various deterministic modeling approaches, which imply an a priori deﬁned underlying mathematical model, we apply probabilistic analysis. Therefore we ﬁrst estimate joint probability density functions (pdfs) of local topography and print reﬂectance using Gaussian Mixture Models (GMMs). From these pdfs we select paper regions with unusual properties, i.e. regions from the tails of the pdfs. These anomaly maps are analyzed for interrelations between the print reﬂectance and surface topography, its gradient and local variance. The degree of interrelation is characterized by the mutual information (MI), a measure to quantify statistical dependence without making assumptions about the linear or nonlinear nature of the regression dependence. The signiﬁcance of the MI values is conﬁrmed by simulation based statistical hypothesis testing. The objective is to offer answers to the question: How does the observation of an exceptional topography point on the paper surface change our information about whether the print quality attainable at that point will be exceptional or not? The results suggest that topography in combination with its local variance have the most prominent interrelation to small scale print anomalies. Furthermore it is shown that regions with abnormal topography have at least ten-fold higher probability to exhibit exceptionally high print reﬂectance, compared to randomly selected regions.
Fundamental Studies of Linting in Offset Printing of Newsprint
Authors:   Australian Pulp and Paper Institute, Monash University, Australia, Batchelor Warren , Sudarno Afriana ,   Australian Pulp and Paper Institute, Monash University, Australia, Gujjari Chamundi ,   Australian Pulp and Paper Institute, Monash University, Australia, Banham Paul ,   Norske Skog Technical Support and Development Group, Boyer, Australia
Published: February 2024

Linting is the removal of material from the surface of uncoated grades of paper during offset printing. Excessive linting reduces image quality and can reduce press productivity. In this paper, web-fed and sheet-fed linting trials have been used to investigate the effect of important press and paper variables on linting. Two of the most important printing parameters affecting linting were the take-off angle from the nip and the printing tone. From analysis of the effects of take-off angle and printing tone, two forces were identiﬁed as being especially important to linting: a ﬁlm ﬂow force in the nip and a tack force from the splitting of the ink ﬁlm. A simple model was presented that could qualitatively explain why printing press speed, printing pressure and ink tack all had smaller effects on linting than would be expected from consideration of tack force alone. Laboratory printing tack tests and other measurements of paper properties were compared with lint measured in the sheet-fed trials. The tack force measured in laboratory printing was found to be lower for improved newsprint compared to newsprint, while the lint in both sheet-fed and web-fed trials was higher for the improved newsprint. Differences in the ﬁlm ﬂow in the nip were suggested to be responsible for both effects. The improved newsprint was also found to have a lower surface strength, as measured by delamination.
Structural Invariance of Stochastic Fibrous Networks
Authors:   School of Mathematics, University of Manchester, PO Box 88, Manchester, M60 1QD, UK, Dodson C.T.J. , Sampson W.W. ,   School of Materials, University of Manchester, PO Box 88, Manchester, M60 1QD, UK
Published: February 2024

We use simulation and analytic modelling to probe the structural similarity reported in the literature for ﬁbre networks with manifestly different degrees of uniformity. From simulations of point processes in the plane to represent random, clustered and disperse ﬁbre centres, we show that the distribution of distances between pairs of centres is very insensitive to the extent of clustering. Further, we quantify the correlation between the lengths of adjacent polygon sides arising from a Poisson line process in the plane as being ρ = 0.616 ± 0.001 and show that this is very insensitive to ﬁbre orientation and only weakly inﬂuenced by clustering. The relevance of this correlation to pore geometry is discussed. In the ﬁnal part we analyze simulated areal density maps and show that their variance relative to that of a random ﬁbre network of the same constituent ﬁbres, as quantiﬁed by the formation number, depends at small scales on the ﬂocculation intensity only and depends at large scales on the number of ﬁbres per ﬂoc only.
Spatial Partitioning of the Structural Properties of Tissue and Towel Grades
Authors:   Department of Paper and Chemical Engineering, Miami University, Oxford, OH USA, 45056, Keller D. S. , Branca D. ,   Faculty of Paper Science and Engineering, SUNY College of Environmental Science and Forestry, Syracuse, New York USA, 13210, Kwon O. ,   Faculty of Paper Science and Engineering, SUNY College of Environmental Science and Forestry, Syracuse, New York USA, 13210
Published: February 2024

This paper describes an investigation conducted to examine the mesoscale structural properties of single-ply tissue and towel papers by mapping thickness, out-of-plane deformation, formation, and density. The uniformity of each of these properties was studied to a zone size of 0.1 mm in mapped regions of about 10 mm square. The sampling regions were partitioned into subsets that were separately analyzed. Regions of interest included wet pressing marks, embossed patterns and through air drying (TAD) pressed patterns. The relationship between thickness and grammage (basis weight) in the different regions of interest were compared. Differences were attributed to the indentation process that could affect the structure in different ways, depending on the process conditions. Six commercial tissue and towel products were tested. The regional differences were most apparent in the results for paper towels. Deformation of the structure to form textured patterns compressed regions and increased the local density. There was selected in-plane movement of fibers, in response to the indentation. The towel sample formed by wet pressing did not show the same extent of densification at the indentation site. The structure was deformed out of plane, but not significantly com- pressed. Tissue samples formed by conventional wet pressing showed increased densification at points of indentation. Differences in the out-of-plane response to the pressing process could be distinguished between different tissue samples.
Introducing a Concept to Link 3D Paper Structure to 2D Paper Properties
Authors:   Institute for Pulp-, Paper- and Fiber Technology, Graz University of Technology, Austria, Hirn Ulrich , Kritzinger Johannes ,   Institute for Pulp-, Paper- and Fiber Technology, Graz University of Technology, Austria, Donoser Michael ,   Institute for Computer Graphics and Vision, Graz University of Technology, Austria, Bauer Wolfgang ,   Graz University of Technology, Austria
Published: February 2024

This paper introduces a concept that spatially links local paper properties from a 3D paper dataset to a 2D paper property map of the same sample. The concept exploits the fact that paper is a planar structure. This permits successive conversion of 3D paper datasets first to a 3D surface (the paper center surface) and further to a plane. The flattened 3D paper data can then be linked to the 2D paper property map. Laser micro holes applied to the paper are employed as marks for alignment of the 2D maps. The key step of the procedure is flattening the paper data from a warped 3D surface to a 2D plane. Some exemplary applications for the introduced method are given. The effect of local coating layer thickness on local brightness and local print density is examined for wood free coated paper. Furthermore, the concept can be applied for quantitative comparison of data from different 3D-imaging techniques. We measured local coating layer thickness on the same paper specimen applying first fan-beam X-ray microtomography and then microtome serial sectioning. The results are compared using point-wise correlation.
Developing a Deeper Understanding of the Constitutive Behavior of Paper
Authors:   Department of Paper and Chemical Engineering, Miami University Oxford, OH 45056, Coffin Douglas W.
Published: February 2024

A constitutive equation for the mechanical behavior of paper is presented. Since the initial work in the late 1940’s rheology studies of paper seem to come in waves and the results have not always been viewed favorably. With the benefit of fifty years of literature and the relative speed of modern computing, a more robust constitutive model is certainly within reach. The presented model captures the essence of the mechanical response and links the stress-strain curve to relaxation and creep in a reasonable manner. Experimental results are provided to illustrate the important components of the behavior and the model can easily be generalized to include more subtle features.
The Influence of Microfibrillated Cellulose, MFC, on Paper Strength and Surface Properties
Authors:   Paper and Fibre Research Institute (PFI AS), Trondheim, Norway, Syverud K. , Gregersen Ø. ,   Norwegian University of Science and Technology (NTNU), Trondheim, Norway, Chinga-Carrasco G. ,   Paper and Fibre Research Institute (PFI AS), Trondheim, Norway, Eriksen Ø. ,   Paper and Fibre Research Institute (PFI AS), Trondheim, Norway
Published: February 2024

This study demonstrates recent advances in microfibrillated cellulose (MFC) research. This novel material, which is mostly com- posed of nano-sized cellulose fibrils seems to have large potential within several applications. Three case studies are considered, i) MFC films that may be applied for packaging applications, ii) MFC applied in the paper bulk and iii) MFC applied as a coating layer on paper. It has been demonstrated that MFC forms films with high strength, high density and low permeability. The tensile strength of the TMP sheets assessed in this study have been increased by more than 20% by addition of 4% MFC to the furnish. Application of MFC as a coating layer on paper forms a dense continuous surface film. However, despite a considerable reduction of the surface roughness, the paper gloss was reduced. This contradictory phenomenon is most probably caused by the MFC layer covering the clay particles on the surface of the base paper.
The Effect of Fibre Orientation on the Zero-span Testing of Paper
Authors:   Department of Chemical Engineering and Applied Chemistry, and the Pulp & Paper Centre University of Toronto Toronto, ON. Canada M5S 3E5, Dolatshahi S. , Kortschot M.T. ,   Department of Chemical Engineering and Applied Chemistry, and the Pulp & Paper Centre University of Toronto Toronto, ON. Canada M5S 3E5
Published: February 2024

In this study, a new technique for producing almost fully aligned paper sheets was developed, and the resulting sheets were used to test the validity of the theory most commonly used to relate zero-span tensile strength to individual ﬁbre strength. The standard theory predicts that a zero-span test of a sheet with randomly oriented ﬁbres should yield a breaking load equal to 3/8 of the load that would be observed if all the ﬁbres were aligned in the direction of loading. It is widely used, in spite of the fact that the underlying assumption of afﬁne deformation is questionable under true zero-span conditions. The results obtained here suggest that the ﬁbre strength may be overestimated because inclined ﬁbres in a zero-span grip actually contribute more than the theory predicts. However, the results also suggest that this effect may be confounded because other factors lead to a variable contribution of individual ﬁbres to the zero-span strength of the sheet.
Degradation Phenomenology and Life Modelling of Paper
Authors:   Doble PowerTest Ltd, Guildford, Surrey, GU3 1NA, UK, Ding Hongzhi
Published: February 2024

This document reviews degradation phenomenology and life modelling of paper, illustrates different approaches, showing their advantages and applicability limits and raises problems relevant to practical applications of degradation indicators and degradation rate models and evaluation of paper permanence and durability. It deals with the fundamentals of paper degradation rate theory and life modelling, seeks to develop the degradation rate equations of paper that will closely track real degradation experimental results over extended period under practical service conditions, shows a collection of degradation rate and life data of different paper and paper insulation materials under a varied of in-service environmental conditions, develops continuous distribution kinetics theory of cellulose and paper degradation to form a united basis in deriving the traditional Ekenstam degradation rate equation and the alternative percentage DP (and TS) loss rate equations recently proposed by the present author and his coworker, and presents effective methodology for combining time temperature superposition method and paper degradation investigation towards a more reliable prediction of rate and life of paper degradation over a long time period under real in-service conditions.
Silks and Their Composites
Authors:   Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS, UK, Vollrath Fritz , Chen Fujia ,   Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS, UK, Porter David ,   Department of Zoology, University of Oxford, South Parks Rd, Oxford, OX1 3PS, UK
Published: February 2024

Silks make not only interesting natural materials but also, in the context of their use by the animals that produce them, fascinating natural composites. Importantly, the material properties of a silk depend not only on the chemistry and subsequent folding pattern of the silk protein themselves but also on the hierarchical structure of the poly-protein ﬁbre. Both, in turn, depend to a large extend on the conditions under which a ﬁbre has been spun and thus depend on the animal’s spinning behaviour. Not surprisingly, this gives the animal a high degree of ﬂexibility in which to use its materials. And, if the materials (and typically silks are multi-faceted) are integrated into structures, then those too can have a range of ultimate properties, depending on the animal’s building behaviour. As both materials and structures have evolved over hundreds of millions of years, much can be gleaned and learned concerning highly adapted and often optimized structure-property-function relationships on the material level as well as on the composite level. Individual silk ﬁbres can range in diameter from 20 to 7000 nm depending on species, animal size, silk type and spinning conditions. The hierarchical structure of a silk ﬁbre can range from very simple to complex i.e. a singular ﬁlament consisting of its molecular chains folded into regions with differing degrees of order to, respectively, bundles of ﬁlaments aggregated and layered into ﬁbre-ropes and covered with coatings of specialist compounds [1]. Presented here are two very different silk ﬁbre and composite types: the many silks and light-weight webs of spiders and the singular silk and solid cocoon of lepidopteran “silkworm” larvae.
Structural features of a society in a state of exception: K. Marx, C. Schmitt, G. Agamben
Authors: Makeiev Serhii
Published: February 2024

The article focuses on the structural aspect of society in a state of exception, on its interpretation by K. Marx, С. Schmitt and G. Agamben. The goal was to reconstruct the understanding and conceptual description of extraordinariness in their direct statements about the structural elements of this state in their publications. Of course, such fragments are few, so the main difficulty was to read out intuitions from the texts that allow them to extend beyond the sphere that is the defining subject of these authors’ analysis. The final result is a certain list of terms and concepts, a kind of thesaurus of structural features of a society in a state of exclusivity. All of these authorities in various fields of knowledge recognize events, such as revolutions, wars, and epidemics, as an inevitable impulse that modifies the state of society. Something that upsets the circumstances of living together within nation-states is something like a devastating earthquake, which can be predicted but not prevented. It is something that abolishes the rules and regulations that are, or are only imagined to be, normal, actualizing a mode of action called the politics of extraordinary. The authors named above look at and try to understand the organics and mechanics of extreme, unusual, exceptional cases, i. e. , states of exceptionality from different paradigmatic perspectives (extraordinary, extraordinary are synonymous with exception). The vocabulary of structural features, which is distinguished from the works reviewed in this article, forms the core of the concept, which can be the methodological basis for studying the state of exceptionality in Ukraine, which is a consequence of the Russian aggression of February 24, 2022.