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A method is proposed for separating light reflected from turbid media with a rough surface into a bulk and a surface component. Dye is added to the sample, thereby increasing absorption and canceling bulk scattering. The remaining reflected light is surface reflectance, which can be subtracted from the total reflectance of an undyed sample to obtain the bulk component. The method is applied to paper where the addition of dye is accomplished by inkjet printing. The results show that the bulk scattered light is efficiently canceled, and that both the spectrally neutral surface reflectance and the surface topography of the undyed paper is maintained. The proposed method is particularly suitable for characterization of dielectric, highly randomized materials with significant bulk reflectance and rough surfaces, which are difficult to analyze with existing methods. A reliable separation method opens up for new ways of analyzing, e.g., biological tissues and optical coatings, and is also a valuable tool in the development of more comprehensive reflectance models.

The overall usefulness of the bursting energy absorption (BEA) was studied for a better analysis of paper strength properties. Additionally, the changes of the BEA during more complex deformations of paper products, e.g., preliminary or simultaneous tensile and burst, were determined. For the purpose of the research, an experimental setup was designed. The results showed that the correlation between BEA and bursting strength was linear, but the proportionality strongly depended on paper grade. Thus, a more accurate method to characterize the bursting resistance (BR) of paper was proposed. The BR parameter is described by the three following parameters: average bursting strength, average bursting energy absorption, and the slope of the fitted linear regression curve (relationship between the bursting energy absorption and the bursting strength). This method revealed new mechanical behaviors of papers related to their preloading. [ABSTRACT FROM AUTHOR]

The article analyses an effect of paper strain rate on energy absorbed during tensile testing. The tests were carried out in the range where the effect of inertia forces could be omitted. A new calculation method is proposed to predict variations in breaking energy caused by changes in strain rate. The method was verified by laboratory tests and calculation results and its practical usefulness was confirmed. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Lucas–Washburn equation is inadequate in predicting water intake at short contact times. [•] The Lucas–Washburn equation inadequate for predicting intake as a function of temperature. [•] The absorption rate increase with temperature is controlled by molecular processes. [•] The adsorbed water on fiber surfaces lowers the solid–gas interfacial energy. [ABSTRACT FROM AUTHOR]

Highlights: [•] Depending on xylan source, a different effect on paper strength was observed. [•] Cationization of xylan improved the strength enhancement. [•] A main influence on the paper strength was the absorption of cationic xylan. [•] Optimal absorption and strength were observed at a medium degree of cationization. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two silane-based coatings were developed to improve the hydrophobicity of the studied paper. [•] The surface properties of the silane coated paper were examined. [•] A series of paper was modified and film pressed onto plywood. [•] We evaluated the surface chemistry and water absorption of plywood after press. [Copyright &y& Elsevier]

Highlights: [•] Modified nanofibrillated cellulose (NFC) added in wet-end paper process for the first time. [•] Mechanical reinforcement and decreased air permeability with both modified and unmodified NFC. [•] Strong diminution of water absorption (divided by more than 6) with modified NFC. [•] Multi-level properties: hydrophobicity, mechanical reinforcement and air permeability. [Copyright &y& Elsevier]

The work is built on a previous research by Wiryana and Berg, in which wicking into four wet-formed paper stripes, consisting of cellulose fibers and four different percentages of the powdered carboxymethyl cellulose (CMC) superabsorbent, was studied experimentally. Because of the swelling of cellulose fibers and CMC powder on contact with water, the wicking was accompanied by a swelling of the matrix. A finite element/control volume (FE/CV)-based computer program is used for the first time to model the wicking in such swelling porous medium. The simulation used a novel form of continuity equation, which included the effects of liquid absorption and matrix swelling, in conjunction with the Darcy's law to model the single-phase flow behind a clearly defined liquid-front. A new method of estimating the time-varying permeability of the paper, based on the absorbed liquid-mass vs. time plots, is also proposed. Later, this time-dependent permeability is used in the numerical simulation to change the permeability in elements behind the moving liquid-front as a function of the time that the element has been wetted by the liquid, since the passage of the liquid-front. The numerical prediction of the wicking-front location as a function of time compares well with the reported experimental data. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2536-2544, 2012 [ABSTRACT FROM AUTHOR]

Abstract: The diffusion process of deuterated water (D2O) in washi (Japanese traditional paper) was investigated by means of a deuterium exchange method and Fourier-transform near-infrared (FT-NIR) transmission spectroscopy. The samples were the modern (AD 2003) hand-made washi and those from an archival collection of cultural artifacts (AD 1791 and 1615). Four absorption bands were identified in the NIR spectral range from 7200 to 6000cm−1 which are due to OH groups in the amorphous, semi-crystalline and two types of crystalline regions of cellulose. The accessibility of D2O increased with decreasing state of order of cellulose, and the saturation accessibility increased with the age of the samples. It was suggested that during aging hemicellulose, which forms a composite with cellulose in paper, was progressively hydrolyzed, resulting in the expansion of inter-molecular distance between cellulose chains. The oldest sample showed a low diffusion rate compared with the others. SEM observation of the textile structures indicated that the oldest sample had two layers due to beating. It was estimated that the tight surface layer blocked the diffusant in the initial stage of the diffusion process. [Copyright &y& Elsevier]

Well-ordered two-dimensional functional nanostructure arrays have a broad range of potential applications in molecular electronics, ultra-high density data storage, biosensors, single-electron, single-photon and quantum computation devices. Various surface nanotemplates that are naturally or artificially patterned at the nanometre scale have been used to guide the formation of highly periodic nanostructure arrays. In this paper, we review recent progress in the development of various surface nanotemplates as well as the self-assembly of nanostructures on them, with particular emphasis on the unique SiC nanomesh template. The formation mechanism of this nanomesh template is attributed to the self-assembly of accumulated carbon atoms into well-ordered honeycomb superstructures at the nanometre scale on the 6H-SiC(0 0 0 1) surface. The size and spacing of unit cells of the SiC nanomesh can be tailored in the 2-2.5 nm range by adjusting the annealing time. This nanomesh is demonstrated to be an effective template for the formation of well-ordered molecular arrays of copper(II) phthalocyanine (CuPc). The growth of C60 on the nanomesh follows a typical Stranski-Krastanov mode, and a complete C60 wetting monolayer can be epitaxially grown on this nanotemplate. It is effective in isolating metal nanoclusters, resulting in the formation of monodispersed Co nanoclusters with a narrow size distribution. The adsorption and desorption of Co nanoclusters and C60 do not change its atomic structure, making it a chemically and thermally stable nanotemplate for the formation of well-ordered nanostructures arrays as well as monodispersed metal nanoclusters. [ABSTRACT FROM AUTHOR]

The transport rate of liquid water, i.e., the water penetration rate, into paper is one of the important physical properties in the printing, coating, and gluing processes. However, some kinds of paper are too thin to permit the measurement of the penetration rate in the direction of the thickness accurately. Thus, a novel method for measurement of the penetration rate has been developed. The large difference in electrostatic capacitance between soaked and dry paper and that in penetration rate between filter and thin paper were utilized as the foundation for this method. The time required for penetration through the whole sheet of thin paper was calculated from the measured penetration curve on the basis of theoretical analysis. As a result of the measurements in a relative humidity range of 40 to 70% it was concluded that this method could be useful in the characterization of thin paper materials with respect to penetration. [ABSTRACT FROM AUTHOR]

Abstract: Cellular structures currently applied in various engineering fields are mainly made of metals and papers. To engineering design textile composite cellular structures, in this paper, comparisons of various essential structural parameters affecting energy absorption and deformation are carried out. These parameters include the opening angle, the cell-wall length, the cell-wall thickness, the bonded cell-wall length, and the bonded cell-wall thickness. The structure geometries are created by in-house computer package which exports IGES files. Two-dimensional finite element analyses are conducted by MSC.Marc Mentat 2001 which imports these IGES files to numerical calculation. Orthotropic mechanical properties of the textile composite cellular structure laminate are applied for the finite element analyses. It is found that the opening angle, the cell-wall length and the cell-wall thickness affect significantly energy absorption and deformation. Strain energy density concentrations appear very seriously around the cell corners during quasi-static impact. [Copyright &y& Elsevier]

Chitosan can be used is precoating, before extrusion coating, to give better adhesion and improve barrier properties. A chitosan from natural polysaccharide was studied as a potential additive in paper coating. Four chitosan solutions were made with concentrations of 0.1%, 0.25%, 0.5%, and 0.75% by weight of total dry coating weight. Bending strength was improved significantly, but tear index and tensile index were improved only slightly. Water absorption was slightly reduced. This preliminary study indicates that chitosan has good adhesion onto cellulose and could be used as an environmentally friendly coating material. Future studies will concentrate on the aroma and oxygen barrier properties of chitosan. Application: Coating paper with chitosan, an abundant material, improves its bending stiffness and MD tensile strength. [ABSTRACT FROM AUTHOR]

Abstract: A void network model, named Pore-Cor, has been used to study the permeation of an ink solvent into paper coating formulations coated onto a synthetic substrate. The network model generated anisotropic void networks of rectangular cross-sectional pores connected by elliptical cross-sectional throats. These structures had porosities and mercury intrusion properties which closely matched those of the experimental samples. The permeation of hexadecane, used as an analogue for the experimental test oil, was then simulated through these void structures. The simulations were compared to measurements of the permeation of mineral oil into four types of paper coating formulation. The simulations showed that the inertia of the fluid as it enters void features causes a considerable change in wetting over a few milliseconds, a timescale relevant to printing in a modern press. They also showed that in the more anisotropic samples, fast advance wetting occurred through narrow void features. It was found that the match between experimental and simulated wetting could be improved by correcting the simulation for the number of surface throats. The simulations showed a more realistic experimental trend, and much greater preferential flow, than the traditional Lucas–Washburn and effective hydraulic radius approaches. [Copyright &y& Elsevier]

The effect of paper sludge content and size on the processibility, mechanical properties, swelling behavior and morphology of PP--EPDM composites were examined. Results show that the increasing content of paper sludge in composites has increased the Young's modulus and water absorption but decreased the tensile strength and elongation at break. At a similar filler content, PP--EPDM composites with the smallest size show the highest mechanical properties but the lowest water absorption resistance. SEM tensile fracture surface of composites show that the smallest size of paper sludge has better filler--matrix interaction than the larger size of paper sludge. Thermogravimetric analysis showed that the increase of paper sludge content has increased the thermal stability of PP--EPDM composites particularly at temperatures above 500°C. [ABSTRACT FROM AUTHOR]

Nano-structured silica with an open network structure has been produced by controlled precipitation from geothermal water. The material has a pore volume, as measured by the oil absorption capacity of about 200–250 g oil. 100 g−1 silica, and the surface area is about 50–60 m2 g−1. It has been used as a filler in newsprint and the technology has been developed on a laboratory scale and progressed to pilot plant production with full scale paper mill manufacturing and commercial printing trials. Print through reductions of 30% for newsprint and 40% for yellow directory grade paper were achieved. Nano-structured calcium silicate with an open framework structure has been formed from sodium silicate solution. This product has a very large pore volume of about 300–550 g oil. 100 g−1 silicate and a large surface area of about 350–600 m2 g−1 depending upon the synthesis method. It has been tested as a filler in newsprint on a laboratory scale and reduced print through by about 40% for 55 gsm newsprint and by about 53% for 45 gsm newsprint. The material is better than nano-structured silica for this application and it substantially outperforms calcined clay. [Copyright &y& Elsevier]

We introduce a novel diagnostic approach for the uncovering of hidden content in layered documents, based on a photoacoustic imaging set‐up with optimised acoustic detection parameters. By exploiting the laser‐induced ultrasound following the intense absorption of pulsed optical radiation by printed ink, this traditional biomedical imaging method is proven capable of revealing text characters buried under several layers of stacked paper sheets at high spatial resolution and excellent contrast levels. Such a remarkable performance benefits from the effective combination of strong light scattering by paper fibrils and the virtually unobstructed propagation of the generated ultrasonic waves through multiple layers, enabling thus the accurate recording of text, even in double‐sided prints, with minimum shadowing artefacts. The imaging effectiveness, the implementation simplicity, the robustness, and the relatively low‐cost features offered by the proposed photoacoustic modality are anticipated to contribute in its wide adoption by the preservation of cultural heritage community, as a powerful diagnostic tool for the in‐depth investigation of complex multilayered objects. [ABSTRACT FROM AUTHOR]