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• Density of a paper has a decisive impact on its air permeability. • Exposure of both historical and common papers to A. niger decreases permeability. • Nano-wollastonite is recommended to improve biological resistance of paper. The effect of nano-wollastonite and Aspergillus niger fungus on permeability of historical and common paper was studied here. Specimens were immersed in aqueous wollastonite nano-suspension (NW) at 10, 20, 30, and 40% concentration, and their permeability was finally compared with that obtained from control specimens. Permeability of each specimen was measured before and after the immersion in NW. To fix solid particles on NW-treated specimens, polyvinyl acetate (PVA) was mixed in all treatments. Results showed that wollastonite significantly limited the growth of A. niger. Permeability of historical specimens was significantly lower than that of the common paper, 29 in comparison to 190 cm3.s−1, respectively. This was due to the higher density in the historical paper, providing lower empty voids and spaces for fluid to pass through. Fungi culture resulted in significant decrease in both paper types. In fact, fungal hyphae penetrated into the specimens, eventually blocking the paths through which fluid could transfer. High significant R-square values were found between permeability values before and after the exposure to A. niger. It was concluded that permeability is closely correlated to the density of paper, and it has a significant effect on the potentiality of fungi hyphae to be penetrated into the texture of papers, affecting the weight loss values. Moreover, NW-suspension can be used to decrease permeability as well as susceptibility to fungal attack. [ABSTRACT FROM AUTHOR]

To optimize the pulping and refining processes of new alternative raw materials for papermaking, researchers generally perform tests that consume considerable time and large amounts of sample. We propose measuring the morphological properties of pulps from orange tree trimmings by image analysis systems, which are fast and user-friendly, to develop models relating key mechanical properties to the dimensions, the deformation and the population of fibers. Data modeling involves multiple linear regression, as used in other studies, and support vector regression, not used before for this purpose, achieving higher R 2 values (up to 0.90). Although tensile, tear and burst tests are still required to obtain accurate values, a quick morphological characterization allows for a rough but satisfactory prediction of paper strength. In this case, chemical pulping and moderate refining are shown to be necessary to obtain pulps of acceptable quality from orange tree trimmings. [ABSTRACT FROM AUTHOR]

In parallel with the development of nanoparticle coatings for protection of paper substrates, detailed descriptions of the surface topography with micro- to nanoscale roughness features are needed. In this work, papers have been coated with poly(styrene-co-maleic anhydride) nanoparticles including different types of vegetable oils and the surface roughness was evaluated at 2000 × 2000 μm 2 to 0.2 × 0.2 μm 2 length scales by combining non-contact optical profilometry (NCP) and atomic force microscopy (AFM). The relationships between roughness data were studied for statistical roughness parameters, spatial roughness parameters and in the frequency domain. In order to compare AFM roughness more accurately, the original images were flattened to remove effects of the underlaying fibrous substrate and highlight features of the nanoparticle coating. More detailed information on the coating topography could be obtained by considering bearing ratio curves and histograms, where it was concluded that the oil-filled coatings form a rather thin and continuous coating that closely follows the shape of the cellulose fibers. The relation between statistical roughness parameters from NCP and AFM follows an exponential trend with relatively low coefficient of determination. The increase in surface roughness with length scale showed a transition point attributed to short- and long-range surface features. Therefore, the correlation length was used as a spatial roughness parameter that provides a successful extrapolation of the average roughness over different length scales in a double logarithmic diagram with very high coefficient of determination. Based on the power spectral density, it was difficult to exactly distinguish between the different types of SMI/oil coatings, as they include similar nanoscale features. The frequency roughness parameters were better suited for extrapolation than statistical roughness parameters but little less efficient than the spatial roughness parameters. [ABSTRACT FROM AUTHOR]

Abstract: The manuscript studied here dates to 19th century, and consists of paper pages and leather bookbinding. This study aims to use analytical techniques in order to identify the components of the manuscript and to explain its deterioration process. Visual assessment, isolation and identification of fungi, pH measurements, and investigation of the surface morphology by a scanning electron microscope (SEM) were used to explain paper and leather deterioration. X-ray diffraction with EDAX, Fourier Transform Infrared Spectroscopy (FTIR), and chemical analysis were used to identify pigments, binder of pigments, ash, lignin, and the α-cellulose content of papers. The shrinkage temperature measurement was used to explain the deterioration process of leather. SEM was used to identify the type of animal skin used for the bookbinding and high performance liquid chromatography (HPLC) was used to identify the vegetable tanning material used with the bookbinding. The results revealed that the ink used was a mixture of carbon with iron gall. The pigments used on the paper were gold leaf or gold shell, cobalt oxide, and mercuric sulfide for the gold, blue and red colors respectively. Sodium chloride was the main salt crystallized on the surface of paper. Calcium carbonate was the filler used in the paper making process. Cotton fibers may have been used as a raw material in the creation of paper. The values of the shrinkage temperature and pH were lower than in normal conditions, indicating that the leather bookbinding suffers from deterioration. Aspergillus sp., and Penicillium sp. were the most dominant fungi found on the manuscript. Goat skin was identified as the animal skin of the bookbinding, and Acacia Arabica was identified the tanning material used with the bookbinding. The condition of the manuscript studied with its components play an important role in its deterioration. [Copyright &y& Elsevier]