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Bagasse sugarcane (BSC) has low fibre strength due to low cellulose content. Hence, by adding a strong secondary fibre that is high in cellulose such as pineapple leaf fibre (PALF), the fibre strength of the system can be improved. High portion of PALF decreased the composite paper performance because the high composition of PALF tends to produce flocs and agglomerates fibres. The arrangement of the fibres in composite paper should be improved so that this agglomerate’s effect could be overcome. A novel multilayer hybrid fibre composite was used. BSC/PALF with several hybrid ratios was studied in terms of the mechanical and moisture properties of the produced paper sheet and the results showed that multilayer hybrid composite paper produced higher in hybrid composite paper’s properties compared with random hybrid composite paper. The colour of multilayer hybrid fibre composite paper resembled the natural bright colour of BSC and the multilayer hybrid fibre composite paper also shown a slightly low weight loss percentage compared with the random hybrid fibre composite paper after 60 days of soil burial test. As a conclusion, multilayer hybrid fibre composite produced the stronger interfibre bonding and overcome the agglomerate’s effect between BSC/PALF compared with random hybrid fibre composite.

Cellulose based nanomaterials have the great potential to be applied to paper as bulk additive or coating material to improve overall final properties, especially in secondary fiber. In the present work, the effect of applying different kinds of cellulose nanofibrils (CNF) to papers obtained from recycled fibers using size press on physical, mechanical and barrier properties was investigated and compared with the sole use of starch as coating material. The coating process of CNF was carried out by the addition of size press grade starch to coating suspension. As a cellulose source, wheat straw was evaluated and CNF was obtained through oxidative and enzymatic pretreatments. Results indicate that starch/CNF suspension improves the overall paper properties. As a result of the deposition of coating suspension contains of 4 % wt. periodate-oxidized CNF onto paper surface, tensile and burst indices of papersheets increased as 52.2 % and 194.4 %. Significant decreases were observed in air permeability as 69.8 %. Compression tests also have been conducted to evaluate papersheets end-use properties. In comparison to the other pretreated CNF, due to is lower viscosity, applying periodate-oxidized CNF as size press significantly increased the mechanical properties of the papers fabricated from the recycled pulps. TUBITAK-TEYDEBTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [1505]; Scientific and Technological Research Council of Turkey, Technology and Innovation Funding Programs Directorate [1505, 5180044] This work was supported by TUBITAK-TEYDEB 1505 (The Scientific and Technological Research Council of Turkey, Technology and Innovation Funding Programs Directorate 1505), Project No. 5180044. WOS:000703585400013 2-s2.0-85108063350

Superhydrophobic surfaces have high potential in self-cleaning and oil-water separation applications. We developed a three-step method for the preparation of superhydrophobic filter paper. It involved citric acid (CA) pretreatment to activate cellulose fibers, coating with cellulose nanofibrils/functionalized silica (CNFs/m-SiO2) slurry to increase surface roughness, and grafting of hexadecyltrimethoxysilane (HDTMS) to enhance water resistance. The water contact angle (WCA) and siding angle (SA) of the prepared filter paper reached 151.5° and 7.5°, respectively. The results showed that, compared to the coated filter paper without the added CNFs, the coated paper with CNFs had higher retention of m-SiO2, thus roughness required for superhydrophobic surface was achieved. Further test under frequent abrasion and acid or alkali conditions showed that CA pretreatment improved the durability of superhydrophobic filter paper due to chemical crosslinking between the modified substrate and m-SiO2. Besides, the prepared superhydrophobic filter paper had outstanding self-cleaning property and high oil-water separation efficiency for various oil-water mixtures. Therefore, it is expected to be used for the treatment of oily wastewater.

The in-situ synthesis of calcium silicate in the fiber can not only meet the requirements for high loading of paper, but also make up and improve the reduction of paper performance caused by filling. In this investigation, the effects of pulp type, beating degree, fiber ratio, reaction time, rotational speed, dosage of lime milk and dispersant on calcium silicate loading and paper properties were investigated. The results showed that when the beating degree was 40 °SR, the ratio of softwood and hardwood pulp was 1:1, the reaction time was 60 min, the rotation speed was 600 r·min−1, the dosage of lime milk was 1.33 times of the theoretical amount, and the dosage of cationic polyacrylamide was 0.3 % (absolutely dry pulp), the ash content of hand-made sheet was 41.2 %, and the loading amount of calcium silicate was 26.3 %. Under this condition, the comprehensive performance of paper was the best.

Cellulose nanofibers isolated from unbleached pulp are characterized by different surface properties due to presence of lignin at their surface, in addition to lower cost than isolated from bleached pulp. In the current work, the effect of cellulose nanofibers isolated from unbleached neutral sulfite and bleached soda rice straw pulps (so called UBCNF and BCNF) on improving paper sheet properties of unbleached and bleached rice straw pulp (so called UBP and BP) was studied. The effect on mechanical properties (tensile strength, burst strength, and tearing resistance) and physical properties (porosity and water vapor permeability) was studied. Scanning electron microscopy (SEM) was used to assist in explaining the obtained results. The result showed that using BCNF and BP resulted in better improvement in mechanical properties and also more effective in reducing porosity of paper sheets than in case of using UBCNF and UBP. These results indicated stronger bonding between nanofibers and pulps’ fibers in case of using BCNF and BP (surfaces rich in cellulose hydroxyl groups) than in case of UBCNF and UBP (surfaces rich in lignin). Water vapor permeability of paper sheets made from unbleached or bleached pulps did not significantly affect by the addition the nanofibers.

The work presented in this paper is focussed on study of structure and properties of coating layers based on natural pigments (ground calcium carbonate and clay) and butadiene acrylonitrile latex as binder in correlation with functional properties of the final coated paper. It is quantified the influence of binder content and pigment type on the structural and liquids penetration properties of coating layer. The obtained results confirm that by increasing of binder content in the coating formulations a reduced efficiency of light-scattering and increased roughness for coated surfaces is obtained. At the high binder amounts (over 15 pph), the coating layer porosity is reduced and as result a lower liquids penetration in the coated papers is obtained.

With the increasing popularity of coated paper, it has been more widely used in printing, publishing, product packaging and commercial promotion. However, coated paper is prone to cracks after printing and folding which exposes to a white area which is referred to as fold cracking. This study investigated the coating properties of paper and coating factors influencing the fold cracking and aimed to provide guidance on how to reduce the problems of fold cracking. This paper mainly discusses the effects of pigment proportion, binder dosage, solids content, coating thickness and calendering pressure on fold cracking of coated paper after printing. Experiments show that when the coating consisted entirely of calcium carbonate, the degree of fold cracking is most serious. With the addition of kaolin, the fold cracking reduces. When the ratio of the number of parts of calcium carbonate to kaolin is 25/75, the area of fold cracking reaches its minimum value of 10.28 %. With increasing solids content of the coating, the fold cracking decreases initially and then increases. When the solids content is 55 %, the fold cracking reaches a minimum. Increased latex content reduced coating thickness and an increase in calendering pressure gradually reduce the degree of fold cracking.

The paper corrugation tube is an innovative kind of energy absorbing structure and shock absorber which can play an important role on the cushioning energy absorption for airdrop equipments and transportation packaging. The deformation characteristics and failure modes of the regular triangle, quadrangle, pentagon and hexagon paper corrugation tubes were comparatively studied by a series of axial static compression experiments, the cushioning energy absorption was evaluated by the seven characteristic parameters (e.g. initial peak force, mean crush force, total energy absorption, specific energy absorption, crush force efficiency, unit area energy absorption and stroke efficiency), and the influences of tube direction, cross-sectional shape, tube length and compression rate on failure modes and cushioning energy absorption were analyzed and compared. These researches showed that the tubes along X direction only have the accordion deformation mode, yet the tubes along Y direction have four deformation modes including steady state progressive buckling, Euler buckling, angular tear and transverse shear. For the paper corrugation tubes along Y direction, the cross-sectional shape has obvious influence on the cushioning energy absorption of structures, and the specific energy absorption and unit area energy absorption of regular triangle and pentagon tubes are better than those of the tubes with regular quadrilateral and hexagonal cross-section at compression rates of 12 and 48mm/min. The tube length of 150 mm or compression rate of 72 mm/min would cause the increase of contribution proportion of non-ideal deformation mode and the decrease of cushioning properties. The paper corrugation tubes along X direction have more stable and controllable deformation mode, yet the paper corrugation tubes along Y direction have better cushioning energy absorption.

Polylactic acid fibrils (PLAf) were employed as a fiber component in papermaking. The addition of 5 wt % of PLAf to bleached kraft birch pulp increased the tensile index of the resulting 100 g/m2 paper sheets by 20 % in comparison to sheets produced without PLAf. By heat-treating the paper sheets containing 5 wt % PLAf, a 35 % higher tensile index in comparison to sheets produced without PLAf was achieved. SEM imaging showed that the heat-treatment caused the PLAf to melt, which formed a film on the fiber web. The PLAf was ultrasonicated in an attempt to make its surface more hydrophilic and anionic and thus more compatible with cellulose. Chemical additives (cationic polyacrylamide, polyethylene imine and polyethylene glycol) were added to the PLAf/cellulose pulp mixture in order to increase the binding between the ultrasonicated PLAf and cellulose. Ultrasonication caused the PLAf length to decrease and the PLAf surface charge changed by 36 %, indicating that the PLAf became significantly more anionic. Neither ultrasonication of PLAf nor the chemical additives improved the paper sheets’ stretchability. Polyethyleneimine as an additive in an amount of 1 % increased the tensile index of heat-treated sheets made with 5 wt % of PLAf by 19 %.

This study analyzed the effect that pulp fibers have on the surface softness component of hygiene paper. The surface softness component has more of an influence on the evaluation of subjective softness results than the bulk softness component. Using the surface softness measurement technique, this study aimed to evaluate the effect that fibers have on the softness of hygiene paper substrate via objective numerical values to measure the surface softness component of hand sheets composed of various pulp species. The results indicate that coarseness effects had the largest effect on softness among the various fiber characteristics, such as average fiber length, width and coarseness. As fiber coarseness increased, a rough surface formed, which resulted in an increase in the mean deviation from the average friction (MMD). Nonwood fibers had long fiber length and low coarseness, which enables the production of hygiene paper with high strength and softness. This study hopefully could lead to the development of various process technologies that may improve the softness of hygiene paper products.

The inorganic core-shell pigment CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} was synthesized using a sol-gel method, and the pigment was applied as a surface coating on inkjet paper to study the influence of inorganic core-shell pigments on the dynamic permeability, surface properties, optical properties and inkjet-printing performance of coated paper. CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} prepared using carboxymethyl cellulose (CMC) had better coverage than that prepared using polystyrene sodium sulfate (PSS) dispersant. The CMC-prepared CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} -a had improved dispersibility, and the solids content of the coating reached 35 %. Inorganic core-shell pigments improve the surface and optical properties of the coated paper, making them similar to those of a reference calcium carbonate-coated paper. The smoothness and gloss improved by 60.8 % and 78.4 %, respectively, compared with those of silica-coated paper. The inkjet solid density and dot definition increased by 28.8 % and 4.1 %, respectively, compared with those of the calcium carbonate-coated paper. Preparing inorganic core-shell pigment CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} is an effective method to fabricate inkjet printing coatings with advantageous microstructures for ink absorption.

The use of clay filler materials in dispersion coatings is a well-established method to provide improved barrier properties to the coated paper substrate, in particular lowering the water vapour transmission rate (WVTR) through the coating. In this paper we demonstrate the use of small spherical silica particles (∼100–220 nm) as an additive to a clay-latex coating formulation is able to provide further improvements to the barrier properties, when compared to the equivalent silica-free coatings. A significant decrease in both the water vapour transmission rate and the direct water uptake of water ( Cobb 120 {\text{Cobb}_{120}} wettability test) is observed for coatings containing as little as 1 % silica additive.

This study is the first, to the best of our knowledge, where waste napkin paper was successfully valorized to low-density (27.2 mg cm−3) cellulose aerogels for oil sorption material. Two simple methods with different gel coagulators, ethanol and sulfuric acid, were used for preparation of the aerogel. Conditions for the alkaline treatment of the raw material and the pre-freezing temperature in the lyophilization process were optimized. It was found that the water and oil sorption capacities of the aerogels were not significantly affected by alkaline treatment, while they could be adjusted by changing the pre-freezing temperature. Although the produced aerogels were initially amphiphilic, hydrophobic surfaces were obtained by vapor deposition of methyltrimethoxysilane (MTMS) and these materials possessed high sorption capacities, up to 32.24 cm3 g−1 (28.56 g g−1) for pump oil and 26.77 cm3 g−1 (39.59 g g−1) for chloroform. This was comparable to aerogels prepared from fresh cellulosic materials via the sol-gel method, as their sorption capacities varied in the range of 14–45 g g−1.

The paper corrugation tube is an attractive and innovative mode of cushioning protection and energy absorption for the general protection and packaging technology of military and civil products. The aims of this paper focus on the dynamic compression characteristics of four kinds of regular polygonal paper corrugation tubes under the conditions of axial drop impacts, and the influence rules of structural parameters and load parameters on the dynamic cushioning energy absorption. The results show that, the tube direction has a crucial effect on the deformation mode of the paper corrugation tubes, the deformation of X-direction paper corrugation tubes has a stable accordion mode, but that of Y-direction paper corrugation tubes is a mixture of steady progressive buckling and other non-ideal modes. The X-direction paper corrugation tubes have lower peak stress, stable and controllable deformation mode with multiple folds, and higher total energy absorption, unit area energy absorption, specific energy absorption and stroke efficiency than the Y-direction paper corrugation tubes. Moreover, the change of cross-section shape of X-direction paper corrugation tubes has no obvious influence on the total energy absorption, while the total energy absorption of Y-direction paper corrugation tube obviously rises with the increase of the number of cross-section edges of the tubes, but the unit area energy absorption, specific energy absorption and stroke efficiency decrease with the increase of the number of cross-section edges of the tubes. Moreover, the increase of the number of cross-section edges of the tubes made the total energy absorption of Y-direction tubes rise, while the total energy absorption of X-direction tubes has no obvious change. But the unit area energy absorption, specific energy absorption and stroke efficiency decrease with the increase of the number of cross-section edges of the tubes. Furthermore, the tube length, impact block mass and impact energy have also important influence on the cushioning energy absorption of the paper corrugation tubes under axial drop impact.

Effects of alkali swelling of kraft pulp fibers and the order of alkali swelling and beating treatments on paper bulk and paper strength were evaluated in terms of NaOH concentration in order to produce high bulk sheet (i. e., high porous and low density sheet). Effects of replacement of part of furnish with the alkali swollen pulp on paper properties were also investigated. It was found that alkali swelling of pulp fiber can increase the bulk of handsheet. NaOH concentration and beating treatment influenced paper bulk and paper strength. Alkali swollen pulp without beating showed the highest handsheet bulk. The paper bulk of alkali swollen pulp with pre-beating was higher than that with post-beating. Paper strength decreased with increasing the bulk of handsheet. In addition, replacement of part of furnish with alkali swollen pulps increased paper bulk, adversely decreasing paper strength. The highest improvement in paper bulk was achieved with the addition of alkali swollen SwBKP without beating.

Paper surface hydrophobization, also referred to as .surface sizing., is often necessary for printing and packaging purposes. Typically, hydrophobic polymeric nanoparticles, in combination with starch are applied on the paper surface at the dry-end of the paper machine. In the surface sizing process, the nature of the nanoparticles, starch type, starch concentration and ratio between starch and nanoparticles, paper quality, ionic strength, and application as well as drying temperature are parameters that influence the result. The aim of this work was to systematically evaluate these parameters in order to create knowledge to be used for optimization of the process. Laboratory scale surface sizing trials were performed and the results from the trials showed that cationic particles gave superior performance compared to anionic particles. Both the starch type and the concentration of the oxidized starch had an impact on the performance. The effect of the ionic strength was found to depend on the particle charge: for cationic particles, the addition of salt was detrimental while for the anionic particles it was beneficial. An increase of the application or the drying temperature was found to enhance the performance up to a temperature around the glass transition temperature of the polymer.

Aqueous cleaning of works of art on paper is one of the most important and delicate steps in a conservation process. It allows the removal of inorganic (metals) and organic substances, such as degradation products and other contaminants. These substances are responsible for yellowing, weakening, and loss of mechanical properties of paper. In this article, the cleaning effect of gellan gum was assessed on xuan paper, a traditional Chinese paper different in composition and papermaking technology compared to many Western papers. To assess the effect of gellan gum on xuan paper, its characteristics were studied before and after cleaning utilizing non-invasive and micro-invasive techniques. Results were compared to those obtained when treating Western papers and indicated that gellan gum can be applied effectively for aqueous cleaning of xuan paper.

Precious organic cultural relics are easily affected by temperature, humidity, and harmful gases in the environment, resulting in embrittlement, fading, mildew, moth damage and other aging forms. An energy-saving and environmentally friendly material is needed to stabilize humidity and adsorb harmful gases in the environment. In this paper, with an intelligent adjustment function, functional paper containing sepiolite and tourmaline natural minerals was successfully prepared. The component of 80 % of wingceltis and 20 % of straw in dry pulp as main raw material was conducive to the desorption of water molecules. As favorable structure inside functional paper, the adsorption point and the adsorption contact area increased by the rough surface of fiber bundles, the addition of sepiolite and the ordered molecular chains of copolymers destroyed. So, the relative humidity could be adjusted to 55 % ± 3 within 2 hours and was stable with functional paper. At the same time, 1.11 ppm sulfur dioxide and 2.98 ppm ammonia could be effectively adsorbed in 10 and 12 h, respectively, by 1 g of paper in a 5 L container. The pH of the paper was adjusted to neutral with tourmaline, even if the pH was changed by acidic or alkaline gas absorption. Therefore, for long-term organic cultural relic preservation, preparing a constant-humidity and clean environment is of great significance. This is possible through this paper.

The effect of paper properties on the strength of starch gluing for Kraft sack papers has been investigated. We analyzed the effect of surface roughness, wettability and glue penetration. Surface roughness was found not to be related to gluing strength, also surface wetting measured by contact angle showed only a weak relation. Liquid penetration measured by ultrasound (ULP) was found to have a substantial correlation to gluing strength. Comparing ULP liquid penetration speed with actual glue uptake during the gluing process we found that they are only moderately connected. We are attributing this to the fact that the penetration and spreading of the glue on the paper is driven by applying an external pressure during the gluing process, which is not the case for the liquid penetration measurement. Investigating how asymmetrical glue penetration affects gluing strength we found that the relationship was low. The best indication for gluing strength turned out to be the surface wetting/substrate swelling parameter from the ultrasonic liquid penetration measurement. We conclude that the main parameter capturing gluing strength combines the influence of fiber wetting and penetration of the glue into the fibers.

In this investigation, softwood pulp and bleached wheat straw pulp were used as raw materials, and Calcium Sulfate Whiskers (CSW) were used as fillers. Based on the structural properties and characteristics of CSW, the printing properties of the paper with CSW, such as whiteness, opacity, pH value, uniformity, Z-direction tensile strength and surface strength, were analyzed. The results showed that CSW has low solubility, high retention and fiber-like appearance. The whiteness of the paper is the best when the filling amount of CSW is 20 %. The paper opacity of softwood pulp increases significantly, and the opacity of bleached wheat straw pulp decreases significantly when CSW is more than 30 %. The addition reduces pH and surface strength of the paper. The evenness of the paper does not change obviously. The Z-direction tensile strength of the paper decreases in the softwood paper, but increases obviously in the bleached wheat straw paper.

Paper is an environmentally friendly, recyclable material whose main material is cellulose, which can be obtained from all kinds of trees and plants, used as writing, printing and packaging material. Due to its structural properties, papers are not resistant to temperature and humidity, as well as problems with ink transfer with its porous structure and experienced negative printability properties. In recent years, especially the growth of the packaging industry has increased the demand for papers with improved printability properties. In order to obtain better printability properties from papers, some processes can be performed in paper production, as well as some surface treatments after production. These processes are paper coating, sizing and calendering. Paper coatings are generally water-dispersed coating solutions with one or more pigments, binders and certain additives to improve the desired properties. With these processes, by filling the gaps between the pores of the paper, a shapely and smooth surface is obtained and good printability is obtained together with the optical and physical properties of the papers. In this study, the interactions and printability properties of different types of pigments with xanthan gum binder were investigated by preparing paper coating formulations using calcium carbonate, barite and talc pigments and xanthan gum as binder. As a result, xanthan is a good coating binder and CaCO 3 {\mathrm{CaCO}_{3}} from the compared pigments is the most suitable compared to the other 2 pigments, considering all the studied areas.

Coated paper with enhanced barrier properties was prepared via a simple layered self-assembly method using hemicellulose and starch as biobased coatings. Effect of the coating on properties of cellulose paper was investigated. Barrier properties of the paper was increasingly strengthened as the coating amount of hemicellulose rose. When the paper was coated with starch (10.7±0.3 g / m 2 \text{g}/{\text{m}^{2}} ) and hemicellulose (6.9±0.2 g / m 2 \text{g}/{\text{m}^{2}} ) successively, the oil resistance of the paper was increased from 0 to grade 7. Air permeability and water vapor transmittance was decreased by 93.8 % and 39.7 %, respectively. The water contact angle of the coated paper reached 91.7° when the amount of hemicellulose was 1.5±0.2 g / m 2 \text{g}/{\text{m}^{2}} . The hydrophobicity of the coated paper was superior to the original paper although it was negatively influenced by the increasing amount of hemicellulose. The improvement of barrier properties of the coated paper was mainly ascribed to the formation of a thin polymer network on paper surface through intermolecular interaction via hydrogen bonds as demonstrated in SEM and FTIR-ATR results. Moreover, tensile strength and rupture resistance of the coated paper was improved. The results offered an environmentally friendly and economical strategy for preparation of food packaging paper with good barrier properties using biobased coating materials.

In this paper, white pixel percentage (WPP) value, as an overall measure of fold crack damages, has been analysed with respect to selected parameters of sample preparation and digitalization process, as well as the results of residual tensile strength. The WPP values were derived by an automated image processing algorithm, developed earlier, based on extensive comparative analysis of the existing computer-aided methods. Results indicate that WPP values correlate well with the extent of fold cracks on the coated samples, as far as the used parameters of sample preparation and digitalization are concerned. In the case of correlation with residual tensile strength, results for samples folded in cross direction revealed that the extent of the visually registered fold cracks agree well with the actual damage, while for samples folded in machine direction, the overall strength losses weren’t alarming, although the fold cracks were detected correctly. In addition, results pointed out that the simplest sample placement position (inner angle of 180°) is not applicable for realistic sample representation. Furthermore, scanners could provide a superior image quality in lab conditions, but for industry application, a camera-based solution would be more purposeful, while micrographs are more suitable for traditional visual analysis.

International audience; A layer of Micro Nanofibrillated Cellulose (MNFC) was added during the formation of TMP paper to create a z-structured paper. A MNFC layer was added either on the top or in the middle of the thickness of a TMP sheet using a Dynamic Sheet Former. The MNFC layer basis weight was varied from 2 to 20 g.m-2 for a final paper basis weight of 60 g.m-2. 3D images of the paper structure were obtained by Synchrotron X-ray microtomography, showing that localized MNFC fibrils were retained in the paper structure. The small dimensions of CNF, particularly in width, and the presence of the calcium carbonate in the MNFC layer permit to clearly differentiate the TMP fibers from the MNFC fibrils. The porosity profiles for 100% TMP sheet and 100% MNFC film present a constant internal bulk porosity at about 75% and 38%, respectively. Porosity profiles of the z-structured paper display the presence of 2 or 3 different porosity zones in the internal bulk region. These results confirm the possibility to design papers with targeted porosity gradients in the z-direction without paper post treatment.

Pigments are often used in water borne barrier coatings but tend to make the coatings prone to failure. The pigment properties effects on this issue is lacking in literature. In this work, coatings that used pigments with different moduli but with similar size and aspect ratio were characterized in terms of water vapor resistance before and after folding. Coatings with talc had better water vapor resistance than coatings with similar sized kaolin. Talc also limited the degradation of barrier properties when folded. Coatings with metalized poly(ethylene terephthalate) (PET) flakes had better failure resistance than coatings with similarly sized rigid mica. Both results are likely caused by the ability of the low modulus pigment to deform and allow for strain to occur in the pigment as well as the latex phase. Styrene-butadiene (SB) and natural rubber (NR) latex coatings had a better failure resistance than styrene-acrylate (SA) latex, which is likely due to their low glass transition temperatures and high strain-to-failure values. However, coatings with high amounts of SB or NR latex may lead to blocking issues in production. Adding kaolin into SA and SB latex mixtures resulted in improved water vapor barrier property and failure resistance.

Paper has been the most significant carrier of written information for many centuries. To prolong the life expectancy of papers, the polyurethane based on nanosilica was used to strengthen the paper fibers in this work. The relation between the mass concentration of polyurethane based on nanosilica and the specific properties of papers (e. g., folding endurance, tensile strength, tearing strength, whiteness and glossiness) were investigated. In addition, the effect of polyurethane based on nanosilica on the acid/alkali resistance and ageing resistance were studied. The results showed that polyurethane based on nanosilica could significantly improve the mechanical properties and ageing resistance of papers.

Paper has a high value of culture, history and scientific research as the cultural carrier of historical inheritance. However, with the passage of time and the change of environment, many paper files are aging and damaged. Therefore, it is of great significance to carry out the protection of paper archives. Chitosan, a natural material, has a good compatibility with paper fibers. In this paper, chitosan (CS) was modified by epoxy cyclohexane (CHO) and methyl methacrylate (MMA) to prepare CS-CHO-g-PMMA emulsion. CS-CHO-g-PMMA was applied to paper protection, and the effects of CS-CHO-g-PMMA on heat aging resistance, reversibility and acid-base resistance were investigated. In order to improve the mechanical strength of paper, CS-CHO-g-PMMA and phosphate ester starch (HPDSP) were blended to determine the optimum ratio. The results showed that the degradation rate of paper sample was slowed down obviously and the coating had certain reversibility. Acid-base resistance experiment showed that CS-CHO-g-PMMA could effectively resisit corrosion of external acid-base to protect the paper. The best combination ratio between CS-CHO-g-PMMA and HPDSP was: m (CS-CHO-g-PMMA): m (HPDSP) = 5:2. Under this compound ratio, the performance indexes of the paper met the requirements, conforming to the “repair as old, keep the original” and other requirements.

The present work reports on a method for the determination of hydrophobic degree of paper packaging material by tracer-assisted headspace gas chromatography. The method was based on adding 40 μL of methanol-water drop on the paper surface for 20 s. After removing the excess water by turning the sample vertically, the sample is placed in a vial and the amount of residual tracer attached on the material surface was accurately quantified by full evaporation headspace gas chromatography. The results show that the present method has a good precision (less than 4.1 %). The present method is simple and accurate and it can be an efficient tool for testing the hydrophobic degree of paper packaging material in batch.

This work has been conducted to investigate the effect of accelerated ageing on the filler-free (control) handsheets and the ones having Precipitated Calcium Carbonate (PCC) and Zeolite (Clinoptilolite) fillers. The diagnosis approach of this work has been based on the use of the techniques of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD). The FT-IR technique has allowed identifying the changes in cellulose components of handsheets. Likewise, the XRD technique has provided to diagnose the changes in crystallinity of the handsheets and fillers. The results found out that PCC and Zeolite fillers could be easily added to the structure of the paper network by changing various experimental variables. The loss of C−O functional groups and the formation of carbonyl groups in handsheets has been analysed by accelerated ageing. The spectroscopy results confirmed that usage of zeolite filler has a retarding and structurally improving effect on the glycosidic linkages. Recent findings have been provided new insights into the role of the synergistic effect of the combination of PCC and zeolite fillers in the decelerating of certain ageing mechanism.

In this study we have recycled two types of waste papers, newspapers and magazines, to prepare paperboard sheets for multipurpose applications. The recycling procedure succeeded in removing most of inorganic contaminants via de-inking process. To enhance the flame retardant ability of paperboard sheets, treatment with varying concentrations (1, 3 and 5 % wt/vol) of organophosphorus-silane compound in the absence and presence of starch (0.2 % wt/vol) was done. The thermal proofing properties of paperboard sheets have been modified after treatment with organophosphorus-silane compound and starch/organophosphorus-silane biocomposite. The results showed that, 3 % (wt/vol) was the minimum concentration to accomplish fire retardancy of paperboard sheets. The addition of starch to the organophosphorus-silane compound enhances the physicomechanical properties of modified paperboard sheets. The paperboard sheets treated organophosphorus-silane compound and starch/organophosphorus-silane biocomposite showed dissimilar activities against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Various analyses were performed to study the physical, chemical, mechanical and thermal properties of the prepared paperboard sheets.

The crystallinity indices (CrI) of Chinese handmade papers were investigated using the X-ray diffraction (XRD) method. Four Chinese handmade papers, Yingchun, Zhuma, Yuanshu and Longxucao papers were used as model substrates of mulberry bark, ramie, bamboo and Eulaliopsis binata papers, respectively. Two forms of the paper samples, paper sheets and their comminuted powders, were used in this study. The results showed that their XRD patterns belong to the cellulose-I type and Iβ dominates the cellulose microstructure of these paper samples. Moreover, it was found that the microstructures and CrIs of cellulose of these papers were changed by the grinding treatment. This work suggested that the sheet form of the handmade papers is suitable to determine CrI by XRD, despite the contribution of non-cellulosic components in the papers. The order of CrIs for these paper sheet samples was Yingchun, Zhuma, Longxucao and Yuanshu papers. Besides CrIs, differences in cross-sectional areas of the crystalline zone of cellulose can be used for comparing different types of handmade papers. It was also found that the CrIs and crystallite size of paper cellulose varied between the sheet samples and the powder samples, illustrating that the pulverisation has a negative influence on the microstructure of the handmade papers.

Theft of archival documents constitutes a serious problem for archives. A possible solution to this problem lies in labelling these documents with codes that are invisible to the naked eye. A possible method could involve use, e.g. of the oxides of lanthanum, dysprosium, samarium, gadolinium and niobium, which have good responses in the XRF spectrum and are normally not present in archival materials. This study is concerned with the impact of these oxides on the properties of lignocellulosic materials. The identification tags were printed on three different kinds of paper supports (Whatman No. 1 filter paper, paper according to ISO 9706 and sulphite pulp). The colour change, average degree of polymerisation, the pH values of an aqueous extract and selected mechanical properties after application of the tag and artificial ageing were studied on all the samples. The measurements showed that the studied oxides do not have a negative effect on the monitored properties of the paper supports and do not affect their long-term ageing behaviour.

Carbon nanotubes (CNTs) were successfully prepared using chemical vapor deposition method on nickel-coated silicon substrates. The CNTs were then modified to obtain functionalized ends. Afterward, acrylate polymers were successfully grafted on the surface of CNTs by atom transfer radical polymerization method. The synthesis process was optimized by studying the surface properties of the composite films. It revealed the existence of chemical bonding between CNTs and polymers. The introduction of CNTs into polymers could improve the water resistance of films. Micro/nano and papillary structures similar to that of lotus leaf were obtained when the polymer matrix was partly etched. The excellent fluid drag reduction performances of film surfaces were expected to be applied in microfluid devices and packaging field.

This article focuses on the properties of paper samples made using foam-laid technology. The effects of three surfactants, namely sodium dodecyl sulphate (SDS), sodium alkyl ether sulphate (SAES), and linear chain alkyl polyglucoside (C8/C10-Gluc), on properties of foam formed paper samples were studied, using chemithermo-mechanical (CTMP) spruce pulp and bleached kraft pulp. The results show that the type of surfactant used in foam forming has significant effects on the mechanical properties and quality of paper. In the presence of ionic polymers, the charge of surfactant has a significant effect on the formation of the paper sample. It was also shown that at AKD dosages ≥ 3 kg/t, the water absorbency of water formed paper samples was greater than that of foam-formed samples made using C8/C10-Gluc. Foam-forming also produced greater dryness after forming and wet-pressing than the water forming method. The type and dosage of surfactant had a significant impact on dewatering. Filler retention of foam-formed samples was significantly higher when using a non-ionic surfactant instead of an anionic surfactant. The effect of the strength additive (cationic starch) in increasing the strength of foam-formed samples was less in the presence of anionic surfactants than with non-ionic surfactants.

Durable papers should exhibit high mechanical strength and good soiling resistance. In this study, cellulose nanofibrils (CNF) was investigated as an additive to the polyvinyl alcohol (PVA) impregnation solution to improve the durability of paper. The impregnation suspensions were prepared by adding CNF to PVA solution in various ratios, and were used to impregnate a base paper. The PVA-CNF suspensions exhibited good dispersion stability; however, the low shear viscosity increased as its CNF content increased. The pickup weights of the papers impregnated with the PVA-CNF suspensions were found to be lower than those of the control sample, which were impregnated with the pure PVA solution only. Although the strength of the paper was not significantly improved by the addition of CNF, when the paper was impregnated with a PVA-CNF suspension containing 5 % CNF content, the product exhibited similar strength to the papers impregnated with only a 3 % PVA solution despite its lower pickup weight. The mechanical strength of the impregnated paper was affected by the pickup weight and penetration of the impregnating agent. The addition of a wet strengthening agent to the mixed suspensions was seen to enhance the wet soiling resistance of the papers.

For the mechanical properties of paper, tensile testing has been widely used. Among the tensile properties, the tensile stiffness has been used to determine the softness of low-density paper. The lower tensile stiffness, the greater softness of paper. Because the elastic region may not be clearly defined in a load-elongation curve, it is suggested to use the tensile modulus which is defined as the slope between the two points in the curve. The two points which provide the best correlation with subjective softness evaluation should be selected. Low-density paper has a much lower tensile strength, but much larger elongation at the break. It undergoes a continuous structural change during mechanical testing. The degree of the structural change should depend on tensile conditions such as the sample size, the gauge length, and the rate of elongation. For low-density paper, the tensile modulus and the tensile strength should be independent of each other. The structure efficiency factor (SEF) is defined as a ratio of the tensile strength to the tensile modulus and it may be used a guideline in developing superior low-density paper products.

A 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.

Increasing 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.

Cellulose fibers swell significantly in NaOH/urea solutions, and swelling increases with a decrease in temperature and an addition of urea. The combined effects of the factors of a pretreatment procedure (sodium hydroxide concentration, urea concentration, temperature, and time) and post-treatment conditions (medium, stirring speed, and time) of preparing fibers on the properties of pulp and the resulting paper sheets were investigated and optimized using single factor experiments. The optimum sodium hydroxide concentration (1 %), urea concentration (8 %), precooling temperature 0 °C, pretreatment time (12 h), post-treatment medium (7 % ( NH 4 ) 2 SO 4 {({\mathrm{NH}_{4}})_{2}}{\mathrm{SO}_{4}} ), post-treatment stirring speed (1500 rpm), and time (30 min) were obtained. Under the optimal conditions, the water retention values and tear, tensile, and burst indexes increased about 54 %, 277 %, 394 %, and 98 %, respectively. This work demonstrates that this technical route can effectively improve fiber swelling capacity and paper strength.

Surface characterization is important and has many applications in the paper industry. It includes both surface roughness and surface friction. In determining the surface roughness of paper and paperboard, non-contact methods such as air-leak methods In characterizing the surface roughness of paper and paperboard, it has been a common practice that the average roughness with the coefficient of variation (COV) has been conventionally determined. This practice, however, this runs the risk of drawing wrong conclusions since two different surfaces having the same average roughness and COV can exhibit totally different properties. To avoid such mistake, a stylus-type contact method has been developed to determine surface roughness of paper and paperboard such as printing & writing (P&W), kraft and liners. In this method, surface roughness profile has been generated to determine its variability which has been defined as the mean deviation from the roughness average, referred to as MDRA. In determining the MDRA, it is noted that thickness measurement is not required. In this method, stylus shape and size, contact force of the stylus to the surface, scan speed and resolution have been identified as the key parameters of generating stable surface roughness profiles. It has been further identified that the optimal conditions on these parameters should depend on paper grade. It is suggested that a stylus-type contact method should be used to determine surface roughness of paper and paperboard to help determine their practical applications such as printing, coating and embossing.

Surface characterization is important and has many applications in the paper industry. Surface characterization requires both surface roughness and surface friction. The relationship between the two has not been fully established for paper and paperboard. It has been a common practice that only the average property and the standard deviation with the coefficient of variation (COV) are reported for surface roughness and friction measurements. This practice, however, provides few information on surface structure and can lead to wrong judgments because two samples having the same average and the COV can have different physical properties. To avoid such mistake, a new surface characterization method has been developed. To this end, surface roughness- and friction-profiles have been obtained using a latest version of Kawabata surface tester (Model: KES-SESRU, Kato Tech, Kyoto Japan). This new version uses the same stylus for both measuring surface roughness and friction under the same operating conditions. It was found that a correlation between the surface roughness and surface friction was very low. This indicates that they should be independent of each other. Therefore, both should be determined for surface characterization.

Due to the micro-sized pores on cellulosic substrate surface and the hygroscopic nature of cellulosic fibers, paper has poor barrier properties. Dispersion coating can improve the barrier properties of cellulosic paper noticeably by forming a continuous, non-porous polymer film on paper surface. In this work, the excellent film-forming performance of polyvinyl alcohol (PVA) was used to seal the surface pores of paper, thus enhancing the barrier properties. Alkyl ketene dimer (AKD) was also added as a coating component to improve the water resistance of paper. Results showed that after PVA/AKD coating hydrophilic base paper changed to hydrophobic one, as proved by water contact angle (WCA) measurements. The water vapor transmission rate (WVTR) of base paper decreased sharply from 543 g/m2·day to 2 g/m2·day in the case of PVA/AKD triple coating, where the threshold of WVTR was reached. Meanwhile, the pristinely non-grease resistant base paper converted to a product with the highest grease resistance level. Furthermore, both elongation at break and tensile strength of base paper improved markedly after PVA/AKD coating. It was concluded that these improved properties were contributed by the combined use of PVA and AKD in the coating.

The potential use of sago pith waste, bamboo, and water hyacinth based on the characteristics of raw materials to make liner paper were studied. The analysis conducted covered the analysis of physical characteristics, chemical components, morphology (SEM), functional groups (FTIR), and crystallinity (XRD). The pulp from the three kinds of fiber was molded into paper with a certain formulation. The parameters of pulp and paper observed covered the alkaline consumption, Kappa number, pulp yield, and paper physical characteristics (grammage, bursting strength, Ring Crush Test/RCT, water content, and water absorption). The chosen paper was the paper whose characteristics resembled the quality parameter of liner paper used by the paper industry and the standard in accordance with the Indonesia’s National Standard (SNI) 14-0095-1996. The microscope images showed that the three said raw materials have long fibers: sago pith waste and water hyacinth has fibers measuring respectively 1.89±0.90 and 2.07±0.39 mm, resembling hard wood, whereas bamboos have longer fibers measuring 4.61±0.72 mm, resembling soft wood. Bamboos have the best fiber composition and characteristics for pulp and liner paper. The two paper formulas that meet the criteria for liner paper are bamboo and bamboo+water hyacinth.

Paper relics are important historical and cultural heritages. However, the paper relics are at risk of ageing, damage and disappearance. In order to delay the aging of paper, improve the strength of paper, solve the problem of poor permeability and stability of traditional resins to paper, the polyurethane was synthesized by polydimethylsiloxane (HTPDMS) and low molecular weight hexamethylene diisocyanate (HDI) trimer, and the chemical and physical properties of paper samples were tested. Results showed the paper coated by HTPDM-modified polyurethane liquid had good mechanical property, the tensile strength was increased from 1105 to 3299 N/m, the folding endurance was increased from 20 to 1024; and had good gloss and brightness; after thermal aging, coated paper can effectively maintain tensile strength, delay folding resistance and tearing strength loss; after acid stability test, the loss ratio of tensile strength was decreased from 34.2 % to 15.7 %, folding endurance was decreased from 57.1 % to 9.7 %; after alkali stability test, the loss ratio of tensile strength was decreased from 29.3 % to 6.6 %, folding endurance was decreased from 82.9 % to 22.0 %. Therefore, the prepared polyurethane material has great application prospects in the protection of paper.

Paper has a crucial impact on the qualitative properties of printed product as properties of the paper’s surface directly impact the ink transfer, consequently, basic optical properties of the print. Although same ISO paper type, papers possess variable surface properties leading to different influence on the ink transfer. The aim of this research was to analyse influence of the surface properties of the paper, including surface free energy, smoothness and gloss of some standard papers used in lithography on the ink transfer while matching the colorimetric values defined by ISO 12647-2:2013. Determination of amount of the ink transfer, optical density, mottling and colour difference of prints were performed to evaluate paper-ink interactions. Results have shown that produced prints differ in the investigated properties. Furthermore, there are significant correlations between the surface free energy of the paper and paper smoothness and the ink transfer. In addition, amount of ink used to produce a standardized print varies for different paper types (even in the same ISO paper classification), meaning difference in ink costs. This research proved the high influence of paper’s certain parameters on the ink transfer by strong correlation coefficients. This enables better process control and optimization of the printing.

Food packaging is the most important output of the printing industry. Giving antibacterial effect to the papers used in food packaging will extend the shelf life of the product and food transfer in healthier conditions. The nanoparticles with known antibacterial activity are nanosilver, nanogold, nanosilica. Binders used in paper coating provide a good nutrient medium for bacteria. In this study, Ag nanoparticles was first synthesized as monodisperse in 10 nm size with polyvinyl pyrrolidone and sodium boron reaction which will give antibacterial properties to paper coatings. The chemical structure of the synthesized Ag nanoparticles is illuminated by fourier transform infrared spectrophotometer (FTIR). Different paper coating formulations containing varying amounts of Ag nanoparticles were prepared with starch binder. Using these mixtures; papers coated with a laboratory-type paper coating machine onto 80 g/m2 paper. Color, gloss, contact angle, surface energy, antibacterial properties of the paper against the E. coli bacteria and S. aureus bacteria were examined. As a result, Ag nanoparticles has been successfully synthesized and used in paper coating. Antibacterial and printability properties were improved by increasing the amount of Ag nanoparticles.

Surface sizing chemical (mostly oxidized or enzymatically modified starch) flows into the pores of cellulose network and also remains on the surface affecting the surface and intrinsic properties of paper. Polyvinyl alcohol (PVA) can be used for surface sizing because it is a water soluble polymer and has high film forming ability. Due to economic constraints, using PVA alone for surface sizing is not a good option. Current study explored the effects of using oxidized starch and PVA in mixed ratios (80:20, 50:50 and 20:80) on mechanical and surface properties of paper. The surface sizing with sizing weight of 3.5±0.3 g/m2 was done. The results of the study showed that the breaking length, burst index, air permeance, gloss, Cobb60 and optical properties like brightness, whiteness, flouroscence of paper were better for mixed ratios in comparison to only oxidized starch. After surface sizing with PVA, the value of air permeance (time of air leak) was increased to 200 Gurley second in comparison to 9 only for base paper. Surface sizing with blends of oxidized starch solution and PVA solution i. e. 80S+20P, 50S+50P and 20S+80P increased the time of air leak by 900 %, 1455 % and 1788 %, respectively in comparison to base paper.

Chemical additives are used singly or in combination to impart functionality to hygiene paper (suggested). In particular, in the hygiene paper making process, dry strength agent, wet strength agent, softener, and other are widely used. The effects of chemical additives on the softness components were evaluated. In the case of surface softness, there was no change in MMD according to the addition of dry and wet strength agents. The MMD (mean deviation from the average friction of coefficient) was decreased by adding a softener, which is the purpose of its addition to the hygiene paper making process. The softness and wet strength were improved when the wet strength agent was added before the softener. In addition, lotion treatment was applied to the surface of tissue paper. The surface softness component of non-silicone-based lotion was similar or improved, which may overcome the problems of silicon-based lotion.

Developing engineered filler with special morphology to increase filler content and deliver paper desirable properties has been deserved much concern. In this work, two engineered calcium silicate fillers with different morphology, namely fly ash based calcium silicate (FACS), fibrous calcium silicate (FCS) were adopted to investigate the effect of filler morphology on paper properties, and natural wollastonite was used for comparison. It is found that FACS exhibits a wrinkled, porous surface while FCS reveals spherical agglomerates composed of needle-like particles. Physical tests demonstrated that in comparison with natural wollastonite with discrete shape, the aggregated porous structure of FACS and FCS showed noticeable improvement in bulk and opacity due to their high specific surface area (112 m2/g v.s 29 m2/g). At around 40 % filler content, the bulk of FACS and FCS filled handsheets increased 59.6 % and 43.8 %, respectively. The findings suggested that the engineered porous calcium silicate can be potentially used as paper filler in light weighted paper.