Search

Purpose: This paper aims to find a suitable solution to treat the solidification paper by using hydroxypropyl cellulose (HPC) to improve the mechanical, physical and chemical properties of paper. Design/methodology/approach: The samples have gone several stages, starting with the manufacture of paper from the linen pulp and the same components of the hardened manuscript papers. It was subjected to artificial aging to reach an age comparable to the manuscript age, then it was subjected to natural aging by inoculation it with A. niger. Mechanical cleaning of the leaves was done with soft brushes. The samples have been consolidated by HPC 2%. Digital microscopy, scanning electron microscopy, mechanical properties measurement, color change, Fourier transform infrared and pH measurements were used to assess the effect of HPC on the qualities of leaves. Findings: HPC succussed in strengthening and restoring the natural, chemical and mechanical properties for the solidified leaves. Originality/value: The solidified papers phenomenon constitutes severe suffering for manuscripts and books conservators. The paper consolidation initial stage is one of the most important conservation stages because paper has lost many natural, mechanical and chemical properties. The most important feature of this study is providing a solution to the hardened leaves strengthening problem and restoring their chemical, natural and mechanical properties. [ABSTRACT FROM AUTHOR]

• BC/ZnO nanocomposite strengthens paper and improves aging resistance. • The nanocomposite imparts antifungal properties to paper. • The nanocomposite helps in deacidification of paper. Paper, commonly used as an information carrier, can become acidified and brittle over time. In this study, 0.3 % bacterial cellulose (BC) composite with 1.0% zinc oxide (ZnO) nanoparticles was prepared and used to coat brittle book paper for deacidification and consolidation. The BC/ZnO nanocomposite was characterized using zeta potential, micro morphology, elemental mapping, X-ray photoelectron spectra, Fourier transform infrared, and thermogravimetric analyses. The results indicated that the composite exhibited good stability. ZnO nanoparticles were bonded to the hydroxyl groups on BC, enhancing the thermal stability of BC. The composite was uniformly sprayed on the paper surface, and the mechanical properties, color difference, readability, pH, and micromorphology of the paper samples were examined before and after the treatment. The BC/ZnO nanocomposite exhibited good deacidification and consolidation effects on paper samples with low impact on the original paper appearance. Moreover, the BC/ZnO nanocomposite showed a good inhibitory effect on fungi growth on paper. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to find an applicable solution for the consolidation of petrified paper after disassembling it to complete other stages of treatment. Design/methodology/approach: The samples were subjected to natural aging by being inoculated with Aspergillus niger until they reached the stage of adhesion and petrification. After that, the leaves were separated, and cellulose nanocrystals were applied, then the leaves were subjected to wet thermal aging for 21 days. Digital microscope, scanning electron microscope, mechanical properties measurement, measurement of color change, Fourier transform infrared spectroscopy and pH measurement were used to evaluate the effects of the cellulose nanocrystal on paper. Findings: The results proved that cellulose nanocrystal (5%) successes consolidation of petrified paper Without affecting its natural, mechanical and chemical properties. Originality/value: This study was based on the effectiveness of cellulose nanocrystal in strengthening the petrified papers and testing its effect on the physical, mechanical and chemical paper properties. [ABSTRACT FROM AUTHOR]

Beeswax is a bio-sourced, renewable, and even edible material that stands as a convincing option to provide paper-based food packaging with moisture resistance. Nonetheless, the difficulty of dispersing it in water limits its applicability. This work uses oxidized, negatively charged cellulose nanofibers along with glycerol to stabilize beeswax-in-water emulsions above the melting point of the wax. The synergistic effects of nanocellulose and glycerol granted the stability of the dispersion even when it cooled down, but only if the concentration of nanofibers was high enough. This required concentration (0.6–0.9 wt%) depended on the degree of oxidation of the cellulose nanofibers. Rheological hindrance was essential to prevent the buoyancy of beeswax particles, while the presence of glycerol prevented excessive aggregation. The mixtures had yield stress and showed pseudoplastic behavior at a high enough shear rate, with their apparent viscosity being positively influenced by the surface charge density of the nanofibers. When applied to packaging paper, the nanocellulose-stabilized beeswax suspensions not only enhanced its barrier properties towards liquid water (reaching a contact angle of 96°) and water vapor (<100 g m−2 d−1), but also to grease (Kit rating: 5) and airflow (>1400 Gurley s). While falling short of polyethylene-coated paper, this overall improvement, attained using only one layer of a biobased coating suspension, should be understood as a step towards replacing synthetic waxes and plastic laminates. [ABSTRACT FROM AUTHOR]

The manufacturing of paper with new functional properties is a current problem today. A method of modifying the surface layer of paper by the partial dissolution of cellulose on its surface is proposed. N-Methylmorpholine-N-oxide (NMMO) is proposed for use as a solvent, the regeneration of which provides an environmentally friendly process. It was shown that among the possible hydrate forms of the solvent, the monohydrate and higher-melting forms are optimal for modifying the paper surface. The temperature–time modes of processing were revealed and the weight gain and density increase in the course of modification were estimated. The structural and morphological features of the original and modified paper were studied by X-ray imaging and scanning microscopy. The NMMO surface treatment makes it possible to vary the air permeability of the paper, making it practically non-permeable. The capillary and pore system were radically transformed after the partial dissolution of cellulose and its coagulation, as the formed cellulose film isolates them, which leads to a decrease in surface absorbency. The processing conditions allowing for the optimization of the optical and strength properties of the modified paper samples are revealed. The resulting paper with a modified N-methylmorpholine-N-oxide surface layer can be used for printing valuable documents. [ABSTRACT FROM AUTHOR]

Water hyacinth (Eichhornia crasspies) was used as a renewable cellulose source to prepare nanofibrillated cellulose (NFC). Due to the porous structure and low lignin content of water hyacinth, a 10 min-treatment time using the high-speed homogenization was sufficient to disintegrate nanofibers. The average width of the NFC treated for 40 min was 16.8 nm. With longer treatment times, a slight decrease in thermal stability of NFC was found while no changes in the crystallinity index of NFC were detected. Moreover, paper was formed from NFC with respect to mechanical treatment times. Results showed NFC treated with longer treatment times could prepare the paper with lower pore sizes between adjacent fibrils and porosity, resulting in higher wettability and mechanical properties. The contact angle of the 40 min-treated NFC paper was 36.0° while this contact angle result could not be measured from the samples of 0 min-treated NFC due to occurrence of large pores between fibers. The tensile strength of the NFC paper with 40 min-treatment time was ~18 times stronger than that of the 0 min-treated NFC paper. Mechanical energy consumption of the high-speed homogenization used to disintegrate NFC was also compared to that of the industrial defibrillation techniques. [ABSTRACT FROM AUTHOR]

This paper presents the limitations and potential of ATR-FTIR spectroscopy applied to the study of cellulosic textile collections The technique helps to differentiate natural fibres according to the content of lignin, pectin, hemicellulose, and wax, although some problematic issues should be considered. The spectral differences derived from the environmental humidity uptake and the plant composition are reviewed and discussed in the light of new experimental data. Diagnostic bands are proposed that can discriminate between different fibres from different plants. The contribution of ageing is also considered, demonstrating that sometimes aged fibres cannot be reliably recognised. In contrast, the potential of ATR-FTIR spectroscopy to discriminate between natural and modified fibres is discussed and proven. The best results were obtained when microinvasive ATR-FTIR spectroscopy was coupled with SEM observations. The proposed protocol was tested on microsamples of various cellulosic materials from traditional Japanese samurai armours dating from the 16th to the 20th centuries (Morigi Collection, Museo delle Culture, Lugano, Switzerland). The results facilitated a complete characterisation of the materials and demonstrated that the protocol can be used to study a wide variety of cellulosic materials, including both natural and man-modified fibres, and paper. [ABSTRACT FROM AUTHOR]

The hydroxyl groups on the cellulose macromolecular chain cause the cellulose surface to have strong reactivity. In this study, 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PDOTES) was used to modify cellulose to improve its triboelectric properties, and a triboelectric nanogenerator (TENG) was assembled. The introduction of fluorine groups reduced the surface potential of cellulose and turned it into a negative phase, which enhanced the ability to capture electrons. The electrical properties increased by 30% compared with unmodified cellulose. According to the principles of TENGs, a self-powered human-wearable device was designed using PDOTES-paper, which could detect movements of the human body, such as walking and running, and facilitated a practical method for the preparation of efficient wearable sensors. [ABSTRACT FROM AUTHOR]

Laser‐induced graphene (LIG) produced by irradiation of paper (paper‐LIG)holds substantial promise for flexible devices. This article presents paper‐LIG humidity and temperature sensors fabricated by single‐step irradiation of common filter paper with a pulsed UV laser (355 nm). The influence of the process parameters on the conversion of cellulose fibers into LIG is discussed based on the resulting morphology, structure, conductivity, and chemical composition, revealing a distinct barrier to transformation and a propagation behavior not seen under CO2 laser irradiation. The obtained material is constituted by a porous, electrically conductive network of fibers. The paper‐LIG relative humidity (RH) and temperature sensors with sensitivities of up to 1.3 × 10−3%RH−1 and ‐ 2.8 × 10−3 °C−1, respectively, are examined in terms of their linearity, reproducibility, and response time. A detailed discussion on the response mechanism is presented in the context of literature, pointing towards the absorption of water molecules in the interlayer spacing of graphene as the main reason for the increase in resistance with RH. Additionally, a contribution from variable range hopping along the ab plane of graphene at high RH is suggested. These results demonstrate the potential of paper‐LIG for low‐cost, sustainable, and environmentally friendly sensing. [ABSTRACT FROM AUTHOR]

There is current interest in replacing petroleum-based additives in consumer paper products with abundantly available, renewable and sustainable biopolymers such as lignin-containing cellulose nanofibers (LCNFs) and cottonseed protein. This research characterized the performance of cottonseed protein isolate with/without LCNFs to increase the dry strength of filter paper. The application of 10% protein solution with 2% LCNFs as an additive improved the elongation at break, tensile strength and modulus of treated paper products compared to the improved performance of cottonseed protein alone. Improvements in tensile modulus and tensile strength were greatest for samples containing larger amounts of lignin and a greater degree of polymerization than for those with less lignin from the same biomass sources. [ABSTRACT FROM AUTHOR]

Colored paper is an important industrial paper grade that has applications in various industrial sectors. The increase in coloring efficiency is a key in decreasing the use of dyes, thus can be considered as a "green" process concept; the coloring efficiency depends on the dye retention and dispersion. This work explores the use of nanocellulose, specifically, TEMPO-oxidized cellulose nanofibers (TOCNF), on the coloring efficiency of the preparation of colored paper. Two dyes (i.e. direct blue GL and reactive red 195 (RR195)) were used. Thanks to the large specific surface area and abundant active sites of TOCNF, its use largely improves the direct blue GL retention during the process. The coloring difference (∆E* ab) reached 5.334 with the addition of 13.6 wt% TOCNF and 1.8 wt% direct blue GL in the pulp furnish. The functional group in the dye is a vital factor in determining the dye retention when one chooses TOCNF to enhance the coloring efficiency in the production of colored paper. Furthermore, TOCNF significantly improved the strength properties of both direct blue GL and RR 195 dyed papers. This work demonstrates the potential of nanocellulose in the production of colored paper in improving the coloring efficiency, thus decreasing the environmental impact of the manufacturing process. [Display omitted] • Nanocellulose (i.e. TOCNF) adopted for colored paper preparation • Coloring efficiency improved by TOCNF due to the dye retention improvement • -COO− in TOCNF deteriorating its combination with negatively-charged dye [ABSTRACT FROM AUTHOR]

Cellulose microspheres (CMS) are a type of spherical regenerated cellulose particles with versatile properties which have been used as carrier materials in medical and technical applications. The integration of CMS into paper products opens up novel application scenarios for paper products in a wide range of fields. However, the incorporation of CMS carriers into paper products is challenging and hitherto no reports do exist in literature. Here, we present a feasibility study to incorporate up to 50 w.% CMS in paper hand sheets using retention aids. Our primary observations highlight the successful formation of uniform paper hand sheets retaining its tensile strengths at elevated CMS concentrations. Sheets with high CMS contents exhibit an increase in density and display enhanced surface smoothness — an outcome of a CMS layer forming atop the fiber base — which effectively bridges voids and rectifies surface irregularities as supported by Gurley testing, infinite focus microscopy and scanning electron microscopy. While our primary objective centered on the general feasibility to manufacture CMS-containing papers, the resulting composite scaffold carries significant potential as a platform for innovative, functional paper-based materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Liquid penetration in porous cellulosic materials is crucial in many technological fields. The complex geometry, small pore size, and often fast timescale of liquid uptake makes the process hard to capture. Effects such as swelling, vapor transport, film flow and water transport within cellulosic material makes transport deviate from well-known relations such as Lucas-Washburn and Darcy's Law. In this work it is demonstrated how Ultra-Fast Imaging NMR can be used to simultaneously monitor the liquid distribution and swelling during capillary uptake of water with a temporal- and spatial resolution of 10 ms and 14.5–18 μm respectively. The measurements show that in a cellulose fiber sheet, within the first 65 ms, liquid first penetrates the whole sheet before swelling takes place for another 30 s. Furthermore, it was observed that the liquid front traps 15 v% of air which is slowly replaced by water during the final stage of liquid uptake. Our method makes it possible to simultaneously quantify the concentration of all three phases (solid, liquid and air) within porous materials during processes exceeding 50 ms (5 times the temporal resolution). We hence believe that the proposed method should also be useful to study liquid penetration, or water diffusion, into other porous cellulosic materials like foams, membranes, nonwovens, textiles and films. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to identify the most common fungal species that grow on paper manuscripts and cause bio-deterioration. It also detects the impact of additive materials on fungal degrading and builds a wide database. Thus, it helps conservators understand this phenomenon. Design/methodology/approach: In total, 15 samples were collected from different paper manuscripts suffering from fungi. The achievement of the study objectives depends on using a variety of analyzes, such as a microbiological study, which indicated that three main fungi grew on the paper samples. Then, a digital microscope and an environmental scanning electron microscope were used to detect the effect of fungi on paper fibers. Fourier transform infrared microscopy was used to identify the binding medium and the X-ray diffraction method was used to measure the crystallinity index of cellulose of the paper samples. Findings: Arabic gum was used as a binder medium with the samples. Aspergillus Niger, Aspergillus Fumigatus and Aspergillus Clavatus were the most common fungal species that grew on the Qur'an papers under investigation. They also caused much common damage to the paper samples. The results of the analyzes also showed that the highest crystallinity index of cellulose was in the samples that contained the lowest rate of fungal growth. Originality/value: This paper highlights the relationship between fungal degradation and the multi-component nature of paper manuscripts. It builds a wide database that correlates the composition and the degradation of the Qur'an papers. [ABSTRACT FROM AUTHOR]

Two kinds of cellulose/ZnO piezoelectric papers are prepared by crushing and dissolving methods. The papers are characterized by SEM and analyzed by a piezoelectric equipment. The differences in the structure and piezoelectric performance of the two kinds of papers are explored. The effects of ZnO add-on amount, thickness of the papers, and pressure on the piezoelectric properties are discussed and compared with a PVDF film. The mutts show that the fibers of the piezoelectric paper prepared by the dissolving method are smooth and tightly bounded to ZnO, which makes ZnO uniformly coat on the surface of the fibers. The higher the pressure, the higher the piezoelectric properties. The thicker the piezoelectric paper, the higher the piezoelectric properties. The piezoelectric paper with 20% ZnO added by the dissolving method has high piezoelectric properties, and the maximum output current is 52.36 nA/cm². The piezoelectric properties of the piezoelectric paper are comparable to the purchased PVDF film. [ABSTRACT FROM AUTHOR]

Summary: Solar steam generation has proven to be a sustainable method to handle water shortage. Various materials for solar steam generation have been introduced in the past few years. However, the utilization of tedious and complicated synthesis to generate a photoactive layer is a matter of concern in the fabrication solar steam generation devices. Thus, improved methods toward cost‐effectiveness by exploring economical materials with simple manufacturing process are urgently and essentially needed. In this study, we first report on manufacturing hybrid membranes using commercially accessible materials, that is, cellulose paper and pencil graphite. The proposed method is to trace and coat a cellulose paper directly with a pencil without the use of solvents and chemicals, and it is possible to create an ecofriendly photoactive layer without a complicated process. The formed pencil graphite‐traced membranes were successfully utilized in solar steam generation and showed excellent steam generation rate of 4.32 kg/m2h which is almost 3.5 times more than that of pristine membrane at solar intensity of 3 Sun. The developed method could be widely utilized in the field of solar steam generation, since it is very facile and simple, and can be integrated to other commonly used materials for solar steam generation such as fabric and wood. In addition, on‐site production is possible, so it has a potential to be utilized in remote and resource‐limited areas for steam generation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The high demand for flexible electroconductive elements, such as organic coatings, is associated with the development of IoT devices, wearable health monitoring devices, and similar devices. To meet cost and environmental standards, the ideal coating should use the richness of nature, be biodegradable, and be water soluble to avoid the use of harmful organic solvents. All of these criteria are met by the composite coating consisting of sodium lignosulfonate (SLS) and multiwall carbon nanotubes (MWCNTs). Furthermore, the SLS/CNT coating on paper substrates is highly electroconductive, hydrophobic, and resistant to annealing, high humidity, bending, and scratching. The electrical conductivity of the SLS/CNT coating varies depending on the substrate used, but it is highly conductive and resistant on all substrates tested. Most importantly, due to the use of abundant and mass produced and cheap materials, the price of a coating containing 77 wt% SLS and 23 wt% CNT, with a sheet resistance of 113 Ω/sq is estimated to be around 2.05 EUR/m2. This coating can be especially beneficial for large-scale applications, such as heating films. [Display omitted] • SLS is an affordable and readily available stabilizer for CNT dispersion in water. • SLS/CNT creates a highly conductive coating on cellulose substrates. • The SLS/CNT coating on paper has potential applications as cost-effective sensors or heaters. • The conductivity of the coating is influenced by the properties of the substrate. [ABSTRACT FROM AUTHOR]

This study examined the use of Plantago psyllium seed husk flour as paper additive with the aim of improving the properties of cellulose sheet. The husk flour was added in 5 wt%, 10 wt%, 20 wt% and 30 wt% to the cellulose suspensions and its effect on the handsheet properties was studied. The results showed that the direct addition of husk flour highly improves the mechanical properties of the handsheets like tensile index (with up to 400 %), burst index (with up to 600 %) and tear index (with up to 1200 %). Cobb and contact angle tests with distilled water showed that the handsheets containing husk flour are more hydrophobic compared to the unmodified handsheets. The Cobb-Unger and contact angle tests with oil revealed that the additive reduces the oil absorbency of the handsheets as well, at the highest by 86 %. Additionally, the water vapor and especially the air barrier properties were improved. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant capacity test showed that the modified handsheets had free radical scavenging properties. The direct addition of Plantago psyllium seed husk flour can be a promising, easy and green method to improve the mechanical and barrier properties, oil and water resistance of cellulose sheets. [ABSTRACT FROM AUTHOR]

Strongly degraded cellulosic artworks usually need deacidification and consolidation. Alkaline nanoparticles are known to be effective in neutralizing the acidity, while cellulose nanocrystals have the potential to be used as compatible and effective strengthening agents. We have grafted cellulose nanocrystals with oleic acid using a 1′1-carbonyldiimidazole-mediated procedure, to increase their dispersibility in organic solvents, and synthesized Ca(OH) 2 or CaCO 3 nanoparticles via a solvothermal process. Grafted nanocellulose and alkaline nanoparticles were used to prepare ethanol-based "hybrids". Prior to the application, the physico-chemical properties of nanocellulose dispersions and "hybrids" were studied by rheology and small-angle X-ray scattering. Cellulose nanocrystals were effectively grafted and stably dispersed in ethanol. It was shown that the use of ethanol as a dispersing medium, and the addition of alkaline nanoparticles act in a synergistic way, increasing the interactions between grafted cellulose nanocrystals, leading to the formation of clusters. These dispersions are thixotropic, a behavior particularly appealing to conservation purposes, since they can be applied in the liquid state, or, when a more confined application is required, they can be applied in a gel-like state. As a result of the application, an improvement in the mechanical properties of paper and an increase of pH were obtained. [ABSTRACT FROM AUTHOR]

The research and development of new products that could partially or completely replace raw materials used for energy production, high value-added chemical products, and even the production of paper, has allowed industrial hemp (Cannabis sativa L.) to become the main raw material for the reactivation of a bio-based economy with high production conditions and capacities. Based on this, the objective of this research is to deepen on the potential use of hemp fiber in the paper industry, supported by studies carried out by the Colombian State regarding the availability of forest crops for commercial purposes, which are basically used for planting and the production of wood resources such as pine and eucalyptus. It has been considered important to demonstrate that hemp, as a source of primary production, provides competitive economic, environmental, and social advantages over traditional crops, even for new sources of bio-based research. [ABSTRACT FROM AUTHOR]

In order to assess the moisture content of wood chips on an industrial scale, readily applicable techniques are required. Thus, near infrared (NIR) spectroscopy was used to estimate moisture in wood chips by means of partial least squares regressions. NIR spectra were obtained in spectrometer with an integrating sphere and optical fiber probe, on the longitudinal and transverse surface of Eucalyptus wood chips. The specimens had their masses and NIR spectra measured in 10 steps during drying from saturated to anhydrous condition. Principal Component Analysis was performed to explore the effect of moisture of wood chip on NIR signatures. The values of moisture content of chips were associated with the respective NIR spectra by Partial Least Squares Regression (PLS-R) and Partial Least Squares Discriminant Analysis (PLS-DA) to estimate the moisture content of wood chips and its moisture classes, respectively. Model developed from spectra recorded on the longitudinal face by the integrating sphere method presented statistics slightly better (R²cv = 0,96; RMSEcv = 7,15%) than model based on optical fiber probe (R²cv = 0,90; RMSEcv = 11,86%). This study suggests that for calibration of robust predictive model for estimating moisture content in chips the spectra should be recorded on the longitudinal surface of wood using the integrating sphere acquisition method. [ABSTRACT FROM AUTHOR]

In the packaging sector of the printing industry, different coating applications are tried and investigated in order to increase the surface appearance and performance characteristics of paper and cardboard. The printability, water and ink absorption capacity, frictional resistance, light sensitivity of the visual graphical design that are going to be printed on the packaging papers are some of them. In this study, different types of cardboards that are used as a packaging material were chosen and coated with nanocrystalline cellulose (NCC)/PVA at different rates (%). In order to determine effective and economical usage conditions, the coating solutions, at three different concentrations as 3 wt.%, 5 wt. %, 7 wt.%, were prepared. The coating was applied on the test papers, which were at the same weights (350 g/m2) and had different surface properties as matte glossy, bright glossy, American Bristol. NCC/PVA existence on the coated paper surface was confirmed with Fourier Transform Infrared Spectroscopy (ATR-FTIR). The impact of the coating, which was prepared at different concentrations, on the packaging materials was studied with respect to thickness, stiffness, water absorbability, contact angle and surface tension. [ABSTRACT FROM AUTHOR]

Combining recycling of paper wastes (WPs) with extrusion‐based additive manufacturing represents a sustainable route to cellular cellulose composites tailored for lightweight construction. Particularly, shear mixing of shredded WPs with an aqueous solution of a polymer binder like polyvinyl alcohol (PVA) yields aqueous pastes suitable for 3D printing. As a shear thinning additive, both WP and microfibrillated cellulose account for enhanced shear thinning and dimensional stability. Opposite to the formation of dense WP/PVA composites by melt extrusion, 3D printing of aqueous pastes produces cellular cellulose/PVA composites exhibiting hierarchical pore architectures. In spite of low densities around 0.8 g cm−3, high Young's modulus (2.0 GPa) and tensile strength (53 MPa) are achieved. Mechanical stability, water resistance, and even flame retardancy simultaneously improve by crosslinking with glyoxal and especially by mineralization. Multimaterial 3D printing combines the 3D dispensing of cellulose/PVA pastes with the simultaneous, staged, or subsequent spraying of aqueous water glass to enable mineralization of composite surface, bulk, and interlayers. Furthermore, the glyoxal‐mediated crosslinking affords thermo‐ and moisture‐responsive cellulose/PVA composites with programmable shape change induced either by heating at 100 °C or by exposure to moisture at 37 °C. [ABSTRACT FROM AUTHOR]

The current analytical techniques for characterizing printing and graphic arts substrates, particularly those used to date and authenticate provenance, are destructive. This limits the amount of data that can be captured from an individual sample. For samples being evaluated in forensic and archeological investigations, any loss or degradation of the materials is undesirable. Furthermore, it is difficult to produce statistically relevant data for such analytes. We have shown elsewhere that a contactless microwave resonant cavity dielectric spectroscopy technique can discriminate between paper samples made from different plant fiber species based on their lignin content. In this publication, we demonstrate the utility of the contactless resonant cavity dielectric spectroscopy (RCDS) technique in the characterization of naturally and artificially aged paper samples. Based on our experimental results, we suggest that the technique could be used in forensic and archeological investigations of unique paper products. [ABSTRACT FROM AUTHOR]

The performance of oil-impregnated paper significantly affects the safety and reliability of transformers. Previous studies on water reducing the breakdown strength of oil-impregnated paper have been mainly due to increasing charge carriers and conductivity. However, the influence of water on the cellulose crystal structure of oil-impregnated paper is still not clear; in particular, its role on breakdown strength remains ambiguous. In this study, the AC breakdown strength and crystal structure of vegetable and mineral oil-impregnated paper with different moisture contents were investigated. The results show that with increasing moisture content, the cellulose crystallinity and crystal size increases linearly, while the breakdown strength decreases. The breakdown strength of vegetable oil-impregnated paper is higher than that of mineral oil-impregnated paper and is less affected by moisture. Herein, a model is proposed on the effects of water on the crystal structure of oil-impregnated paper and the correlation of breakdown strength with crystal structure is reported. [ABSTRACT FROM AUTHOR]

Paper-based platforms for biological studies have received significant attention given that cellulose is ubiquitous, biocompatible, and can be readily organized into tunable fibrous structures. In the latter form, effect of complexity in surface morphologies (roughness, porosity and fiber organization) on cell-substrate interaction has not been thoroughly explored. We infer that altering the properties of a fibrous material should lead to significant changes in cellular microenvironment and direct the deposition of structurally analogous extracellular matrix (fiber-fiber templating) like collagen. Here, we elucidate the effect of varying paper roughness and surface chemistry on NIH/3T3 fibroblasts via organization of excreted collagen. Collagen intensity was found to increase linearly with paper porosity, indicating a 3D culture platform. The intensity, however, decays over time due to biodegradation of the substrate. Stability can be improved by introducing fluorinated alkyl silanes to yield hydrophobic paper. This process concomitantly transforms the substrate to a 2D-like scaffold where collagen is predominantly assembled on the surface, thus changing the cellular microenvironment. Altering surface energy also led to fluctuations in collagen intensity and organization over time for smooth (calendered) paper substrates. We infer that the increased roughness improves collagen adsorption through capillary driven petal effect. In general, the influence of the substrate simultaneously affects its ability to host collagen and guide orientation. These findings offer insights into the effects of secondary structures and chemistry of fibrous polymeric materials on cell culture, which we propose as vital parameters when using paper-based platforms. Unlabelled Image • Collagen secreted from NIH/3T3 fibroblast cells increases linearly with paper porosity. • Paper transitions from 3D to 2D cell culture scaffold when rendered hydrophobic. • Hydrophobic paper relies on capillary driven petal effect for collagen adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sonication improves the absorption of metallic salt in the paper. • Ultrasound catalyzes the synthesis of metallic nanoparticles. • A longer sonication time during salt absorption increases the number of nanoparticles obtained. • Nanoparticles obtained by sonochemistry are an easy and reproducible method to modify paper. This work focuses on a systematic method to produce Ag, Cu, and Ag/Cu metallic nanoparticles (MNPs) in situ assisted with ultrasound on cellulose paper. By tuning the concentration of AgNO 3 and CuSO 4 salt precursors and ultrasound time, combined with a fixed concentration of ascorbic acid (AA) as a reducing agent, it was possible to control the size, morphology, and polydispersity of the resulting MNPs on cellulose papers. Notably, high yield and low polydispersity of MNPs and bimetallic nanoparticles are achieved by increasing the sonication time on paper samples pre-treated with salt precursors before reduction with AA. Moreover, mechanical analysis on paper samples presenting well-dispersed and distributed MNPs showed slightly decreasing values of Young's modulus compared to neat papers. The strain at break is substantially improved in papers containing solely Ag or Cu MNPs. The latter suggests that the elastic/plastic transition and deformation of papers are tuned by cellulose and MNPs interfacial interaction, as indicated by mechanical analysis. The proposed method provides insights into each factor affecting the sonochemistry in situ synthesis of MNPs on cellulose papers. In addition, it offers a straightforward alternative to scale up the production of MNPs on paper, ensuring an eco-friendly method. [ABSTRACT FROM AUTHOR]

• Preparation of dual functional humidity humidity-sensitive paper using sustainable nanoclay and beeswax. • Increment of actuation degree up to 110° (30 %RH) from 40° (90 %RH). • Able to detect humidity from changes in electrical resistances (150-700kΩ). A highly humidity-responsive paper can detect moisture or OH-attached molecules at the sub-micron or nano level range. Applying hydrophilic nanoclay as an active material for water sensing would reduce the fabrication cost while remaining environmentally friendly. In this communication, we report the preparation of a nanoclay-inspired dual-responsive smart film that can signal humidity levels from mechanical and electrical responses. The paper will bend as the nanoclay layer swells whereas the resulting bending strain will trigger the electrical resistance changes in the hydrophobic electrically conductive graphite-beeswax layer. [ABSTRACT FROM AUTHOR]

Stretchable micropower sources with high energy density and stability under repeated tensile deformation are key components of flexible/wearable microelectronics. Herein, through the combination of strain engineering and modulation of the interlayer spacing, freestanding and lightweight MXene/bacterial cellulose (BC) composite papers with excellent mechanical stability and a high electrochemical performance are first designed and prepared via a facile all-solution-based paper-making process. Following a simple laser-cutting kirigami patterning process, bendable, twistable, and stretchable all-solid-state micro-supercapacitor arrays (MSCAs) are further fabricated. As expected, benefiting from the high-performance MXene/BC composite electrodes and rational sectional structural design, the resulting kirigami MSCAs exhibit a high areal capacitance of 111.5 mF cm−2, and are stable upon stretching of up to 100% elongation, and in bent or twisted states. The demonstrated combination of an all-solution-based MXene/BC composite paper-making method and an easily manipulated laser-cutting kirigami patterning technique enables the fabrication of MXene-based deformableall-solid-state planar MSCAs in a simple and efficient manner while achieving excellent areal performance metrics and high stretchability, making them promising micropower sources that are compatible with flexible/wearable microelectronics. [ABSTRACT FROM AUTHOR]

Highlights • A paper-based TIM is fabricated using graphene and p-polymer. • The thermal conductivity is measured using laser flash method. • The fabricated graphene paper has significantly enhanced in-plane thermal conductivity. • The fabricated graphene paper has good mechanical, thermal and electrical characteristics. Abstract In this study, an innovative thermal interface material (TIM) paper based on a composite of cellulose and graphene is investigated experimentally. Six types of commercially-available papers: a wool paper; an aqua satin; a merit paper; a new craft board; and two oriental traditional papers (Bulgyeong and Daerye) are used to fabricate the paper-graphene composites via bar coating and a slot die coating. The fabricated TIM papers are lightweight, flexible and robust against tensile strength. The in-plane and through-plane thermal conductivities of the TIM papers are measured using a laser-flash-method (LFM). The measured in-plane thermal conductivities are of the order of 5 W/m-K, whereas the through-plane thermal conductivities are of the order of 0.1 W/m-K. These results suggest that the addition of graphene significantly enhance the in-plane thermal conductivity of papers, while the through-plane thermal conductivities are not significantly improved. The mechanical properties of the TIM papers are also tested. This work provides a new possibility for development of next-generation thermal interface materials with good thermal and mechanical properties. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic illustration of graphene cellulose (G-C) paper fabrication, application for 3D multilayered laminate cell-laden constructs, and ensuing "origami-inspired" sculpting for 3D tissue engineering and regeneration. Highlights • Efficient method for graphene-cellulose (G-C) paper fabrication. • G-C paper is electroconductive, mechanically robust, flexible and biocompatible. • G-C paper can be employed for 2D or 3D stem cell support and differentiation. • G-C papers with cell-laden alginate can be stacked as 3D multilayered constructs. • Multilayered cell-laden constructs can be further configured by folding or rolling. Abstract Graphene-based materials represent advanced platforms for tissue engineering and implantable medical devices. From a clinical standpoint, it is essential that these materials are produced using non-toxic and non-hazardous methods, and have predictable properties and reliable performance under variable physiological conditions; especially when used with a cellular component. Here we describe such a biomaterial, namely smart graphene-cellulose (G-C) paper, and its suitability for traditional planar two-dimensional (2D) or three-dimensional (3D) human cell support, verified by adipose-derived stem cell (ADSC) culture and osteogenic differentiation. G-C paper is prepared using commercially available cellulose tissue paper as a substrate that is coated by immersion-deposition with graphene oxide (GO) followed by reduction to reduced graphene oxide (RGO) without the use of toxic organic solvents. The fabrication process is amenable to large scale production and the resultant papers have low electrical resistivity (up to ∼300 Ω/sq). Importantly, G-C papers can be configured to 3D constructs by lamination with alginate and further modified by folding and rolling for 3D "origami-inspired" cell-laden structures. [ABSTRACT FROM AUTHOR]

Highlights • Cellulose nanofibrils(CNF)/graphene nanoplatelets(GnP) hybrid papers were prepared with a simple water-based method. • CNF and hot-pressing efficiently enhance the mechanical properties of the GnP paper. • The CNF reinforced GnP paper demonstrates high electrical conductivity. • Mechanical flexibility and electrical conductivity of the papers are controllable. Abstract Mechanically flexible and high electrically conductive multilayered graphene nanoplatelets (GnP)/cellulose nanofibrils (CNF) composite papers were successfully fabricated through a vacuum-assisted self-assembly technique. The morphology observation showed that highly disassembled CNF were achieved by high-pressure homogenization of water-based cellulose slurry, and the homogenized CNF uniformly interpenetrated within the microporous GnP paper network. The analyses of mechanical properties and morphology suggest that the CNF effectively bridged the adjacent GnP sheets and efficiently strengthened the GnP papers by producing strong GnP/CNF interfacial interactions resulting from mechanical interlocking, van der Waals forces and hydrogen bonds between the GnP and the CNF. Moreover, it was noticed that hot-pressing pressure is necessary to be applied on samples to produce stronger papers with higher electrical conductivity. As the CNF loading reached 60 wt%, the Young's modulus and tensile strength of the hot-pressed GnP/CNF hybrid paper were significantly increased to 9.1 GPa and 57.7 MPa, respectively. In addition, a high electrical conductivity of 26.8 S/cm was retained for the paper with 30 wt% CNF. Our approach provides a facial and eco-friendly fabrication route to produce strong and highly conductive GnP/CNF papers which are of great practical appeal as a new type of nanomaterials in various fields. [ABSTRACT FROM AUTHOR]

Flexible-hybrid printed electronics (FHPE) is a rapidly growing discipline that may be described as the precise imprinting of electrically functional traces and components onto a substrate such as paper to create functional electronic devices. The mass production of low-cost devices and components such as environmental sensors, bio-sensors, actuators, lab on chip (LOCs), radio frequency identification (RFID) smart tags, light emitting diodes (LEDs), smart fabrics and labels, wallpaper, solar cells, fuel cells, and batteries are major driving factors for the industry. Using renewable and bio-friendly materials would be advantageous for both manufacturers and consumers with the increased use of (FHPE) electronics in our daily lives. This review article describes recent developments in cellulose and nanocellulose-based materials for FHPE, and the necessary developments required to propagate their use in commercial applications. The aim of these developments is to enable the creation of FHPE devices and components made almost entirely of cellulose materials. [ABSTRACT FROM AUTHOR]

Heat and moisture treatments were shown to affect restoration of the capillary-porous structure of paper folders that was lost during drying. Thermodynamic functions of cellulose water of hydration were calculated for hydrothermal treatment over broad ranges of time and temperature. The effects of saturated vapor with high state parameters on paper strength were demonstrated. [ABSTRACT FROM AUTHOR]

For many centuries, paper was considered the main support for recording cultural achievements all over the world. Archives represent the historical memory of our past, and the book conservation represents one main concern since many books and documents kept in libraries and archives are at risk because of their fragility. The use of portable, not destructive technique like NIR μ-Raman spectroscopy represents a valid instrument for monitoring the documentary heritage. In the present study, we investigated the degradation process, associated to the polymers breaking, in order to propose a successful kinetic model for determining the ageing time of cellulose. We compared the calculated results with respect to both experimental samples and literature data, covering a period of seven centuries, from XV to XXI centuries. Proposed model starts directly from Raman spectra, in particular by monitoring the band at 1100 cm − 1 ascribed to C-O-C inter-monomers bond, whose relative intensity is related to the cellulose chain length. We obtained a very good agreement with the experimental data with 8% of accuracy. Finally, with the help of Density Functional Theory (DFT) simulations, we confirmed our model by studying the structure and the grade of cellulose crystallinity in the paper. In particular, the reverse trend of the band at 900 cm − 1 , related to the crystallinity grade of the cellulose, and the band at 1100 cm − 1 , as a function of the dimer unit cell structure, supported the kinetic model, suggesting a shear stress like effect as the origin of the cellulose chain length decrease. [ABSTRACT FROM AUTHOR]

Widening the methodology of chromophore analysis in pulp and paper science, a sensitive gas-chromatographic approach with electron-capture detection is presented and applied to model samples and real-world historic paper material. Trifluoroacetic anhydride was used for derivatization of the chromophore target compounds. The derivative formation was confirmed by NMR and accurate mass analysis. The method successfully detects and quantifies hydroxyquinones which are key chromophores in cellulosic matrices. The analytical figures of merit appeared to be in an acceptable range with an LOD down to approx. 60 ng/g for each key chromophore, which allows for their successful detection in historic sample material. [ABSTRACT FROM AUTHOR]

High-resistance paper was manufactured by laccase-grafting of carboxymethyl cellulose (CMC) and chitosan (CPX) on Kraft pulp fiber. The reaction was mediated in the presence of laccase by one of the following polyphenols in the presence of air: gallic acid (GA), vanillic acid (VA) and catechol (1,2-DHB). Enzyme was added at constant loading (24 kg ton-1), 1% pulp consistency, 0.005% CMC, pH = 6.3 ± 0.5 and 2 mM of mediator. CPX content was assessed at two levels (0% and 0.005%). Treated pulps were analyzed by different mechanical tests (ring crush, mullen, corrugating medium test (CMT) flat crush of corrugating medium test and tension). An improvement in these parameters was obtained by biopolymer coupling and selected mediator. When using GA, three parameters increased more than 40%, while ring crush increased 120%. For the case of VA, properties were enhanced from 74% to 88% when CPX was added. For 1,2-DHB, there was not found a statistically significant difference between the results in the presence of CPX. Scanning electron microscopy, confocal microscopy, FTIR and 13C NMR were used in all papers in order to evaluate grafting. Hence, it was possible to correlate polymerization with an improvement of paper's mechanical properties. [ABSTRACT FROM AUTHOR]

Pontamine fast scarlet 4B is a red paper and textiles dye that has recently been introduced as a fluorescent probe for plant cell walls. Pontamine exhibits bifluorescence, or fluorescence dependent on the polarization of the excitation light: Because cellulose is aligned within the cell wall, pontamine-labelled cell walls exhibit variable fluorescence as the excitation polarization is modulated. Thus, bifluorescence measurements require polarized excitation that can be directly or indirectly modulated. In our confocal microscopy observations of various cellulose samples labelled with pontamine, we modulated excitation polarization either through sample rotation or by the confocal's scanfield rotation function. This variably rotated laser polarizations on Leica confocal microscopes, but not those from other makers. Beginning with samples with directly observable microfibril orientations, such as purified bacterial cellulose, the velamen of orchid roots and the inner S2 layer of radiata pine compression wood, we demonstrate that modelling the variations in pontamine fluorescence with a sine curve can be used to measure the known microfibril angles. We then measured average local microfibril angles in radiata pine samples, and showed similar microfibril angles in compression and normal (opposite) wood. Significantly, bifluorescence measurements might also be used to understand the degree of local cellulose alignment within the cell wall, as opposed to variations in the overall cellulose angle. [ABSTRACT FROM AUTHOR]

Paper has been used to engineer many types of bio-diagnostics. A major issue to most paper-based bio-diagnostics is the biomolecule instability causing the short shelf-life of the diagnostics. Commercial papers contain various polymeric additives. Polyamidoamine-epichlorohydrin (PAE), a polyelectrolyte typically used as wet-strength agent, is commonly used in filter papers and paper towels, which are often used as substrate in bioactive paper. However, the effect of cellulose or polymeric additives on antibody bioactivity is unknown. This limits paper optimization for diagnostic applications. In this study, model papers were made with and without PAE addition. IgM Anti-A blood typing antibody was physisorbed and dried on paper, aged for up to 9 weeks at different relative humidity (RH) conditions and the antibody activity was measured. The antibody bioactivity was represented as blood typing efficiency measured by image analysis. The surface chemical composition was measured using X-ray photoelectron spectroscopy (XPS). Antibody bioactivity loss was promoted by elevated RH, corresponding to increased paper water content. PAE significantly reduces the paper water content under ambient environment. Antibody bioactivity is higher on paper made with PAE under the high humidity conditions (57.6%–84.3% RH). However, under conditions of humidity saturation (100%RH), PAE shows little effect on reducing paper water content nor on protecting antibody bioactivity. These results demonstrate the water content of paper to be associated with antibody bioactivity loss. [ABSTRACT FROM AUTHOR]

Degradation of cellulose in historic manuscripts with iron gall ink leads our heritage to deterioration. Direct aqueous or non-aqueous methods of treatment, which are often used in practice, can damage the authenticity of documents. Therefore, other methods without any wet curative procedures during treatment are in great request. The aim of this work was to evaluate the efficiency of interleaving treatments performed with interleaves containing organic (tetrabuthylammonium bromide and 1-ethyl-3-methylimidazolium bromide) and inorganic (KI and KBr) halide salts on the stability of paper with iron gall ink during ageing. The effect of interleaving was compared with 1) the efficiency of direct treatment of samples and 2) the established conservation procedure-calcium phytate/calcium hydrocarbonate treatment. To evaluate the stabilization effect of different compounds and the efficiency of particular conservation technique measurements of the polymerization degree (viscosimetry, size exclusion chromatography-SEC) and pH were performed before and after accelerated ageing. Colour change in paper samples was determined by reflection measurement using an integrating sphere with a halogen light source. The condition of paper fibers was studied using optical microscopy and scanning electron microscopy (SEM). The tentative results demonstrate that the effective stabilization of paper containing iron gall ink during ageing may successfully be achieved by interleaving using alkaline paper impregnated with KBr. [ABSTRACT FROM AUTHOR]

Materials with new and improved functionalities can be obtained by modifying cellulose with gold nanoparticles (AuNPs) via the in situ reduction of a gold precursor or the deposition or covalent immobilization of pre-synthesized AuNPs. Here, we present an alternative biomolecular recognition approach to functionalize cellulose with biotin-AuNPs that relies on a complex of 2 recognition elements: a ZZ-CBM3 fusion that combines a carbohydrate-binding module (CBM) with the ZZ fragment of the staphylococcal protein A and an anti-biotin antibody. Paper and cellulose microparticles with AuNPs immobilized via the ZZ-CBM3:anti-biotin IgG supramolecular complex displayed an intense red color, whereas essentially no color was detected when AuNPs were deposited over the unmodified materials. Scanning electron microscopy analysis revealed a homogeneous distribution of AuNPs when immobilized via ZZ-CBM3:anti-biotin IgG complexes and aggregation of AuNPs when deposited over paper, suggesting that color differences are due to interparticle plasmon coupling effects. The approach could be used to functionalize paper substrates and cellulose nanocrystals with AuNPs. More important, however, is the fact that the occurrence of a biomolecular recognition event between the CBM-immobilized antibody and its specific, AuNP-conjugated antigen is signaled by red color. This opens up the way for the development of simple and straightforward paper/cellulose-based tests where detection of a target analyte can be made by direct use of color signaling. [ABSTRACT FROM AUTHOR]

Paper-based electronics have been attracting significant attention because of their inexpensive, renewable, and eco-friendly substrates. In this study, Cu-based composite inks composed of a copper-based metal-organic decomposition (MOD) ink and Cu flakes were prepared as precursors to obtain conductive Cu films on untreated cellulose paper. Copper-based MOD inks have not been explored for the production of conductive Cu films on cellulose paper because the properties of the paper, such as high porosity, high permeability, and surface roughness, are not favorable to obtain continuous conductive Cu films. However, using our method, we have obtained Cu films on paper with resistivities that are ∼10 times lower than those of films on polyimide or glass substrates. Importantly, the Cu films on paper exhibited better mechanical resistance than those on a polyimide substrate, without any pre-treatment of the paper surface. [ABSTRACT FROM AUTHOR]

Viologen-based liquid electrochromic mixtures provide high performance in terms of optical contrast and response time. However, their use in flexible ECDs is quite limited due to the risk of leakage and difficult manufacturing and handling. Herein, it is demonstrated that the incorporation of viologen-based electrochromic mixtures into paper-matrix is a promising solution to overcome the mentioned issues. The performance of flexible paper-based devices using both water-free and water-based formulations containing viologens is assessed for the first time and compared with paper-free devices. The benefits of using paper on the homogeneity, life-time (operating devices above 1000 redox cycles) and robustness against bending (operating devices above 200 bending cycles) is proven: while short-circuits, inhomogeneous coloration and ITO-etching usually occur in the paper-free devices, these concerns are avoided when the liquid mixtures are embedded within the paper-matrix while keeping the good electrochromic performance typically provided by liquid formulations. Additionally, a patterned bi-chromic (blue-green) device is presented as a proof-of-concept to show the potential of these paper-based systems in the field of flexible EC displays. [ABSTRACT FROM AUTHOR]

Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reductive amination to evaluate the multiplexing capacity of luminescence resonance energy transfer (LRET) between UCNPs and quantum dots (QDs). This is the first account of a multiplexed bioassay strategy that demonstrates the principle of use of a single form of UCNP as donor and three different color emitting QDs as acceptors to concurrently determine three analytes. Broad absorbance profiles of green, orange and red QDs that spanned from the first exciton absorption peak to the UV region were in overlap with a blue emission band from UCNPs composed of NaYF 4 that was doped with 30% Yb 3+ , 0.5% Tm 3+ , allowing for LRET that was stimulated using 980 nm near-infrared radiation. The characteristic narrow and well-defined emission peaks of UCNPs and QDs allowed for the collection of luminescence from each nanoparticle using a band-pass optical filter and an epi-fluorescence microscope. The LRET system was used for the concurrent detection of uidA, Stx1A and tetA gene fragments with selectivity even in serum samples, and reached limits of detection of 26 fmol, 56 fmol and 76 fmol, respectively. [ABSTRACT FROM AUTHOR]

In this review, we summarize the recent progress in thermal conductivity analysis of nanocellulose materials called cellulose nanopapers, and compare them with polymeric materials, including neat polymers, composites, and traditional paper. It is important to individually measure the in-plane and through-plane heat-conducting properties of two-dimensional planar materials, so steady-state and non-equilibrium methods, in particular the laser spot periodic heating radiation thermometry method, are reviewed. The structural dependency of cellulose nanopaper on thermal conduction is described in terms of the crystallite size effect, fibre orientation, and interfacial thermal resistance between fibres and small pores. The novel applications of cellulose as thermally conductive transparent materials and thermal-guiding materials are also discussed. [ABSTRACT FROM AUTHOR]

Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5–12 nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus . [ABSTRACT FROM AUTHOR]

Even though gamma radiation application, also at the minimum dosage required for disinfection, causes depolymerization and degradation of the paper substrate, recently published papers seemed, instead, to suggest that γ-rays application could be envisaged in some conditions for Cultural Heritage original documents and books. In some of the published papers, the possible application of γ-rays was evaluated mainly by using mechanical tests that scarcely reflect the chemical modifications induced in the cellulosic support. In the present article the effect of low dosage γ-irradiation on cellulosic substrates was studied and monitored applying different techniques: colorimetry, spectroscopic measurements, carbonyl content and average viscometric degree of polymerization. Two different papers were investigated, a non-sized, non-filled cotton paper, and a commercial permanent paper. To simulate a real deteriorated document, which could need γ-rays irradiation, some samples were submitted to a hydrolysis treatment. We developed a treatment based on the exposition of paper to hydrochloric acid vapors, avoiding any contact of the samples with water. This method induces a degradation similar to that observed on original documents. The samples were then irradiated with 3 kGy γ-rays at a 5258 Gy/h rate. The aforementioned analyses were performed on the samples just irradiated and after artificial ageing. All tests showed negative effects of gamma irradiation on paper. Non-irradiated paper preserves better its appearance and chemical properties both in the short term and after ageing, while the irradiated samples show appreciable color change and higher oxidation extent. Since the Istituto centrale restauro e conservazione patrimonio archivistico e librario is responsible for the choice of all restoration treatments that could be applied on library and archival materials under the protection of the Italian State ( http://www.icpal.beniculturali.it/allegati/DM-7-10-2008-Istituto.pdf ), it has been evaluated that the modifications induced by γ-rays irradiation are not acceptable as safe conservation treatment ( http://www.icpal.beniculturali.it/allegati/Nota_uso_raggi_gamma.pdf ). [ABSTRACT FROM AUTHOR]

This study focuses on the changes in properties of cellulose-based paper, which can take place as a consequence of its contamination by dust particles. The PM1 (fine) and PM10 (coarse) fractions of the dust particles from archival repositories were collected on cellulose filters Whatman 41, polytetrafluorethylene, and quartz filters. The latter two types of samples were subsequently analyzed gravimetrically, with ion chromatography, PIXE, and the thermal–optical transmission method, giving mass, ionic, elemental carbon, and organic carbon concentrations. After artificial aging, the viscosity-average degree of polymerization of cellulose (DPv) was measured. It was confirmed that cellulose-based paper can undergo substantial changes when contaminated by dust particles and artificially aged. The decrease of the DPvof cellulose showed a negative correlation with the deposited mass of sulfate ions in the dust particles. Considering the particle size fraction, the results suggest the decisive importance of the fine (PM1) particles. The results provide better understanding of how particulate matter contributes to the chemical degradation of cellulose-based paper. Such knowledge is of importance when considering appropriate conservation measures in archives, libraries, and galleries. [ABSTRACT FROM AUTHOR]

Cellulose oxidative and hydrolytical degradation is one of the greatest problems for the conservation of paper supports. To contrast these degradation processes, both deacidification and reduction of the oxidized functions are needed. Dealing with original documents, it is often impossible to perform the two mentioned treatments in aqueous solutions and in a distinct subsequent way, because of the fragility of the artifacts. After studying, in a separate way, an effective deacidifier (calcium propionate) soluble in ethyl alcohol and many reducers (boron complexes), able to act in different non-aqueous solvents, it was decided to test a simultaneous method of deacidification and reduction in ethanol. This paper presents the chemical-physical results obtained by applying simple deacidification and simultaneous deacidification-reduction on laboratory paper samples that were artificially aged and then re-measured after 10 and 15 years of natural aging. Results show that all alcoholic treatments are very effective: papers are stable also after a long period of both artificial and natural aging. [ABSTRACT FROM AUTHOR]