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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]

An effective strategy was demonstrated to design an electromagnetic interference (EMI) shielding paper via a facile surface treatment on paper. TEMPO-oxidized cellulose nanofibers (TOCN) were first integrated with Ti 3 C 2 T x MXene, and subsequently cast onto a filter paper with cationic guar gum (CGG) in a sequential way. TOCN and CGG generated a self-assembling hydrogel and formed a MXene-containing hydrogel film on top of the filter paper. The hydrogel film enhanced the tensile strength (9.49 MPa) of composite paper, and resulted in a 17 % increase as compared to the control. The composite paper containing 80 mg MXene (namely, 2.07 mg·cm−2) showed a conductivity of 3843 S·m−1 and EMI shielding effectiveness (EMI SE) of 49.37 dB. Furthermore, the 2-layer assembled TC-M 80 hydrogel composite paper achieved an EMI SE of 73.99 dB. Importantly, this composite paper showed higher EMI SE and lower thickness than a lot of reported materials. The presence of TOCN and CGG also protected MXene against several solvents and the incorporation of polydimethylsiloxane (PDMS) further improved the durability of the composite paper. This work provides a novel and simple strategy to design robust, ultrathin and flexible EMI shielding materials, and it might also inspire other work in paper-based functional materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Xylan is primarily found in the secondary cell wall of plants providing strength and integrity. To take advantage of the reinforcing effect of xylan in papermaking, it is crucial to understand its role in pulp fibers, as it undergoes substantial changes during pulping. However, the contributions of xylan that is added afterwards (extrinsic) and xylan present after pulping (intrinsic) remain largely unexplored. Here, we partially degraded xylan from refined bleached softwood kraft pulp (BSKP) and adsorbed xylan onto BSKP. Enzymatic degradation of 1 % xylan resulted in an open hand sheet structure, while adsorption of 3 % xylan created a denser fiber network. The mechanical properties improved with adsorbed xylan, but decreased more significantly after enzymatic treatment. We propose that the enhancement in mechanical properties by adsorbed extrinsic xylan is due to increased fiber-fiber bonds and sheet density, while the deterioration in mechanical properties of the enzyme treated pulp is caused by the opposite effect. These findings suggest that xylan is decisive for fiber network strength. However, intrinsic xylan is more critical, and the same properties cannot be achieved by readsorbing xylan onto the fibers. Therefore, pulping parameters should be selected to preserve intrinsic xylan within the fibers to maintain paper strength. [Display omitted] [ABSTRACT FROM AUTHOR]

Understanding water absorbency in paper is challenging as fibre swelling and out-of-plane deformation occur simultaneously during liquid imbibition. Liquid absorption is commonly accessed by gravimetric tests, which provides limited information on the local spatial and temporal distribution of fluid in the substrate. In this work, we developed iron tracers to map liquid imbibition in paper by in situ precipitation of iron oxide nanoparticles during passage of the wetting front. The iron oxide tracers were found to be robustly attached to the cellulosic fibres. After liquid absorption tests, absorbency was investigated by mapping the distribution of iron in 3D using X-ray micro-computed tomography (μCT) and in 2D using energy-dispersive X-ray spectroscopy. We demonstrate a difference in tracer distribution between the wetting front and the fully saturated region supporting that imbibition proceeds in two phases, i.e. liquid percolation through the cell wall initially prior to filling of the external pore spaces. Critically, we demonstrate that these iron tracers enhance image contrast and allow for new imaging modalities in μCT for fibre networks. [Display omitted] [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]

Polyurethane elastomer (PUE) composites were synthesized with a low additive content of waste natural cellulosic fibers from office paper. A new technology combining prepolymer method with physical blending and modification was adopted. The results showed that cellulosic fibers were covalently bonded to polyurethane molecular chains and served as a cross-linking agent making the degree of phase separation decrease. Even so, the lowest additive content of cellulosic fibers (1 wt%) in this work could make polyurethane still hold a certain degree of phase separation. Besides, thermal stability of polyurethane was improved from 288 to around 300 °C even at the low cellulosic fibers content. PUE with 3% cellulosic fibers had the better interfacial compatibility between cellulosic fibers and polyurethane causing the greater thermal reinforcement. PUE with 4% and 5% cellulosic fibers had the worse interfacial compatibility generating the better damping capacity indicating that cellulosic fibers could improve damping performance of polyurethane, especially polyurethane with 5 wt% fibers. It meant that cellulosic fibers had a potential application in damping materials. [ABSTRACT FROM AUTHOR]

Herein, we report on the preparation of novel cellulose-PEG biohybrid papers with wet strength properties. The biohybrid paper sheets are obtained using a two-step procedure where ω- or α, ω-azide functionalized PEG chains are anchored onto alkyne-functionalized wood fibers through CuAAC ligation in mild and aqueous conditions. The incorporation of the PEG grafts mostly occurs at the periphery of the cellulose fibers and degrees of substitution up to 0.028 are obtained. The presence of PEG grafts significantly increases the tensile, burst and tear strength properties in the wet state, the reinforcement being more pronounced for fibers grafted with α,ω-azide PEG. This reinforcement is consistent with a relatively sparse hetero-crosslink reaction creating inter-fiber covalent bonds and forming a cellulose network within the cell wall. [ABSTRACT FROM AUTHOR]

During the last two decades, cellulose nanofibres (CNF) have emerged as a promising, sustainable reinforcement with outstanding potential in material sciences. Though application of CNF in papermaking is recent, it is expected to find implementation in the near future to give a broader commercial market to this type of cellulose. The present review highlights recent progress in the field of the application of cellulose nanofibres as additives in papermaking. The effect of CNF addition on the wet end process is analysed according to the type of pulp used for papermaking. According to the literature consulted, improvement in paper’s overall properties after CNF addition depended not only on the type and amount of CNF applied, but also in the pulp’s origin and treatment. Bulk and surface application of CNF also presented significant differences regarding paper’s final properties. This review also revises the mechanisms behind CNF reinforcing effect on paper and the effect of chemically modified CNF as additives. [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]

The sustainable, efficient use of renewable bio-based additives in the production of various materials fits well into the concept of sustainability. Here, the concept of coaggregation of mineral filler particles and starch granules for improving filler-fiber interaction in paper-based cellulosic networks is presented. Coaggregation of precipitated calcium carbonate filler particles and uncooked, unmodified corn starch granules by cationic polyacrylamide (a cationic high molecular weight polymer flocculant) in combination with bentonite (an anionic microparticle) prior to addition to cellulosic fiber slurry delivered enhanced filler bondability with cellulosic fibers. For instance, under the conditions studied, preaggregation resulted in an increase in filler bondability factor from 9.24 to 15.21 at starch dosage of 1% (on the basis of the dry weight of papermaking stock). The swelling and gelatinization of the starch granules in starch-filler preaggregates or hybrids enabled the “bridging” of the gaps in cellulosic networks, leading to structural consolidation and strength enhancement. [ABSTRACT FROM AUTHOR]

Gaseous acetic acid is formed under conditions of storage of historic paper objects. Its presence not only promotes hydrolytic cleavage of cellulose, but also causes acetylation of the cellulosic material to very small degree. The acetylation reaction proceeds under ambient conditions and without catalyst. Different analytical methods were used to prove the presence of organic acetates on cellulosic paper matrices. DESI-MS in combination with 2H-isotopic labeling showed the presence of sugar fragments with different acetylation patterns. A method based on Zemplen saponification was applied and worked also in the presence of a large excess of acetic acid and/or inorganic acetates. The acetylation effect was quantified for model papers and original, naturally aged paper samples. While cellulose acetylation was clearly proven to be another general pathway of paper aging, further studies of this acetylation phenomenon are needed with regard to conservational aspects and suitable paper storage conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Well-dispersed Fe 3 O 4 nanoparticles (NPs) were synthesized by a co-precipitation method in the presence of cellulose nano-crystals (CNC) as the template. The thus prepared Fe 3 O 4 NPs were then used as a coating agent for the preparation of conductive paper. Fourier transform infrared spectroscopy (FTIR) results revealed that the Fe 3 O 4 NPs were immobilized on the CNC through interactions between the hydroxyl groups of CNC and Fe 3 O 4 . Scanning transmission electron microscopy (STEM) images showed that the Fe 3 O 4 NPs prepared in the presence of CNC can be dispersed in the CNC network, while the Fe 3 O 4 NPs prepared in the absence of CNC tended to aggregate in aqueous solutions. The conductivity of the Fe 3 O 4 NPs coated paper can reach to 0.0269 S/m at the coating amount of 14.75 g/m 2 Fe 3 O 4 /CNC nanocomposites. Therefore, the thus obtained coated paper can be potentially used as anti-static packaging material in the packaging field. [ABSTRACT FROM AUTHOR]

The nanofibrillated cellulose (NFC) was used as substrates to carry triclosan (TCS), which was then applied as a coating agent for impacting antibacterial property to paper while also improving its strength. The TCS-loaded NFC material was further characterized. UV–vis spectra results showed that a characteristic absorption band at 282 nm was observed, which was attributed to triclosan, confirming its successful loading onto NFC. The antibacterial activity tests indicated that the coated paper exhibited excellent antibacterial activity against Escherichia coli , and the growth inhibition of bacteria (GIB) increased as the loading amount of triclosan coated on paper increased. The GIB can reach 98.7% when the 0.023 g TCS-loaded NFC was coated on paper. Meanwhile, the tensile and tear index of the coated paper increased by 18.0% and 26.4%, respectively compared to the blank paper. Therefore, the triclosan-loaded paper could be potentially used in the medical field. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans CECT 7291 seems to be a good option for the restoration of degraded paper. In this work BC layers are cultivated and purified by two different methods: an alkaline treatment when the culture media contains ethanol and a thermal treatment if the media is free from ethanol. The main goal of these tests was the characterization of BC layers measured in terms of tear and burst indexes, optical properties, SEM, X-ray diffraction, FTIR, degree of polymerization, static and dynamic contact angles, and mercury intrusion porosimetry. The BC layers were also evaluated in the same terms after an aging treatment. Results showed that BC has got high crystallinity index, low internal porosity, good mechanical properties and high stability over time, especially when purified by the alkaline treatment. These features make BC an adequate candidate for degraded paper reinforcement. [ABSTRACT FROM AUTHOR]

The saltwater immersion method was developed to inhibit mould growth on flood- or tsunami-damaged paper. Commercially available fine paper used for printing and writing showed decreased tensile indices after saltwater immersion. The salt remaining in the paper tended to increase the moisture content because of the salt deliquescence and moisture in the air. The tensile index was restored by removing salt from the paper. Crystallization and distribution of salt in interfibre pores were also considered to influence interfibre rebonding. The difference in the fibre responses to saltwater depended on the relationship between nano-scaled pores in the fibre walls, osmotic pressure, and the degree of sizing, which resulted in low water retention values. More of the starch applied as a surface sizing agent was dissolved or dispersed during distilled water immersion than saltwater immersion. This loosened the fibre network, which was a factor that decreased the sizing degree of the paper. [ABSTRACT FROM AUTHOR]

Highlights: [•] Carboxymethyl cellulose (CMC) was oxidized to form dialdehyde CMC (DCMC). [•] Guanidine hydrochloride (GH) was grafted onto the DCMC to obtain DCMC-GH. [•] The coating of DCMC-GH onto paper resulted in the improvement of paper strength. [•] The DCMC-GH-coated paper exhibited excellent antimicrobial activities. [Copyright &y& Elsevier]

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

Highlights: [•] Oxidative group profiling of small ancient cellulose fragments coated with beeswax. [•] The main mechanism of deterioration was identified for the first time. [•] Beeswax coated cellulose was purely hydrolytically damage, no oxidation. [•] Hydrolysis caused by microorganisms secreting cellulolytic enzymes. [ABSTRACT FROM AUTHOR]

Highlights: [•] No external catalyst is required for citric acid crosslinking of cellulosic fibres. [•] We propose a mechanism for self-catalysed esterification of cellulosic fibres. [•] Crosslinking is facilitated by high curing temperature and citric acid dose. [•] Crosslinking increases linerboard compressive strength at high humidity. [•] Crosslinking extends lifetime of corrugated boxes under cycling high humidity. [ABSTRACT FROM AUTHOR]

Highlights: [•] A method to increase both strength and stretchability of paper is proposed. [•] The layer-by-layer technique is used to build up a multilayer onto pulp fibres. [•] The addition of salt in the system is a critical parameter. [•] Hyaluronic acid/polyallylamine is the most efficient system. [•] Strain at break and strength of treated paper sheets are increased by a factor 3. [ABSTRACT FROM AUTHOR]

Highlights: [•] Paper/caseinate and paper/caseinate/chitosan films were developed. [•] Chitosan layer on dry caseinate-coated paper provided the best functional properties. [•] Chitosan significantly increased the elongation at break of coated paper. [•] Caseinate/chitosan bilayer systems seemed to be appropriate paper coating materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] In this study we prepare Ag-NPs and Ag @ TiO2 composites as antibacterial nanomaterials. [•] Paper coated by PS nanocomposites containing Ag-NPs and Ag @ TiO2 composites. [•] We conclude that the prepared paper sheet characterize by SEM, EDAX and mechanical properties was evaluated. [•] Paper sheet coated by PS nanocomposites exhibited antimicrobial effect. [•] These Paper sheet can be used as food packaging materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] CNFs-based flexible transparent conductive paper was successfully prepared. [•] Optoelectronic properties of paper can be controlled by the times of LbL assembly. [•] Transparent conductive paper has good optoelectronic properties. [•] Transparent conductive paper has excellent flexibility and mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: Cellulose fiber has been modified by mechanical and chemical means in order to improve paper properties, which respond to moisture and temperature. When the cellulose is first refined and then etherified using hydroxypropylation under dry conditions, the paper sheets prepared from the hydroxypropylated cellulose show improved elongation. When the level of hydroxypropylation is high enough, the paper sheets also become transparent. Additionally, the effect of cellulose activation using different mechanical methods has been compared by esterification reactions. It is shown that removal of water is the most crucial step for the esterification reactions while other methods have a lesser impact. The paper sheets prepared from the esterified cellulose fibers show an increase in contact angles and high hydrophobicity. [Copyright &y& Elsevier]

Paper-based packaging generally has poor performances in the gas/oil barriers. This work reports a paper-based packaging material prepared via the modification of conventional papers with TEMPO-oxidized cellulose nanofibers (TOCN)/cationic guar gum (CGG) hydrogel film. Specifically, the hydrogel film modification was realized through a layer-by-layer deposition on paper. The hydrogel film modification significantly improved the mechanical and barrier properties of the paper. Specifically, the 4-layer hydrogel film modified paper showed a tensile strength of 34.03 MPa and a burst strength of 510 kPa, respectively. In contrast, the unmodified paper exhibited a tensile strength of 26.78 MPa and a bursting strength of 388 kPa. The packaging performance of this TOCN/CGG hydrogel film modified paper was demonstrated via the fresh mooncake packaging test. Such hydrogel film not only provided the oil resistance, but also maintained the mooncake's freshness. This material can serve as a green and sustainable food packaging. [Display omitted] • A TOCN/CGG self-assembled hydrogel film modified paper reported • A 27% increase in tensile strength with the 4-layer hydrogel film modification • A kit number of 11 with the 4-layer hydrogel film modification • Freshness retention of mooncakes observed as packaged with modified paper [ABSTRACT FROM AUTHOR]

Abstract: We report on the synthesis of cellulose paper bearing a cationic porphyrin, designed for antimicrobial applications. Tricationic porphyrin has been covalently grafted on paper, without previous chemical modification of the cellulosic support, using 1,3,5-triazine derivative as linker. The obtained porphyrin-grafted paper was characterized by infrared (ATR-FTIR), UV–visible and diffuse reflectance UV–vis (DRUV) spectroscopies to confirm the triazine linkage. Thermogravimetric analysis (TGA) was used to investigate thermal properties of grafted paper. Antimicrobial activity of porphyrin–cellulose material was tested under visible light irradiation against Staphylococcus aureus and Escherichia coli. The two bacterial strains deposited on the resulting photosensitizing filter paper are efficiently killed after illumination. [Copyright &y& Elsevier]

Abstract: A silver nanoparticle colloid was prepared by a modified Tollens method using d-glucose as the reduction agent. The obtained nanoparticles were used for the modification of pine, linter and recycled cellulose fibers. Although the silver contents were relatively low (0.05–0.13wt.%), the cellulose-sheets prepared from the modified fibers show improved mechanical and viscoelastic properties. The tensile index (strength) increased with up to 30% in comparison to the index of the sheets obtained from the untreated fibers. The influence of the nanoparticles on the viscoelastic properties of the cellulose sheets was investigated by dynamic mechanical analysis (DMA) in the temperature range from −120 to 20°C and with a force frequency of 100Hz. A broad relaxation transition positioned at −80°C was observed in the loss modulus spectrum of all the cellulose sheets, while the Ag-modified sheets exhibited higher storage moduli values in the whole temperature range. The antimicrobial activity tests show that the pine, silver and recycled cellulose fiber sheets with silver nanoparticles can be successfully employed to prevent the viability and growth of the common pathogens Staphylococcus aureus, Escherichia coli and Candida albicans. [Copyright &y& Elsevier]

Abstract: Conducting polymers have generated a great deal of interest because of their physical and chemical properties as well as their potential application in industry particularly in packaging applications. However one of short comings of most conducting polymer is that they are often formed as intractable films that are difficult to process. To overcome this problem we have incorporated conducting polymer, namely polyaniline into sheets of paper in order to create new composite material which combine the universal properties of paper product with the chemical and electrically conducting properties of the conducting polymer. Paper conducting polymer composite have been prepared by polymerizing aniline directly onto the paper sheet using ammonium peroxydisulfate (APS) as an oxidant at different temperatures. The prepared composite was characterized by FT-IR and SEM. The thermo-oxidative degradation was studied by thermo gravimetric analysis (TGA); electrical conductivities measurements of the composites were significantly increased over those of the precursor paper. [Copyright &y& Elsevier]

Abstract: Existing laser and inkjet printers often produce adverse effects on human health, the recycling of printing paper and the environment. Therefore, this paper examines the thermogravimetry curves for printer paper, analyzes the discoloration of paper using heat-induction, and investigates the relationship between paper discoloration and the heat-inducing temperature. The mechanism of heat-induced printing is analyzed initially, and its feasibility is determined by a comparative analysis of heat-induced (laser ablation) printing and commercial printing. The innovative concept of heat-induced inkless eco-printing is proposed, in which the required text or graphics are formed on the printing paper via yellowing and blackening produced by thermal energy. This process does not require ink during the printing process; thus, it completely eliminates the aforementioned health and environmental issues. This research also contributes to related interdisciplinary research in biology, laser technology, photochemistry, nano-science, paper manufacturing and color science. [Copyright &y& Elsevier]

Abstract: The effects of glycerol concentration and coating weight on biopolymer-coated paper properties were investigated using response surface methodology. Tests were run on the coated papers to determine water vapor barrier and mechanical properties. Coating weight was the most important parameter affecting water vapor permeability (WVP). Conversely, increasing coating weight led to a decrease in WVP and to an increase in tensile strength (TS) of the resulting coated papers. The papers coated with sodium caseinate (NaCAS) exhibited lower WVP values than those coated with other biopolymers. The TS of the papers coated with hydroxypropylmethylcellulose (HPMC) and chitosan was not affected by the glycerol concentration. HPMC-coated papers were higher in TS and %E than the other coated papers. For all types of coated paper, a maximum level of coating weight and level of glycerol concentration within range of 18.72–26.11% were found to be optimum for minimum WVP and maximum TS and %E. [Copyright &y& Elsevier]

Abstract: Wheat straw has been used as a pulping resource in China for many years. Wheat straw pulp (WSP) was widely used to substitute high quality chemical pulps such as those made from wood in producing writing and printing paper to reduce production cost of the resultant paper products and to improve paper smoothness without sacrificing paper strength. In this study, the process of co-refining of WSP and bleached hardwood kraft pulp (BHKP) was compared with the traditional separate refining and then blending these two pulps. The differences in refining energy consumption, the resultant pulp morphological and drainage properties, as well as the mechanical properties of the paper handsheets made of the resultant pulps were examined to explore the potential advantages of the co-refining process. The results show that the co-refining process has the potential to reduce refining energy consumption by at least 30% without affecting handsheet tensile and tear strength at a slightly lower re-wet tensile strength. [Copyright &y& Elsevier]

There is interest in replacing inorganic fillers in paper, coatings and plastics with renewable organic fillers to improve the economics, performance and environmental aspects of such products. Starch microcellular foam (SMCF) particles are promising materials in this regard. This research was undertaken to produce SMCF particles and characterize their morphology, optical properties and interaction with water. SMCF particles were produced using corn starch; which was solubilized in water. The foam structure was created by precipitating the starch using ethanol in a solvent exchange technique. The starch was also reacted with alkyl ketene dimer (AKD) wax at different levels in order to understand if the AKD could impart water resistance to the particles. Two methods were used to incorporate AKD: (1) the AKD was coated onto foam particles after foam formation, and (2) the AKD was blended with the starch before foam particle formation. Hexane extraction was used to purify a portion of each of the samples to determine if unreacted AKD existed with the starch matrix. Particles with porous structure and high brightness were developed for all combinations of starch and AKD. The brightness of the particles was significantly higher than that of the uncooked starch, presumably due to the development of a porous structure. For the AKD coated particles a minimum amount of AKD charged was needed to develop a high contact angle, low solubility, and low water retention value, higher levels of AKD in AKD coated particles did not further alter these properties. This indicates that the changes in properties with AKD level with coated particles is a surface phenomena. Starch AKD blends did not show any increased resistance to water relative to the particles with no AKD blended. This is due to the ethanol used in the precipitation process extracting the AKD, which was confirmed by elemental analysis. The particles, even with the 10% AKD coated or blended, lost their porous structure upon rewetting. Further work needs to be performed to more effectively hydrophobize the starch foams with AKD. [Copyright &y& Elsevier]

Cellulose degree of polymerisation (DP) was determined in paper pulps and commercial powder celluloses before and after the enzymatic treatment with a blend of cellulases and hemicellulases. Three different methods were used: (i) chemical method, based on the measurement of the cellulose reducing power; (ii) viscosimetry; and (iii) gel permeation chromatography. Although based in very different principles, the three methods find similar DP values in the case of pure cellulose with narrow molecular weight distributions. The chemical method is more sensitive to detect enzymatic depolymerisation and appears to provide a good estimation of the number-average DP. GPC data offers more detailed information about the enzymes mode of action on the fibres, showing that cellulose hydrolysis in the presence of the commercial preparation Celluclast 1.5L follows a layer-by-layer solubilisation mechanism. [Copyright &y& Elsevier]

Capillary zone electrophoresis was used for a comprehensive characterisation of several classes of degradation products from old books. Using different methods with direct and indirect UV detection, three categories of organic compounds were investigated, namely low-molar mass organic acids, aromatic lignin derivatives, and simple carbohydrates. The occurrence of these compounds in paper depended on the state of degradation and on the type of pulp. Formic, acetic, glycolic, succinic, and lactic acids originated from holocellulose degradation. In lignocellulosic papers, acetosyringone, 4-hydroxyacetophenone, 4-hydroxybenzaldehyde, vanillin, vanillic acid, furoic acid, and 4-hydroxybenzoic acid were attributable to the lignin fraction. These two classes of compounds could be analysed directly from the aqueous extracts of papers. Glucose and cellooligomers formed through cleavage of the cellulose chain, while the hydrolysis of hemicelluloses yielded mainly pentoses among which arabinose and xylose were the most abundant. The carbohydrates were derivatised with 4-aminobenzoic acid ethyl ester prior to analysis. All the organic compounds identified were found in a panel of papers from various origin (rag, kraft, and groundwood pulps) and diverse states of deterioration, whether naturally or artificially aged. The production of these compounds was followed during the accelerated ageing of the papers and an attempt to pointing to possible molecular indicators of paper degradation was made. [Copyright &y& Elsevier]

Cellulosic nanomaterials are in the focus of academia and industry to realize light-weight biobased materials with remarkable strength. While the effect is well known, the distribution of these nanomaterials are less explored, particularly for paper sheets. Here, we explore the 3D distribution of micro and nanosized cellulosic particles in paper sheets and correlate their extent of fibrillation to the distribution inside the sheets and subsequently to paper properties. To overcome challenges with contrast between the particles and the matrix, we attached probes on the cellulose nano/microparticles, either by covalent attachment of fluorescent dyes or by physical deposition of cobalt ferrite nanoparticles. The increased contrast enabled visualization of the micro and nanosized particles inside the paper matrix using multiphoton microscopy, X-ray microtomography and SEM-EDX. The results indicate that fibrillary fines enrich at pores and fiber-fiber junctions, thereby increasing the relative bonded area between fibers to enhance paper strength while CNF seems to additionally form an inner 3D network. [ABSTRACT FROM AUTHOR]

• Cellulose-based solutions can improve environmental performance of food packaging. • Food products require specific barrier functions from cellulose-based packaging. • Eco-design enables quantifying environmental performance and identifying trade-offs. • Fulfilling the barrier requirements for food product packaging is crucial. This short communication describes the climate change impacts of using cellulose, and more precisely cellulosic fiber-based materials, in food packaging, representing current and emerging industrial state of the art technology, without specific reference to current scientific advances. First, the different types of cellulosic fiber-based packaging materials, which can be used to replace fossil-based packaging materials, are presented for flexible and rigid applications. The focus is on technological solutions with packaging properties that enable the protection of commonly sold food products. The manufacturing processes associated with these cellulosic fiber-based materials is described and the environmental impact assessment of 4 selected case studies presented: stand-up pouches, flexible flow wraps, frozen or chilled food trays, and molded pulp lids. A simplified eco-design Life Cycle Assessment (LCA) was then performed to compare each solution with its fossil-based counterpart. Differences and similarities between the various cellulosic solutions have been identified. Furthermore, the assessment confirms that cellulosic fiber-based materials have reduced environmental impacts as compared to fossil-based counterparts, if a similar packaging weight is obtained. Indeed, all impacts of plastics are between 3 and 5 kg CO 2 eq/kg, while all impacts of cellulosic fiber-based materials are below 1.5 kg CO 2 eq/kg. [ABSTRACT FROM AUTHOR]

In 2020 the Cellulose and Renewable Materials Division (CELL) of the American Chemical (ACS) society celebrates its 100th anniversary. The following paper is based on a chapter from the book commissioned by the Division (Patterson, 2021). CELL is one of the most successful and dynamic Divisions in the ACS. It has evolved throughout its history to remain relevant and productive. One of its strengths is its diversity, while staying true to its founding vision. This perspective was present at its founding, and the following paper surveys the world of cellulose and renewable materials from the dawn of history to 1920. CELL has both industrial and scientific roots and has always welcomed the full range of participants from these communities. Rather than operating as separate tribes, the two groups have fostered innovations in each other. Many aspects of cellulose science and technology are discussed from antiquity to the early 20th century. [ABSTRACT FROM AUTHOR]

• MNFC preparation by chemo-refining route - potential to implement in paper industry. • Pretreatment with sodium meta-periodate and sodium chlorite followed by refining. • Nano and micro range fibres with improved WRV and carboxylic content. • Improved paper properties after MNFC addition without lowering pulp drainability. Micro-nanofibrillated cellulose was prepared using bleached mixed hardwood pulp by a low energy consuming chemo-refining approach having potential to be implemented easily in paper industry. Bleached mixed hardwood pulp was pretreated with sodium meta-periodate and sodium chlorite and micro-nanofibrillated by using refining in Valley beater. Scanning electron microscopy images of prepared micro-nanofibrillated cellulose showed 87 % fibre distribution in nano range, 4.47 ± 0.5 g/g water retention value and 2.13 ± 0.1 meq/100 g carboxyl content. Carboxylation effect of given chemical pretreatment was further confirmed by FTIR analysis. Paper handsheets, having bleached mixed hardwood pulp and prepared micro-nano-fibrillated cellulose, resulted in about 5% lower bulk with 27 %, 32 % and 87 % higher breaking length, burst factor and double fold, respectively than control (without nano-fibrillated cellulose). Prepared micro-nanofibrillated cellulose addition didn't show negative effect on pulp drainability (33 °SR). This work showed that micro-nanofibrillated cellulose might also be prepared using conventional routes of paper industry to improve paper properties. [ABSTRACT FROM AUTHOR]

• Waste paper was used to obtain nanocrystalline cellulose (CNC). • The obtained CNC was compared with CNC from cotton linter. • The biocidal activity of CNC added with Ag nanoparticles was assessed. • The growth of Aspergillus niger on Whatman paper is inhibited by CNC/Ag coating. • The mechanical properties of Whatman paper improve by the CNC coatings. Waste paper is an environmentally friendly source of cellulosic material. Here we propose a new treatment based on nanocrystalline cellulose (CNC) for paper preservation and consolidation. Suspensions of CNC were prepared by sulfuric acid hydrolysis using waste paper as cellulose source (CNC WP) and compared with CNC from cotton linter (CNC CL). Both CNCs were obtained with good yield, showing high crystallinity index and comparable morphology, as demonstrated by DLS-ELS, XRD, FTIR, Raman and TEM analyses. CNCs were mixed with silver nanoparticles (CNC/Ag) and their biocidal activity was tested against Escherichia coli and Bacillus subtilis , measuring the minimum inhibitory concentration. CNCs were exploited as treatments for biocidal activity and consolidation on Whatman paper. The presence of silver nanoparticles doesn't affect aesthetic appearance of the original paper and prevents the growth of Aspergillus niger fungus. Mechanical tests demonstrated that the coatings by CNC based products improve stretch and toughness of the paper support. [ABSTRACT FROM AUTHOR]