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This work was focused on the manufacturing of strawboard from agricultural waste like wheat straw (WS) and rice straw (RS) as natural resources of fibre by a sustainable and eco-friendly approach. Pineapple crown waste (PCW) fibre was used to replace the binder chemicals that are being used in the strawboard manufacturing industries to improve their quality in terms of mechanical strength properties. The strawboard with admirable properties like 4.74 mN·m2/g tear index, 14.96 N·m/g tensile indexes, 1526 m breaking length, 8.87 burst factor, and 20.3 stiffness factor was developed by adding 40% of PCW with 60% of WS pulp which was prepared by hydrothermal treatment of the material at 165 °C followed by the refiner mechanical pulping of the material. In addition to that, blending 60% RS with the same quantity of PCW pulp could develop strawboard with similar properties as that of wheat straw, which met the grade A and grade B strawboard required specifications as per Indian Standard: 2647–1967. The step towards utilizing agricultural waste to develop chemical-free strawboard not only minimizes the dumping of waste into the open field but also reduced the chemical utilization by the strawboard manufacturing industries, with PCW fibre that has been measured about 43% and 48% longer than WS and RS fibre, these could be the main reasons for developing such kind of strawboard with high mechanical properties. The fibre quality (morphology, crystallinity, and functional groups) of the different materials used was verified by different characterization techniques, such as FE-SEM, XRD, and FTIR-ATR analysis. [ABSTRACT FROM AUTHOR]

Cellulosic fiber from rice straw provides a sustainable alternative to the environmental menace of the field burning problem. Response surface methodology and artificial neural network were applied in the organosolv pulping process to evaluate the responses of total pulp yield (TPY, %), holocellulose content (HC, %), and Klason lignin (KL, %). The optimum input parameters for these reactions were solvent ratio (formic acid: acetone 8:2), chemical doses (68%), time (269 min), and temperature (106 °C) with a response value of TPY (49.8%), HC (80.35%) and KL (3.85%). Artificial neural networks showed better-optimized results as compared to the response surface methodology. An exceptional fiber separation was observed using SEM analysis, while FT-IR analysis confirmed the significant removal of lignin as per drastic reduction in the absorption band at around 1505 cm−1. The cellulose maximization and lignin reduction in the optimized pulp were also confirmed using EDX, XRD, and TGA analysis. Further, the effects of the addition of cationic starch, carboxymethyl cellulose, and xanthan gum were studied for making fiber composite hand sheets. The surface properties were optimum at the bio-additive doses of 3% (oven-dried) in both cases. However, the strength properties reached the maximum with the addition of 2% bio-additives. Nevertheless, cationic starch showed more suitable bio-additive for hand sheet packaging papers with better surface and strength properties. This study determined the optimum organosolv process parameters at the lab scale and further confirmed the suitability of the developed material for packaging applications with improved strength, surface, and optical properties. [ABSTRACT FROM AUTHOR]

This research explores the potential of agricultural waste, specifically flax straw, as a sustainable raw material for eco-friendly packaging materials. This study investigates a three-stage delignification process involving nitric acid, alkaline treatment, and organosolvent solutions. This method effectively removes lignin from the straw, resulting in high-quality technical pulp with 67.7% α-cellulose and a significantly reduced ash content (8.5%). X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were employed to characterize the treated flax straw. XRD analysis revealed changes in the cellulose structure, while TGA indicated enhanced thermal stability compared to untreated straw. Microscopic analysis of the pulp fibers shows a parallel and aligned arrangement, suggesting a high fiber content and a strong paper lattice. The particle size distribution of the ground pulp, influenced by fiber size, has implications for the packing density and mechanical properties of the final product. This study demonstrates the potential of agricultural waste as a sustainable source for packaging materials, contributing to the circular economy and waste reduction. [ABSTRACT FROM AUTHOR]

In this study, a comparative analysis of silver nanoparticles treatment and chitosan coating on packaging paper barrier properties was carried out. In order to examine the water, grease, and antibacterial barrier properties of silver nanoparticle-treated and chitosan-coated laboratory-obtained paper samples, a mixture of bleached softwood and hardwood celluloses was used. In order to conduct the comparative analysis SEM, water contact angle, Cobb60, and Kit tests were carried out on a cellulose sample, and four paper samples (three of them treated with silver nanoparticles—1, 2, and 3 mL/20 cm2 or chitosan coated—0.5, 1, and 2 g/m2) together with the inhibition activity against nine Gram-positive and Gram-negative bacteria, yeast, and fungal strains. The study found out that increasing the silver nanoparticle treatment and chitosan coating led to improved water resistance, while grease resistance was improved only for chitosan coated paper samples. Additionally, paper treated with 3 mL/20 cm2 of silver nanoparticles had the highest antibacterial protection (81.6%) against the Gram-positive bacterium Staphylococcus aureus, followed by Gram-negative Escherichia coli (75.8%). For the rest of the studied microorganisms, the average efficiency of the treated paper was 40.79%. The treatment of the paper with 1 and 2 mL/20 cm2 of silver nanoparticles was less effective—27.13 and 39.83%, respectively. The antibacterial protection of 2 g/m2 chitosan-coated paper samples was the most effective (average 79%) against the tested bacterial, yeast, and fungal strains. At 1 and 0.5 g/m2 chitosan coatings, the efficiency was 72.38% and 54.67%, respectively. Gram-positive bacteria, yeasts, and fungal strains were more sensitive to chitosan supplementation. [ABSTRACT FROM AUTHOR]

The present work reveals the potential application of dialdehyde and carboxylated nanocellulose for the in-situ reduction of Ag+ and immobilization as silver nanoparticles (AgNPs) on cellulose surfaces. Tollens' reagent (Ag(NH3)2OH) at concentrations ranging from 5·10–3 to 10–1 M was incorporated in both dialdehyde cellulose (DAC) and dialdehyde-modified TEMPO-oxidized cellulose nanofibers (DA-TOCNFs). The results showed that DA-TOCNFs facilitated faster reduction of Ag+ and effective immobilization of AgNPs on the nanocellulose surface. The resulting suspensions exhibited stability and demonstrated strong antimicrobial activity against Bacillus subtilis when coated on paper surfaces. Importantly, the coated papers did not show significant silver migration to food simulants B (3 vol% acetic acid) and D1 (ethanol/water mixture, 50 vol%), indicating the potential of these suspensions for active food packaging. The advantages of using DA-TOCNFs over DAC were attributed to their higher cationic demand and ζ-potential, resulting in a higher density of binding sites. Moreover, the charged and entangled network of DA-TOCNFs allowed for the individualization of AgNPs, unlike DAC, where some agglomerations were observed. Overall, this study presents an improved single-step process for the synthesis of AgNPs on nanocellulose surfaces, highlighting their potential for safe and high-performance applications in food packaging. Paper sheets coated with nanocellulose/AgNPs suspensions fully inhibited the growth of B. subtilis, at least for one month after coating, and caused damage to their cell membranes. This research provides a one-pot facile route to fabricating hybrid nanocellulose/AgNPs systems, stable in water, and may be used directly as a coating layer for board and paper active packaging with little or even undetectable release of Ag. [ABSTRACT FROM AUTHOR]

Recycling leather waste, which accumulates in large quantities in tanneries, and producing packaging paper with improved properties reduces the environmental burden and is at the same time economically efficient. A modified fibrous mass of waste from tanned and untanned leather scraps, waste paper, and acrylic emulsion was obtained and packaging paper based on them was produced. Alkaline modification of tanned leather waste - chrome shavings - leads to an increase in the electrokinetic potential and, accordingly, the stability of the fibrous suspension, partial hydrolysis of skin collagen occurs with the formation of new polar groups, and at the same time, the degree of cross-linking of the skin increases. In the paper composition, new intermolecular bonds are formed between cellulose and skin collagen. The microstructure, elemental composition, morphology, thermal and physical-mechanical properties of modified chrome shavings and composite paper were determined. A significant improvement has been achieved in the main parameters of paper: surface density (decrease by 16-25%), breaking load and breaking length (increase by 15-23%), number of double bends (increase by 2-6 times) in comparison with paper obtained from pure waste paper, and also to a greater extent compared to paper obtained from unmodified leather waste.

Nanofibrillated cellulose (NFC) and its combined usage with cationic starch and a cationic copolymer of acrylamide were studied in relation to the properties of paper. Independent pulp treatments using additives separately included 0%, 5%, 10%, and 15% refined long fiber pulp, 3 and 6% NFC, 0.75 and 1.5% cationic starch and 0.07% and 0.15% cationic polyacrylamide and combined treatments. Handsheets were made of the above treatments, and finally their optical and microscopic properties were evaluated. Increasing the NFC content to 6% increased the brightness and yellowness of the white liner by 13% and 21%, respectively. The liner opacity was also reduced by 1%. Additionally, increasing NFC by 6% compared to imported long fibers, the brightness and yellowness of the white liner increased 5.44% and 6.3%, respectively. The liner opacity was also reduced by 1%. A 1.5% cationic starch addition to NFC increased the brightness of the white liner by 4.4%, its whiteness increased 1.5%, and its yellowness increased 2.1%. The opacity of the liner was also reduced by 7.1%. The use of NFC and cationic starch can improve the optical properties of the white liner, while imported long fibers may be problematic.

In the present study, an environmentally friendly oil- and water-resistant paper was developed using a holo-lignocellulosic nanofibril (LCNF)-based composite coating. The LCNF was prepared from wheat straw using a biomechanical method. Characterizations of oil- and water-resistant coated paper and the effect of LCNF content on the performance of the coated paper were confirmed by combining contact angle analysis, Cobb 300s, and mechanical performance tests. The results show that the barrier performance and mechanical strength of the coated paper were greatly improved with the increase of LCNF content. The contact angle of oil and water of coated paper containing 50% LCNF were 69° and 78°, respectively, while the contact angle of oil and water of the base paper were only 30° and 20°, respectively. Cobb 300s values reduced from 110 g/m2 to 30 g/m2 when the LCNF content increased from 50% to 90%. Moreover, under the coating amount of 20 g/m2, the tensile strength of the coating paper was 0.980 KN/m, an increase of 10.11% compared with the base paper. The bursting strength reached 701.930 KPa, which was 10.75% higher than the base paper. In short, it is feasible to prepare LCNF from wheat straw, and apply it to produce water-proof and oil-proof paper. The water-proof and oil-proof paper developed in this study not only offers a novel approach to addressing white pollution but also presents a new research avenue for exploring the potential applications of agricultural waste. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate highly efficient alkyl ketene dimer (AKD) emulsions to improve the hydrophobicity of cellulose paper. AKD emulsions stabilized by guar gel were obtained; the guar gel was prepared by hydrogen bond cross-linking sodium tetraborate and guar gum. The cross-linking was confirmed by combining FTIR and SEM. The effect of guar gel on the performance of the AKD emulsions was also studied by testing AKD emulsions stabilized by different guar gel concentrations. The results showed that with increasing guar gel concentration, the stability of the AKD emulsions improved, the droplet diameter decreased, and the hydrophobicity and water resistance of the sized packaging paper were gradually enhanced. Through SEM, the guar gel film covering the AKD emulsion droplet surface and the three-dimensional structure in the aqueous dispersion phase were assessed. This study constructed a scientific and efficient preparation method for AKD emulsions and provided a new method for the application of carbohydrate polymer gels which may avoid the adverse effect of surfactant on paper sizing and environmental problems caused by surfactant bioaccumulation. [ABSTRACT FROM AUTHOR]

In this study, a comparative analysis of silver nanoparticles treatment and chitosan coating on packaging paper barrier properties was carried out. In order to examine the water, grease, and antibacterial barrier properties of silver nanoparticle-treated and chitosan-coated laboratory-obtained paper samples, a mixture of bleached softwood and hardwood celluloses was used. In order to conduct the comparative analysis SEM, water contact angle, Cobb60, and Kit tests were carried out on a cellulose sample, and four paper samples (three of them treated with silver nanoparticles—1, 2, and 3 mL/20 cm2 or chitosan coated—0.5, 1, and 2 g/m2) together with the inhibition activity against nine Gram-positive and Gram-negative bacteria, yeast, and fungal strains. The study found out that increasing the silver nanoparticle treatment and chitosan coating led to improved water resistance, while grease resistance was improved only for chitosan coated paper samples. Additionally, paper treated with 3 mL/20 cm2 of silver nanoparticles had the highest antibacterial protection (81.6%) against the Gram-positive bacterium Staphylococcus aureus, followed by Gram-negative Escherichia coli (75.8%). For the rest of the studied microorganisms, the average efficiency of the treated paper was 40.79%. The treatment of the paper with 1 and 2 mL/20 cm2 of silver nanoparticles was less effective—27.13 and 39.83%, respectively. The antibacterial protection of 2 g/m2 chitosan-coated paper samples was the most effective (average 79%) against the tested bacterial, yeast, and fungal strains. At 1 and 0.5 g/m2 chitosan coatings, the efficiency was 72.38% and 54.67%, respectively. Gram-positive bacteria, yeasts, and fungal strains were more sensitive to chitosan supplementation.

In the present study, an environmentally friendly oil- and water-resistant paper was developed using a holo-lignocellulosic nanofibril (LCNF)-based composite coating. The LCNF was prepared from wheat straw using a biomechanical method. Characterizations of oil- and water-resistant coated paper and the effect of LCNF content on the performance of the coated paper were confirmed by combining contact angle analysis, Cobb 300s, and mechanical performance tests. The results show that the barrier performance and mechanical strength of the coated paper were greatly improved with the increase of LCNF content. The contact angle of oil and water of coated paper containing 50% LCNF were 69° and 78°, respectively, while the contact angle of oil and water of the base paper were only 30° and 20°, respectively. Cobb 300s values reduced from 110 g/m2 to 30 g/m2 when the LCNF content increased from 50% to 90%. Moreover, under the coating amount of 20 g/m2, the tensile strength of the coating paper was 0.980 KN/m, an increase of 10.11% compared with the base paper. The bursting strength reached 701.930 KPa, which was 10.75% higher than the base paper. In short, it is feasible to prepare LCNF from wheat straw, and apply it to produce water-proof and oil-proof paper. The water-proof and oil-proof paper developed in this study not only offers a novel approach to addressing white pollution but also presents a new research avenue for exploring the potential applications of agricultural waste.

The alarming global deforestation rate has great impacts on the output of the Pulp and paper Industry since wood is the principal papermaking fiber material. Although, generally, bamboo is an alternative cellulolytic fiber source, the species and culm age have great effects on its papermaking potential. Based on the methods by the International Association of Wood Anatomists (IAWA), this work assessed the characteristics of fibers from the axial culm sections of six-month plantation-grown Oxythenantera abyssinica and Beema bamboo (which was cloned from Bambusa balcoaa) for paper production. The lengths of the fibers ranged from 1.89 to 2.39 mm while the diameters were 0.025–0.031 mm. The fiber lumen diameter and wall thickness were 0.014–0.018 mm and 0.004–0.006 mm, respectively. Fibers from the species had their runkle ratios below 1, slenderness ratios above 70 and flexibility ratios above 50. These characteristics compare well with the recommendations for fibers often used for the production of packaging, writing and printing papers. Establishment of plantations of Beema bamboo and O. abyssinica is encouraged as they will serve as good raw material base for the paper industry within six months of planting. Additionally, their planting will contribute to meeting Sustainable Development Goals 1 and 13.

The aim of the present study was to investigate highly efficient alkyl ketene dimer (AKD) emulsions to improve the hydrophobicity of cellulose paper. AKD emulsions stabilized by guar gel were obtained; the guar gel was prepared by hydrogen bond cross-linking sodium tetraborate and guar gum. The cross-linking was confirmed by combining FTIR and SEM. The effect of guar gel on the performance of the AKD emulsions was also studied by testing AKD emulsions stabilized by different guar gel concentrations. The results showed that with increasing guar gel concentration, the stability of the AKD emulsions improved, the droplet diameter decreased, and the hydrophobicity and water resistance of the sized packaging paper were gradually enhanced. Through SEM, the guar gel film covering the AKD emulsion droplet surface and the three-dimensional structure in the aqueous dispersion phase were assessed. This study constructed a scientific and efficient preparation method for AKD emulsions and provided a new method for the application of carbohydrate polymer gels which may avoid the adverse effect of surfactant on paper sizing and environmental problems caused by surfactant bioaccumulation.

The alarming global deforestation rate has great impacts on the output of the Pulp and paper Industry since wood is the principal papermaking fiber material. Although, generally, bamboo is an alternative cellulolytic fiber source, the species and culm age have great effects on its papermaking potential. Based on the methods by the International Association of Wood Anatomists (IAWA), this work assessed the characteristics of fibers from the axial culm sections of six-month plantation-grown Oxythenantera abyssinica and Beema bamboo (which was cloned from Bambusa balcoaa) for paper production. The lengths of the fibers ranged from 1.89 to 2.39 mm while the diameters were 0.025–0.031 mm. The fiber lumen diameter and wall thickness were 0.014–0.018 mm and 0.004–0.006 mm, respectively. Fibers from the species had their runkle ratios below 1, slenderness ratios above 70 and flexibility ratios above 50. These characteristics compare well with the recommendations for fibers often used for the production of packaging, writing and printing papers. Establishment of plantations of Beema bamboo and O. abyssinica is encouraged as they will serve as good raw material base for the paper industry within six months of planting. Additionally, their planting will contribute to meeting Sustainable Development Goals 1 and 13. [ABSTRACT FROM AUTHOR]

Food packaging manufacturers often resort to lamination, typically with materials which are neither non-biodegradable nor biobased polymers, to confer barrier properties to paper and cardboard. The present work considers a greener solution: enhancing paper's resistance to moisture, grease, and air by aqueous coating suspensions. For hydrophobization, a combined approach between nanocellulose and common esterifying agents was considered, but the water vapor transmission rate (WVTR) remained excessively high for the goal of wrapping moisture-sensitive products (>600 g m−2 d−1). Nonetheless, oil-repellant surfaces were effectively obtained with nanocellulose, illite, sodium alginate, and/or poly(vinyl alcohol) (PVA), reaching Kit ratings up to 11. Regarding air resistance, mineral-rich coatings attained values above 1000 Gurley s. In light of these results, nanocellulose, minerals, PVA, pullulan, alginate, and a non-ionic surfactant were combined for multi-purpose coating formulations. It is hypothesized that these materials decrease porosity while complementing each other's flaws, e.g., PVA succeeds at decreasing porosity but has low dimensional stability. As an example, a suspension mostly constituted by nanocellulose, sizing agents, minerals and PVA yielded a WVTR of roughly 100 g m−2 d−1, a Kit rating of 12, and an air resistance above 300 s/100 mL. This indicates that multi-purpose coatings can be satisfactorily incorporated into paper structures for food packaging applications, although not as the food contact layer. [ABSTRACT FROM AUTHOR]

This study measured the decrease in some mechanical properties of kraft paper used in packaging and bag production by examining the colour changes occurring in accordingly prepared standard samples subjected to UV influence. Thus, it is aimed to predict the mechanical properties of packages that have been exposed to sunlight over long periods of time with the colour change measurement, which is a non-destructive test, without the packaging deformation. Since there are mechanical differences between the cross-machine width and machine length of fabricated papers, these were measured separately. Measurements were made on papers exposed to UV for 0, 120, 240, 360, 480, 600, and 720 h. Tensile strength, strain at break, and tensile energy absorption (TEA) values were measured and also predicted for the kraft paper. For the prediction, the time and colour change values were used as independent variables, whereas the mechanical properties were taken as the dependent variables. The relationship between the time and colour change and the tensile strength, strain at break, and TEA variables in both the crossmachine and the machine directions were significant at the 5% level, and the R2 values were within acceptable limits. The results showed that the mechanical properties of the papers under UV effect decreased proportionally with the increase of the UV time. [ABSTRACT FROM AUTHOR]

The predicted scarcity of wood-based fibre supplies has necessitated the search for alternative sources including non-woods by paper manufacturers. As a raw material for pulping, hemp bast fibre has some potential. To provide a guide for the pulp and paper industries, the suitability of hemp bast fibres for the pulp and paper industries was evaluated in this study, and blending trials with wastepaper pulp were conducted. In the hemp bast fibre preparation, the length of the fibres was first reduced to 4 mm. Subsequently, kraft pulping was applied to them. Along with the preparation of wastepaper pulps, hemp bast fibres and wastepaper handsheets were prepared according to a blending plan. Finally, the handsheets were subjected to paper strength tests. The properties of raw, cooked and beaten hemp bast fibres were investigated by characterisation methods such as optical microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy. Additionally, carbohydrate components, solubility and ash content tests were run on raw hemp bast fibres. As a result of the experiments and analyses, the targeted results were achieved. Following the resolution of the fibrillation problem, it was determined that hemp bast fibre pulp can be used in adequate blends of wastepaper pulp when the strength values of the end product are desired to be increased (including CMT, CCT, RCT, SCT, stiffness and tear resistance) or decreased (air resistance). [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.

The paper presents the research results on the properties of the pulp coniferous and deciduous wood composition in its original state and paper made from it, proposes a mechanism to increase the waterfast and waterproof food packaging paper by surface treatment with a composition based on polyamidepichlorohydrin with polyvinyl alcohol and urea. The study was conducted in order to ensure an increase in the consumer properties of packaging paper, since when packaging materials encounter food products, their structure can change under the influence of moisture, steam, and gas. Polyamidaminepichlorohydrin was used as the main component of the composition for paper processing, as functional additives: polyvinyl alcohol and urea. The above-mentioned starting materials are environmentally friendly, since foreign inclusions in food packaging materials would pose a serious danger to human health and life, as well as to the brand image of the product in which they would be detected. It was proved that high waterfastness and waterproofness, as well as the necessary level of barrier, protective and operational properties of packaging material for food products cannot always be obtained by introducing a significant amount of polyamidaminepichlorohydrin, so the paper investigated the mechanism of interacting cellulose fibers of paper with polyamidaminepichlorohydrin, and also proved the possibility of its use to obtain packaging paper with a given set of properties. It was found that the consumption of up to 4–6% polyamidaminepichlorohydrin provides the main increase in the mechanical strength of packaging paper, both in wet and dry conditions. The resulting waterfast and waterproof material can be used for food packaging.

High yield pulps (HYP), manufactured in mechanical and chemimechanical pulping processes, are mainly used in graphic papers and paper grades where a high bulk is preferable, like in paperboards. Moreover, packaging papers with very high demands on both dry and wet strength could be manufactured from HYP in a near future. Preferred bonds between fibre components (long fibres, shortened fibres and fines) in the various paper grades are quite different. In the review, plausible effects of mechanical interlocking, intermolecular interactions ("physical bonding"), hydrogen bonds, intermixing of polymers, additives and possible specific interactions in the formation of strong bonds in sheet structures from HYP are discussed. A required condition for high bond strength in sheets from HYP furnishes is that fibre components are forced into sufficiently close contact. This is to a great extent impeded if the fibre walls are too stiff. Consequently, the current review focuses on both how fibre fractions should preferably be developed for different end uses and how suitable bonds might be achieved in different paper grades. The ideal type of bonds is certainly different depending on the demands on the final paper quality. [ABSTRACT FROM AUTHOR]

Developing environmentally friendly barrier coatings as an alternative to petroleum-based polymer packaging is a challenge. Cellulose nanofibres (CNF) films have exhibited great potential as water and gas barrier layers. Recycled paper was multi-layer coated with three commercial CNF (mechanical (M-CNF), TEMPO (T-CNF) and carboxymethylated (C-CNF)) using two metering systems (wound rod and blade micrometer) and two drying methods (tension-free contact drying and air drying). The coatability and rheological behaviour of the CNF suspensions were analysed. The gas, water and grease barrier properties of the CNF coated papers were determined and compared with the results of paper coated with cationic starch. The three CNF suspensions and the starch suspension were successfully coated using both metering systems. In the multi-layer coating, air drying yielded higher coat weights than contact drying, and the difference was more noticeable in M-CNF and T-CNF coated samples. A lack of uniformity observed in CNF coatings increased with the number of coating layers. M-CNF coated samples had a whitish surface with a uniform appearance, but coating was insufficiently compact to provide barrier properties. T-CNF coating exhibited a cracked surface and consequently provided no barrier properties. Drying stresses caused breakage of T-CNF coating, which could be explained by the drop in apparent viscosity at much lower rheological shear stresses in the T-CNF suspension. C-CNF showed successful coatability and provided barrier properties to paper with both metering systems and drying methods. Air permeance decreased considerably and the water wettability of the paper decreased by 60% compared to the reference paper, even with a single coating layer (about 1 g·m−2). In addition, a greaseproof paper (grease resistance >1800 s and kit no >10) was obtained with multi-layer C-CNF coating. Although water vapour permeability at 90 % RH and 20 °C decreased slightly with a single layer of CNF coating, higher amounts of CNF did not improve this parameter. • Evaluation of CNF coatability in metering and drying systems employed in papermaking • Air stream drying led higher CNF coat weights in multi-layer application. • Cracked coating under drying stresses was related to rheological behaviour of CNF. • Carboxymethylated CNF can be used as pre-coating to improve paper barrier properties in papermaking. • A greaseproof paper by multi-layer carboxylated CNFs coating could achieved [ABSTRACT FROM AUTHOR]

The paper presents the research results on the properties of the pulp coniferous and deciduous wood composition in its original state and paper made from it, proposes a mechanism to increase the waterfast and waterproof food packaging paper by surface treatment with a composition based on polyamidepichlorohydrin with polyvinyl alcohol and urea. The study was conducted in order to ensure an increase in the consumer properties of packaging paper, since when packaging materials encounter food products, their structure can change under the influence of moisture, steam, and gas. Polyamidaminepichlorohydrin was used as the main component of the composition for paper processing, as functional additives: polyvinyl alcohol and urea. The above-mentioned starting materials are environmentally friendly, since foreign inclusions in food packaging materials would pose a serious danger to human health and life, as well as to the brand image of the product in which they would be detected. It was proved that high waterfastness and waterproofness, as well as the necessary level of barrier, protective and operational properties of packaging material for food products cannot always be obtained by introducing a significant amount of polyamidaminepichlorohydrin, so the paper investigated the mechanism of interacting cellulose fibers of paper with polyamidaminepichlorohydrin, and also proved the possibility of its use to obtain packaging paper with a given set of properties. It was found that the consumption of up to 4–6% polyamidaminepichlorohydrin provides the main increase in the mechanical strength of packaging paper, both in wet and dry conditions. The resulting waterfast and waterproof material can be used for food packaging. [ABSTRACT FROM AUTHOR]

The expediency of using a sunflower as an alternative raw material for the cellulose and paper industry and peroxyacetic acid as a cooking solution of a plant material is substantiated. The catalytic action of Na2WO4, Na2MoO4 and TiO2 on the process of delignification of sunflower stalks with hydrogen peroxide in the acetic acid was studied. The resulting peracetic cellulose with sodium tungstate has high quality indices. The indices of the lignin extraction selectivity by per oxoacetic delignification of sunflower stalks are calculated. The paper-making properties of the organic solvent cellulose from sunflower stalks are determined. The possible usage in the production of packaging paper has been evaluated. [ABSTRACT FROM AUTHOR]

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

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

Needs for biodegradable packaging materials are growing to reduce the negative environmental impact of petroleum-based polymer packaging. Barrier paper packaging is in demand as environmentally-friendly barrier coating materials to improve biodegradability and recyclability. Cellulose nanofibril (CNF) is considered an alternative to conventional polymers for barrier coatings due to the barrier properties of its films. In this work, various types of CNFs were prepared and coated on linerboard and wood-free paper to evaluate the barrier properties of these papers against air, liquid water, water vapor, oxygen, and grease, and the major factors of the barrier performance of the CNFs-based coatings were investigated. A coat weight of at least 10 g/m2 was desirable to impart efficient the barrier properties to papers. The average fibril size and hydrophobicity were strongly related to the barrier properties. CNFs with smaller fibril sizes are beneficial for enhancing barrier properties, and hydrophobization improves the water resistance. Hydrophobic functional groups with sufficient chain lengths decreased the water vapor barrier properties. The average fibril diameter of CNFs may be related to the air resistance, oxygen barrier properties, and grease resistance. [ABSTRACT FROM AUTHOR]

The poor barrier properties and hygroscopic nature of cellulosic paper impede the wide application of cellulosic paper as a packaging material. Herein, a polyvinyl alcohol (PVA)-based polymer coating was used to improve the barrier performance of paper through its good ability to form a film. Alkyl ketene dimer (AKD) was used to enhance the water resistance. The effect of the absorptive characteristics of the base paper on the barrier properties was explored, and it was shown that surface-sized base paper provides a better barrier performance than unsized base paper. Nanoclay (Cloisite Na+) was used in the coating formulation to further enhance the barrier performance. The results show that the coating of PVA/AKD/nanoclay dispersion noticeably improved the barrier performance of the paper. The water vapor transmission rate of the base paper was 533 g/m2·day, and it decreased sharply to 1.3 g/m2·day after the application of a double coating because of the complete coverage of the base paper by the PVA-based polymer coating. The coated paper had excellent water resistance owing to its high water contact angle of around 100°. The grease resistance and mechanical properties of the base paper also improved after coating. This work may provide inspiration for improving the barrier properties of packaging paper through the selection of a suitable base paper and coating formulation.

In recent years, a significant surge in the mass of generated waste with varying morphological composition has been observed. Packaging made of both plastic and paper has an increasing share in the municipal solid waste stream. The multiplicity of packaging means that proper methods and installations are needed to appropriately manage the waste generated from it. A special type of packaging waste is made of paper and cardboard and it is considered as biodegradable waste. It can be processed in both mechanical (material) and biological treatment processes. Thanks to the microorganisms involved in biological treatment processes, the organic matter present in waste should be decomposed (biodegradable). The main aim of the study was to analyze the dynamics of the biodegradation process of selected packaging waste made of paper and cardboard in various research environments. The waste used for the analysis differed primarily in grammage. The dynamics of the decomposition rate of the examined waste was analyzed for materials placed in 4 different research environments. The analysis showed significant differences in the rate of biodegradation of the tested waste. Differences were also found in the rate of material decomposition in individual research environments. Materials with low grammage such as paper towels and sandwich paper wrapper were the fastest to biodegrade. [ABSTRACT FROM AUTHOR]

Highlights • A food-safe superhydrophobic packaging paper was fabricated. • The method relied on combination of layer-by-layer assembly and wax treatment. • Moisture and air barrier properties of superhydrophobic paper was improved. • The obtained superhydrophobic paper showed promising prospect in food packaging. Abstract We presented a facile method for preparing a food-safe superhydrophobic packaging paper with improved moisture and air barrier properties in this study, which is combining construction of polymer-nanoclay hybrid multilayers with subsequent carnauba wax treatment. The polymer-nanoclay hybrid multilayers consisting of quadlayers of carrageenan (CR)/chitosan (CS)/montmorillonite (MMT)/CS were created using layer-by-layer (LbL) assembly. The surface chemical compositions, potentials and morphologies of the CR/CS/MMT/CS multilayer-modified paper samples were investigated. The paper sample modified with a wax-treated (CR/CS/MMT/CS) 2 multilayer gave a water contact angle of 151.4°. Compared with original paper, this superhydrophobic paper sample showed comparable tensile strength and excellent barrier properties against water vapor and air. Moreover, the obtained paper was used for strawberries packaging at ambient temperature, and it was very effective at reducing the weight loss and maintaining titratable acidity compared with the unpackaged strawberries, which might has a great potential as food packaging materials. [ABSTRACT FROM AUTHOR]

Nanotechnology applied to pulp and paper sector enables production of nanostructured papers with excellent strength properties. The addition of lignocellulose nanofibrils (LCNF) to traditional kraft pulps is an attractive alternative for production of improved packaging papers. In relation to cellulose nanofibrils (CNF), LCNF application in unbleached papers has the advantage of eliminating the costs of bleaching chemicals and potential advantages in drainage. One aim of this study was producing and characterizing LCNF from eucalypt (E) and pine (P) unbleached pulps and comparing the results with the traditional CNF. Another aim of the work was evaluating LCNF as an additive for production of kraftliner and sackraft nanostructured packaging papers. LCNF proved to be a viable additive for the production of high-strength nanostructured papers while relying on low energy consumption during the refining process. LCNF addition had positive effects on the mechanical properties of the nanostructured papers produced, resulting in significant increases in strength properties. [ABSTRACT FROM AUTHOR]

Elongation is an important property of many packaging board and paper grades. Paper with high extensibility could provide an alternative for oilbased packaging materials. Micro- (CMF) and nanofibrillated (CNF) cellulose are known to increase the strength of a paper, but their effect on the drying shrinkage and elongation is not well-studied. In this work, paper was reinforced with fibrillated material. Added fibrillated material increased the drying shrinkage, which was generally proportional to the increase of paper elongation before breakage. Results differed depending on the fibrillated material and how it was added to paper (wet-end addition or spray application). The papers were dried unrestrained in order to achieve the highest elongation potential for the paper. Spray application of CMF increased elongation by 13%, while wet-end additions increased elongation by 20% and also strength by 10%, but only with high dosages. Spray application of oxidized-CNF improved elongation by 33%, while wetend applications increased only strength by 20%. Thus, boosting the drying shrinkage with fibrillated cellulose is one potential way to increase elongation and 3D formability of paper. [ABSTRACT FROM AUTHOR]

Hydrophobic noncrystalline porous starch (NCPS) containing microporous and amorphous structures was prepared from native corn starch via heat treatment, solvent exchange, and alkyl ketene dimer (AKD) modification. Then, antibacterial packaging was produced by combining silver nanoparticles with the hydrophobic NCPS (hydrophobic NCPS/Ag) and employing this biobased coating as a layer on the base paper. The antibacterial activity, strength, and barrier properties of the hydrophobic NCPS/Ag-coated paper were measured. In addition, the fine porous surface of NCPS, the distribution of the silver nanoparticles in hydrophobic NCPS as well as the network structure of uncoated paper and coated paper were characterized by scanning electron microscopy. Meanwhile, the hydrophobicity of the corn starch, hydrophobic NCPS, uncoated paper, and coated paper were determined using water contact angles. The silver nanoparticles had a positive effect on the antibacterial activity against Escherichia coli and Staphylococcus aureus. The air permeability, oil resistance, water vapor transmission rate, water absorption, whiteness, tensile strength, and burst strength improved compared to the uncoated paper. [ABSTRACT FROM AUTHOR]

Creating efficient water-borne dispersions based mainly on renewable materials for coating of flexible packaging paper was the aim of this study. The effects of an ethylene modified poly(vinyl alcohol) grade and a standard poly(vinyl alcohol) on the oxygen and water vapor barrier performance of corn starch and potato starch coatings was studied. The results showed that a coating composition with a high fraction of a renewable polymer was effective in keeping the oxygen barrier at a technically and commercially applicable level. An ethylene modified poly(vinyl alcohol) grade was found to provide lower oxygen transmission rates at high relative humidity, as compared to a standard poly(vinyl alcohol) grade. The oxygen barrier properties of blends of starch and poly(vinyl alcohol) were similar to that of the pure modified poly(vinyl alcohol) in the range from 0% starch to 60% starch. This was observed with both hydroxypropylated and octenyl succinate modified starch grades. The drying conditions of the mixed starch:poly(vinyl alcohol) coatings were based on drying trials with pure poly(vinyl alcohol) coatings. Drying at moderate temperatures indicated the possibility to slightly decrease water vapor transmission rate by higher drying temperature. Several secondary effects of increased drying temperature such as coating hold-out and formation of defects may also be of importance. [ABSTRACT FROM AUTHOR]

In the research, paper was successfully coated with curdlan and chitosan (CR/CH) coating solutions at different ratios (CR/CH ≈ 10:0, 8:2, 6:4, 5:5, 2:8, 4:6, 0:10% w/w). The novelty of this paper is in the use of combination of curdlan and chitosan, which led to a positive effect on the mechanical and water barrier properties. The tensile properties were improved when the ratio between polymers was 5:5. Coated papers were further investigated for their bursting strength, tear and bending resistance. Pure curdlan coating worsen the tensile and moisture properties and allowed to prepare the blend coatings with different amounts of chitosan. The equilibrium thickness of coatings as a function of curdlan content and tensile strength has shown a decrease in tensile strength. This has resulted in reduction of tensile strength especially at higher thickness. The resulting blend curdlan/chitosan coatings exhibited good water barrier and mechanical properties and could be used in many fields. [ABSTRACT FROM AUTHOR]

The migration behaviour of four photo-initiators (BP, EHA, MBP and Irgacure 907) was studied by ‘printing’ onto four different food-packaging materials (Kraft paper, white cardboard, Polyethylene (PE)-coated paper and composite paper) and tracking movement into the food simulant: Tenax-TA (porous polymer 2,6-diphenyl furan resin). The results indicated that the migration of the photo-initiators was related to the molecular weight and log Ko/wof each photo-initiator. At different temperatures, the migration rates of the photo-initiators were different in papers with different thicknesses. The amount of each photo-initiator found in the food was closely related to the food matrix. The Weibull model was used to predict the migration load into the food simulants by calculating the parametersτandβand determining the relationship of the two parameters with temperature and paper thickness. The established Weibull model was then used to predict the migration of each photo-initiator with respect to different foods. A two-parameter Weibull model fitted the actual situation, with some deviation from the actual migration amount. [ABSTRACT FROM PUBLISHER]

The conventional package paper was coated with biodegradable montmorillonite/chitosan nanocomposite, in order to extend the application scope of paper. The effect of coating weight, montmorillonite dispersion rate, montmorillonite and dispersant content on the surface and penetration properties of montmorillonite/chitosan nanocomposite coated paper were being investigated. The surface properties of the coated paper were observed by using scanning electron microscope (SEM) and atomic force microscope (AFM). The water permeation and water vapor barrier properties were confirmed through penetration dynamics analyzer (PDA) and water vapor permeability tester (WVP), respectively. The results indicated that montmorillonite/chitosan nanocomposite had a poorer formation than pure chitosan, but it had better water vapor barrier properties. The paper coated with lower content of montmorillonite, or with higher dispersion speed and dispersant content, had better smoothness and elongation. Additionally, the coated paper had excellent barrier properties under the conditions of high montmorillonite and dispersant content, dispersion rate and coating weight. [ABSTRACT FROM AUTHOR]

This study reports on the development of bio-based hydrophobic coatings for packaging papers through deposition of polyhydroxybutyrate (PHB) particles in combination with nanofibrillated cellulose (NFC) and plant wax. In the first approach, PHB particles in the micrometer range (PHB-MP) were prepared through a phase-separation technique providing internally-nanosized structures. The particles were transferred as a coating by dip-coating filter papers in the particle suspension, followed by sizing with a carnauba wax solution. This approach allowed partial to almost full surface coverage of PHB-MP over the paper surface, resulting in static water contact angles of 105°-122° and 129°-144° after additional wax coating. In the second approach, PHB particles with submicron sizes (PHB-SP) were synthesized by an oil-in-water emulsion (o/w) solvent evaporation method and mixed in aqueous suspensions with 0-7 wt % NFC. After dip-coating filter papers in PHB-SP/NFC suspensions and sizing with a carnauba wax solution, static water contact angles of 112°-152° were obtained. The intrinsic properties of the particles were analyzed by scanning electron microscopy, thermal analysis and infrared spectroscopy, indicating higher crystallinity for PHB-SP than PHB-MP. The chemical interactions between the more amorphous PHB-MP particles and paper fibers were identified as an esterification reaction, while the morphology of the NFC fibrillar network was playing a key role as the binding agent in the retention of more crystalline PHB-SP at the paper surface, hence contributing to higher hydrophobicity. [ABSTRACT FROM AUTHOR]

The moisture resistance of Kraft paper was greatly improved when it was coated with silylated soybean oil that was cured via silanol condensation. This moisture barrier coating was prepared from LowSat ® Soybean oil that was grafted with vinyltrimethoxysilane (VTMS) using a relatively simple process based on the “Ene reaction”. The viscosity of the resulting oil was unaffected by the silylation reaction and remained low (32 cPs). Thus, the paper coating process required no solvent, additional diluent or the need to emulsify the oil which provided a convenient one-component cure system. Dibutyltin dilaurate (DBTDL) was found to be an effective condensation catalyst and under optimal conditions complete cure was achieved in a short period of time. The cure rate was a function of the catalyst concentration, available water and the temperature. Initially, Kraft papers were coated with the silylated soybean oil in the lab and this process was followed by a pilot scale-up using a commercial gravure roll coater. Cobb values and water vapor transmission rate indicated the cured coating provided a good barrier coating. Scanning electron microscopy (SEM) images of the coated paper confirmed a uniform coating with good adhesion of the coating material to the paper. [ABSTRACT FROM AUTHOR]

The antimicrobial properties of bagasse paper sheets coated with natural polymers (chitosan, different ratios of (gelatin/glycerol) + chitosan, hemicellulose, hemicellulose + glycerol, hemicellulose+chitosan) or synthetic organophosphorus dimer compounds were evaluated in this work. Hemicelluloses showed moderate activity against Bacillus subtilis and Candida albicans, while chitosan showed weak activity against B. subtilis. The condition that offered the highest inhibitory activity of bagasse paper was the one coated with 1,3-diaryl-2,2,2,4,4,4- hexachlorocyclodiphosph(V)azane (where aryl is p-chloroaniline or p-anisidine). The developed bagasse papers were evaluated against Gram-positive bacteria, Gram-negative bacteria, yeasts, and fungi. The highest inhibitory activity was obtained at a concentration of 200 mg/mL for p-chloroaniline with an inhibition zone that varied for different microbes from 6.9 mm to 26 mm. The highest inhibitory activity was obtained at 300-250 mg/mL for panisidine against most of the pathogenic microorganisms with an inhibition zone that varied for different microbes from 8 mm to 14.75 mm. The observed antimicrobial and antifungal activity properties for bagasse paper coated with 1,3-diaryl 2,2,2,4,4,4- hexachlorocyclodiphosph(V)azane could be attributed to the presence of Cl, P atoms, and the lone pair of electrons on N atoms in the structure of the dimers. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various topics within the issue including a method of improving the antimicrobial activity of bagasse packaging paper, effect of reservoir pressure on calcium sulfate and barium sulfate precipitation, and methylene blue as redox mediator.

In this study, antimicrobial packaging was prepared by mixing colloidal silver nanoparticles with cellulose nanofiber (CNF) and depositing this hybrid coating (CNF/Ag) as a layer on different paper substrates. The CNF/Ag-coated papers were then characterized by scanning electron microscopy (SEM). In addition, their antimicrobial activity, and barrier and strength properties were assessed. SEM showed deposition of Ag nanoparticles on the surface of CNF and formation of a relatively smooth, dense coating layer on the paper surface. The results also demonstrated that the CNF/Ag coating exhibited good antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. Although the coating coverage was influenced by paper surface characteristics and coat weights, almost all properties (except water absorption of greaseproof paper) including the water vapor transmission rate, oil resistance, and tensile strength of the CNF/Ag-coated papers were improved in comparison with uncoated papers. [ABSTRACT FROM AUTHOR]