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The production of paper–polymer composite materials based on polystyrene and plant extracts of coniferous trees is described. The resulting bioplastics have increased resistance to biodegradation and are a promising basis for use as reinforcing polymer systems of cellulose-containing materials used for the production of packaging materials and special-purpose papers as part of electrical devices for various purposes. It has been shown that the inclusion of plant extracts makes it possible to improve the physical and mechanical properties of paper composites and ensure their resistance to biocorrosion. The conducted research makes it possible to expand the areas of application of paper materials and products based on them. [ABSTRACT FROM AUTHOR]

Cellulosic material is considered to be excellent for food packaging due to its low cost, easy degradability, and high recyclability rates. However, its application is still limited due to its porous structure and high hydrophilicity, which provide high permeabilities to grease, gas and water vapor. One solution to fix these issues and to bring new functionalities that can also extend food shelf life is to coat the paper substrate with biopolymers containing nanoparticles and/or components with antioxidant and/or antimicrobial activities. In this regard, the aim of this study was to review some aspects of the current knowledge critically and didactically on applications of biopolymer-based coatings incorporated with active components and/or nanoparticles on paper/paperboard materials usually applied as primary cellulosic active packaging. Studies have shown that this combination can positively improve the physical, mechanical, and barrier properties of cellulosic packaging, along with the enhancement of antioxidant and antimicrobial activities. A better understanding of these aspects enables the use of other active compounds to develop more functionality to the packaging itself as well as to apply it to food packaging in general. [ABSTRACT FROM AUTHOR]

The fines fraction in mechanical pulp, produced during wood processing can impact the mechanical properties of the resulting paper positively or negatively, making them potential additives for paper strength improvement at the right loading level. To enhance fines' effectiveness as paper strength additives that have heterogeneous surface chemistries, this work employed a regioselective surface esterification method conducted under mild conditions in acetone, with the addition of succinic anhydride and imidazole. This approach converted surface hydroxyl groups of fines into carboxylic acid groups, resulting in a final content of near 0.5 mmol g−1. This modification increased fines' hydrophilicity, as evidenced by enhanced moisture absorption capacity in dynamic vapor sorption analysis. These fines with additional functionality strengthened intermolecular bonding, leading to over 150% enhancement in tensile strength and Young's modulus when cast into thin films. Fines were substituted at 10–20 wt.% concentration to the fiber fraction of softwood thermomechanical pulp (TMP) and bleached chemi-thermomechanical pulp (BCTMP) forming handsheets. It was observed that fines modified with succinic anhydride and imidazole were more effective in enhancing paper strength, including tensile (up to 30%), burst (up to 39%) and tear (up to 4%) indices. This improvement was likely due to enhanced intermolecular bonding between modified fines and the fiber surfaces. By modifying mechanical pulp fines with succinic anhydride and imidazole, we have converted a potential heterogeneous waste product from the industry into a valuable by-product to enhance paper performance. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) and chitosan (Cht) have been studied extensively for oxygen and water vapour barrier coatings in biodegradable, compostable or recyclable paper packaging. However, rare studies have been performed by using scalable, inexpensive, and fast continuous slot-die coating processes, and none yet in combination with fast' and high-throughput near-infrared (NIR) light energy drying. In this frame, we studied the feasibility of a moderately concentrated (11 wt%) anionic CNC and (2 wt%) cationic Cht coating (both containing 20 wt% sorbitol related to the weight of CNC/Cht), by using plain and pigment pre-treated papers. The effect of coating parameters (injection speed, dry thickness settings) were investigated on coating quantity (dry weight, thickness) and homogeneity (coverage), papers' structure (thickness, grammage, density), whiteness, surface wettability, barrier (air, oxygen and water vapour) properties and adhesion (surface strength). The coating homogeneity was dependent primarily on the suspensions' viscosity, and secondarily on the applied coating parameters, whereby CNCs could be applied at 1–2 times higher injection speeds (up to 80 mL/min) and versatile coating weights, but required a relatively longer time to dry. The CNCs thus exhibited outstanding air (4.2–1.5 nm/Pa s) and oxygen (2.7–1.1 cm3 mm/m2 d kPa) barrier performance at 50% RH and 22–33 g/m2 deposition, whereas on top deposited Cht (3–4 g/m2) reduced its wetting time and improved the water vapour barrier (0.23–0.28 g mm/m2 d Pa). The balanced barrier properties were achieved due to the polar characteristic of CNCs, the hydrophobic nature of Cht and the quantity of the applied bilayer coating that can provide sustainable paper-based packaging. [ABSTRACT FROM AUTHOR]

Flexible and small-scale energy storage technologies are critical for future applications such as wearable electronics. In this context, paper has emerged as a lightweight, low-cost, and ecologically friendly flexible substrate for energy storage devices. This paper presents a simple method for fabricating a micro-supercapacitor (MSC) using a wax printing approach that can achieve high resolution without requiring complex processes. In addition, the developed MnO2–Au-paper (MAP) microelectrodes with high porosity exhibit enhanced charge and ion transfer while maintaining a stable flexibility. The solid-state micro-supercapacitor delivers a very large areal capacitance of 624.32 mF cm−2 at 0.2 mA cm−2 and is stable under external stress. The highest energy and power densities obtained for the present MSCs (55.5 μWh cm−2 and 1.59 mW cm−2, respectively), are much larger than those previously reported for pseudocapacitive MSCs, including flexible ones. [ABSTRACT FROM AUTHOR]

The paper and pulp industry stands out to be one of the industries that are growing at a fast pace. Besides their characteristics such as high water consumption of 695.7 million m3 per year and subsequent high energy consumption, there are plenty of environmental impacts arising from this industry. Approximately 300 different types of harmful organic pollutants such as phenols, dioxins, and other organic substances are the significant effluents of the paper and pulp industry. As per the regulations set by the world health organization (WHO), the permissible limit of such pollutants is less than 1 ppm. Since the complete degradation of these pollutants is difficult to achieve using conventional techniques, advanced oxidation processes (AOPs) are widely being used as promising alternatives. On the other hand, depleting non-renewable energy resources are forcing industries to look for energy-efficient technologies. Photocatalysis is one such AOPs, which has the potential to solve the energy-wastewater nexus and is the primary focus of this review in terms of waste treatment from the paper and pulp industry. The photocatalytic materials induce photoreactions by receiving photon energy from light. However, harnessing light energy to the fullest is a challenge owing to the limited share of UV spectrum in sunlight. Different composite photocatalysts at different loadings, pollutant concentrations, and contact time along with their respective efficiencies are reported. The enhancement in thermodynamic driving force due to shift in Fermi energy levels with a suitable example is explained. The dependence of photocatalysis on various factors such as organic species, temperature, and light intensity makes it tough to predict the precise kinetic model in real-life experiments. The hydrogen production from the degradation of organic pollutants was discussed vividly and by optimization of the processes, an estimated amount of 0.45% of the total world's energy could be produced from the paper and pulp industry alone. [ABSTRACT FROM AUTHOR]

Cellulosic-based materials such as hemp fabric and paper have combined characteristics of renewability, biodegradability, flexibility, and recyclability. However, regular products are not suitable for use in unconventional applications due to inherent limitations, and accordingly, enabling new capabilities is a necessity. To this end, the conversion of regular hemp fabric and paper into high-strength products with hydrophobic function via surface engineering was explored. The fluorinated waterborne polyurethane (FWPU) emulsions were first synthesized as functional coatings by in-situ polymerization. The structure and properties of the FWPU emulsion and film were characterized by FTIR, XRD, SEM, TG, and XPS. The results showed that the grafting of perfluorooctanol imparts WPU film excellent hydrophobicity, and the water contact angle increases from 71.2° to 105.9°. After the FWPU coating, the water contact angles of the hemp fabric and paper increase from 0° to 117.1° and 112.8°, respectively. Quite encouragingly, the coating generation of waterborne polyurethane-derived functional additives led to the increase of mechanical strength by more than 23% and 82%, in the case of qualitative filter paper and hemp fabric. Meanwhile, the folding strength of filter paper is increased by 132 times. Overall, this functionalized waterborne polyurethane coating would direct paper and hemp fabric toward diversified applications. [ABSTRACT FROM AUTHOR]

The terahertz spectrum of paper has been measured from room temperature to cryogenic temperatures. As the paper is cooled, the main absorption lines move to higher frequencies. The same behaviour is observed for two types of paper. The spectrum at base temperature provides the most direct comparison yet with calculations made using density functional theory, which assume the studied material to be at absolute zero temperature. These unique experiments should spur the development of better theoretical models of cellulose and cognate materials. [ABSTRACT FROM AUTHOR]