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Fourier transform infrared spectroscopy (FTIR) spectrum of the polyamine (Polycoat38 ® ) resin synthesized.
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Tissue paper is of high importance worldwide and, continuously, research is focused on improvements of the softening and durability properties of the paper which depend specifically on the production process. Polyamide-amine-epichlorohydrin (PAE) resins along with release agents are widely used to adhere the paper to the yankee dryer (creping cylin...
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... Examples of paper grades that benefited from the early application of PAAE are tissue and towel products, followed by liquid packaging boards, tea bag and currency. Today, although PAAE is used mainly in paper products and molded pulp products, studies have shown that it can be used to protect antibody bioactivity on paper-based bio diagnostics [77,[87][88][89][90]. ...
Additives are ingredients used in papermaking to enhance fiber properties, introduce special properties to the paper and improve the efficiency of the paper making process. Wet strength agents, sizing agents, dry strength agents, fillers, retention aids, defoamers, dyes and pigments are common additives used in paper mills. Poor retention of wet strength additive such as PAAE (polyamide epichlorohydrin) and hydrophobicity loss due to ASA (alkenyl succinic anhydride) and AKD (alkyl ketene dimer) size reversion not only increase cost and reduce product quality in the mill but also increase customer complaints and rejections.
In this study, a method was developed to quantify and study the parameters that govern PAAE retention in paperboard. PAAE applications, performance, and recyclability were also investigated. In addition, ASA bonding mechanism to the fiber was investigated, and experiments were performed under different environmental conditions to determine the environmental parameters that initiate or catalyze ASA and AKD size reversion.
The results of these studies indicated that PAAE can be quantified after hydrolysis and derivatization to diethyl adipate. PAAE retention increases as the pulp freeness decreases. Instead of freeness, fiber surface charge can be used to predict PAAE retention. The results also indicated that high presence of lignin in the sheet provides wet strength and low PAAE retention due to low availability of carboxylic groups on the fiber. On the contrary, when the lignin is removed, the retained amount of cationic PAAE increases due to the availability of anionic carboxylic groups on the fiber resulting in high wet strength; lignin is potential biomaterial based wet strength.
Investigations revealed that ester bond formation between ASA and cellulose is insignificant and is not a prerequisite for sizing effectiveness. Although, hydrolyzed ASA contributes to the sizing performance, direct application of hydrolyzed ASA to the pulp leads to flocculation and does not achieve sizing. The results revealed that ASA and AKD size reversions are significantly light and oxygen dependent. The oxidative photodegradation mechanisms of the sizing agents are explored and possible mechanisms are proposed.
... Examples of paper grades that benefited from the early application of PAAE are tissue and towel products, followed by liquid packaging board, tea bag and currency. Today, although PAAE is used mainly in paper products and molded pulp products, studies have shown that it can be used to protect antibody bioactivity on paperbased bio diagnostics (Huang et al. 2017;Crisp and Riehle 2018;Valencia et al. 2020;Qin et al. 2022; Astute Analytica 2023). ...
Polyamidoamine epichlorohydrin (PAAE) is the preeminent permanent wet strength additive used in papermaking. Wet strength additives are used to improve paper resistance to a rupture force in wet environments. The invention of PAAE in 1957 was an innovation, as it improved paper properties by giving superior wet strength in humid or wet conditions. It was rapidly adopted by the industry. Despite PAAE’s long history, the mechanism of PAAE interaction with fiber has not been fully understood. Therefore, fundamental understanding of PAAE mechanism needs to be investigated to improve its utilization in making sustainable paper products. These areas include an understanding of repulping methods and optimal PAAE dosages for better cost and performance. This paper investigates different generations of PAAE, the application method, and its impact on paper recyclability. Three generations of PAAE are currently on the market with at least two newer iterations under development. Critical application parameters that need to be understood include determination of the bonding mechanism, optimal dosage, and retention parameters. The main drawback of PAAE application is it makes paper recycling difficult. Several repulping methods are proposed for better recyclability and sustainability in the papermaking process.
... These could be attributed to the highly cationic nature of HGel-GNPslysine, which contributes to strong adhesion to skin tissue, resulting in remarkably enhanced adhesion strength. 43,62,63 Histological evaluation ...
Current trends in wound care research focus on creating dressings for diverse wound types, aiming to effectively control the wound healing process. We proposed a wound dressing composed of oxidized hyaluronic acid and amine gelatin with embedded lysine-modified gelatin nanoparticles (HGel-GNPs-lysine). This dressing improves mechanical properties and reduces degradation rates. The storage modulus for HGel-GNPs-lysine was 3,800 Pa, exceeding that of HGel (1,750 Pa). The positively charged surface of GNPs-lysine effectively eliminated Escherichia coli and Staphylococcus aureus. In a diabetic mice model (C57BL/6), HGel-GNPs-lysine immobilized with basic-fibroblast growth factor promoted granulation tissue thickness and collagen density. Gene expression analysis indicated that HGel-GNPs-lysine reduced inflammation and enhanced angiogenesis. This study highlights that HGel-GNPs-lysine could offer alternative treatment strategies for regulating the inflammatory response at the injury site in wound dressing applications.
... Whatever the cause, a release agent, such as those shown in Fig. 24, can be used as part of the solution. Such agents are routinely used, for instance, to optimize the creping of tissue paper (Valencia et al. 2020). Trials are recommended not only to select an important additive but also to be able to judge a suitable low level of addition so that the treatment does not lead to other issues, such as deposits or slipperiness. ...
Molded cellulosic pulp products provide eco-friendly alternatives to various petroleum-based packaging systems. They have a long history of reliable usage for such applications as egg trays and the shipping of fruits. They have recently become increasingly used for the packaging of electronics, wine bottles, and specialty items. Molded pulp products are especially used in applications requiring cushioning ability, as well as when it is important to match the shapes of the packed items. Their main component, cellulosic fibers from virgin or recycled wood fibers, as well as various nonwood fibers, can reduce society's dependence on plastics, including expanded polystyrene. However, the dewatering of molded pulp tends to be slow, and the subsequent evaporation of water is energy-intensive. The article reviews strategies to increase production rates and to lower energy consumption. In addition, by applying chemical treatments and processing approaches, there are opportunities to achieve desired end-use properties, such as grease resistance. New manufacturing strategies, including rapid prototyping and advances in tooling, provide opportunities for more efficient form factors and more effective packaging in the future.
... In addition to the modification of fiber pulps, chemical additives are used to modify properties or improve the production process for different materials. Different chemical additives used in the tissue paper industry are designed and applied according to different needs such as dry strength agents, wet strength agents, softeners and lotions [13,14]. Usually, these additives are cationic as the fibers carry negative charges and they are also more effective in much lower concentrations than anionic polymers. ...
... Usually, these additives are cationic as the fibers carry negative charges and they are also more effective in much lower concentrations than anionic polymers. Nevertheless, these cationic additives normally adhere in excess to the paper, negatively affecting the creping process and the product quality [14]. The addition of strength agents can ensure that tissue products remain integrated when applied in wet conditions while the addition of debonding agents can improve the softness and bulk of these products [15][16][17][18][19][20][21]. ...
The furnish management of tissue materials is fundamental to obtain maximum quality products with a minimum cost. The key fiber properties and fiber modification process steps have a significant influence on the structural and functional properties of tissue paper. In this work, two types of additives, a commercial biopolymer additive (CBA) that replaces the traditional cationic starch and micro/nanofibrillated cellulose (CMF), were investigated. Different formulations were prepared containing eucalyptus fibers and softwood fibers treated mechanically and enzymatically and both pulps with these two additives incorporated independently and simultaneously with drainage in the tissue process range. The use of these additives to reduce the percentage of softwood fibers on tissue furnish formulations was investigated. The results indicated that a maximum of tensile strength was obtained with a combination of both additives at the expense of softness and water absorbency. With a reduction of softwood fibers, the incorporation of additives increased the tensile strength and water absorbency with a slight decrease in HF softness compared with a typical industrial furnish. Additionally, a tissue computational simulator was also used to predict the influence of these additives on the final end-use properties. Both additives proved to be a suitable alternative to reduce softwood fibers in the production of tissue products, enhancing softness, strength and absorption properties.
Laboratory tests were conducted in an effort to determine the effects on paper machine process attributes and the properties of paper made from recycled copy paper furnish upon the addition of chemical agents that are commonly used in the production of hygiene tissue products. Due to continuing growth in tissue and towel grades of paper, such agents are experiencing greater usage. Charge titration test results revealed that certain dry strength agents associated with tissue manufacturing have the potential to shift the balance of charge in papermaking furnish to less negative or even positive values. Creping adhesive was found to contribute to fine particle retention, especially when present at relatively high levels. Release aid and a polyacrylate dispersant had the opposite effect. Low addition levels of both a creping adhesive and a debonding agent surprisingly increased a wide range of strength attributes of paper handsheets in comparison to sheets prepared from unaltered recycled copy paper furnish. The debonding agent decreased paper strength at higher levels of addition. Such effects appear to depend not only on the expected effects of agents themselves, but also on how they affect the charge balance of the wet-end system.
Common tissue paper manufacturing trends aim at partial or total replacement of softwood pulp with hardwood pulp for its production, such as bleached eucalyptus kraft pulp (BEKP), in order to optimize the process and the final product properties such as softness. However, the use of a single type of hardwood fiber results in lower strengths of both wet and dry webs. To maintain necessary strength and desired properties, the incorporation of several additives is often required. In this context, low molecular weight polyethylene glycol (PEG) and different wet strength resins, such as polyamideamine-epichlorohydrin (PAE) and glyoxalated polyacrylamide (GPAM) resins, were combined to achieve an innovated product with improved properties. In particular, wet and dry tensile strength was significantly improved when combining PEG and wet strength resins, especially observed in tissue papers prepared with PAE resin, high-charge cationic agent and bulk applied aqueous PEG solution. Noteworthy that water absorption capacity and softness of tissue paper were not critically affected by PEG incorporation, regardless of application method used (in bulk or by spray).
Tissue products such as facial tissue and paper towels have been playing a crucial role in promoting hygiene and maintaining good health, since they are commonly available and widely used nowadays. The production of low-density tissue paper typically involves a key creping process that contains pressing and adhering the wet web onto a high-speed Yankee cylinder, followed by releasing the creped sheet with a stationary creping blade to form periodic micro-folds within the tissue structure. This paper discusses and reviews the mechanisms of tissue creping technology, as well as the factors that impact the creping process and tissue properties. These factors primarily include the dryness of the tissue web, creping rate, properties of the pulp raw material, Yankee coating, crepe doctor blade, and tissue drying machines. It is indicated that the creping process, as a multifaceted and integrated treatment for tissue production, can be significantly enhanced through the concerted efforts of the aforementioned factors to achieve greater creping efficiency. However, further endeavors are necessary to address the constraints stemming from the pilot experimental equipment and data, as well as modeling simulation, to enable a more comprehensive examination of the creping process and its mechanism. This review offers a practical overview and comprehensive understanding of the creping technology and its underlying factors for tissue production.
Cancer biomarkers are crucial indicators of cancer status and progression that aid in early detection and
more effective treatment of the disease. The loss of 5-hydroxymethylcytosine (5hmC), an oxidation product
of 5-methylcytosine (5mC), is a recurrent epigenetic biomarker across various types of cancers. Therefore,
accurately quantifying 5hmC holds great potential for various clinical applications. However, distinguishing
5hmC from 5mC using conventional methods is challenging. In this study, we developed a rapid and highly
selective electrochemical sensor for label-free detection of 5hmC-enriched DNAs using a graphitic carbon
nitride (g-C3N4)-modified gold transducer. Two-dimensional g-C3N4 sheets were synthesized via direct
pyrolysis of urea under ambient or nitrogen atmospheres and drop-cast onto the gold electrode.
Subsequently, 5hmC-containing DNAs were immobilized onto g-C3N4 via hydrogen bonding between the
–OH of 5hmC and the -NH2 of g-C3N4. The developed sensor demonstrated high sensitivity, selectivity,
remarkable reproducibility, and stability, with a low oxidation potential (0.23 V) and an extremely low limit
of detection (0.316 pM) for 5hmC. The sensor was also tested for its applicability to real samples using
primary liver samples from mouse models, in which 5hmC levels were diminished due to either Tet gene
knockout or hepatocellular carcinogenesis. The sensor effectively detected reduced genomic 5hmCs in TET-
deficient livers and hepatocellular carcinomas compared to controls. Thus, this novel sensing strategy has
the potential to develop clinically applicable sensors for early cancer diagnosis and prognosis evaluation by
rapidly quantifying genomic 5hmC.
The article is devoted to solving an important scientific and technical task, improving the technology of production of tissue-paper. The study pays special attention to the problems related to the use of recovered paper, microscopic images of the surface of samples obtained from recovered paper sampling at various stages of the production of tissue-paper at the enterprise of Syktyvkar Tissue Group OJSC are presented. The main result of scientific research was a preliminary assessment of the study of the recovered paper stock preparation technology at the enterprise, for which the sampling from various stages of production were examined by a scanning electron microscope, which made it possible to visually assess the degree of cleaning of recovered paper from impurities from images of the microstructure of the surface of various scales. The chemical composition of the main additives was established by energy-dispersive X-ray spectral micro assay (EDX). Preliminary assessment of the nature of contamination, visual assessment of the microstructure of samples obtained from recovered paper stock from various stages of cleaning, allowed the engineers of the enterprise to evaluate the effectiveness of individual units of the stock preparation department for the production of tissue-paper. The obtained data will make it possible to specify the scientific and technical task and direct subsequent scientific work to improve the recovered paper stock preparation unit, which more requires perfection.
