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A novel dimensionless index for optimizing the thermo-hydraulic performance of steam condensation in horizontal rotating channels of a multi-channel cylinder dryer
ABSTRACT: The comprehensive performance of steam condensation in horizontal rotating channels, which involves a trade-off between heat transfer enhancement and flow resistance, lacks a unified evaluation criterion. This deficiency is particularly critical for applications such as a multi-channel cylinder dryer (MCD) in paper machines, where rotational operation enhances drying efficiency. To address this gap, this study introduces a novel dimensionless index, W/Eu, defined as the ratio of the dimensionless heat transfer coefficient (W) to the dimensionless pressure drop (Eu), thereby taking into account both heat transfer and flow resistance characteristics comprehensively. A functional relationship for this index was established with respect to channel spacing (Wr) and steam mass flux (G), followed by a theoretical optimization analysis.
Journal articles
Editorial: Advancing barrier science and protective materials: The 2025 winners of TAPPI Journal Best Research Paper Award and Honghi Tran Prize, TAPPI Journal April 2026
At the end of each year, the TAPPI Journal Editorial Board Members nominate papers for consideration as recipient of the Best Research Paper and Honghi Tran Prize from that year, looking for outstanding contributions that push the science and engineering boundaries of fiber-based materials. For 2025, the Board nominated 10 papers and evaluated each nomination in terms of scientific merit, innovation, creativity, and clarity. After voting on the papers earlier this year, the Editorial Board chose two co-winning papers for this distinct honor.
Prediction of residual calcium carbonate (CaCO3) in the lime kiln of a kraft pulp mill
ABSTRACT: In a kraft pulp mill, the rotary lime kiln is responsible for converting calcium carbonate (CaCO3) into calcium oxide (CaO) to be reused in the causticizing plant. An important parameter of the calcination efficiency and the product quality is the amount of CaCO3 not converted to CaO, commonly defined as residual carbonate. This parameter is usually determined through laboratory analysis, which introduces delays in process control and limits the ability to make timely operational adjustments.
Aging and degradation of oil and grease barrier papers coated with bio-based starch–wax emulsion
ABSTRACT: The long-term performance and stability of bio-based barrier coatings are critical for sustainable packaging. In this study, the aging and degradation of a biobased starch–wax emulsion coating were examined on two different base papers. Coated samples were stored for 8 months at 23°C and 50% relative humidity (RH) in their original reels to minimize external exposure and isolate internal aging effects. Multiple aging intervals were analyzed using advanced methods to assess both chemical composition and physical structure.
Improving barrier performance of coated paper and paperboard using a multi-layer approach
ABSTRACT: Market demand for barrier coated packaging paper and paperboard has been on a steady rise and is forecasted to further increase. As a result, there is a continued interest in improving barrier coating functionalities, which is currently an active area of investigation.
Journal articles
Adhesion with purpose: The value of primers in sustainable flexible packaging, TAPPI Journal July 2025
ABSTRACT: Primers play a crucial role in flexible packaging by providing adhesion, enhancing performance, and improving the overall quality of packaging structures. As the packaging industry shifts towards more sustainable solutions, it brings new challenges for meeting adhesion requirements. Different types of sustainable materials, with their complicated physical and chemical properties, usually result in poor adhesion in extrusion coating or extrusion lamination, whether this is due to fast crystallization, secondary crystallization, low processing temperature, lack of functional groups, or a combination thereof. Water-based primers ensure that these innovations meet both functional and environmental standards for the packaging of tomorrow. Conventional water-based primers, including polyethyleneimine (PEI) and ethylene acrylic acid (EAA), offer significant advantages in sustainable packaging design by chemically modifying the surface of the substrate to enhance adhesion. In this study, we will discuss adhesion issues in three case studies involving sustainable packaging materials: (1) extrusion coating of polyvinyl alcohol (PVOH) on paper; (2) extrusion lamination of paper and metallized film with starch biopolymer; and (3) extrusion coating of polyhydroxyalkanoates (PHA) on paper. These cases represent three adhesion challenges related to sustainable materials, namely fast crystallization rate, low processing temperature, and secondary crystallization. A three-step adhesion improvement procedure was employed to identify the proper primer in each case study. This procedure included a wetting-out test with primer, an adhesion test, and an extrusion test with priming. In our results, strong fiber tearing or destructive bonds were achieved in each case with the help of water-based primers. These results demonstrate the value of water-based primers in enabling the transition to more sustainable packaging structures without compromising performance.
Journal articles
Conversion of paper-grade pulp from rice straw into dissolving pulp, TAPPI Journal June 2025
ABSTRACT: About 1,165 million metric tons of rice straw is generated every year worldwide, which can be a good source for the circular bioeconomy. In this research paper, the paper-grade pulp from rice straw was converted to dissolving-grade pulp by fractionation in a biorefinery initiative. Rice straw was cooked at an optimum condition of 8% potassium hydroxide (KOH) charge for 120 min at 150°C and produced a pulp yield of 47.2% with a kappa number of 18.5. Subsequently, D0(EP)D1 bleaching was carried out for the produced pulp, and the brightness of the pulp reached to 82.4%. From the black liquor, 16.5% of the lignin and 11.9% of the hemicellulose were isolated for producing biobased products and chemicals, and then the spent liquor was used for soil amendment. The bleached pulp was fractionated in a Bauer McNett fiber classifier. The pulp fibers retained on 16-, 30-, and 50-mesh screens were used as a longer fiber fraction pulp, and pulp fibers retained on 100- and 200-mesh screens were used as a shorter fiber pulp. The longer and shorter fiber fraction pulps were analyzed for cellulose, R10, pentosan, and viscosity. The long fiber fraction pulps were characterized by higher cellulose (88.2% vs. 83.1%) and lower pentosan (11.3% vs. 13.0%) content than the shorter fiber fraction pulps. The longer fiber fraction was further treated with cold KOH to remove residual hemicellulose. The KOH extraction reduced pentosan content in pulp to 6.3% and increased á-cellulose content to 91.3%. The short fiber fraction was converted to monomeric sugars using cellulase enzymes with varying reaction time, temperature, and consistency. The efficiency of cellulase activity was assessed through glucose yield and residual dry weight. A temperature of 45°C, 5.0 pH, 5% consistency, and 6 filter paper units/gram (FPU/g) o.d. pulp resulted in maximum sugar conversion of 85.7%.
Journal articles
In-situ process monitoring in deep-drawing of paper using partially transparent tools, TAPPI Journal August 2025
ABSTRACT: The production of three-dimensionally formed packaging from paper by deep drawing usually leads to the occurrence of wrinkles, which result from the high tangential compressive stresses in the flange area and the limited flowability of the material. Wrinkles, although mostly tolerated in industry, end in both a reduced visual appearance and a reduction in usability for packaging, as with, for example, when gas-tightness is required. Previous research efforts have been limited to determining the wrinkle distribution after completion of forming and removal of the formed part. Consequently, the possibility of understanding the sequence of formation of individual wrinkles in the inhomogeneous material is lost. To remedy this situation, a method for local in-situ process monitoring is presented. Using a transparent die and an industrial camera, the flange area can be observed during the forming process. An image processing algorithm is applied to analyze the local development of the deep drawing process from the continuously recorded image data. The method described can be used to analyze the draw-in behavior and wrinkle formation locally and continuously over the drawing depth. The blank holder force influences the draw-in and the wrinkle pattern both locally and throughout the drawing process. A more precise understanding of the wrinkle formation will allow for more efficient process control in the future.
Journal articles
On the design of corrugated boards: A new FEM modeling and experimental validation, TAPPI Journal August 2025
ABSTRACT: This study presents a simplified finite element modeling (FEM) approach suitable for large structures made of corrugated boards, such as customized packages, based on a homogenization method, which is combined with correction factors for internal mechanisms. The homogenization process reduces computational time by transforming flute geometries into equivalent elastic models. In large deformations and in the presence of contact for a given geometry, the effective elastic modulus in the thickness direction, as well as the effective thickness of the structure, are corrected by two statistical Weibull distributions representing the contact and buckling mechanisms in a corrugated board. The Weibull parameters are obtained via experimental analysis, and such a process is then validated. The results demonstrate that the statistical parameters (â1 = 0.14, â2 = 1.31) can be used for the simplistic representation of corrugated boards, being computationally efficient. This research contributes to the optimization of corrugated packaging design, specifically by simplifying FEM models for faster, yet equally accurate, simulations.
Journal articles
Editorial: Investing in Amercian advanced manufacturing, TAPPI Journal June 2025
ABSTRACT: American manufacturing is seeing a renewal, which is needed to boost jobs in America, particularly in the middle and manufacturing base of the country. The ongoing tariff situation emphasizes the importance of protecting domestic manufacturing. There is U.S. congressional agreement, in principle, to bring back manufacturing to the United States. However, given how the global trade and manufacturing space has shifted in the last four decades, it may not be a comparative advantage to manufacture low margin and labor-intensive products. Officials in the current U.S. Administration have stated that manufacturing of socks and T-shirts is not necessarily in the interest of the United States, but focusing on value-added products is essential. While silicon chips, solar panels, and batteries are key items of interest, advanced textile materials such as those that find applications in industrial products and composites, products that can save human lives, and products for protecting the environment are highly-valued items that cater to national security.