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Contrasting underlying mechanisms of different barrier coating types, TAPPI Journal January 2018
Contrasting underlying mechanisms of different barrier coating types, TAPPI Journal January 2018
Journal articles
Analysis of wrinkle formation and propagation during paperboard deep drawing, TAPPI Journal October 2026
ABSTRACT: Paper-based packaging is becoming increasingly important as a sustainable alternative to plastics. Among forming processes, deep drawing is particularly promising due to its high cost-effectiveness, short processing times, and suitability for large-scale production. A major challenge, however, lies in the formation of wrinkles, which impair the visual quality, functional performance, and dimensional stability of the packaging, thereby affecting subsequent processes such as filling, printing, and sealing. This study focuses on analyzing the occurrence and propagation of wrinkles during the deep drawing of paperbased materials to derive fundamental insights and strategies for prevention. The wrinkles arise from tangential compressive stresses in the flange and the material’s limited thickening, leading to local stability failures once a critical stress threshold is exceeded. A combined approach of experimental investigations, numerical simulations, and analytical considerations was used to examine a rotationally symmetrical part. A transparent die enabled spatial observation of wrinkle initiation and growth. First, wrinkles were found to typically initiate in the cross direction (CD), while most wrinkles develop in the machine direction (MD). By comparing analytically and numerically determined stress distributions, the mechanisms of wrinkle formation can be understood both locally and temporally, thereby enabling the prediction of wrinkle occurrence.
Journal articles
Aqueous polymer dispersions from long chain cellulose fatty acid ester for coating of paperboard, TAPPI Journal October 2026
ABSTRACT: Fiber-based substrates are coated with aqueous polymer dispersions to obtain the necessary barrier properties for, e.g., food service, takeaway, and other packaging applications. There is interest to replace non-renewable substances driven by the concerns over the price stability and depletion of fossil resources, environmental and safety issues, and legislative actions. In this study, we demonstrated that stable aqueous polymer dispersions with solids content of at least 35% can be prepared from a long chain cellulose fatty acid ester (cellulose octanoate) using both solvent-based and thermomechanical processes. In the solvent-based process, water and additives were mixed with a polymer dissolved in chloroform followed by solvent removal. In the thermomechanical method, water and stabilizers were added into polymer melt under mixing in a pressurized reactor. Dispersions were tested as coatings on paperboard and assessed for their grease resistance and water and oil barrier. Oil barrier was clearly improved with most of the dispersions. In addition, proper film formation was necessary for achieving improved water barrier. However, the stabilizing system had a clear impact on the dispersion stability and the water barrier performance of these coatings.
Journal articles
Magazine articles
Impact of fiber structure on edge-wicking of highly-sized paperboard, TAPPI JOURNAL August 2018
Impact of fiber structure on edge-wicking of highly-sized paperboard, TAPPI JOURNAL August 2018
Journal articles
A method to produce paperboard with a lightweight low-density coating, TAPPI Journal November 2025
ABSTRACT: In this work, a method is described in which a coating layer is produced that consists of a network of bubble-shaped air-filled voids within the coating. This is accomplished by instantaneously flash-drying all the water in the coating as it exits the application nip. The nip is formed between a polished chrome drum and a deformable press roll. The combination of the drum temperature, nip pressure, and nip width allow for sufficient energy to be transferred to the coating to completely flash-dry the coating material. The pressure within the nip is sufficient to allow the coating to superheat within the nip, then flash boil as it exits the nip. This boiling effect and resulting expansion are constrained by the roll surface, resulting in a coated surface that mirrors the polished chrome surface. The coating immobilizes while in the process of boiling, which preserves the bubble structure. With a coat weight of 5 g/m2, a flat, smooth surface is produced. This process was scaled up to a mill production machine layout and run at speeds as high as 450 m/min.
Journal articles
Magazine articles
Review of coating cracking and barrier integrity on paperboard substrates, TAPPI JournalDecember 2024
Authors: Joel C. Panek and Peter W. Hart | TAPPI J. 21(11): 589(2022) - ABSTRACT: Barrier packaging formats are major growth areas for the pulp and paper industry. It is technically challenging to maintain barrier properties during converting and end-use applications. Improved manufacturing capabilities and coating formulation knowledge will help maintain barrier integrity and enable growth of barrier products in challenging applications. These improvements will accelerate product development and commercialization, and allow faster response to product performance issues such as cracking. The literature on coating cracking provides knowledge mostly on the effects of coating formulations and to a lesser extent on substrate effects. Despite a large number of publications dedicated to coating failures, the approach to improve coating cracking remains empirical, and the transferability between studies and to real life applications has not been well established. Model development that successfully predicts commercial performance is in its infancy. However, some of these simplified models do a fairly good job predicting experimental data. The current work reviews the state of understanding as regards coating and barrier cracking and highlights the need for more research on cracking and barrier integrity.
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
Magazine articles
Incorporation of post-consumer pizza boxes in the recovered fiber stream: Impacts of grease on finished product quality, TAPPI Journal March 2021
ABSTRACT: Grease and cheese contamination of used pizza boxes has led to misunderstanding and controversy about the recyclability of pizza boxes. Some collection facilities accept pizza boxes while others do not. The purpose of this study is to determine whether typical grease or cheese contamination levels associated with pizza boxes impact finished product quality. Grease (from vegetable oil) and cheese are essentially hydrophobic and in sufficiently high concentration could interfere with interfiber bonding, resulting in paper strength loss.Findings from this study will be used to determine the viability of recycling pizza boxes at current and future con-centrations in old corrugated containers (OCC) recovered fiber streams. These findings will also be used to inform the acceptability of pizza boxes in the recycle stream and educate consumers about acceptable levels of grease or cheese residue found on these recycled boxes.
Journal articles
Magazine articles
Development of converging-diverging multi-jet nozzles for molten smelt shattering in kraft recovery boilers, TAPPI Journal March 2021
ABSTRACT: The effective shattering of molten smelt is highly desired in recovery boiler systems. Ideally, shatter jet nozzle designs should: i) generate high shattering energy; ii) create a wide coverage; and iii) minimize steam consumption. This study proposes a novel converging-diverging multi-jet nozzle design to achieve these goals. A laboratory setup was established, and the nozzle performance was evaluated by generating jet pressure profiles from the measurement of a pitot tube array. The results show that the shatter jet strength is greater with a large throat diameter, high inlet pressure, and a short distance between the nozzle exit and impingement position. Increasing the number of orifices generates a wider jet coverage, and the distance between the orifices should be limited to avoid the formation of a low-pressure region between the orifices. The study also demonstrates that an optimized converging-diverging multi-jet nozzle significantly outperformed a conventional shatter jet nozzle by achieving higher energy and wider coverage while consuming less steam.
Journal articles
Magazine articles
Quantification of vegetable oil in recycled paper, TAPPI JOURNAL September 2020
ABSTRACT: Vegetable soybean oil is commonly used in cooking foods that are packaged in takeaway paper-board containers. Vegetable oil is hydrophobic, and in sufficiently high concentration, could interfere with interfiber bonding and result in paper strength loss. In order to quantify the effect of oil on the resulting paperboard strength, it is necessary to quantify the oil content in paper. A lab method was evaluated to determine the soybean oil content in paper. Handsheets were made with pulps previously treated with different proportions of vegetable oil. Pyrolysis gas chromatography-mass spectrometry (pyGCMS) was used to quantify the amount of oil left in the handsheets. The results revealed a strong correlation between the amount of oil applied to the initial pulp and the amount of oil left in the handsheets.In addition, the effect of vegetable oils on paper strength may be affected by the cooking process. Vegetable oil is known to degrade over time in the presence of oxygen, light, and temperature. The vegetable oil was put in an oven to imitate the oil lifecycle during a typical pizza cooking process. The cooked oil was then left at room temperature and not protected from air (oxygen) or from normal daylight. The heated, then cooled, oil was stored over a period of 13 weeks. During this time, samples of the aged oil were tested as part of a time-based degradation study of the cooked and cooled oil.