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Journal articles
Open Access
Using multi-method analysis to identify challenging paper machine deposits and defects, TAPPI Journal March 2025

ABSTRACT: Based on its speed and versatility, Fourier transform infrared (FTIR) spectroscopy is the industry’s common starting point for analysis of a paper machine deposit or defect sample. However, certain contaminants and papermaking process additives cannot be precisely identified solely by infrared spectral interpretation. This lack of specificity could lead to a misinterpretation of the composition of the deposit or defect. A multi-method analysis uses data from two or more analytical techniques, including FTIR spectroscopy, microbiological staining/phase contrast microscopy, pyrolysis-gas chromatography/mass spectrometry (Pyro-GC/MS), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), to produce a more specific assessment of a sample’s composition. This paper discusses the use of a multi-method analysis in deposit and defect analysis and presents several case studies that demonstrate how this comprehensive approach can often produce an interpretation result of greater conviction and value to the papermaker.

Journal articles
Magazine articles
Open Access
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
Magazine articles
Open Access
Slot die coating of nanocellulose on paperboard, TAPPI Journal January 2018

Slot die coating of nanocellulose on paperboard, TAPPI Journal January 2018

Journal articles
Magazine articles
Open Access
On the nominal transverse shear strai to characterize the severity of creasing, TAPPI JOURNAL April 2018

On the nominal transverse shear strai to characterize the severity of creasing, TAPPI JOURNAL April 2018

Journal articles
Magazine articles
Open Access
Fundamental understanding of removal of liquid thin film trapped between fibers in the paper drying process: A microscopic approach, TAPPI Journal May 2020

ABSTRACT: In the fabrication of paper, a slurry with cellulose fibers and other matter is drained, pressed, and dried. The latter step requires considerable energy consumption. In the structure of wet paper, there are two different types of water: free water and bound water. Free water can be removed most effectively. However, removing bound water consumes a large portion of energy during the process. The focus of this paper is on the intermediate stage of the drying process, from free water toward bound water where the remaining free water is present on the surfaces of the fibers in the form of a liquid film. For simplicity, the drying process considered in this study corresponds to pure convective drying through the paper sheet. The physics of removing a thin liquid film trapped between fibers in the paper drying process is explored. The film is assumed to be incompressible, viscous, and subject to evaporation, thermocapillarity, and surface tension. By using a volume of fluid (VOF) model, the effect of the previously mentioned parameters on drying behavior of the thin film is investigated.

Journal articles
Open Access
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
Application of spruce wood flour as a cellulosic-based wood additive for recycled paper applications— A pilot paper machine study, TAPPI Journal October 2021

ABSTRACT: This study gives a first insight into the use of wood flour as a plant-based and cellulosic-based alternative additive for newsprint and paperboard production using 100% recycled fibers as a raw material. The study compares four varieties of a spruce wood flour product serving as cellulosic-based additives at addition rates of 2%, 4%, and 6% during operation of a 12-in. laboratory pilot paper machine. Strength properties of the produced news-print and linerboard products were analyzed. Results suggested that spruce wood flour as a cellulosic-based additive represents a promising approach for improving physical properties of paper and linerboard products made from 100% recycled fiber content. This study shows that wood flour pretreated with a plant-based polysaccharide and untreated spruce wood flour product with a particle size range of 20 µm to 40 µm and 40 µm to 70 µm can increase the bulk and tensile properties in newsprint and linerboard applications.

Journal articles
Magazine articles
Open Access
Review of coating cracking and barrier integrity on paperboard substrates, TAPPI Journal November 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
Magazine articles
Open Access
Convolutional neural networks enhance pyrolysis gas chromatography mass spectrometry identification of coated papers, TAPPI Journal August 2024

ABSTRACT: In the evolving paper industry, accurate identification of coated paper components is essential for sustainability and recycling efforts. This study employed pyrolysis-gas chromatography mass spectrometry (Py-GCMS) to examine six types of coated paper. A key finding was the minimal interference of the paper substrate with the pyrolysis products of the coatings, ensuring reliable analysis. A one-dimensional convolutional neural network (1D-CNN) was employed to process the extracted ion chromatograms directly, simplifying the workflow and achieving a predictive accuracy of 95.2% in identifying different coating compositions. Additionally, the study high-lighted the importance of selecting an optimal pyrolysis temperature for effective feature extraction in machine learning models. Specific markers for coated papers, including polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polybutylene succinate (PBS), polylactic acid (PLA), and waterborne polyacrylates (WP), were identified. This research demonstrates a novel approach to coated paper identification by combining Py-GCMS with machine learning, offering a foundation for further studies in product quality and environmental impact.

Journal articles
Open Access
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.