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Perfluoroalkyl and polyfluoroalkyl substances (PFAS) — Fibrous substrates, TAPPI Journal September 2023
ABSTRACT: Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been implemented during the finishing process of textiles such as upholstery, clothing, personal protective equipment, and sports gear to provide water resistance. Currently, PFAS are still present at quantifiable levels in consumer products and food, even though many companies have started to phase out PFAS treatment with non-toxic water repellant replacements given the possible detrimental health effects suggested by current research. This paper is a detailed review that focuses on how PFAS are implemented in textile production and sources of PFAS contamination during chemical treatments. This review also addresses current legislation on PFAS emissions and trade regulations to decrease exposure of consumers due to toxicokinetics and mechanisms of action through-out the body that are still not well understood. This paper includes a literature review on possible PFAS related health conditions shown from past research and contains suggested toxicity levels, exposure routes, duration, and pathways detailed to the best of our ability.
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Root cause analysis of cationic polymer additive efficiency decline in virgin and recycle containerboard mills, TAPPI Journal January 2020
ABSTRACT: It is well known that retention, drainage and strength polymers struggle to perform (if at all) in virgin containerboard mills. In-depth studies have been undertaken in this area for more than seven years, investigating the issue from all directions. A key finding of this work is that soluble lignin is detrimental to chemical efficiency. A strong correlation exists between decreased chemical efficiency and high soluble lignin. Both recycled systems and virgin systems have been studied, and this correlation holds true regardless of furnish. The primary area of concern is virgin container-board, because these mills tend to have the highest lignin levels. Some highly closed recycled mills can also build elevated lignin levels that can negatively affect chemical efficiency.
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Numerical analysis of slot die coating of nanocellulosic materials, TAPPI Journal November 2020
ABSTRACT: Nanocellulosic coatings as a food packaging material are of commercial interest due to their nontoxic nature, renewability, and excellent barrier properties. Complex shear-thinning rheology poses challenges in designing and sizing equipment to pump, mix, and process the suspension and actual coating process. This study aims to determine the effectiveness of computational fluid dynamics (CFD) in predicting nanocellulosic suspension flow in light of existing rheological data. We employ and compare three distinct rheological models to characterize the rheology and flow of nanocellulose suspensions through a slot die coater, where the model parame-ters are established from existing slot rheometry measurements. A volume-of-fluid (VoF) based finite volume meth-od is employed to simulate the flow in a slot die operated in an unconventional metering mode. Results with the Casson model predict the presence of unyielded regions in the flow, which was not captured using the power law model. These stagnation regions will incur coatability issues stemming from flow intermittencies and lead to poten-tial defects in the coating layer, including fracture. The results suggest that a rheological model that includes yield stress should be considered while modeling such flows. A need for better rheological data to model nanocellulosic flows, especially at high consistencies and shear rates, is also highlighted.
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Orifice geometry as a tool for evaluating extensional flow resistance of barrier coating colors, TAPPI Journal November 2024
ABSTRACT: Knowledge of extensional flow behavior of coating colors can be beneficial for improving runnability and eliminating defects in various coating processes. The current work evaluates the use of an orifice geometry attached to a commercial capillary viscometer as a tool to obtain extensional flow properties of barrier coating dispersions. By measuring the pressure drop across the orifice as a function of flow velocity, the method presents the flow resistance as Euler number at industrially relevant high deformation rates. The results agree with the earlier results obtained with a capillary entrance pressure loss technique. The type of polymer additive is shown to control the extensional flow resistance, with high molecular weight linear flexible polymers such as polyethylene oxide (PEO) and polyvinyl alcohol (PVOH) having highest impact. The orifice method offers advantages over other approaches, including the need for only a small sample amount, ease of measurement, and access to high deformation rates.
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Comparing a linear transfer function-noise model and a neural network to model boiler bank fouling in a kraft recovery boiler, TAPPI Journal, July 2024
ABSTRACT: Boiler bank fouling reduces heat transfer efficiency in kraft recovery boilers. Here, we model the relationships between boiler parameters and boiler bank pressure drop, an indicator of fouling, based on recovery boiler operating data. We compared two models: an autoregressive integrated exogenous (ARIX) model and a feedforward neural network. The ARIX model better simulates boiler bank pressure drop compared to the neural network (R2 of 0.64 vs. 0.58). Based on the ARIX model, we identified six boiler parameters that significantly influence boiler bank fouling and their relative contributions. Finally, we demonstrate how the models can simulate boiler bank pressure drop given artificial perturbations in boiler parameters.
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Rheological behavior of magnetic pulp fiber suspensions, TAPPI Journal June 2021
ABSTRACT: This paper is focused on the rheology of magnetic pulp suspensions in absence and presence of an external magnetic field. Magnetic fibers were prepared by the lumen loading method using bleached eucalyptus fibers and cobalt ferrite (CoFe2O4) nanoparticles. The effect of mass consistency, temperature, concentration of magnetic fibers, and magnetic field strength on yield stress and apparent viscosity of the suspensions were investigated. In the absence of an applied field, a dependence of yield stress with consistency, as well as with the percentage of magnetic fibers present in the suspension, was found. In flow tests, all the suspensions exhibited shear-thinning behavior, showing that the viscosity is only affected by the consistency of the suspension. On the other hand, magnetorheological measurements show a negative effect of the applied magnetic field on the viscosity of the suspension.
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Effects of lignin chemistry on oxygen delignification performance, TAPPI JOURNAL July 2018
Effects of lignin chemistry on oxygen delignification performance, TAPPI JOURNAL July 2018
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Effect of ring formation on burner flame stability in lime kilns, TAPPI JOURNAL May 2018
Effect of ring formation on burner flame stability in lime kilns, TAPPI JOURNAL May 2018
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Prediction of box failure from paper data for asymmetric corrugated board, TAPPI JOURNAL August 2018
Prediction of box failure from paper data for asymmetric corrugated board, TAPPI JOURNAL August 2018
Journal articles
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Improving the inkjet codability of folding boxboard, TAPPI Journal February 2019
Improving the inkjet codability of folding boxboard, TAPPI Journal February 2019