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Journal articles
Filtration performance of face masks and facepiece respirators used during COVID-19 pandemic, TAPPI Journal February 2025
ABSTRACT: The rapid spread of SARS-CoV-2 has created challenges for societies, healthcare settings, businesses, and institutions. To curb virus transmission, various measures like lockdown, social distancing, hand hygiene, and using appropriate personal protective equipment (PPEs), including face masks, have been recommended. Face masks and facepiece respirators are considered to act as barriers against microbial transmission from person to person. In this study, we selected barrier materials used during the COVID-19 pandemic that included four non-medical face masks and three facepiece respirators. Facepiece respirators were distributed by the U.S. Administration through pharmacy outlets. Results showed that facepiece respirator R95 has the highest filtration efficiency (above 99%), which remains more or less the same over different particle sizes. The N95 respirator’s filtration efficiency was lower than that of R95, but its barrier resistance was lower than that of the R95, indicating that it can be comfortably used over longer duration. Face masks were evaluated using ASTM F 3502-24 for their barrier performance. At 0.1 and 0.3 ìm particle size, domestically manufactured masks met the standard for higher performance. Interestingly, the results indicate that quality of raw materials and manufacturing standards play important roles, as is evident in domestically manufactured face mask and facepiece respirators.
Journal articles
Comparison of the application of polysaccharide-based barrier coatings on paper using film press and spray coating, TAPPI Journal January 2025
The growing demand for sustainable packaging has spurred research into biopolymer-based solutions and their application to paper substrates. This study compares the application of low solids, high viscous aqueous solutions of alginate and chitosan on two different paper substrates using a laboratory film press coater and a purpose-built spray coating unit, with a focus on barrier performance and practical industry considerations. Key parameters investigated are air flow rate, water vapor transmission rate, and grease resistance. Results showed that due to the low solids content of the applied biopolymer solutions, film press coating required a double-layer application for coat weights exceeding 4 g/m², making it less viable for industrial application. In contrast, spray coating allowed for higher application weights in a single step. The barrier properties of spray coated samples, compared to film press coatings, varied with the paper substrate: spray coating performed better on one substrate and worse on the other. Contact angle measurement of the substrates suggested that spray coating is more suitable for a more hydrophilic substrate because of improved surface wetting. The study also identified issues with drying conditions and pinholes affecting the quality of spray coated samples, indicating a need for further research to optimize these parameters.
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.
Journal articles
The effect of Stachys floridana Shuttlew.ex Benth extract as an additive on the chemical properties of chitosan biodegradable film, TAPPI Journal June 2025
ABSTRACT: The purpose of this study is to explore chitosan with Stachys floridana Shuttlew. ex Benth (SFSB) extract as an additive to prepare an active film. The effects of the SFSB extract on the physical, antioxidant, and bacteriostatic properties of chitosan biodegradable films were studied. The results showed that the addition of SFSB extract significantly improved the antioxidant and antibacterial properties of the film, and its biodegradation rate increased rapidly. Compared to the control film, the water solubility was lower at 19.40%, the expansion degree was higher at 288.90%, the water vapor permeability (WVP) was 0.364 g·mm/(m²·d·kPa), the surface hydrophobicity increased, and the mechanical strength was also improved. The contact angle increased to 89.3°. In addition, as the amount of SFSB increased, the thermal stability of chitosan-Stachys floridana Shuttlew. ex Benth (CS-SFSB) films also increased significantly, and their ultraviolet (UV) blocking ability was gradually enhanced. The results indicate that CS-SFSB has potential as a food packaging material.
Journal articles
Magazine articles
A feasibility study of using the organic Rankine cycle for power generation from the flue gases of recovery boilers, TAPPI Journal August 2022
ABSTRACT: Almost 415 tons/h of flue gases with a temperature of 160°C are released to the atmosphere from the recovery boiler of a pulp mill with capacity of 1000 air dried (a.d.) metric tons of pulp per day. This is a large waste heat stream that can be used to generate power, to decrease the operating costs of a pulp mill, and to save carbon dioxide (CO2) emissions. In this work, the feasibility of using an organic Rankine cycle (ORC) with ammonia as the working fluid to generate power from the flue gases of recovery boilers is studied. CHEMCAD and Taguchi methods are used for simulation of the process and for optimization of operating conditions, respectively. The temperature of the ammonia and flue gases at the exit of evaporator, exit pressure of the pump and turbine, and the degree of subcooling of ammonia at the exit of the condenser are five operating parameters that are manipulated to optimize the process. Three different scenarios are defined: minimizing the net power cost, maximizing the ORC efficiency, and maximizing the net profit. Different aspects of these scenarios, such as net power generation, cost, efficiency, and CO2 emission savings are discussed, and optimum operating conditions are reported.
Journal articles
Magazine articles
Causes of poor dregs settling in a green liquor clarifier, TAPPI Journal August 2022
ABSTRACT: A study was conducted to examine the most likely parameters responsible for poor dregs settling at a kraft mill over a 2.5-year period, using multivariate data analysis (MVDA) and machine learning (ML) techniques. The dregs settling behavior seems to be seasonally influenced, implying that wood quality variation can be a factor. The results from the MVDA/ML analysis show that poor dregs settling is correlated to incomplete combustion and/or low load conditions in the recovery boiler, low sulfidity in the causticizing plant, and high flow in the green liquor•weak wash cycle. Compositions of dregs and black liquor were also examined to identify correlations with impaired dregs settling. The results show that poor dregs settling strongly correlates with high silicon (Si) content in dregs and moderately correlates with high iron (Fe) and high aluminum (Al) contents, and with low bulk density in dregs. For mills that experience dregs settling or green liquor filtering issues, regular compositional analyses of dregs, green liquor, weak wash, and black liquor are recommended in order to monitor the dynamics of silicon and other constituents in the recovery cycle.
Journal articles
Magazine articles
Utilization of kraft pulp mill residuals, TAPPI Journal February 2022
ABSTRACT: Kraft pulp mills produce on average about 100 kg of solid residuals per metric ton of pulp produced. The main types of mill waste are sludge from wastewater treatment plants, ash from hog fuel boilers, dregs, grits, and lime mud from causticizing plants and lime dust from lime kilns. Of these, about half is disposed of in landfills, which highlights the need and potential for waste recycling and utilization. Sludge is either incinerated in hog fuel boilers to generate steam and power or used in various forms of land application, including land spreading, composting, or as an additive for landfill or mine waste covers. The majority of hog fuel boiler ash and causticizing plant residues is landfilled. Alkaline residuals can be conditioned for use in land application, manufacture of construction materials, and production of aggregates for road work. This technical review summarizes residuals utilization methods that have been applied in pulp and paper mills at demonstration- or full-scale, and therefore may act as a guide for mill managers and operators whose goal is to diminish the costs and the environmental impact of waste management.
Journal articles
Magazine articles
Calender barring review with experiences, TAPPI Journal July 2022
ABSTRACT: Excessive calender vibration affects all styles of calender stacks from single to multi-nip, all hard rolls, or a combination of hard and soft rolls. Calender vibration can be forced vibration or self-excited vibration. Forced vibration occurs at the first few harmonics of the calender roll rotational speeds and is caused by imbalance, misalignment, eccentricity, etc. Self-excited vibration, the focus of this paper, occurs at higher frequencies. Feedback paths for self-excited vibration must be understood in order to ameliorate the problem. This is presented in the context of the historical development of the theory of self-excited feedback mechanisms, followed by a survey of self-excited feedback mechanisms in various types of calender stacks. Methodology to determine which feed-back path is present and techniques to control or eliminate the resulting vibration follow. To obtain a flavor of the types of problems faced and practical remedial actions, a variety of experiences with barring issues are provided.
Journal articles
Magazine articles
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
Effectiveness of masks in the suppression of COVID-19 cases during the ongoing pandemic in India, TAPPI Journal October 2022
ABSTRACT: Perhaps the worst predicament faced by humanity in the twenty-first century is the COVID-19 pandemic, which is caused by the SARS-CoV-2 virus. Most parts of the world, including India, went into lockdowns for some period because of the massive increase in cases throughout 2020. Face masks became an important counter-measure for protecting the populace, health professionals, and medics, particularly during the period prior to the mass availability of vaccines. This study intends to evaluate the effectiveness of face masks in limiting the spread of the virus. The data for the number of COVID-19 cases was analyzed from January 1, 2022 to May 31, 2022, using Python programming. This timeframe involved face mask mandates and no mask requirement, and hence was considered to be ideal for analyzing the usefulness of face masks. A decline in cases during the mandate was observed, while the opposite occurred without the mandate. The outcome of the research showed that face masks are effective additional measures against the spread of SARS-CoV-2. This study elevates the value of personal protective equipment (PPE), such as face masks, made with nonwovens and other fabrics, as lifesavers in the case of airborne diseases such as COVID-19 and other pulmonary disorders.