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A model black liquor formulation for use in development and evaluation of membranes for concentrating weak black liquor, TAPPI Journal February 2022
ABSTRACT: As part of a larger program to develop robust membranes for concentrating weak black liquor prior to the evaporation step, several commercially available membranes were tested for suitability in this application. Given the variation in kraft black liquor for various wood species, the mill-to-mill variations, and the challenges of obtaining fresh samples, the need became apparent for a synthetic reference black liquor that would allow any membrane developer to test a new prototype membrane and compare the results with others. We present a formulation for a model black liquor (MBL) similar to real kraft black liquor in the composition of the major species that can be formulated from readily available reagents. The MBL was tested with two commercial membranes and resulted in similar levels of lignin retention as the real black liquor. It also showed similar viscosity behavior to real black liquor as a function of solids content.
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Editorial: Unlock the gates! TAPPI Journal moves to fully Open Access research for all, TAPPI Journal March 2022
At TAPPI’s Board of Director’s meeting in February, Peter Hart, associate editor of TAPPI Journal and also a member of TAPPI’s Board of Directors, gave a presentation on the benefits of the journal being fully OA, including the face that its research would serve to advance science and engineering by easily circulating through a broader community that studies these industry.
Journal articles
Magazine articles
Application of ATR-IR measurements to predict the deinking efficiency of UV-cured inks, TAPPI Journal January 2022
ABSTRACT: In recent years, ultraviolet (UV)-curable ink has been developed and widely used in various printing applications. However, using UV-printed products (UV prints) in recovered paper recycling causes end-product dirt specks and quality issues. A new method was developed that can distinguish UV prints from other prints by means of attenuated total reflectance infrared (ATR-IR) spectroscopy. Application of this method could allow more efficient use of UV prints as raw materials for paper recycling.First, a mill trial was performed using UV prints alone as raw materials in a deinked pulp (DIP) process. Second, test prints were made with four types of UV inks: a conventional UV ink and three different highly-sensitive UV inks. Each print sample had four levels of four-color ink coverage patterns (100%, 75%, 50%, and 25%). Next, deinkability of all prints was evaluated by laboratory experiments. Finally, each print was measured using the ATR-IR method, and the relationship between the IR spectra and deinkability was investigated. Mill trial results showed that UV prints caused more than 20 times as many dirt specks as those printed with conventional oil-based ink. There were variations in recycling performance among UV prints taken from bales used for the mill trial. Lab tests clearly revealed that not all UV-printed products lead to dirt specks. In order to clarify the factors that affected deinkability of UV prints, the print samples were investigated by lab experiments. Key findings from lab experiments include: • The number of dirt specks larger than 250 µm in diameter increased as the ink coverage increased. • Higher ink coverage area showed stronger intensity of ATR-IR spectral bands associated with inks. These results indicate that deinkability of UV prints could be predicted by analysis of ATR-IR spectra. • Finally, the method was applied for assessment of recovered paper from commercial printing presses. It was confirmed that this method made it possible to distinguish easily deinkable UV prints from other UV prints. Based on these findings, we concluded that the ATR-IR method is applicable for inspection of incoming recovered paper.
Journal articles
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Web lateral instability caused by nonuniform paper properties, TAPPI Journal January 2022
ABSTRACT: Lateral or cross-machine direction (CD) web movement in printing or converting can cause problems such as misregistration, wrinkles, breaks, and folder issues. The role of paper properties in this problem was studied by measuring lateral web positions on commercial printing presses and on a pilot-scale roll testing facility (RTF). The findings clearly showed that CD profiles of machine direction (MD) tension were a key factor in web stability. Uneven tension profiles cause the web to move towards the low-tension side. Although extremely nonuniform tension profiles are visible as bagginess, more often, tension profiles must be detected by precision devices such as the RTF. Once detected, the profiles may be analyzed to determine the cause of web offset and weaving problems.Causes of tension profiles can originate from nonuniform paper properties. For example, by means of case studies, we show that an uneven moisture profile entering the dryer section can lead to a nonuniform tension profile and lateral web movement. Time-varying changes in basis weight or stiffness may also lead to oscillations in the web’s lateral position. These problems were corrected by identifying the root cause and making appropriate changes. In addition, we developed a mathematical model of lateral stability that explains the underlying mechanisms and can be used to understand and correct causes of lateral web instability.
Journal articles
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Microbial load and proliferation associated with various face mask types and sources during the COVID-19 pandemic, TAPPI Journal January 2022
ABSTRACT: Due to the shortage of personal protective equipment during the COVID-19 pandemic, homemade face coverings were recommended as alternatives. However, the capability of alternative face coverings to proliferate microbes have not been fully documented. The current study evaluated bacterial load and proliferation associated with the use of common face masks during the COVID-19 pandemic. Mask type-specific and surface-related bacterial load and pattern were noticeable in the study. Results indicated that roadside masks are among samples that contained relatively higher initial bacterial load. The highest number of bacterial forming colonies were observed in the inner surface of mask samples. Proliferation of microbes over time was also noticeable among the non-certified face coverings included in the study. Sterilization or washing of non-certified fabric face masks before use is recommended.
Journal articles
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Determining operating variables that impact internal fiber bonding using Wedge statistical analysis
ABSTRACT: In this study, Wedge statistical analysis tools were used to collect, collate, clean up, plot, and analyze several years of operational data from a commercial paper machine. The z-direction tensile (ZDT) and Scott Bond tests were chosen as representative of fiber bond strength. After analyzing thousands of operational parameters, the ones with the most significant impact upon ZDT involved starch application method, starch penetration, and the amount of starch applied. Scott bond was found to be significantly impacted by formation and refining. Final calendering of the paper web has also shown an impact on internal fiber bonding.
Journal articles
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Editorial: Looking forward, looking back, TAPPI Journal January 2022
ABSTRACT: Much like 2020, 2021 was another year of remarkable highs and lows delivered by the COVID-19 pandemic. Vaccines, variants, and infection surges altered the way we behaved personally and professionally last year. As we move into 2022, we are now grappling with health and business concerns from the omicron variant that has overwhelmed hospitals in some areas and contributed to a global supply chain crisis. The ability to adjust has once again become a key skill in adapting to our shifting “new normal.”
Journal articles
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Study on the effect of aluminum diethyl phosphinate in synergy with ammonium polyphosphate on the flame retardancy of cellulose paper, TAPPI Journal April 2025
ABSTRACT: This paper involved the synergistic incorporation of ammonium polyphosphate (APP) and diethyl aluminum phosphinate (AlPi) as flame-retardant fillers for producing flame-retardant paper. The research revealed that APPs were square particles with a smooth surface, and their solubility was 0.29 g/100 mL at 20°C, which increased to 4.12 g/100 mL at 60°C. The surfaces of AlPis were rough and irregular. The solubility of AlPi was 0.023 g/100 mL at 20°C, and the solubility remained stable when the temperature increased. The addition of AlPi had a minor influence on the pulp beating degree. The tensile strength of kraft/APP/AlPi decreased with the increase of the AlPi addition. For a paper with 20 wt% APP and 0 wt% AlPi, the limiting oxygen index (LOI) value was 27.2%, and it burned completely at the eighth second during vertical combustion. When the AlPi additive content increased to 20 wt%, its LOI value increased to 32.2%, and the vertical combustion self-extinguished as soon as the flame was removed. Scanning electron microscopy (SEM) showed that the char residue of the kraft/APP/AlPi had a more complete fiber network structure than that of kraft/APP. The Raman spectroscopy indicated that the area ratio of the D (amorphous phase; disordered graphite vibration) band to the G (crystal phase; graphite carbon vibration) band (ID/ IG) ratio of kraft/APP/AlPi was lower than that of kraft/APP, meaning that the graphitization degree of the char residue of kraft/APP/AlPi was higher than that of kraft/APP, which indicated the kraft/APP/AlPi had better flame retardancy.
Journal articles
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Investigation on the recycling of sulfuric acid from pretreatment of cellulose for nanocellulose preparation, TAPPI JOURNAL February 2020
ABSTRACT: Sulfuric acid is often used to pretreat cellulose prior to homogenization and conversion to nanocellulose. It would be economically significant to reuse the acid to close the overall value chain loop. The target of this work was to investigate the effect of recovery and recycling frequency of sulfuric acid from the pretreatments on the pretreatment yield of water-insoluble cellulose solid residue, and to explore the relationship between the nanocellulose size prepared by recovery of acid and number of cycles. The surface properties of the nanocelluloses were measured, including content of sulfate groups, absolute zeta potential, crystallinity, and thermal stability.
Journal articles
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On increasing wet-web strength with adhesive polymers, TAPPI JOURNAL February 2020
ABSTRACT: Fiber-fiber adhesion, called “bonding” in the old paper physics literature, is a critical component of the overall strength of dry paper. With freshly formed very wet pulp fiber webs, all evidence suggests there are no fiber-fiber crossings with significant adhesive joint strength. With water removal, a point will be reached where fiber-fiber adhesion starts to contribute to the overall wet-web strength.The literature reveals very few examples of polymers that increase fiber-fiber joint strength in freshly formed webs. Here, we summarize the literature and explain why it is so difficult to promote fiber-fiber wet adhesion with polymers. Nevertheless, ongoing research in areas as diverse as tissue engineering scaffolds and biomimetic adhesives gives clues to future developments. Advances in paper machine engineering have lessened the importance of wet-web strength. By contrast, a critical issue in many of the evolving nanocellulose technologies is the strength of objects first formed by aqueous processing, the green strength—the strength of wet bodies before drying. For exam-ple, 3-D printed nanocellulose objects and ultralow density cellulosic aerogels can be destroyed by capillary forces during drying. There is a need for adhesives that strengthen freshly formed, wet lignocellulosic joints.