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Journal articles
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
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
Effects of different parameters on the morphology of electrospun cellulose acetate/polyaniline nanocomposite, TAPPI Journal February 2025
ABSTRACT: Cellulose is the most abundant naturally occurring polysaccharide. Its inherent mechanical stability, biocompatibility, biodegradability, and abundant hydroxyl groups available for derivatization provide benefits in the production of fiber-based materials such as conductive fibers. Cellulose derivatives, including cellulose esters such as cellulose acetate (CA), are readily generated in the fiber form following dissolution using a variety of solvents. Electrospinning is one of the emerging technologies with an outstanding ability to regenerate fibers in the nanoscale range. Polyaniline (PANI) is a conductive polymer that is popular for its high chemical stability, nontoxicity, good processability, and stable intrinsic redox state. This study explored the fabrication of a conductive PANI/CA nanocomposite through electrospinning. Working conditions, electrospinning variables, and solution parameters were established to produce coherent PANI/CA nanofibers. The effects of varying CA concentration, amount of PANI, molecular weight of CA, and feed flowrate on the morphology of the nanofibers were investigated.
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
Magazine articles
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.
Editorial: Critical literature reviews in open source journals, TAPPI Journal June 2023
ABSTRACT: We stand on the shoulders of giants” is a famous metaphor used by Sir Isaac Newton. This testifies to the fact that new information or discoveries are built on understanding and analyzing earlier information. Particularly in science, technology, engineering, and math (STEM) fields, it is important to have thorough analysis of earlier research activities in a particular field to propose a new direction of research, to evolve new ideas, and to develop new test methods and standards. It is a mandatory and required aspect of every original research paper to have a Literature Review section in the introductory part of the paper.
External fibrillation of wood pulp, TAPPI Journal June 2023
ABSTRACT: Pulp refining produces external fibrillation consisting of fibrils tethered to fiber surfaces, in addition to loose fibrils and fines. Both contribute to a larger bonding area that increases paper strength, but tethered fibrils have less likelihood of being washed out during papermaking. This study postulates the mechanism by which refining produces external fibrillation and the optimum conditions for doing so.The postulated mechanism is surface abrasion during sliding of fibers in refiner gaps. External fibrillation occurs when forces are great enough to partially dislodge fibrils from fiber surfaces, but not large enough to break the fibrils. The refining intensities to achieve these forces were determined by a mathematical model and experiments using a laboratory disc refiner. The optimum intensities in terms of specific edge load (SEL) for chemical pulps were about 0.1 J/m for hardwoods and 1.0 J/m for softwoods. An extension of this study suggested that abrasion may also account for most of the energy consumed in the mechanical pulping process.
A fast and non-destructive alternative to the burnout method for paperboard quality inspections using phase-contrast X-ray imaging, TAPPI Journal February 2023
ABSTRACT: An X-ray based quality inspection method for paperboard was implemented and tested as a fast and non-destructive alternative to the burnout method. An argument against X-ray imaging for inspection of paper and paperboard has been that X-ray absorption is low in paper. To overcome this limitation, we used phase-contrast X-ray imaging (PCXI), which gives higher contrast than conventional attenuation-based imaging for low-absorbing materials such as paper. The suggested PCXI method was applied to previously prepared and quality rated samples using the burnout method. A strong similarity between the burnout images and the PCXI images was observed. In conclusion, further development of the phase-contrast X-ray method would provide an interesting option for replacing or complementing the standard burnout method.
Mechanistic aspects of nanocellulose–cationic starch–colloidal silica systems for papermaking, TAPPI Journal February 2023
ABSTRACT: Optimization of a chemical additive program for a paper machine can require attention to both colloidal charges and kinetic effects. This work considered an additive program with two negatively charged substances (nanofibrillated cellulose [NFC] and colloidal silica) and two positively charged items (cationic starch and cationic acrylamide copolymer retention aid). Results were shown to depend on charge interactions; however, that clearly was not the whole story. Some findings related to cationic demand, dewatering, fine-particle retention, and flocculation among fibers were best explained in terms of at least partly irreversible complexation interactions between the charged entities. Adjustments in ratios between oppositely charged additives, their sequences of addition, and effects of hydrodynamic shear levels all affected the results. In general, the most promising results were obtained at a cationic starch level of 0.25% to 0.5% based on sheet solids in systems where the cationic starch was used as a pretreatment for NFC.
An analytical method to quantitatively determine the amount of polyamide epichlorohydrin (PAE) in paperboard and white water, TAPPI Journal February 2023
ABSTRACT: Polyamide epichlorohydrin (PAE) is a permanent wet strength resin. When applied to paperboard, some amount of resin is retained in the sheet, and some is lost to the white water. An analytical method for quantify-ing the amount of PAE retained in the sheet and lost into the white water has been developed. This method hydrolyz-es the PAE to adipic acid, which in turn is derivatized to diethyl adipate and quantified by pyrolysis gas chromatogra-phy–mass spectrometry (pyGCMS). In addition, the hydrolysis conditions of the PAE were studied by the Taguchi approach, and PAE material balances around the dry sheet and white water for 3 and 6 lb/ton PAE applications have been performed. The PAE resin recovery was 95.4% with 65.0% in the sheet for the 3 lb/ton PAE-charged paper-board, and the recovery was 96.7% with 36.1% in the sheet for the 6 lb/ton PAE-charged paperboard.