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Mineral/microfibrillated cellulose composite materials: High performance products, applications, and product forms, TAPPI JOURNAL September 2018
Mineral/microfibrillated cellulose composite materials: High performance products, applications, and product forms, TAPPI JOURNAL September 2018
Journal articles
Magazine articles
Enhancement of processability, surface, and mechanical properties of paper based on rice straw pulp using biopolymers for packaging applications, TAPPI Journal July 2019
ABSTRACT: wo biopolymers, chitosan and oxidized starch, were used as wet-end additives to improve the strength properties of the paper because of their biodegradable and non-hazardous qualities. The present study reports the improvement in surface and strength properties of packaging-grade paper made with rice straw pulp using biopolymers, chitosan, oxidized starch, and surface sizing added at the wet end of the paper machine.Use of chitosan at all doses from 0.5 to 10 kg/ton enhanced important surface and strength properties of paper. The breaking length, tear index, burst index, ring crush strength, stretch, tensile energy absorption index, and Taber stiff-ness of the paper with 10 kg/ton of chitosan as a wet-end additive showed 22%, 14%, 20%, 59%, 16%, 44%, and 48% improvement, respectively, in comparison to control, (i.e, without its addition). The Cobb60 was also reduced by 45%, showing better resistance to water in comparison to rice straw paper alone. The effects of chitosan added at the wet end on the paper surface were investigated using Fourier transform infrared spectroscopy (FTIR). The use of 10 kg/ton of chitosan at the wet end reduced the color and total suspended solids in the back water of the papermak-ing system by 55% and 51%, respectively. Further enhancement in the surface and strength properties of paper was observed following surface sizing with oxidized starch.
Journal articles
Magazine articles
Creating adaptive predictions for packaging-critical quality parameters using advanced analytics and machine learning, TAPPI Journal November 2019
ABSTRACT: Packaging manufacturers are challenged to achieve consistent strength targets and maximize pro-duction while reducing costs through smarter fiber utilization, chemical optimization, energy reduction, and more. With innovative instrumentation readily accessible, mills are collecting vast amounts of data that provide them with ever increasing visibility into their processes. Turning this visibility into actionable insight is key to successfully exceeding customer expectations and reducing costs. Predictive analytics supported by machine learning can provide real-time quality measures that remain robust and accurate in the face of changing machine conditions. These adaptive quality “soft sensors” allow for more informed, on-the-fly process changes; fast change detection; and process control optimization without requiring periodic model tuning.The use of predictive modeling in the paper industry has increased in recent years; however, little attention has been given to packaging finished quality. The use of machine learning to maintain prediction relevancy under ever-changing machine conditions is novel. In this paper, we demonstrate the process of establishing real-time, adaptive quality predictions in an industry focused on reel-to-reel quality control, and we discuss the value created through the availability and use of real-time critical quality.
Journal articles
Magazine articles
Kraft recovery boiler operation with splash plate and/or beer can nozzles — a case study, TAPPI Journal Octobr 2021
ABSTRACT: In this work, we study a boiler experiencing upper furnace plugging and availability issues. To improve the situation and increase boiler availability, the liquor spray system was tuned/modified by testing different combinations of splash plate and beer can nozzles. While beer cans are typically used in smaller furnaces, in this work, we considered a furnace with a large floor area for the study. The tested cases included: 1) all splash plate nozzles (original operation), 2) all beer can nozzles, and 3) splash plate nozzles on front and back wall and beer cans nozzles on side walls. We found that operating according to Case 3 resulted in improved overall boiler operation as compared to the original condition of using splash plates only. Additionally, we carried out computational fluid dynamics (CFD) modeling of the three liquor spray cases to better understand the furnace behavior in detail for the tested cases. Model predictions show details of furnace combus-tion characteristics such as temperature, turbulence, gas flow pattern, carryover, and char bed behavior. Simulation using only the beer can nozzles resulted in a clear reduction of carryover. However, at the same time, the predicted lower furnace temperatures close to the char bed were in some locations very low, indicating unstable bed burning. Compared to the first two cases, the model predictions using a mixed setup of splash plate and beer can nozzles showed lower carryover, but without the excessive lowering of gas temperatures close to the char bed.
Journal articles
Pre-damping effects on water absorption and drying dynamics in flexographic printing, TAPPI Journal November 2025
ABSTRACT: Optimizing flexographic printability can involve the ink and the substrate, as well as the printing process. It has been widely reported in the literature that controlling topography of the substrate and its porosity are vital for good flexographic printability, especially when using water-based inks. This study focuses on how pre-damping a surface impacts liquid absorption and improves wet trapping (ink on ink with no intermediate drying) in flexographic printing. A Prüfbau universal print tester was adapted to analyze flexographic wet-on-wet ink printing and trapping using yellow and magenta inks for contrast. Slow drying of the first ink layer (yellow) leads to mottle when the second layer (magenta) is applied. The study explores the “wet sponge” hypothesis: a pre-damped surface should absorb liquid faster. The Lucas- Washburn equation describes long-term absorption, but it does not capture short-term uptake, which instead follows a linear dependence on time.
Journal articles
ABSTRACT: Laboratory experiments with bleached kraft furnish were carried out to quantify the effects of major differences in electrical conductivity of papermaking process water (due to the addition of sodium sulfate) on the performance of various paperm
ABSTRACT: Laboratory experiments with bleached kraft furnish were carried out to quantify the effects of major differences in electrical conductivity of papermaking process water (due to the addition of sodium sulfate) on the performance of various papermaking additives. Batches of refined pulp were prepared with conductivity levels of 168 (tap water), 1000, and 10,000 ìS/cm. The absolute values of the calculated zeta potential, in various cases, were shown to decrease with increasing logarithm of electrical conductivity. The performance of retention aid systems, including cationic polyacrylamide (cPAM), were not adversely affected by increased salinity, even up to an electrical conductivity level of 10,000 ìS/cm. In fact, treatment involving sequential addition of cPAM and colloidal silica showed superior retention of mineral filler at the highest conductivity level. Likewise, combinations of papermaking additives that promote the dewatering of paper continued to perform well in furnish prepared with increasing salinity. The ability of various chemical systems to induce flocculation among papermaking fibers decreased moderately at the highest level of salinity considered.
Journal articles
Magazine articles
Predicting strength characteristics of paper in real time using process parameters, TAPPI Journal March 2022
ABSTRACT: Online paper strength testing methods are currently unavailable, and papermakers have to wait for manufacture of a complete reel to assess quality. The current methodology is to test a very small sample of data (less than 0.005%) of the reel to confirm that the paper meets the specifications. This paper attempts to predict paper properties on a running paper machine so that papermakers can see the test values predicted in real time while changing various process parameters. This study was conducted at a recycled containerboard mill in Chicago using the multivariate analysis method. The program provided by Braincube was used to identify all parameters that affect strength characteristics. Nearly 1600 parameters were analyzed using a regression model to identify the major parameters that can help to predict sheet strength characteristics. The coefficients from the regression model were used with real-time data to predict sheet strength characteristics. Comparing the prediction with test results showed good correlation (95% in some cases). The process parameters identified related well to the papermaking process, thereby validating the model. If this method is used, it may be possible to predict various elastic moduli (E11, E12, E22, etc.) in the future as the next step, rather than the traditional single number “strength” tests used in the containerboard industry, such as ring crush test (RCT), corrugating medium test (CMT), and short-span compression strength test.
Journal articles
Magazine articles
Dynamic CFD modeling of calcination in a rotary lime kiln with an external dryer, TAPPI Journal August 2023
ABSTRACT: Mid-kiln ring formation is a problem in lime kilns that may be related to fluctuations in the start location of calcination. To calculate fluctuations in bed and gas temperature profiles within a lime kiln with an external dryer, a dynamic two-dimensional (2D) axisymmetric computational fluid dynamics (CFD) gas model with a methane burner implemented in ANSYS Fluent, coupled by mass and heat balances to a one-dimensional (1D) bed model, was developed. The dynamic model was used to calculate changes in the location where calcination starts with fluctuations in operational conditions using pulp mill data. This model simulates radiative, convective, and conductive heat transfer between the gas, wall, and bed to determine the axial bed temperature in the kiln. The calcination reaction is described using a shrinking core model that allows for the prediction of the location at which calcination begins and the degree of calcination achieved. The solid motion within the kiln is modeled using Kramer’s equation modified for transient response. Steady-state and dynamic simulation results were compared to data from an industrial dry lime kiln, and good agreement was found. A sensitivity analysis was also performed to provide insight on how operating conditions and model variables impact the calcination location and degree of calcination. Of the variables examined, the fuel rate and the feed temperature had the largest impact on both the calcination location and degree of calcination in the kiln. Model predictions of a period of ring formation in the industrial kiln showed that the start location of calcination fluctuated by more than 2 m on either side of the mean of regular operation, warranting further investigation of the importance of these fluctuations on mid-kiln ring formation.
Journal articles
Magazine articles
Enhancing tissue wet pressing performance and dry end material efficiency for cost savings, TAPPI Journal May 2024
ABSTRACT: The steadily growing global tissue paper demand lays a foundation for new technologies targeting tissue production optimization, as well as improved material and time efficiency. Tissue making is an especially energy-intensive field of paper industry, creating unique demands for performance in wet pressing and drying processes to cut energy usage. Intelligent roll solutions offer new tools for tissue making to achieve these goals. These tools aim at improving press nip, moisture, and tension profiles; reeling nip and parent roll hardness profiles; rewinder runnability; and end product web handling characteristics in converting. Intelligent rolls can be utilized in all the main processes and positions on tissue production lines. With these tools, production cost reductions and energy savings can be obtained by optimizing the press nip-to-Yankee cylinder contact, avoiding moisture profile errors requiring overdrying with the Yankee hood and reducing reeling/winding broke under low nip load conditions typical to tissue windups. The intelligent roll system consists of a helically mounted force or temperature sensors, roll covers, measurement electronics, digital radio transmission, and a receiver system connected to a user interface or the mill automation system. What distinguishes these implementations is that no layout changes or added external measurement devices are required, helping to fit into compact tissue machine environments, regardless of the equipment type • traditional, hybrid, or through-air drying (TAD) concept. In tissue processing equipment, the optimal positions for these rolls are press nip rollers, reeling cylinders, rewinder or converting line paper lead rolls, or rewinder winding drums. In addition to these, temperature profile measurements are utilized, with the main application being the sheet temperature profile detection after Yankee drying for moisture profile and drying process optimization.
Journal articles
Local delamination in pharmaceutical blister packages • A thermomechanical theory on buckling of heat-sealed composite laminates in flexible packaging, TAPPI Journal July 2025
ABSTRACT: Pharmaceutical blister packages consist of cavities made from a thick polymeric form foil and a thin aluminum lid foil. Heat-sealing technology is usually used to bond the lid foil to the form foil. Occasionally, the sealed area shows buckling defects of the lid foil, which allow contamination to enter into the cavity. A contaminated product is a worst-case scenario for pharmaceutical production and must be avoided. We discuss a thermomechanical theory on buckling defects in blister packages and derive strategies to avoid these. The theory is based on the assumption that the seal of a blister packaging behaves like a laminate of thin composite layers under compressive load. Literature research on buckling of thin laminated films, thermal behavior of polymers, and seal strength of heat-sealed polymers provides the technical and physical background to elaborate the theory. The theory comprises three elements: an initial condition regarding thermal load and precedent defects; a buckling condition; and a crack propagation condition. The plausibility of the theory is verified using model calculations and heat-seal tests. The paper concludes with strategies against buckling of heat-sealed lid foils and an outlook on other applications in laminating and coating of polymer films.