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Journal articles
Improving barrier performance of coated paper and paperboard
ABSTRACT: Market demand for barrier coated packaging paper and paperboard has been on a steady rise and is forecasted to further increase. As a result, there is a continued interest in improving barrier coating functionalities, which is currently an active area of investigation. In this work, a multi-layer approach was adopted that involved applying a biowax emulsion, latex, or a combination of biowax and latex top coating layer onto the kaolin/latex (20/80, 50/50, 65/35, or 70/30) precoated solid bleached sulfate (SBS) paperboard. Our main objective was to demonstrate the effect of these top coating layers on various barrier properties, especially water vapor transmission rate (WVTR) at high relative humidity (RH) and high temperature (90% RH; 38°C), known as tropical/jungle test conditions. While the top coat with latex and/or biowax showed dramatic improvement in both water resistance (Cobb) and WVTR, the biowax coating increased contact angle significantly compared to the latex top coat. Contact angle increased from about 65° for the latex top coat to as high as 96° for the biowax top coat. Generally, it is much more difficult to improve WVTR at the jungle conditions below 100 g/m2/day, even with the high aspect ratio platy pigment. However, using the coating strategies adopted in this study, we were able to achieve WVTR values notably below 50 g/m2/day at the tropical test conditions, as well as significant improvements in regard to fold crack barrier integrity at high kaolin clay usage.
Journal articles
Prediction of residual calcium carbonate (CaCO3) in the lime
ABSTRACT: In a kraft pulp mill, the rotary lime kiln is responsible for converting calcium carbonate (CaCO3) into calcium oxide (CaO) to be reused in the causticizing plant. An important parameter of the calcination efficiency and the product quality is the amount of CaCO3 not converted to CaO, commonly defined as residual carbonate. This parameter is usually determined through laboratory analysis, which introduces delays in process control and limits the ability to make timely operational adjustments. This work presents a predictive model that functions as a soft sensor for the residual carbonate in a lime kiln of a Brazilian kraft pulp mill. This model was able to estimate residual CaCO3 every 30 min using routinely measured online process variables, which is a considerable reduction from the 6-h average laboratory measurement. The correlation coefficient (r) between the model predictions and the mill values was 0.83, with a mean absolute error (MAE) of 0.33%. Considering the effect of the residence time throughout the lime kiln proved to be decisive in obtaining a satisfactory prediction result. After model validation, a variable importance analysis showed that the carbon monoxide (CO) concentration in the stack flue gas (in ppm), secondary air temperature (in oC), and fan speed (in %) were the most influential variables in predicting the residual carbonate content. Combined with commonly used operation expertise, this subset of variables can serve as additional information to achieve smoother lime kiln operation.
Journal articles
Editorial: Honoring the contributions of Dr. Mahendra Doshi
n this column, we would like to recognize the contributions to TAPPI and TAPPI Journal made by Dr. Mahendra Doshi, who passed away in April. A long-time member of TAPPI and a TAPPI Journal Editorial Board Member for many years, he is recognized for his research in screening system analysis, wax, and stickies removal in the field of recycling. Doshi was a pioneer in stickies classification and measurement methods for macro and micro stickies. During his career, he consulted with paper mills all over the world, providing mills with solutions for deinking, wax, stickies, yield, dirt count, and brightness.
Journal articles
Combining Charge Distributions and Heats of Interaction to P
Combining Charge Distributions and Heats of Interaction to Probe Filled Papermaking Furnish Flocculation Mechanisms, 1993 Papermakers Conference Proceedings
Journal articles
The Impact of the Summer Effect on Ink Detachment and Remova
The Impact of the Summer Effect on Ink Detachment and Removal
Journal articles
Sintering of fireside deposits and its impact on plugging in kraft recovery boilers, TAPPI JOURNAL April 1988 88APR109
Sintering of fireside deposits and its impact on plugging in kraft recovery boilers, TAPPI JOURNAL April 1988
Journal articles
Combined effect of fiber fines and dissolved organics on tissue properties, TAPPI JOURNAL April 1988 88APR141
Combined effect of fiber fines and dissolved organics on tissue properties, TAPPI JOURNAL April 1988
Journal articles
The role of diffusion during initial delignification of alkaline pulping, TAPPI JOURNAL April 1988 88APR145
The role of diffusion during initial delignification of alkaline pulping, TAPPI JOURNAL April 1988
Journal articles
Correlating the on-line measurement of ultrasonic velocity with strength properties, TAPPI JOURANL April 1988 88APR149
Correlating the on-line measurement of ultrasonic velocity with strength properties, TAPPI JOURANL April 1988
Journal articles
Measurement of strains in a paper tensile specimen using computer vision and digital image correlation-Part 2: Tensile specimen test, TAPPI JOURNAL April 1988 88APR153
Measurement of strains in a paper tensile specimen using computer vision and digital image correlation-Part 2: Tensile specimen test, TAPPI JOURNAL April 1988