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About TAPPI Journal

An internationally recognized technical publication for over 60 years, TAPPI Journal (TJ) publishes the latest and most relevant research on the forest products and related industries in digital format. A stringent peer-review process and distinguished editorial board of academic and industry experts set TAPPI Journal apart as a reliable source for impactful basic and applied research and technical reviews. TAPPI Journal is going Open Access. Read more.

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Editorial: Vamsi Jasti: New nonwovens expert joins TAPPI Journal editorial board, TAPPI Journal July 2020

July 01, 2020

ABSTRACT: TAPPI and the TAPPI JOURNAL (TJ) editorial staff would like to welcome a new member to the TJ Editorial Board, Vamsi Krishna Jasti, Ph.D., a nonwovens product development scientist and product development manager at Ahlstrom-Munksjo Nonwovens LLC in Windsor Locks, CT, USA. He has more than 10 years of professional and academic experience n the area of fibert processing, product development, nonwovens processing, surface modification, and static electrification in countries ranging from India and Germany to China and the United States.

Equilibrium moisture content in wet pressing of paper, TAPPI Journal July 2020

July 01, 2020

ABSTRACT: Equilibrium moisture is a limiting factor in achieving high solids in the later stages of pressing or pressing low basis weight grades. We have developed a model that relates equilibrium moisture directly to the pore size distribution of fibers as measured by the solute exclusion technique. The model shows that chemical pulping and refining increase equilibrium moisture by increasing pore volume at given pore sizes in fibers, which leads to lower pressed solids and greater energy expenditure in the dryer section. Means to increase equilibrium moisture without compromising pulp strength are briefly discussed.

Combatting lime kiln ringing problems at the Arauco Constitución mill, TAPPI Journal July 2020

July 01, 2020

ABSTRACT: The lime kiln at the Arauco Constitución mill experienced severe ringing problems requiring it to be shut down for ring removal every 3 to 6 months. The mill controlled the problems by blasting ring deposits off during operation with its existing industrial shotgun and a newly installed Cardox liquid carbon dioxide (CO2) cartridge system. Various ring blasting procedures were tested to determine the optimum ring location and thickness to blast; the optimum depth to insert the CO2 cartridge into the kiln; and the most effective blasting frequency and sequence to employ. The best strategy was found to be the weekly blasting operation that alternated between the liquid CO2 cartridge and the industrial shotgun, with the CO2 cartridge inserted into the ring mass, 20 cm (8 in.) away from the refractory brick surface, and the shotgun aimed at rings at about 28 m (92 ft) from the kiln discharge end. With each blasting event removing considerably more rings than before, it takes a longer time for rings to rebuild, allowing the kiln to run continuously between annual maintenance shutdowns with only a few short (< 4 h) downtimes for ring removal. This substantially reduces the costs associated with ring removal and lime replacement during unscheduled shutdowns.

Viscoelastic web curl due to storage in wound rolls, TAPPI Journal July 2020

July 01, 2020

ABSTRACT: Winding is often the final operation in a roll-to-roll manufacturing process. Web materials, i.e., materials that are thin compared to their length, are wound into rolls because this form is the only practical means to store them. The resulting bending strains and associated stresses are large for thick webs and laminates. As many webs are viscoelastic on some time scale, bending stresses lead to creep and inhomogeneous changes in length. When the web material is unwound and cut into discrete samples, a residual curvature remains. This curvature, called curl, is the inability for the web to lie flat at no tension. Curl is an undesirable web defect that causes loss of productivity in a subsequent web process. This paper describes the development and implementation of modeling and experimental tools to explore and mitigate curl in homogenous webs. Two theoretical and numerical methods that allow the prediction of curl in a web are developed: a winding software based on bending recovery theory, and the implementation of dynamic simula-tions of winding. One experimental method is developed that directly measures the curl online by taking advantage of the anticlastic bending resulting from the curl. These methods are demonstrated for a low-density polyethylene web.

Wet pressing and product quality: Review of previous pilot machine trials, TAPPI Journal July 2020

July 01, 2020

ABSTRACT: The purpose of wet pressing is to remove water by mechanical means to consolidate the web and minimize the energy expended in the dryer section. In this process, paper is compacted and densified to degrees that impact end-use performance. Average density is increased by pressing, which has implications for grades where stiffness is important. The z-direction density gradients can affect printing and converting. Lastly, pressing affects surface quality of paper and its response to printing. Broadly speaking, the final press nip dominates the paper surface roughness and the early press nips affect printing performance.