Search
Use the search bar or filters below to find any TAPPI product or publication.
Filters
Content Type
Publications
Level of Knowledge
Committees
Collections
Journal articles
Magazine articles
Dissolution of wood components during hot water extraction of spruce, TAPPI Journal May 2023
ABSTRACT: The purpose of this study was to investigate the autohydrolysis of softwood, which is the main chemical operation in both hot water extraction and steam explosion. Control of the process and monitoring its course were ensured by the careful choice of experimental setup and conditions: a milled spruce material was extracted in a small flow-through reactor to minimize degradation of the dissolved material and to enable analysis of the resulting liquors extracted at selected time points. The obtained liquid and solid fractions were analyzed for sugar composition and acetic acid concentration. The results showed that partially degraded hemicelluloses were extracted; hemicelluloses side chains were cleaved off and detected as monomers, while deacetylation was limited. Chain scissions of cellulose were observed as a result of autohydrolysis.
Journal articles
Magazine articles
Paper bending stiffness and web tension measurement from a running web using a vacuum and computer imaging, TAPPI Journal May 2023
ABSTRACT: A novel method for measuring the bending stiffness of paper online during manufacturing is introduced. The method uses photometric stereo imaging to detect the shape of the deflection surface caused by a controllable pressure difference over the paper’s surfaces. The hardware for the measurement is based on a combination of two existing sensors, which has accelerated and facilitated the development of the implementation. The deflection and loads are tied together by the governing differential equation for the bending of an orthotropic elastic plate with selected simplifications. An approach to resolve material parameters and in-plane loads without knowledge of traditional boundary conditions is suggested. The presented method was tested in a paper mill during manufacturing. For bending stiffnesses measured online, correlation coefficients 0.88 and 0.92 were obtained compared to state-of-the-art laboratory measurements. However, the results gained from a moving web are noisy and the data requires correction of the slope and an off-set. Although several issues remain to be resolved before the method can be considered as an accurate measurement for industrial use, the theoretical background, the performance of online implementation, and the results are promising. Possible causes for the observed discrepancies and the future development of the method are discussed.
Journal articles
Electrochemical Removal of Color and Toxicity from Bleached
Electrochemical Removal of Color and Toxicity from Bleached Kraft Effluents, 1994 Environmental Conference Proceedings
Journal articles
Aging and degradation of oil and grease barrier papers coate
ABSTRACT: The long-term performance and stability of bio-based barrier coatings are critical for sustainable packaging. In this study, the aging and degradation of a biobased starch•wax emulsion coating were examined on two different base papers. Coated samples were stored for 8 months at 23°C and 50% relative humidity (RH) in their original reels to minimize external exposure and isolate internal aging effects. Multiple aging intervals were analyzed using advanced methods to assess both chemical composition and physical structure. The water vapor transmission rate (WVTR) of both coated papers increased during the first 15 days, but after eight months, the WVTR dropped below the initial values. Fourier transform infrared (FTIR) results supported these trends by showing a marked rise in the polarity index (PI), occurring predominantly within the first 15 days. The overall observations, including increases in the PI, carbonyl index (CI), and absolute absorbance in the hydroxyl region, confirm that both hydrolysis and oxidation occurred during aging. The gradual increase in the aliphatic C•H stretching peaks indicated that wax components moved toward the surface over time. The non-uniform surface enrichment of oleophilic wax following migration contributed to the decline in Kit rating upon aging by facilitating oil and grease wetting and penetration. At the same time, increased wax concentration at the surface helped improve the water vapor barrier performance during long-term aging. Scanning electron microscopy (SEM) imaging revealed distinct surface cracks over time on the starch-wax emulsion coated papers. The FTIR analysis supported these observations through an increase in the conformational disorder index (CDI) with aging. Physical changes were further reflected in the barrier performance, as the heptane vapor transmission rate (HVTR) increased significantly for both coated papers over the 8-month period.
Journal articles
A novel dimensionless index for optimizing the thermo-hydrau
ABSTRACT: The comprehensive performance of steam condensation in horizontal rotating channels, which involves a trade-off between heat transfer enhancement and flow resistance, lacks a unified evaluation criterion. This deficiency is particularly critical for applications such as a multi-channel cylinder dryer (MCD) in paper machines, where rotational operation enhances drying efficiency. To address this gap, this study introduces a novel dimensionless index, W/Eu, defined as the ratio of the dimensionless heat transfer coefficient (W) to the dimensionless pressure drop (Eu), thereby taking into account both heat transfer and flow resistance characteristics comprehensively. A functional relationship for this index was established with respect to channel spacing (Wr) and steam mass flux (G), followed by a theoretical optimization analysis. The analysis reveals that W/Eu decreases monotonically as Wr increases and increases monotonically as G increases, ultimately diverging as G ™¨ ™‡. Consequently, for any given operational range, the theoretical maximum performance is achieved at the boundary condition of minimum channel spacing (Wr ™¨ 0) and maximum allowable mass flux (G = Gmax). This work provides a clear theoretical directive for the design and optimization of high-efficiency rotating heat exchanger systems, offering valuable insights for enhancing the drying performance of microchannel dryers in paper machines and similar rotary thermal systems.
Journal articles
Magazine articles
Formic acid pulping process of rice straw for manufacturing of cellulosic fibers with silica, TAPPI Journal August 2021
ABSTRACT: Emerging technology has the potential to develop entirely new approaches for producing cellulose fiber-based materials along with fuels and chemical raw materials like lignin and furfural. Rice straw is a rich source of cellulosic fibers and inorganic micronic-sized particles termed as ash. They can prove helpful in development of new or enhanced agricultural residue-based materials and products that offer cost effective substitutes for nonrenewable materials used in different domestic and industrial applications. Lignocellulose is an abundant material that is submicronic at the basic level. Rice straw is a fibrous lignocellulosic material obtained as agricultural residue, but it differs from most crop residues in its high content of silicon dioxide (SiO2). Ash content on a dry weight basis ranges from 13% to 20%, varying according to the state of conservation of the straw after harvest. The ash in rice straw has nearly 75% SiO2. The particle size analysis shows variation from a few microns to hundreds of microns for inorganic residues left after burning at high temperatures above 550°C. Proximate analysis of rice straw shows that it contains 54% to 56% holocellulose and 15% to 18% lignin, both of which are natural biopolymers. The compound analysis shows the different compounds present in rice straw ash.Rice straw is available in hundreds of million tons in India and other Asian countries, so suitable technologies are required to convert rice straw from a biomass waste to useful bioproducts like pulp, paper, and paperboard. This research paper is intended to obtain pulp with fibers having inherent silica present in it to give high opacity paper and better bonding between fibers.
Journal articles
Magazine articles
Technological evaluation of Pinus maximinoi wood for industrial use in kraft pulp production, TAPPI Journal August 2021
ABSTRACT: This study characterized Pinus maximinoi wood and evaluated its performance for pulp production. Samples of Pinus taeda wood were used as reference material. For both species, wood chips from 14-year-old trees were used for the technological characterization, pulping, bleaching process analysis, and pulp properties. A modified kraft pulping process was carried out targeting kappa number 28±5% on brownstock pulp. The bleaching sequence was applied for bleached pulp with final brightness of 87±1 % ISO. Refinability and resistance properties were measured in the bleached pulps. Compared to P. taeda wood, P. maximinoi showed slightly higher basic density (0.399 g/cm³) and higher holocellulose (64.5%), lignin (31.1%), and extractives content (4.5%), along with lower ash content (0.16%). P. maximinoi tracheids showed greater wall thickness (6.4 µm) when compared to P. taeda tracheids. For the same kappa number, P. maximinoi and P. taeda resulted in similar screened yield, with an advantage observed for P. maximinoi, which resulted in lower specific wood consumption (5.281 m³/o.d. metric ton), and lower black liquor solids (1.613 metric tons/o.d. metric ton). After oxygen delignification, P. maximinoi pulp showed higher efficiency on kappa reduction (67.2%) and similar bleaching chemical demand as P. taeda pulp. Compared to P. taeda pulps, the refined P. maximinoi pulps had similar results and the bulk property was 10% higher. Results showed that P. maximinoi is an interesting alternative raw material for softwood pulp production in Brazil.
Journal articles
Magazine articles
Can carbon capture be a new revenue opportunity for the pulp and paper sector?, TAPPI Journal August 2021
ABSTRACT: Transition towards carbon neutrality will require application of negative carbon emission technologies (NETs). This creates a new opportunity for the industry in the near future. The pulp and paper industry already utilizes vast amounts of biomass and produces large amounts of biogenic carbon dioxide. The industry is well poised for the use of bioenergy with carbon capture and storage (BECCS), which is considered as one of the key NETs. If the captured carbon dioxide can be used to manufacture green fuels to replace fossil ones, then this will generate a huge additional market where pulp and paper mills are on the front line. The objective of this study is to evaluate future trends and policies affecting the pulp and paper industry and to describe how a carbon neutral or carbon negative pulp and paper production process can be viable. Such policies include, as examples, price of carbon dioxide allowances or support for green fuel production and BECCS implementation. It is known that profitability differs depending on mill type, performance, energy efficiency, or carbon dioxide intensity. The results give fresh understanding on the potential for investing in negative emission technologies. Carbon capture or green fuel production can be economical with an emission trade system, depending on electricity price, green fuel price, negative emission credit, and a mill’s emission profile. However, feasibility does not seem to evidently correlate with the performance, technical age, or the measured efficiency of the mill.
Journal articles
Use of Simulation Models in the On-Line Control and Optimiza
Use of Simulation Models in the On-Line Control and Optimization of the Refining Process, 1991 Engineering Conference Proceedings
Journal articles
Case Histories of Three Yankee Cracking Incidents Associated
Case Histories of Three Yankee Cracking Incidents Associated with Shell Edge Extensions, 1991 Engineering Conference Proceedings