Search
Use the search bar or filters below to find any TAPPI product or publication.
Filters
Content Type
Publications
Level of Knowledge
Committees
Event Type
Collections
Journal articles
Magazine articles
The effect of contact time between CPAM and colloidal silica on the flocculation behavior in the approach flow, TAPPI Journal January 2021
ABSTRACT: Multicomponent wet-end systems have become increasingly common in papermaking, with the objective of improving the retention-formation-dewatering relationship. It is quite common to use at least a cationic polymer, often in combination with an anionic microparticle. In some cases, a fixative is also used. However, there is still debate on the optimal implementation of these systems. In particular, optimizing the contact time of the cationic polymer prior to addition of the anionic microparticle is still poorly understood. In this work, we investigate the effect of the contact time of a cationic polyacrylamide (CPAM) prior to addition of colloidal silica on the flocculation response in a flowing fiber suspension. The effect of using a fixative is also investigated. Focused beam reflectance measurements (FBRM) are combined with zeta-potential measurements for optimizing the addition levels of a two- and three-component system, as well as for elucidating the effect of contact time on CPAM performance. Trials are then performed on a pilot scale flow loop, where the time between addition of these two components is varied and the resulting flocculation response is characterized using high-speed filming and image analysis techniques. It is shown that the efficacy of CPAM can be improved through use of a fixative and that a longer CPAM contact time may be beneficial in terms of immediate flocculation; however, hydrodynamic shear tends to dominate the flocculation response regardless of contact time due to floc rupture.
Journal articles
Magazine articles
Three-dimensional visualization and characterization of paper machine felts and their relationship to their properties and dewatering performance, TAPPI Journal July 2021
ABSTRACT: Polymeric felts are commonly used in the papermaking process on the paper machine wet end, in the press section, and in the dryer section. They provide an important function during paper manufacturing, including as a carrier or support; as a filter media assisting with water removal on the paper machine; in retention of fibers, fines, and fillers; and in some applications, such as tissue and towel, to impart key structural features to the web. These felts can have highly interwoven complex internal structures comprised of machine direction and cross-machine direction yarns of varying sizes and chemical compositions. Here, we present a non-intrusive three-dimensional (3D) image visualization method using advanced X-ray computed tomography (XRCT). This method was used to characterize the complex 3D felt structure and determine the water removal characteristics of some commonly used paper machine felts. The structural features analyzed include porosity; specific pore-yarn interfacial surface area; 3D pore size distribution; 3D fiber or yarn-size distribution; and their variations through the thickness direction. The top, middle, and bottom layers of the felt have very different structures to assist with water removal and impart paper properties. The size distribution of the yarns, as well as the pores in the different layers of the felt, are also inherently different. These structural features were non-intrusively quantified. In addition, variation in the structural characteristics through the thickness of the felts and its potential role in papermaking is explored. In addition to the 3D structural characteristics, permeability characteristics and water removal characteristics, including rewetting of select felt samples, have also been experimentally determined. It is interesting to observe the relationship between key structural features and permeability and water removal characteristics. These relationships can provide additional insights into press felt design, as well as ways to improve product properties and the dewatering efficiency and productivity of the paper machine.
Journal articles
Magazine articles
Addressing production bottlenecks and brownstock washer optimization via a membrane concentration system, TAPPI Journal July 2021
ABSTRACT: Advancements in membrane systems indicate that they will soon be robust enough to concentrate weak black liquor. To date, the economic impact of membrane systems on brownstock washing in kraft mills has not been studied and is necessary to understand the viability of these emerging systems and their best utilization.This study investigated the savings that a membrane system can generate related to brownstock washing. We found that evaporation costs are the primary barrier for mills seeking to increase wash water usage. Without these additional evaporation costs, we showed that our hypothetical 1000 tons/day bleached and brown pulp mills can achieve annual savings of over $1.0 MM when operating at higher dilution factors and fixed pulp production rate. We then investigated the impact of increasing pulp production on mills limited by their equipment. In washer-limited mill examples, we calculated that membrane systems can reduce the annual operating cost for a 7% production increase by 91%. Similarly, in evaporator-limited mill examples, membrane systems can reduce the annual operating cost for a 7% production increase by 86%. These results indicated that membrane systems make a production increase significantly more feasible for these equipment-limited mills.
Journal articles
Magazine articles
Setting priorities in CNF particle size measurement: What is needed vs. what is feasible, TAPPI Journal February 2023
ABSTRACT: Measuring the size of cellulose nanomaterials can be challenging, especially in the case of branched and entangled cellulose nanofibrils (CNFs). The International Organization for Standardization, Technical Committee 6, Task Group 1—Cellulosic Nanomaterials, is exploring opportunities to develop standard methods for the measurement of CNF particle size and particle size distribution. This paper presents a summary of the available measuring techniques, responses from a survey on the measurement needs of CNF companies and researchers, and outcomes from an international workshop on cellulose nanofibril measurement and standardization. Standardization needs differed among groups, with Japanese companies mostly requiring measurements for product specification and production control, and other companies mostly needing measurements for safety/regulatory purposes and for grade definitions in patents. Among all the companies, average length and width with percen-tiles (D(10), D(50), D(90)) were the most desired measurands. Workshop participants concurred that defining the location(s) on the CNF at which to measure the width and the length is an urgent and complex question. They also agreed that methods are needed for rapid particle size measurement at the nanoscale. Our recommendation within ISO is to start work to revise the definition of CNFs and develop sample preparation and measurement guidelines. It was also recommended that further research be done to reproducibly prepare hierarchical branched CNF structures and characterize them, develop automated image analysis for hierarchical branched CNF structures, and develop a classification system encompassing measurements at multiple size ranges from micro- to nanoscale to fully characterize and distinguish CNF samples.
Journal articles
Magazine articles
An analytical approach to assess the interrelation of surface properties and softness of tissue paper, TAPPI Journal February 2023
ABSTRACT: The tissue industry constantly strives for improving the overall quality of tissue paper, as customers pay more attention to special quality features when it comes to a purchase decision between different products. As producers need to optimize their processes and furnish mixtures to keep production costs low, accurate and fast methods are crucial for characterization of important tissue properties. Here, we present a method for the characterization of the tissue surface regarding roughness and describe its relation to the tissue surface softness properties, based on a sample set of dry-creped bath tissue (DCT) with different amounts of softwood (SW), hardwood (HW), and nonwood pulp (NWP). The surface of tissue is complex and consists of several overlying structural features; thus, the optical non-contact measurement principle of focus variation was used to provide robust and reliable topographical surface information. Based on the obtained 3D data, areal surface analysis was performed to determine the surface roughness of the tissue samples, which is described by the developed interfacial areal ratio (Sdr) and the power spectral density (PSD). To determine the surface softness properties (TS7) of the tissue, a widely-used tissue softness analyzer (TSA) in the industry was employed. The surface softness (TS7) and the stiffness (D) parameters of this instrument were considered for surface and structural characterization. The results of the surface roughness (Sdr and PSD) and surface softness TS7 measurements show a good linear correlation, with higher surface roughness implying a higher TS7. The presented evaluation of these aspects of tissue softness allows an objective, fast, and accurate assessment of the relevant properties in addition to standard panel tests and is also applicable to other hygiene products.
Journal articles
Magazine articles
Effect of fly ash-based calcium silicate on physical properties of cardboard paper, TAPPI Journal July 2023
ABSTRACT: This work reported the possibility of using fly ash-based calcium silicate (FACS) as filler for papermaking and waste fiber to synthesize cardboard paper. The adverse effects of FACS filler on paper strength were improved by using cationic starch modification, surface size, and interlayer-filled technology. Physical property tests indicated that the increase of filler content leads to a decrease in paper strength and an increase in bulk, but at the same content, the strength properties of paper modified by cationic starch were significantly improved, and the absorption resistance was lower. The paper had better absorption resistance than the original FACS paper after surface size. In addition, the absorption resistance and strength of the interlayer filling paper were better than the original FACS-filled paper, and the absorption resistance was the best. The results support the potential use of FACS as a low-cost filler for cardboard paper production.
Journal articles
Magazine articles
Experimental study and prediction of two-phase flow pattern distribution diagrams in multi-channel cylinder dryer, TAPPI Journal July 2023
ABSTRACT: The multi-channel cylinder dryer (MCD) is designed to improve heat transfer. Although there are numerous research studies on the pressure drop, heat transfer characteristics, and flow pattern in static state of MCD, there is little research on the flow pattern in the rotating state. In this paper, the distribution of flow pattern in MCD under different rotating speeds and steam mass flow rates is studied. Furthermore, the logistic regression method (LR) is used to predict the flow pattern diagrams. The results show that in the front section of the flow channel, the flow pattern is basically annular flow, which is not affected by mass flow rate and rotating speed. On the other hand, wavy flow, vortex flow, slug flow, and bubble flow can be observed when the fluid enters the middle and the end section. The higher the rotating speed and the steam mass flow rate, the more the flow pattern tends to be an annular and wavy flow. At the end of the passage, the flow pattern is mainly slug flow. The predicted flow pattern diagrams are in good agreement with the experimental result, and to obtain an effective flow pattern in the middle and the end section of the flow channel, the influence of increasing rotating speed is greater than that of increasing steam mass flow rate. However, the specific rotating speed, steam mass flow rate, and other parameters should still be set by combining with the actual situation. This work can provide some references for the further study of MCD flow characteristics.
Options to Close the Water Cycle of Pulp and Paper Mills by Using Evaporation and Condensate Reuse, 1996 Minimum Effluent Mills Symposium Proceedings
Options to Close the Water Cycle of Pulp and Paper Mills by Using Evaporation and Condensate Reuse, 1996 Minimum Effluent Mills Symposium Proceedings
Colloidal Properties of Dissolved Kraft Lignin, 1992 Papermakers Conference Proceedings
Colloidal Properties of Dissolved Kraft Lignin, 1992 Papermakers Conference Proceedings
Multilayer Plastics Packaging Recycling (A Myth or Reality?)
Multilayer Plastics Packaging Recycling (A Myth or Reality?), 1990 Polymers, Laminations & Coatings Conference Proceedings