| 1. |
- Athley, Karin, et al.
(författare)
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Mechanical retention - Influence of filler floc size and grammage of the fibre web
- 2012
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:2, s. 202-207
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Tidskriftsartikel (refereegranskat)abstract
- An investigation of the impact of particle size on the mechanical retention of particles in a fibre network has been conducted. The particles used were five sets of quartz particle fractions having fairly narrow particle size distributions with average particle size ranging from a few μm to around 100 μm. The particles were used to model flocculated filler aggregates as part of a larger study of the effect of pre-flocculation on mechanical retention. Pre-flocculation of the filler is a possible strategy to increase the filler content of paper without deterioration of strength properties. A modified laboratory hand sheet former, known as the Rapid Drainage Device (RDD) was used. The major modification consisted of a long pipe that acted as a suction leg, which provides a dewatering vacuum at the same level as on a paper machine. The experimental results showed that mechanical filler retention increased linearly with particle size and grammage of the fibre layer above a critical grammage which depended on particle size. The linear relation was also seen in a pilot scale trial on the FEX pilot-paper machine at Innventia. During this trial fine paper was produced using pre-flocculated filler where the mean particle size of the flocs and fibres was measured in the flow to the headbox. The results from this pilot trial show that mechanical retention is an important part of the total filler retention. Drainage time and therefore drainage resistance increased with the grammage of the fibre layer and amount of quartz particle added. Drainage time, compared at total grammage (i.e. the sum of fibre and quartz particle grammage) was lowest for a fraction of medium-sized particles, with a median size of 35 μm. There was no obvious effect on retention or drainage resistance of a change in the dewatering pressure from 27.5 to 41.5 kPa.
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| 2. |
- Athley, Karin, et al.
(författare)
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Optimizing the benefit of retention chemicals
- 2014
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Konferensbidrag (refereegranskat)abstract
- Pre-flocculation of filler has been tested as a concept for improving the retention of filler and the strength properties of the sheet. The impact of the size of the filler floes on the mechanical retentionin a fibre network was investigated using a modified laboratory hand sheet former. The mechanical retention was found to increase linearly with both particle size and grammage of the fibre web. These results were confirmed in a full scale production trial on the FEX pilot paper machine at Innventia. Here different filler floe sizes were created through different chemical pre-flocculation strategies. The particle size in the flow to the headbox was measured with FBRM, and a linear relation between particle size and filler retention was found. Corresponding linear relation was seen in a pilot trial when adding filler and retention aid conventionally. This implies that mechanical retention constitute an important part of the filler retention not only upon pre-flocculation but also with conventional addition of filler and retention aid. Thus, the particle size before the headbox can be a good indicator of the retention level. For the conventional application of a two component retention aid system, the increased filler retention correlated to impaired formation and decreased sheet strength. On the contrary, pre-flocculation led to an increase in both sheet strength and filler retention, demonstrating the advantage of pre-flocculating filler.
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| 3. |
- Han, Shaobo, et al.
(författare)
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A Multiparameter Pressure–Temperature–Humidity Sensor Based on Mixed Ionic–Electronic Cellulose Aerogels
- 2019
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Ingår i: Advanced Science. - : Wiley. - 2198-3844.
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Tidskriftsartikel (refereegranskat)abstract
- Pressure (P), temperature (T), and humidity (H) are physical key parameters of great relevance for various applications such as in distributed diagnostics, robotics, electronic skins, functional clothing, and many other Internet-of-Things (IoT) solutions. Previous studies on monitoring and recording these three parameters have focused on the integration of three individual single-parameter sensors into an electronic circuit, also comprising dedicated sense amplifiers, signal processing, and communication interfaces. To limit complexity in, e.g., multifunctional IoT systems, and thus reducing the manufacturing costs of such sensing/communication outposts, it is desirable to achieve one single-sensor device that simultaneously or consecutively measures P–T–H without cross-talks in the sensing functionality. Herein, a novel organic mixed ion–electron conducting aerogel is reported, which can sense P–T–H with minimal cross-talk between the measured parameters. The exclusive read-out of the three individual parameters is performed electronically in one single device configuration and is enabled by the use of a novel strategy that combines electronic and ionic Seebeck effect along with mixed ion–electron conduction in an elastic aerogel. The findings promise for multipurpose IoT technology with reduced complexity and production costs, features that are highly anticipated in distributed diagnostics, monitoring, safety, and security applications. © 2019 The Authors.
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| 4. |
- Thorman, Sofia, et al.
(författare)
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Dynamic out-of-plane compression of paperboard — Influence of impact velocity on the surface
- 2024
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Ingår i: TAPPI Journal. - : Technical Assoc. of the Pulp and Paper Industry Press. - 0734-1415. ; 2024-February, s. 113-122
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Tidskriftsartikel (refereegranskat)abstract
- Processes that convert paperboard into finished products include, for example, printing, where the paperboard is subjected to rapid Z-directional (ZD) compression in the print nip. However, measuring and evaluating the relevant properties in the thickness direction of paperboard are not necessarily straightforward or easy. Measuring at relevant, millisecond deformation rates further complicates the problem. The aim of the present work is to elucidate some of the influences on the compressive stiffness. Both the initial material response and the overall compressibility of the paperboard is studied. In this project, the effect on the material response from the surface structure and the millisecond timescale recovery is explored. The method utilized is a machine called the Rapid ZD-tester. The device drops a probe in freefall on the substrate and records the probe position, thus acquiring the deformation of the substrate. The probe is also allowed to bounce several times on the surface for consecutive impacts before being lifted for the next drop. To investigate the time dependent stiffness behavior, the probe is dropped several times at the same XY position on the paperboard from different heights, thus achieving different impact velocities. The material response from drops and bounces combined allows study of the short-term recovery of the material. The material in the study is commercial paperboard. The paperboard samples are compared to material where the surface has been smoothed by grinding it. Our study shows that there is a non-permanent reduction in thickness and a stiffening per bounce of the probe, indicating a compaction that has not recovered in the millisecond timescale. Additionally, a higher impact velocity has an initial stiffening effect on the paperboard, and this is reduced by smoothing the surface.
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| 5. |
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| 6. |
- Thorman, Sofia, et al.
(författare)
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Rapid, Out-Of-Plane Compression of Paperboard – Influence of Impact Velocity on The Surface
- 2023
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Ingår i: <em>TAPPICon 2023 - "Rock the Roll: Unleashing the Harmonies of the Paper Industry"</em>. - : TAPPI Press.
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Konferensbidrag (refereegranskat)abstract
- Industry processes, such as printing, subjects paperboard to rapid, Z-directional compression. However, measuring and evaluating the relevant properties in the thickness direction are not necessarily straight forward or easy. Measuring at relevant, millisecond, deformation rates complicate the problem further. The aim of the present work is to elucidate on some of the influences on the compressive stiffness. Both the initial material response and the overall compressibility of the paperboard is studied. In this project the effect on the material response from the surface structure and the millisecond time-scale recovery is explored. The method utilized is a machine called the Rapid ZD-tester. The device drops a probe in free fall on the substrate and records the probe-position, thus acquiring the deformation of the substrate. To investigate the time dependent stiffness behavior the probe is dropped several times at the same xy-position on the paperboard from different heights, thus achieving different impact velocities. The probe is also allowed to bounce several times on the surface before lifted for consecutive drops. The drop-bounce cycle allows study of the short-term recovery of the material. The material in the study is commercial paperboard. The paperboard samples are compared to material where the surface has been smoothed by grinding it. Our study shows that there is a non-permanent reduction in thickness and a stiffening per bounce of the probe, indicating a compaction that has not recovered in the millisecond timescale. Additionally, a higher impact velocity has an initial stiffening effect on the paperboards, and that this is reduced by smoothing the surface.
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