| 1. |
- Ander, Paul, et al.
(författare)
-
CRUW Mechanical Pulping sub-project 1: Effect of different refining pressures and energy using spruce TMP pulps from Braviken
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The mechanical pulping industry faces continued rising energy costs and increasing competition for raw material. In order to produce improved products based on mechanical pulp at lower energy consumption it is necessary to have a better understanding of the development of fundamental fibre properties during the processes. In particular, changes in fibre collapsibility, fibre fibrillation and fibre and surface development are of great interest. The overall goal of the CRUW Mechanical Pulping project is “Support development of more energy efficient mechanical pulping processes by increasing the knowledge on ultrastructural phenomena in mechanical pulping”. This project is working closely together with the Industrial Research College for Mechanical Pulping Technology bringing in the ultrastructural competence to more clearly understand and explain phenomena observed in these projects thus making it easier to develop new and improved processes to reduce energy consumption. This report presents results from CRUW Mechanical Pulping sub-project 1: ”Effect of different refining pressures and energy using spruce TMP pulps from Braviken”. The influence of temperature on the softening of lignin and hence improved (easier) fibre separation and treatment was noted earlier (Becker et al. 1977; Salmén 1984). Based on this knowledge, different process alternatives have been suggested to reduce energy demand for the refining process. One of the earliest publications on a technical system utilizing higher temperature and pressure was by Höglund et al. 1997 (Thermopulp). These results have been reproduced in many studies and are today considered general knowledge. There are however many practical problems with such a system. For example, the resulting very small refining gaps are difficult to control and it has therefore taken time to establish this technology in the industry. In the new TMP line at Braviken, the refiners are equipped to run at higher temperature/pressure than normal and it has therefore been interesting to study these pulps in order to explain the effects on pulp/fibres at an ultrastructural level. It should be noted that in a fibre-water-steam system, temperature and pressure are not independent variables and higher pressure means higher temperature and vice versa
|
|
| 2. |
- Cordova, Armando, 1970-, et al.
(författare)
-
Heterogeneous Thiol-ene Click Modifications Of Solid Polysaccharide-based Materials
- 2016
-
Patent (populärvet., debatt m.m.)abstract
- This invention concerns the first environmentally benign heterogeneous modification of polysaccharide-based material in native solid state by thiol-ene “click chemistry”. The direct reaction of a thiol with an un-activated double or triple bond by thiol-ene and thiol-enyne click modification is thermally or photochemically catalyzed and is completely metal-free and allows for a highly modular approach to modifications of fibers and fiber-based materials.
|
|
| 3. |
- Daniel, Geoffrey, et al.
(författare)
-
Energy consumption in refining of Scots pine and Norway spruce TMP is governed by fibre morphology and ultrastructure
- 2009
-
Ingår i: SPCI meddelande / The Swedish Association of Pulp and Paper Engineers. - 0280-6800. ; , s. 82-86
-
Konferensbidrag (refereegranskat)abstract
- Studies on the different behaviour of Scots pine and Norway spruce during thermomechanical pulping were conducted to find reasons for explaining the greater energy consumption of pine. Well characterized wood samples from clear-cut trees and thinnings were used in pilot scale trials to produce highly characterized pulps. Structural and topochemical differences found between pine and spruce likely to have a strong negative impact on energy included: i) presence of a greater proportion of latewood fibres in pine annual rings with thick secondary cell walls and concomitant reduced fibre collapsibility; ii) ultrastructural differences in the location of fractures at the fibre secondary wall level during primary refining with pine showing greater resistance to refining although it defibrated easier than spruce; iii) that fibre separation and fibre development were sequential processes in pine and not concurrent as in spruce; and iv) the greater amounts of extractives in pine and their redistribution onto the surfaces of fibres and fines during processing
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Hafrén, Jonas, et al.
(författare)
-
Fiber- and fine fractions-derived effects on pulp quality as a result of mechanical pulp refining consistency
- 2014
-
Ingår i: Wood Science and Technology. - : Springer Science and Business Media LLC. - 0043-7719 .- 1432-5225. ; 48, s. 737-753
-
Tidskriftsartikel (refereegranskat)abstract
- High-yield pulping of wood chips using low-consistency (LC) refining in combination with primary-stage high-consistency (HC) refining has previously been shown to produce paper with quality parameters (tensile strength and light-scattering coefficient) commonly targeted for newsprint with significantly less refining energy input than using only HC refining. However, questions remain on the differences in the refining action between the two refiner types and for high-yield pulping, the refiner energy demand is a crucial process parameter. Therefore, fines- and fiber-fraction development in HC and LC refining has been studied in detail using Bauer-McNett fractionation, and the respective tensile strengths of the different fractions have been compared. Quantitative and qualitative (morphological) characteristics of the isolated fine fractions have also been analyzed in detail using a newly developed automated fluorescence microscopy method and scanning electron microscopy. The results suggest the difference in LC/HC pulp properties (strength and optical) is partly derived from deviating fiber and fines morphologies and mass balances. The quality of the fines generated during HC and LC refining also differs. LC-refined pulps contain thinner fibrillar fines (thread-like) and HC-refined pulps broader fibrils such as lamellae-type fines. Flake-like fines from the outer fiber wall decreased in relative amount with energy input.
|
|
| 10. |
|
|
