| 1. |
- Fernando, Dinesh, et al.
(författare)
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Subproject 2: Effect of using low-energy segments for producing TMP pulps at Braviken
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The effects of pressurized compressive chip and low dosage sulphite pretreatments were evaluated for production of thermomechanical pulp in mill scale trials using Norway spruce (Picea abies) at the Braviken paper mill (Holmen Paper AB, Sweden). The aim of the study was to provide knowledge leading to the improvement of energy efficiency during the production of mechanical pulps suitable for news and improved new grade papers. Pulps produced in the mill trials were characterized using conventional pulp and paper testing and by advanced methods including image analysis, FTIR with multivariate analysis, Simons staining with statistical analysis, spectral imaging and HCL fibre cleavage. Sulphite pre-treatment gave a linear dose response in tensile index and light scattering with addition of sulphite (≥ 1.2% Na2SO3). The maximum in tensile index and light scattering at a sulphur content of 0.2% (as Na2SO3) reported previously was not found in this mill study. Low dosage sulphite pre-treatment increased delamination/internal fibrillation of fibres indicating increased fibre flexibility. These fibres produced denser sheets with higher tensile index and slightly reduced light scattering at certain specific energy consumption. The specific energy consumption needed to produce pulp at a certain tensile index was reduced by 320 kWh/BDT (15%) for chips pre-treated with ~1.2% Na2SO3 compared with untreated chips. This gave a reduction in light scattering for sulphite pre-treated pulps when compared at equal tensile index. Image analysis of fibre cross-sections provided information of the composition of the total fibre population, fibre cross-sectional compactness as well as effects of sulphite treatment. Results showed a fairly constant fibre population (40% early-/60% latewood) existing in all samples and for higher energy to cause greater fibre splitting of untreated fibres particularly of latewood fibres. Increasing the amount of sulphite reduced fibre splitting with less severe fibre delamination for pulps refined at 1820 and 1850 KWh/ADT. Sulphite treatment seemed in general to induce more refining of early- than latewood fibres. SEM observation on fibres revealed high degree of deformation along the fibre axis that could also be seen on the fibre crosssections analyzed. FTIR analyses indicated that the highest degree of sulphonation (10 kg/BDT) gave rise to different fibre separation mechanisms during refining compared with the reference unsulphonated pulps providing a different fibre surface and thereby mechanical properties. Multivariate analysis of FTIR spectra suggested the exposed fibre surface to be richer in hemicellulose for sulphonated pulped fibres. This could provide for a better binding surface and higher strength for paper. However, no clear pattern of differences in the distribution images and therefore the microdistribution of xylan were determined. Statistical analysis of the Simons´ staining of fibres indicated that both the energy input and chip pre-treatment significantly induced wall delamination and internal fibrillation (D/IF) of pulp fibres. It was shown that the fibre development of pulp 10(1580) (with lowest SEC) gained via improved wall D/IF was almost similar to that shown for pulp 00(1850) (with highest SEC). This indicates that an energy efficient refining can be obtained with 10 kg/BDT sulfite pre-treatment prior to refining and will produce the most flexible fibres. Spectral imaging showed sulphite treatment of impressarefiner chips to improve the optical properties of pulps with a clear dose-response shown at both higher and lower SEC levels, the former having the largest effect on whiteness. Photochemical effects of sulfonation using reflectance intensities showed complex results regarding lignocellulosic autofluorescence. Unlike wood, impressarefiner chips and pulp fibres showed a clear blue-shifted fluorescence maximum characteristic for a shortened conjugated system indicating that both the chipping and Impressafiner pretreatment induced a minor degradation of the lignocellulosic matrix that can be measured using spectral imaging. Refining however, increased the red edge fluorescence of the sulfonated whole long fibre fraction with a similar effect on the lignin fluorescence of wood. Using the HCL method of fibre analysis no significant trend for the effect of sulphite treatment was noted and only minor differences in fibre length were detected.
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| 2. |
- Ander, Paul, et al.
(författare)
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ASPECTS ON BLEACHING AND TEMPO-MEDIATED OXIDATION OF WHEAT STRAW PULP FRACTIONS
- 2012
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Ingår i: Bioresources. - 1930-2126. ; 7, s. 3051-3063
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Tidskriftsartikel (refereegranskat)abstract
- This study outlines research concerning wheat straw fines, including their impact on pulp bleachability, their modification by chemical means, and their use as a dry strength enhancer in a paper application. Results show that primary fines constituting about 23% of the whole wheat straw pulp had a large negative impact on pulp bleachability. The differences in response to bleaching were due to the different properties of the fines, i.e. higher kappa number, higher metal ion content, lower brightness, and lower viscosity compared to that of fibers. It was also shown that the fines fraction is more difficult to oxidize and does not reach as high fiber charge levels as that of the other fractions. However, at a dosage of >= 3 mmol hypochlorite/g it was possible to prepare nanofibers from wheat straw fines that showed a good strength-enhancing effect in a paper product. The fact that removal of fines from wheat straw pulps by fractionation improves bleachability and also drainage properties at the same time, while simultaneously the fines can be modified and used as a strength enhancer, is very interesting when evaluating the potential of this type of annual plant as a source for production of different paper products.
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| 3. |
- Ander, Paul, et al.
(författare)
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CRUW Mechanical Pulping sub-project 1: Effect of different refining pressures and energy using spruce TMP pulps from Braviken
- 2010
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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
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| 4. |
- Ander, Paul, et al.
(författare)
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Differences between Scots pine and Norway spruce TMP pulps as revealed bt the HCL method
- 2009
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Ingår i: SPCI meddelande / The Swedish Association of Pulp and Paper Engineers. - 0280-6800. ; , s. 322-324
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Konferensbidrag (refereegranskat)abstract
- The HCl method was used to compare pine and spruce TMP pulps. Delignification gave much stronger fibre cleavage by HCl (3.5-5x for Stage 3) indicating that lignin and hemicelluloses protect the fibres from acid attack. Cleavage per fibre for TMP was similar as kraft pulps, while spruce TMP was more sensitive to HCl than pine TMP. A more robust secondary wall and a lower number of dislocations and weak points may be related to the higher refining energy needed for pine TMP pulps
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| 5. |
- Ander, Paul, et al.
(författare)
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Sub-project 10: CRUW Mechanical Pulping Enzyme treatment of chips for energy reduction in TMP
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to evaluate the possibilities of using enzymes for pre-treating softwood chips as a means of lowering the energy demand in mechanical pulping, impregnation and refining trials were performed using a set of different enzymes. The enzymes tested pectinase, xylanase and mannanase gave increased sugar release in the impregnation trials indicating that most of the sugar released occurred in the first 60 minutes and that activities thereafter seemed to level off. Refining trials using a small Wing refiner showed that for chips treated for 60 minutes with pectinase, xylanase and mannanase no energy savings to a given freeness level was observed. The property development was similar to that of reference pulps in the case of pectinase and xylanase while for chips treated with mannanase a less favourable development of the tensile index was noted. For chips treated for two hours, using xylanase or pectinase, energy savings could be observed for pectinase treated chips down to a freeness level of 200 CSF. However when refined further, the properties approached those of the reference pulp. Considering the much higher enzymatic activity reached when the initial fibre material was further disintegrated it is assumed that the possibilities for enzymes to attack desired structures of the intact fibre wall may have been too few even in the case of Impressafiner treated material.
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| 6. |
- Bari, Ehsan, et al.
(författare)
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Fungal behavior and recent developments in biopulping technology
- 2024
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Nature. - 0959-3993 .- 1573-0972. ; 40:7
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Tidskriftsartikel (refereegranskat)abstract
- Biological pretreatment of wood chips by fungi is a well-known approach prior to mechanical- or chemical pulp production. For this biological approach, a limited number of white-rot fungi with an ability to colonize and selectively degrade lignin are used to pretreat wood chips allowing the remaining cellulose to be processed for further applications. Biopulping is an environmentally friendly technology that can reduce the energy consumption of traditional pulping processes. Fungal pretreatment also reduces the pitch content in the wood chips and improves the pulp quality in terms of brightness, strength, and bleachability. The bleached biopulps are easier to refine compared to pulps produced by conventional methodology. In the last decades, biopulping has been scaled up with pilot trials towards industrial level, with optimization of several intermediate steps and improvement of economic feasibility. Nevertheless, fundamental knowledge on the biochemical mechanisms involved in biopulping is still lacking. Overall, biopulping technology has advanced rapidly during recent decades and pilot mill trials have been implemented. The use of fungi as pretreatment for pulp production is in line with modern circular economy strategies and can be implemented in existing production plants. In this review, we discuss some recent advances in biopulping technology, which can improve mechanical-, chemical-, and organosolv pulping processes along with their mechanisms.
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| 7. |
- Breijaert, T. C., et al.
(författare)
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Self-assembly of ferria – nanocellulose composite fibres
- 2022
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Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 291
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Tidskriftsartikel (refereegranskat)abstract
- An environmentally benign synthesis of a magnetically responsive carboxymethylated cellulose nanofibril-based material is reported. Applied experimental conditions lead to the in-situ formation of magnetite nanoparticles with primary particle sizes of 2.0–4.0 nm or secondary particles of 3.6–16.4 nm depending on whether nucleation occurred between individual carboxymethylated cellulose nanofibrils, or on exposed fibril surfaces. The increase in magnetite particle size on the cellulose fibril surfaces was attributed to Ostwald ripening, while the small particles formed within the carboxymethyl cellulose aggregates were presumably due to steric interactions. The magnetite nanoparticles were capable of coordinating to carboxymethylated cellulose nanofibrils to form large “fibre-like” assemblies. The confinement of small particles within aggregates of reductive cellulose molecules was most likely responsible for excellent conservation of magnetic characteristics on storage of this material. The possibility for using the material in drug delivery applications with release rate controlled by daylight illumination is presented. © 2022 The Author(s)
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| 8. |
- Cai, Shengzhen, et al.
(författare)
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Mechanical properties and decay resistance of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate-epoxidized linseed oil copolymer
- 2016
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 70, s. 885-894
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Tidskriftsartikel (refereegranskat)abstract
- Equilibrium moisture content (EMC), mechanical properties, and durability of Scots pine (Pinus sylvestris L.) sapwood modified by vinyl acetate epoxidized linseed oil (WVA-ELO) have been studied. Microscopic observations revealed that the impregnated copolymer is mainly in cell walls, rays, resin canals, and a small fraction in the cell lumens. Under the same climate conditioning, the EMC of the treated wood was in the range of 6.0%-8.2%, which was significantly lower than that of untreated wood (about 12%). Mechanical tests performed on paired samples (control and treated) showed a slight reduction on the mechanical properties of WVA-ELO. The decay resistance against basidiomycete fungi of WVA-ELO was significantly improved as demonstrated by laboratory tests. It was found that 8% weight percentage gain (WPG) was sufficient to ensure decay resistance against the test fungi with <5% mass loss (ML), which led to durability class (DC) of 2.
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| 9. |
- Cleary, Michelle, et al.
(författare)
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Genotypes of Fraxinus excelsior with different susceptibility to the ash dieback pathogen Hymenoscyphus pseudoalbidus and their response to the phytotoxin viridiol - A metabolomic and microscopic study
- 2014
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 102, s. 115-125
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Tidskriftsartikel (refereegranskat)abstract
- Eight European ash (Fraxinus excelsior) genotypes with different known susceptibility to Hymenoscyphus pseudoalbidus were tested against the phytotoxin viridiol and their response described at the microscopic and metabolomic level. All ash genotypes were sensitive to the toxin and necrosis was detectable after 24 h. Among the three viridiol concentrations used in the experiment, the lowest concentration (14.7 mu M) yielded markedly lower mean damage scores compared to those resulting from seedlings tested at higher dosages. The highest damage scores were associated with the susceptible ash clones S-101, S-106 and S-125, but also with resistant clone R-104. Three resistant clones (R-131, R-121, and R-118) had lower mean damage scores compared to susceptible clones. Wilting of leaves was more common 48 h after treatment and more pronounced on seedlings with high damage scores. The resulting lesions generally lacked browning of tissue and displayed only surface disruption of cells in direct contact with the toxin. A delay in symptom development was evident on all five resistant clones tested with the two higher concentrations of viridiol. LC-HRMS and MS/MS analyses of ash seedling extracts suggest several secoiridoid compounds as well as compounds related to abscisic acid (ABA) to be produced in response to viridiol. ABA-cysteine and xanthoxin were found at significantly higher concentrations in susceptible clones compared to resistant clones after treatment with viridiol, suggesting a primary role of ABA in response to stress. The results observed in this study suggest that genetic resistance to H. pseudoalbidus among ash genotypes may be explained, in part, by the varied response to phytotoxins produced by the fungus. (C) 2014 Elsevier Ltd. All rights reserved.
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| 10. |
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