No description available.

When faced with challenging technical problems, R&D personnel would often turn to technical papers to seek inspiration for a solution. The building of a corpus of such papers and the easy retrieval of relevant papers by the user in his query is an area that has not been systematically dealt with. This is an attempt to build such a corpus for manufacturing R&D personnel. Manufacturing Corpus Version 1 (MCV1) is an archive of more than 1400 relevant manufacturing engineering papers between 1998 and 2000. In this paper, the origins and motivation of building MCV1 is discussed. The innovative coding process which is specially designed for manufacturing companies will be presented. All other relevant issues, like coding policy, category codes and input documents, will be explained. Finally, two quality indicators which integrate all concerns about coding quality will be examined. / Singapore-MIT Alliance (SMA)

Studies on strength delivery and related fields have so far concentrated on finding the locations in the mill where fibres are damaged and what the damages consist of. However, fibres will invariably encounter mechanical stresses along the fibreline and in this thesis a new concept is introduced; the vulnerability of fibres to mechanical treatment. It is hypothesised that fibres with different properties have different abilities to withstand the mechanical forces they endure as they are discharged from the digester and transported through valves, pumps and various washing and bleaching equipment. In the thesis, results are presented from trials where pulps with significantly different hemicellulose compositions were high-intensity mixed at pH 13, 70°C and 10% pulp consistency and pulp strength evaluated. By varying alkalinity and temperature, pulps with different carbohydrate composition could be obtained. High alkali concentration and low temperature resulted in high glucomannan content and low xylan content, whereas cooking at low alkali concentration and high temperature rendered a pulp with low glucomannan and high xylan content. The high alkalinity pulp was stronger, determined as tear index at given tensile index. The pulp viscosity was also higher for this pulp. However, when the pulps were subjected to high-intensity mixing, the high alkalinity pulp lost in tear strength and the re-wetted zero-span tensile strength was substantially reduced. The pulp cooked at high alkalinity was thus interpreted as being more vulnerable to mechanical treatment than the pulp obtained by cooking at low alkalinity. Another pair of pulps was manufactured at high and low sodium ion concentrations, but otherwise with similar chemical charges. The pulp obtained by cooking at low sodium ion concentration became stronger, evaluated as tear index at a given tensile index and the curl index was substantially lower, 8% compared to 12% for the pulp cooked at a high sodium ion concentration. The viscosity was 170 ml/g higher for the pulp manufactured at low sodium ion concentration. When the pulps were subjected to high-intensity mixing, the tear strength of the pulp manufactured at high sodium ion concentration was reduced. The re-wetted zero-span tensile index decreased also after mixing. The pulp obtained by cooking at higher sodium ion concentration was thus interpreted as being more vulnerable to mechanical treatment than the pulp manufactured at lower sodium ion concentration. In the thesis, two reasons for the low strength delivery of industrially produced pulps compared to laboratory-cooked pulps are put forward. Since the ionic strength of mill cooking liquor systems is much higher than is normally used in laboratory cooking, this can partly explain the difference in strength between mill- and laboratory-cooked pulp. A higher sodium ion concentration was shown in this thesis work to give a pulp of lower strength. Secondly, it is suggested that the difference in retention time of the black liquor in laboratory cooking and continuous mill cooking systems can explain the difference in tensile strength between laboratory-cooked and mill-produced pulp. The black liquor in a continuous digester has a longer retention time in the digester than the chips. This gives a longer time for the dissolved xylan to degrade and, as a consequence, the xylan deposited on the mill pulp fibres will be more degraded than the xylan deposited on the laboratory-cooked pulp fibres. In the thesis, results are also presented from studies using different strength-enhancing chemicals. The fibre surfaces of bleached never-dried and once-dried pulp were modified by the polyelectrolyte multilayer technique using cationic and anionic starch. Although the pulps absorbed the same amount of starch, the never-dried pulp reached a higher tensile index than the once-dried pulp. When the starch-treated never-dried pulp was dried and reslushed it still had higher tensile index than the never-dried untreated pulp. The starch layers were thus able to counteract part of the hornification effect. The never-dried starch treated pulps were subsequently dried, reslushed and beaten. Pulp with starch layers had a better beatability evaluated as the tensile index obtained after given number of PFI revolutions than dried untreated pulp. Hence, there is a potential to increase the tensile index of market pulp by utilising the polyelectrolyte multilayer technique before drying. Addition of CMC to bleached mill pulp and laboratory-cooked pulp increased the tensile strength to the same degree for both pulps. CMC addition had a straightening effect on the fibres, the shape factor increased and this increased the zero-span tensile strength also. / QC 20100519

Wood fibres is a type of natural fibres suitable for composite applications. The abundance of wood in Swedish forests makes wood-fibre composites a new and interesting application for the Swedish pulp and paper industry. For large scale production of composites reinforced by wood fibres to be realized, the mechanical properties of the materials have to be optimized. Furthermore, the negative effects of moisture, such as softening, creep and degradation, have to be limited. A better understanding of how design parameters such as choice of fibres and matrix material, fibre modifications and fibre orientation distribution affect the properties of the resulting composite material would help the development of wood-fibre composites. In this thesis, focus has been on the fibre-matrix interface, wood-fibre hygroexpansion and resulting mechanical properties of the composite. The importance of an efficient fibre-matrix interface for composite properties is well known, but the determination of interface properties in wood-fibre composites is difficult due to the miniscule dimensions of the fibres. This is a problem also when hygroexpansion of wood fibres is investigated. Instead of tedious single-fibre tests, more straightforward, macroscopic approaches are suggested. Halpin-Tsai’s micromechanical models and laminate analogy were used to attain efficient interface characteristics of a wood-fibre composite. When Halpin-Tsai’s model was replaced by Hashin’s concentric cylinder assembly model, a value of an interface parameter could be derived from dynamic mechanical analysis. A micromechanical model developed by Hashin was used also to identify the coefficient of hygroexpansion of wood fibres. Measurements of thickness swelling of wood-fibre composites were performed. Back-calculation through laminate analogy and the micromechanical model made it possible to estimate the wood-fibre coefficient of hygroexpansion. Through these back-calculation procedures, information of fibre and interface properties can be gained for ranking of e.g. fibre types and modifications. Dynamic FT-IR (Fourier Transform Infrared) spectroscopy was investigated as a tool for interface characterization at the molecular level. The effects of relative humidity in the test chamber on the IR spectra were studied. The elastic response of the matrix material increased relative to the motion of the reinforcing cellulose backbone. This could be understood as a stress transfer from fibres to matrix when moisture was introduced to the system, e.g. as a consequence of reduced interface efficiency in the moist environment. The method is still qualitative and further development is potentially very useful to measure stress redistribution on the molecular level. / QC20100714

The chemical interactions between the main wood components i.e., cellulose, hemicelluloses and lignin are of fundamental importance for understanding the chemical aspects of wood formation and its reactivity during fibre processing e.g during chemical pulping of wood. Future progress in the development of new high value products from wood will greatly depend on a detailed knowledge of how the fibre elements interact with each other in the biological material. The existence of covalent bonds between lignin and carbohydrates (LCC) has been one of the most controversial issues in the field of wood chemistry. Only until recently, the existence of such bonds has in its entirety been shown by way of indirect analyses, normally suffering from low yields obtained at rather drastic conditions. Furthermore, previous studies on LCC have been targeted on studying the specific lignin carbohydrate linkage and less emphasis has been put on the whole LCC networks. Detailed structural studies of entire LCC are therefore of importance in understanding the chemistry involved in wood formation and wood reactivity. The aim of this study was to isolate intact LCC from wood and corresponding chemical pulps made from it in quantitative yield and to clarify their detailed chemical structure. For the first time, a method for the quantitative analysis of lignin-carbohydrate complexes (LCCs) in softwood is presented and it could be concluded that no carbohydrate-free lignin was present in these wood fibres. From mildly ball-milled wood, all lignin was isolated as LCCs in a sequence involving a partial enzymatic hydrolysis of cellulose, subsequent swelling and quantitative dissolution, into 4 major fractions; a galactoglucomannan-lignin-pectin LCC (GalGlcMan-L-P) containing ~8% of the wood lignin, a glucane LCC (Glc-L) containing ~4% of the wood lignin, a xylan-lignin-glucomannan network LCC (Xyl-L-GlcMan) (with a predominance of xylan over glucomannan) containing ~40% of the wood and a glucomannan-lignin-xylan network LCC (GlcMan-L-Xyl) (with a predominance of glucomannan over xylan) containing ~48% of the wood lignin. From unbleached kraft pulps, 85 - 90% of residual lignin was found to be chemically bonded to carbohydrates. The effect of the degree of delignification on the LCC types during kraft pulping and during subsequent oxygen stage was studied in order to understand the role of LCC for the stability of residual lignin. For both processes, high delignification rates were observed for the xylan-rich LCC and cellulose-rich LCC fractions, whereas the glucomannan-rich LCC was relatively stable. After a severe oxygen stage, almost all the residual lignin was isolated in the latter complex. Thioacidolysis in combination with gas chromatography was used to determine the content of β-O-4 structures in the lignin. Periodate oxidation and methanol determinations were used to quantify the phenolic hydroxyl groups, whereas size exclusion chromatography (SEC) of the thioacidolysis fractions was used to monitor any differences between the original molecular size distribution and that after the delignification processes. Major differences between the various LCC fractions were observed, clearly indicating that two different forms of lignin are present in the wood fibre wall. These forms are linked to glucomannan and xylan respectively. The xylan linked lignin was found to consist largely of β-O-4 structures indicating a rather linear coupling mode, whereas the glucomannan linked lignin was more heterogeneous with respect to the known lignin inter-unit linkage types. Based on these findings, a modified arrangement of the fibre wall polymers is suggested. From acid sulfite pulp (Kappa number 11) residual lignin was isolated at ~80% yield on LCC basis. About 60% was linked to xylan, 30% to glucomannan and 10% to glucans. These values differ greatly from those obtained for softwood pulped to a similar kappa number by the Kraft method. Model compound studies indicated that the benzyl ether type of LC linkage were likely to survive cleavage at the acidic sulfite pulping conditions / QC 20101026

No description available.

<i>In the Stillness of Your Presence</i> is an installation that explores how embodiment can function in creating meditative states and how non-cognitive powers of knowing might lead to a sort of consciousness of a different order. This work brings together poetic contemplation, sensorial knowledge and visuality.

No description available.

No description available.

No description available.