<p>Transverse anisotropy is an important phenomenon of practical and scientific interest. Although the presence of ray tissue explains the high radial modulus in many hardwoods, experimental data in the literature shows that this is not the case for pine. It is possible that anisotropy in softwoods may be explained by the cellular structure and associated deformation mechanisms.</p><p>An experimental approach was developed by which local radial modulus in spruce was determined at sub-annual ring scale. Digital speckle photography (DSP) was used, and the density distribution was carefully characterized using x-ray densitometry and the SilviScan apparatus. A unique set of data was generated for radial modulus versus a wide range of densities. This was possible since earlywood density shows large density variations in spruce. Qualitative comparison was made between data and predictions from stretching and bending honeycomb models. The hypothesis for presence of cell wall stretching was supported by data.</p><p>A model for wood was therefore developed where both cell wall bending and stretching are included. The purpose was a model for predictions of softwood moduli over a wide range of densities. The relative importance of the deformation mechanisms was investigated in a parametric study. A two-phase model was developed and radial and tangential moduli were predicted. Comparison with experimental data showed good agreement considering the nature of the model (density is the only input parameter). Agreement is much better than for a regular honeycomb model. According to the model, cell wall bending dominates at both low and high densities during tangential loading. In radial loading, cell wall stretching dominates at higher densities.</p>

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 122-130).

Lignin is one of the most common biopolymers in the world. Together with cellulose andhemicellulose it constitutes the fibers in the wood. It has a high molecular weight due to its complexstructure consisting of crossed-linked phenolic monomers and is concatenated with different types ofcarbon and ether bonds.In pulping processes, lignin is extracted in large quantities and used on site to produce energy for milloperations but is also removed as a waste product. This enables a product with high resources andaccessibility due to lignin's diverse properties. Therefore, lignin has the potential to be utilized inhigher value applications such as polymer materials, as well as a source of platform chemicals. Atpresent, the value applications of lignin are promising as additives for different kinds of productssuch as emulsifiers and especially as biofuel due to lignin's high carbon content.New technologies for development for utilization lignin are emerging for different kinds ofapplications due to lignin’s biocompatibility. The possibilities of lignin combined with existingresearch of nanotechnology gives opportunities to improve biomedical applications. By designinglignin derived nanoparticles with incorporated magnetic materials, the NPs obtainsuperparamagnetic properties which can be utilized for target drug delivery. This could be promisingagainst intractable cancer such as pancreatic cancer.This report presents a protocol for developing magnetic lignin nanoparticles from the lowestmolecular weight kraft lignin fractions of eucalyptus (hardwood) and spruce (softwood). By a methodof self-assembly, particles with a doughnut and core-shell morphology, as indicated by SEM and TEM,were yielded with a 10-50μL content of water-stabilized magnetite. The particle size distribution andzeta potential were determined by DLS and the possibility of the particles being suitable forbiomedical applications was discussed.

Lignin is one of the main components in wood and during the chemical pulping processes it is degraded and dissolved into the cooking liquor. The current challenge is to meet the need for energy and raw materials, and reform to a more environmentally sustainable society, so there is a great interest in using kraft lignin as a raw material for energy, materials and as source of chemicals. ) To meet this goal, it is essential to obtain kraft lignin with desirable properties. The overall goal of this master thesis project was to understand the relationship between kraft process conditions and the structure and properties of the dissolved lignin. Wood chips of pine, spruce and eucalyptus were pulped with the kraft process at constant temperature and similar alkali charge and sulphidity to different cooking times. From the collected black liquor, the dissolved kraft lignin was precipitated by acidification with sulphuric acid. It was observed that longer cooking time yields more precipitated material, where pine gave the highest yield. There was a significant difference in colour of the precipitated between eucalyptus and the softwood samples. Some the characteristic properties of the collected samples were investigated. Results from the Klason lignin and ionic chromatography showed variation in lignin and carbohydrate composition depending on raw material and cooking time. This was also indicated by results lignin carbohydrate ratio from analytical pyrolysis. However, the analytical pyrolysis data showed that the relative composition of lignin and carbohydrates was similar independent on pulping time and raw material. The sulphur content was higher for eucalyptus lignin compared to the softwood lignin. Pine lignin with the longest pulping time had the highest total phenolic content. Spruce lignin with the longest cooking time had the highest glass transition temperature. / Lignin är en av de största byggstenarna i träd och andra växtmaterial, både till storlek och mängd. Under kemiska massaframställningsprocesser, som sulfatprocessen, bryts strukturen ned och lignin löses ut i kokvätskan. Ligninets värmevärde tas till vara, genom att det förbränns i sodapannan. Med den utmaning som dagens samhälle står inför, där fossila råvaror ska ersättas med förnyelsebara, finns ett allt större intresse att se vilka andra användningsområden som kan finnas för lignin, som grön råvara för energi, material och kemikalier. Det krävs därför kunskap om hur lignin med lämpliga egenskaper ska kunna utvinnas. Målet med detta examensarbete var att undersöka hur vedråvara och koktid under sulftakoket påverkar egenskaper hos det utlösta ligninet. I denna studie kokades vedflis av tall, gran och eukalyptus enligt sulfatprocessen och det utlösta ligninet analyserades efter tre olika koktider. Längre koktid ledde till mer utfällt material. Det var en tydlig skillnad i färg mellan lignin från eukalyptus och de från barrveden, gran och tall Eukalyptusligninet var mörkare med en tydlig grönaktig färgskiftning. Längre koktid medförde även ett mer lättfiltrerbart lignin. Mängden lignin, bestämt som mängd Klason lignin efter sur hydrolys, var högre i utfällningen efter kok av eukalyptus jämfört med efter kok av barrved. Resultaten från den analytiska pyrolysen visar däremot på rakt motsatt förhållande. Enligt den analytiska pyrolysen är det något mindre mängd lignin i utfällningen efter eukalyptuskok. Orsaken kan vara att vid kvantitativ bestämning av lignin som Klason lignin, kommer det oorganiska materialet att fällas ut tillsammans med ligninet, varvid mängden Klason lignin även inbegriper askmängden. Mängden lignin som lösts ut under koket ökar med ökad koktid, men andelen lignin i det utfällda materialet ändras inte med koktiden. Svavelhalten var högre för (utlöst) eukalyptuslignin än för granlignin och talllignin. Talllignin med den längsta koktiden hade den högsta totala halten fenol. Gran lignin med den längsta koktiden hade det högsta värdet på glastransitionstemperaturen.

Transverse anisotropy is an important phenomenon of practical and scientific interest. Although the presence of ray tissue explains the high radial modulus in many hardwoods, experimental data in the literature shows that this is not the case for pine. It is possible that anisotropy in softwoods may be explained by the cellular structure and associated deformation mechanisms. An experimental approach was developed by which local radial modulus in spruce was determined at sub-annual ring scale. Digital speckle photography (DSP) was used, and the density distribution was carefully characterized using x-ray densitometry and the SilviScan apparatus. A unique set of data was generated for radial modulus versus a wide range of densities. This was possible since earlywood density shows large density variations in spruce. Qualitative comparison was made between data and predictions from stretching and bending honeycomb models. The hypothesis for presence of cell wall stretching was supported by data. A model for wood was therefore developed where both cell wall bending and stretching are included. The purpose was a model for predictions of softwood moduli over a wide range of densities. The relative importance of the deformation mechanisms was investigated in a parametric study. A two-phase model was developed and radial and tangential moduli were predicted. Comparison with experimental data showed good agreement considering the nature of the model (density is the only input parameter). Agreement is much better than for a regular honeycomb model. According to the model, cell wall bending dominates at both low and high densities during tangential loading. In radial loading, cell wall stretching dominates at higher densities. / QC 20101119

An experiment was designed to test the hypothesis that each softwood pulp is unique and requires a specific, well defined mechanical treatment to derive its maximum strength potential. Three bleached softwood Kraft pulps and respective wood samples were sourced from both the Northern and Southern Hemispheres. The raw fibre characteristics of P. patula (Southern Hemisphere), P. menziesii (Northern Hemisphere) and P. mariana (Northern Hemisphere) were measured and compared. The raw pulp sheets were refined at different energies and intensities under controlled laboratory conditions using a 12” single disc pilot refiner. Results were assessed to determine the raw fibre characteristics, optimum refining conditions and the relative refined strength potential for each of the three samples. Results from anatomy measurements on the three wood samples differed significantly. P. patula exhibited a relatively high proportion of springwood growth in the early growing years. As the P. patula aged and formed mature wood there was a significant increase in the frequency of latewood formation. This was characterized by an abrupt and significant increase in the wall thickness, beyond that of the two Northern softwood samples. When the cell wall thickness increased, the lumen width and fibre diameter of the P. patula decreased significantly, yielding extremely coarse, stiff fibres. The Northern P .mariana and P. menziesii samples were characterized by a relatively consistent transition between high and low densities from the pith to the bark of the tree. The Southern P. patula had a unique density trend with an increasing frequency of high density peaks indicative of an increased latewood formation from the pith to the bark. The slower growing Northern P. menziesii and P. mariana samples did not have as clear a differentiation in fibre characteristics between juvenile and mature wood formation. The Northern samples did however contain a significantly higher proportion of juvenile latewood growth than the P. patula. However, the difference in fibre characteristics between earlywood and latewood formation was not as significant as that noted with the Southern P. patula Fibre morphology measurements on the unrefined bleached Kraft pulps also revealed significant differences between the three samples. The average MORFI LAB01 results on the P. patula defined fibres with a high coarseness and relatively low number of fibres per gram of pulp. The extremely coarse latewood fibres formed during mature wood growth being the most likely source. However, P. patula was also characterized with a high fibre flexibility and large lumen, characteristics consistent with earlywood fibres. The Pulmac Z-Span 3000 was used to define the individual fibre strength, when due consideration was given to the number of fibres per gram, the corrected Pulmac results suggested P. patula had the strongest fibres. When refined, using a standard disc refining programme, P. patula exhibited a fast freeness development. Conventional thinking would suggest that this was an indication of a weaker fibre. However, this species had a robust morphology compared to the Northern Hemisphere woods. The theory developed in this dissertation suggests that the effect of coarseness and the concomitant number of fibres per gram plays a significant role. These two parameters are not included in the “traditional” refining calculations. The applied refining load and intensity was calculated on the flow of the pulp passing through the refiner. The calculation did not consider the actual number of fibres present in that specific volume. The implication is that when a fixed refining load is applied to a pulp with coarse fibres there may be a higher effective load on those fewer fibres (resulting in fibre cutting and fines generation). In this case, the Northern samples have a comparatively low coarseness and more fibres per gram with each receiving a smaller portion of the total load and intensity. In terms of refined pulp properties, P. patula developed a relatively high bulk and tear index consistent with coarse, rigid fibres. The Northern P. mariana and P. menziesii samples produced a pulp with good tensile properties, consistent with a greater number of finer, collapsible fibres with a higher relative bonding area. P. patula fibres were extremely heterogeneous in nature containing the smallest relative lumen width during latewood formation and the largest lumen width during earlywood growth. As a result, P. patula contains extremes of both fine and coarse fibres in the same blend. It may be more beneficial for this species than the others to improve both the tear and tensile properties through fibre fractionation with appropriate development of the separate accepts and rejects streams. In terms of fibre development, low intensity refining parameters maximized the tensile strength of the Southern P. patula. The Northern P. mariana and P. menziesii samples had a greater number of fibres per gram of pulp requiring both a higher refining energy and intensity to develop the pulp to its maximum potential. To develop optimum tear results, high intensity refining, with a relatively low specific energy provided optimum results for all 3 samples. Results confirmed that there were significant differences in the fibre morphology both between the three different species and between the two Hemispheres. There was strong evidence that the fibre characteristics dictate the manner in which a fibre responds to refining which in turn determines the relative contribution to specific refined pulp properties. It may be possible to use fibre characteristics to determine the appropriate refining parameters for optimal fibre development which will enhance the value of the end product. To derive the maximum strength potential from P. patula pulp samples, it is recommended that further studies investigate Hydracyclone fractionation and the concomitant benefits of refining the separate streams. Furthermore, a separate study on fibre morphology and refining characteristics of the same species grown in both the Northern and Southern Hemisphere would provide valuable insight. / Thesis (M.Sc.Eng)-University of KwaZulu-Natal, Durban, 2009.

Wood from coniferous trees is an important source of renewable biomass. It can contribute to provision of carbon neutral energy, biomaterials and housing for a growing population. Softwood is mainly composed of cellulose, galactoglucomannan, xylan and lignin. This thesis focuses on the biosynthesis and function of Glucuronic acid (GlcA) decorations on softwood xylan. Results demonstrate that this GUX (GlucUronic acid substitution of Xylan)-dependent xylan branching is critical for the maintenance of biomass recalcitrance in a model vascular plant Arabidopsis thaliana. Experiments employing in vitro and in planta activity assays show that conifer transcriptomes encode at least two distinct GUX enzymes which are active glucuronosyltransferases. Interestingly, these enzymes have different specific activities, with one adding evenly spaced GlcA branches and the other one being able to add consecutive decorations. It is possible that these different patterns of xylan branching may have an impact on ability of xylan to interact with cellulose fibrils. To investigate the role for xylan binding to cellulose, Arabidopsis mutant plants in which this interaction is lost were evaluated alongside transgenic mutant lines in which the interaction may be restored. Results of this analysis indicate that the presence of cellulose-bound xylan might have an influence on plant vasculature integrity and thus it may have an effect on plant growth and biomass properties. Moreover, further results indicate that some xylan cellulose interaction is likely to occur in cell wall macrofibrils which can be detected in softwood. Taken together, this thesis provides insights into the process of conifer xylan glucuronidation and the possible role these branches may be playing in the maintenance of softwood recalcitrance and mechanical properties. In addition to identifying potential mutagenesis targets for improving softwood processing, this work is a proof of concept for the use of GUX enzymes for in vivo and in vitro biosynthesis of novel xylan structures with potential industrial application.

<p>Chemical pulp fibres from wood are commonly used in products associated with packaging as well as with printing and writing. The prevalent way of liberating fibres is by subjecting wood chips to Kraft cooking. This process has a history of almost 130 years and should be both well described and well established. However, new products and new applications that use fibres as an important renewable resource make it all the more important that the properties of fibres be controllable. The properties of wood fibres are influenced by their carbohydrate composition which, in turn, is dependent on the cooking conditions used. This thesis studies the degradation and dissolution of the different carbohydrates during Kraft cooking and summarizes the results in kinetic expressions.</p><p>Industrial wood chips from Norway spruce (Picea abies) were cooked at a high liquor-to-wood ratio in an autoclave digester at varying concentrations of hydroxide ions, hydrogen sulphide ions and sodium ions as well as varying temperatures. The pulps were analysed for carbohydrate composition, kappa number, content of hexenuronic acid and the pure cellulose viscosity, i.e. only the cellulose content in the pulp sample was used for calculating the viscosity. Kraft cooking of Eucalyptus urophylla and Eucalyptus grandis was also studied, using industrial liquor-to-wood ratios, to examine the relationship between hexenuronic acids and the amount of xylan in the pulp samples.</p><p>For Kraft cooking of Norway spruce it was found that an increase in the concentration of hydroxide ions increased the rate of dissolution of the carbohydrates and the degradation of the cellulose degree of polymerization (DP). However, measured at a kappa number of 30, it is seen that a low hydroxide ion concentration can lower the carbohydrate yield and the pure cellulose viscosity dramatically. The hydroxide ion concentration not only affects the rate of dissolution but also the amount of xylan that reacts in the slower, final phase. Both cellulose and hemicelluloses were found to be affected by the hydrogen sulphide ion concentration. The dissolution of cellulose and hemicelluloses at varying sodium ion concentrations was found to be affected in different directions. The effect of sodium ion concentration on the DP was found to be dependent on the method of evaluation. The pulp viscosity was found to be affected twice as much by the sodium ion concentration than the pure cellulose viscosity was. For Kraft cooking of hardwood it was found that a high xylan yield not always is synonymous with a high hexenuronic acids content.</p>

Today’s market offers an ever-increasing range of cellulose pulps (derivative pulps) made fromvarious wood types through different delignification processes. Each pulp segment has its uniquecharacteristics, which makes it difficult for the producer of cellulose derivatives to choose the mostsuitable pulp for optimum processability and product quality. The objective of this study was toimprove knowledge of cellulose pulps and to describe how different pulp properties affectprocessability and quality in the production of viscose dope and cellulose ethers.Ten pulp samples were investigated, originating from both sulfite and sulfate processes, with highand low viscosities and with softwood and hardwood as raw material. The pulps were analyzed fortheir properties and then processed to viscose dope and a cellulose ether in two separate pilotfacilities. The intermediates in the viscose process as well as the quality of the viscose dope andcellulose ether were analyzed and the results correlated to pulp properties.Multivariate regression methods were applied to investigate the dominating physical and chemicalproperties of each pulp and pulp segment, and to study the use of spectroscopic analyses inpredicting pulp origin, concentration and composition of hemicelluloses as well as the content ofreducing end groups in cellulose. For the production of viscose dope, the models presented showedthe most important pulp properties for good cellulose reactivity and viscose filterability. In addition,the properties affecting gel formation, flocculation, degree of substitution and clarity in theproduction of cellulose ether were highlighted. The study also emphasized the need to supplementthe use of conventional analyses on pulps and viscose intermediates with other analytical methods,such as molecular weight distribution and carbohydrate analysis, to better predict the quality ofboth viscose dope and viscose fiber.The results of the present study could be useful to predict the origin and properties of new pulps, toreplace or supplement otherwise expensive pulp analyses, and to assess the impact of pulpproperties on the production of cellulose derivatives without extensive pilot-scale trials.

Chemical pulp fibres from wood are commonly used in products associated with packaging as well as with printing and writing. The prevalent way of liberating fibres is by subjecting wood chips to Kraft cooking. This process has a history of almost 130 years and should be both well described and well established. However, new products and new applications that use fibres as an important renewable resource make it all the more important that the properties of fibres be controllable. The properties of wood fibres are influenced by their carbohydrate composition which, in turn, is dependent on the cooking conditions used. This thesis studies the degradation and dissolution of the different carbohydrates during Kraft cooking and summarizes the results in kinetic expressions. Industrial wood chips from Norway spruce (Picea abies) were cooked at a high liquor-to-wood ratio in an autoclave digester at varying concentrations of hydroxide ions, hydrogen sulphide ions and sodium ions as well as varying temperatures. The pulps were analysed for carbohydrate composition, kappa number, content of hexenuronic acid and the pure cellulose viscosity, i.e. only the cellulose content in the pulp sample was used for calculating the viscosity. Kraft cooking of Eucalyptus urophylla and Eucalyptus grandis was also studied, using industrial liquor-to-wood ratios, to examine the relationship between hexenuronic acids and the amount of xylan in the pulp samples. For Kraft cooking of Norway spruce it was found that an increase in the concentration of hydroxide ions increased the rate of dissolution of the carbohydrates and the degradation of the cellulose degree of polymerization (DP). However, measured at a kappa number of 30, it is seen that a low hydroxide ion concentration can lower the carbohydrate yield and the pure cellulose viscosity dramatically. The hydroxide ion concentration not only affects the rate of dissolution but also the amount of xylan that reacts in the slower, final phase. Both cellulose and hemicelluloses were found to be affected by the hydrogen sulphide ion concentration. The dissolution of cellulose and hemicelluloses at varying sodium ion concentrations was found to be affected in different directions. The effect of sodium ion concentration on the DP was found to be dependent on the method of evaluation. The pulp viscosity was found to be affected twice as much by the sodium ion concentration than the pure cellulose viscosity was. For Kraft cooking of hardwood it was found that a high xylan yield not always is synonymous with a high hexenuronic acids content.