Various chemical properties can be used to characterise dissolving pulp. The quality of the pulp must be carefully controlled to ensure that it meets the requirements for its intended use and the further processes to be applied. If it is to be used to prepare viscose, or other cellulose derivatives, the key prop-erties of the pulp are its accessibility and reactivity. The studies described in this thesis investigated the potential utility of multivariate analysis of chemi-cal and spectral data for determining the properties of dissolving pulp. Dis-solving pulps produced by a two-stage sulfite process, both in the laboratory and a factory were produced pulps for this purpose. The analyses showed that pulp with high reactivity had short cellulose chains, low molecular weight, low polydispersity, low hemicellulose content, high content of ace-tone-extractable compounds, and high surface charge compared to pulp with low reactivity. Important chemical properties of the pulp, such as viscosity and alkali resistance, were successfully predicted from near infrared spectra. Predicting the reactivity, or the viscose filterability, of the pulp was more complex. Several chemical methods for analyzing the reactivity of the pulp were examined. The influence of the cellulose structure at the supermolecu-lar level on the reactivity of the pulp was explored by multivariate analysis of solid state 13C nuclear magnetic resonance spectra. Structural variables considered included: differences in hydrogen bonding, contents of hemicel-lulose, amorphous cellulose and crystalline cellulose I and II. Pulps with high reactivity have higher contents of cellulose I and amorphous cellulose than pulps with low reactivity, which have higher contents of cellulose II and hemicellulose.

<p>Cellulosans tillgänglighet och reaktivitet är nyckelparametrar vid framställning av regenererad cellulosa och cellulosaderivat. Det är välkänt att på grund av cellulosans kristallina struktur är tillgängligheten begränsad för lösningsmedel och olika reagens. Till exempel kan en inhomogen substitution av hydroxylgrupperna i cellulosakedjan resultera i cellulosaderivat av sämre kvalitet. Baserat på detta har en del av arbetet i denna studie fokuserat på att förbättra cellulosans tillgänglighet och reaktivitet genom att studera effekten av olika enzymatiska behandlingar med monokomponent endoglukanaser. Resultaten visar att närvaron av en cellulosabindande domän fyller en viktig funktion för att öka cellulosans reaktivitet, men strukturen för den katalytiska domänen visade sig ha den största inverkan på cellulosans tillgänglighet. I kompletterande studier har även effekten av en mekanisk förbehandling i kombination med enzymatisk behandling utvärderats. Kombinationen av förbehandlingarna resulterade i en positiv effekt, cellulosans reaktivitet kunde ökas i större omfattning.</p><p>I dag används huvudsakligen dissolvingmassor som råvara vid framställning av cellulosaregenerat och cellulosaderivat. Kraven för dessa s.k. specialmassor är högt cellulosainnehåll samt lågt hemicellulosa- respektive lignininnehåll. På grund av dessa specifika krav är produktionskostnaderna för dessa massor högre än konventionella sulfatmassor. Den andra delen av studien har därför fokuserat på möjligheten att använda dessa sulfatmassor som dissolvingmassa. Det har visats att kombinationen av enzymatiska behandlingar med monokomponent endoglukanas och xylanas följt av ett alkaliskt steg kan resultera i massor där kraven uppfylls med avseende på cellulosans reaktivitet, och cellulosa- respektive hemicellulosainnehåll.</p> / <p>The accessibility and reactivity of cellulose are key parameters on the manufacturing of cellulose derivatives and regenerated cellulose. It is well known that, due to the crystalline structure of cellulose, the accessibility of solvents and reagents is limited. For instance, an inhomogeneous substitution of the hydroxyl groups of the cellulose chain might lead to the production of derivatives of low quality. As a consequence, part of this work has focused on improving the accessibility and reactivity on cellulose by studying the effect of different monocomponent endoglucanases. It has been demonstrated that the presence of the cellulose-binding domain plays an important role on the enhancement of cellulose reactivity; however, the structure of the catalytic domain has been showed to have the highest influence on this parameter. Furthermore, the influence of mechanical treatment prior to enzymatic treatment has been examined. The combination of pretreatments showed a positive effect enhancing to a larger extent the cellulose reactivity.</p><p>Currently, dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. The requirements for these so-called “special pulps” are a high cellulose content and a low hemicelluloses and lignin content. As a result of these specific demands, the production costs of these pulps are higher than those of common kraft pulps. The second part of this work, therefore, has been focused on the study on the viability of converting kraft pulps into dissolving pulps. It has been demonstrated that the combination of enzymatic treatments using a monocomponent endoglucanase and a xylanase together with the addition of an alkaline step could fulfil the requirements of a commercial dissolving pulp in terms of cellulose reactivity and cellulose and hemicellulose content.</p>

Different pulps were chemically (nitren) and biologically (enzyme) treated in order to improve the chemical accessibility and dissolution capacity in cold NaOH. The treatments effect on the pulp properties was accessed by studying the changes on their chemical and macromolecular structure and by analyzing the dissolution performance in cold NaOH.The nitren treatment has the effect of removing a large part of the xylan present in a dissolving pulp and is also removing mannans. Increasing the nitren concentrations will extract also cellulose and decrease its mean molar mass. These extractions are favorable for the dissolution in cold NaOH–water, being more effective with higher nitren concentrations. A maximum of 44.7% increase on the dissolution yield was achieved.The new enzymatic treatment shows a higher efficiency on promoting fibers accessibility to NaOH ions, (directly correlated with the enzymatic load), allowing a maximum increase of 150% on the dissolution yield. A slight decrease of the average molar mass was also seen. The different pulps reacted differently to the treatments, showing that the pulping pretreatments have an influence on the enzymatic efficiency. Using a mixture of enzymes and endoglucanase showed that the synergistic effect of these two enzymes is more effective on cellulose activation.Both nitren and enzymatic treatments are improving the pulp chemical accessibility mostly by modifying the structure of the primary wall and S1 wall. This promotes the swelling of these wood cell structures, allowing the access of the NaOH solvating ions into fiber regions not accessible on the original pulp. The nitren is disassembling the fiber surface with extraction of hemicelluloses and degrading the cellulosic structure.The use of this enzyme on the cellulose pulps activation towards dissolution in cold NaOH is of great importance. It presents a high potential in both technical, with further development and industrial implementation, and fundamental research fields, with further studies on mechanisms of cellulose activation.The work was performed in Cemef - Mines ParisTech, Sophia Antipolis, France, and TI / Hamburg University, Germany and financed by Sappi, Tembec, Lenzing, Viskase and Spontex and had support from EPNOE (European Polysaccharide Network of Excellence). / Different pulps were chemically (nitren) and biologically (enzyme) treated in order to improve the chemical accessibility and dissolution capacity in cold NaOH. The treatments effect on the pulp properties was accessed by studying the changes on their chemical and macromolecular structure and by analyzing the dissolution performance in cold NaOH.The nitren treatment has the effect of removing a large part of the xylan present in a dissolving pulp and is also removing mannans. Increasing the nitren concentrations will extract also cellulose and decrease its mean molar mass. These extractions are favorable for the dissolution in cold NaOH–water, being more effective with higher nitren concentrations. A maximum of 44.7% increase on the dissolution yield was achieved.The new enzymatic treatment shows a higher efficiency on promoting fibers accessibility to NaOH ions, (directly correlated with the enzymatic load), allowing a maximum increase of 150% on the dissolution yield. A slight decrease of the average molar mass was also seen. The different pulps reacted differently to the treatments, showing that the pulping pretreatments have an influence on the enzymatic efficiency. Using a mixture of enzymes and endoglucanase showed that the synergistic effect of these two enzymes is more effective on cellulose activation.Both nitren and enzymatic treatments are improving the pulp chemical accessibility mostly by modifying the structure of the primary wall and S1 wall. This promotes the swelling of these wood cell structures, allowing the access of the NaOH solvating ions into fiber regions not accessible on the original pulp. The nitren is disassembling the fiber surface with extraction of hemicelluloses and degrading the cellulosic structure.The use of this enzyme on the cellulose pulps activation towards dissolution in cold NaOH is of great importance. It presents a high potential in both technical, with further development and industrial implementation, and fundamental research fields, with further studies on mechanisms of cellulose activation.The work was performed in Cemef - Mines ParisTech, Sophia Antipolis, France, and TI / Hamburg University, Germany and financed by Sappi, Tembec, Lenzing, Viskase and Spontex and had support from EPNOE (European Polysaccharide Network of Excellence).

Cellulosans tillgänglighet och reaktivitet är nyckelparametrar vid framställning av regenererad cellulosa och cellulosaderivat. Det är välkänt att på grund av cellulosans kristallina struktur är tillgängligheten begränsad för lösningsmedel och olika reagens. Till exempel kan en inhomogen substitution av hydroxylgrupperna i cellulosakedjan resultera i cellulosaderivat av sämre kvalitet. Baserat på detta har en del av arbetet i denna studie fokuserat på att förbättra cellulosans tillgänglighet och reaktivitet genom att studera effekten av olika enzymatiska behandlingar med monokomponent endoglukanaser. Resultaten visar att närvaron av en cellulosabindande domän fyller en viktig funktion för att öka cellulosans reaktivitet, men strukturen för den katalytiska domänen visade sig ha den största inverkan på cellulosans tillgänglighet. I kompletterande studier har även effekten av en mekanisk förbehandling i kombination med enzymatisk behandling utvärderats. Kombinationen av förbehandlingarna resulterade i en positiv effekt, cellulosans reaktivitet kunde ökas i större omfattning. I dag används huvudsakligen dissolvingmassor som råvara vid framställning av cellulosaregenerat och cellulosaderivat. Kraven för dessa s.k. specialmassor är högt cellulosainnehåll samt lågt hemicellulosa- respektive lignininnehåll. På grund av dessa specifika krav är produktionskostnaderna för dessa massor högre än konventionella sulfatmassor. Den andra delen av studien har därför fokuserat på möjligheten att använda dessa sulfatmassor som dissolvingmassa. Det har visats att kombinationen av enzymatiska behandlingar med monokomponent endoglukanas och xylanas följt av ett alkaliskt steg kan resultera i massor där kraven uppfylls med avseende på cellulosans reaktivitet, och cellulosa- respektive hemicellulosainnehåll. / The accessibility and reactivity of cellulose are key parameters on the manufacturing of cellulose derivatives and regenerated cellulose. It is well known that, due to the crystalline structure of cellulose, the accessibility of solvents and reagents is limited. For instance, an inhomogeneous substitution of the hydroxyl groups of the cellulose chain might lead to the production of derivatives of low quality. As a consequence, part of this work has focused on improving the accessibility and reactivity on cellulose by studying the effect of different monocomponent endoglucanases. It has been demonstrated that the presence of the cellulose-binding domain plays an important role on the enhancement of cellulose reactivity; however, the structure of the catalytic domain has been showed to have the highest influence on this parameter. Furthermore, the influence of mechanical treatment prior to enzymatic treatment has been examined. The combination of pretreatments showed a positive effect enhancing to a larger extent the cellulose reactivity. Currently, dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. The requirements for these so-called “special pulps” are a high cellulose content and a low hemicelluloses and lignin content. As a result of these specific demands, the production costs of these pulps are higher than those of common kraft pulps. The second part of this work, therefore, has been focused on the study on the viability of converting kraft pulps into dissolving pulps. It has been demonstrated that the combination of enzymatic treatments using a monocomponent endoglucanase and a xylanase together with the addition of an alkaline step could fulfil the requirements of a commercial dissolving pulp in terms of cellulose reactivity and cellulose and hemicellulose content. / QC 20101117

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Chemistry, Durban University of Technology, Durban, South Africa, 2015. / This thesis forms part of the Council for Scientific and Industrial Research, Forestry and Forest Products Research Centre (CSIR-FFP) biorefinery project which aims at developing and implementing novel industrial processes production of cellulose textile fibres. The focus of this study is to investigate the dissolution of South African Eucalyptus raw (unbleached) and final (bleached) dissolving pulp and saw dust wood in an ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [Emim][OAc] and the co-solvents [dimethylsulfoxide (DMSO)] or [dimethylformamide (DMF)] mixtures, to obtain regenerated cellulose by the further addition of water and acetone. The IL/co-solvent mixtures were able to dissolve the raw and final pulp samples at 120 ˚C for 6 hours whereas the sawdust wood dissolved in 10 hours. The IL/DMF mixture gave higher cellulose recoveries of 41.88 % for the raw pulp, 49.89 % for the final pulp sample and 32.50 % for sawdust wood while the IL/DMSO mixture gave a recovery of 15.25 % for the raw pulp sample, 36.25 % for the final pulp sample and 17.83 % for the sawdust wood sample. The regenerated cellulose materials were characterized by Fourier Transformer Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Thermo gravimetric Analysis (TGA) and Powder X-Ray Diffraction (pXRD), and compared with a standard microcrystalline of cellulose. It was observed that the FTIR and NMR spectra of the regenerated cellulose and MCC were similar which then indicates that no chemical reaction occurred during the dissolution and regeneration process of cellulose. SEM and X-ray diffraction (XRD) patterns of the results showed that after dissolution the cellulose I (native form), the crystalline structure was completely converted into cellulose II (amorphous) structure, and this was due to the removal of lignin and decrease in cellulose crystallinity. TGA results showed that the regenerated cellulose samples have higher char yields compared to the MCC which is due to the IL remaining in the regenerated cellulose. It was also observed that the addition of the co-solvents decreased the viscosity of the IL mixture, facilitating dissolution of the cellulose that led to additional swelling and reduction of the recalcitrant nature of the cellulose crystalline structure and intermolecular interactions. This led to increased accessibility and dissolution of the cellulose. The findings in this study have the potential to bring ILs closer to applications for biomass technology in particular for an economically viable dissolution method for biomass because ILs have a benefit of being easily separated from the anti-solvent, which provides a simple solution for IL recycle ability and re-use. The novel aspect of this study is: . This is the first study in the South African context to examine the influence of the lignin on the dissolution and regeneration of Eucalyptus sawdust wood and dissolving pulp. / D

Single stage and two-stage sodium sulfite cooking were carried out on either spruce, pine or pure pine heartwood chips to investigate the influence of several process parameters on the initial phase of such a cook down to about 60 % pulp yield. The cooking experiments were carried out in the laboratory with either a lab-prepared or a mill-prepared cooking acid and the temperature and time were varied. The influences of dissolved organic and inorganic components in the cooking liquor on the final pulp composition and on the extent of side reactions were investigated. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. A better understanding of the delignification mechanisms during bisulfite and acid sulfite cooking was obtained by analyzing the lignin carbohydrate complexes (LCC) present in the pulp when different cooking conditions were used. It was found that using a mill-prepared cooking acid beneficial effect with respect to side reactions, extractives removal and higher stability in pH during the cook were observed compared to a lab-prepared cooking acid. However, no significant difference in degrees of delignification or carbohydrate degradation was seen.  The cellulose yield was not affected in the initial phase of the cook however; temperature had an influence on the rates of both delignification and hemicellulose removal. It was also found that the  corresponding activation energies increased in the order:  xylan, glucomannan, lignin and cellulose. The cooking temperature could thus be used to control the cook to a given carbohydrate composition in the final pulp. Lignin condensation reactions were observed during acid sulfite cooking, especially at higher temperatures. The LCC studies indicated the existence of covalent bonds between lignin and hemicellulose components with respect to xylan and glucomannan. LCC in native wood showed the presence of phenyl glycosides, ϒ-esters and α-ethers; whereas the α-ethers  were affected during sulfite pulping. The existence of covalent bonds between lignin and wood polysaccharides might be the rate-limiting factor in sulfite pulping. / The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way. Thus, this thesis is focused on the initial phase of sodium based single stage bisulfite, acid sulfite and two-stage sulfite cooking of either 100 % spruce, 100 % pine or 100 % pine heartwood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate. LCC (Lignin carbohydrates complexes) studies were carried out to investigate the influence of different cooking conditions on lignin carbohydrate linkages.

<p>Detta examensarbete genomfördes från begäran av två företag, Pöyry Sweden AB, Karlstad och Kiram AB. Arbetet var uppdelat i två delar, en litteraturstudie samt en experimentell del. I litteraturstudien kartlades olika processer för framställning av dissolvingmassa och olika processer för beredning av viskosfiber. Utöver det sammanställdes även några av de ledande aktörerna av joniska vätskor samt applikationer för cellulosabaserade produkter. Fokus genom hela arbetet har legat på svavelfria processer som t.ex. användandet av joniska vätskor för upplösning av cellulosa. I den experimentella delen undersöktes det om man via en förhydrolys följt av ett soda-AQ kok, en svavelfri process, kunde producera dissolvingmassa. Utöver produktion av dissolvingmassa undersöktes också filtratet som drogs av efter förhydrolysen.</p><p>Under den experimentella delen varierades olika parametrar för att se hur det påverkade kvaliteten av massan. De parametrar som varierades vid förhydrolysförsöken var tid och antrakinon (AQ), för soda-AQ koket varierades tid, AQ och effektiv alkali (EA) halt. För ett förhydrolysförsök varierades även vätske/vedförhållandet. Vilka betingelser som skulle användas samt de mål som skulle uppnås fick man fram under litteraturstudien.</p><p>För att nå målet med ett utbyte på ca 85 % efter förhydrolysen krävdes en temperatur på 160°C och tid på 1 timme för en förhydrolys med enbart vatten. Hypotesen om att en AQ tillsats redan vid förhydrolysen skulle sänka utbytet visades inte stämma, man fick då istället ett ökat utbyte. Målet för massorna efter soda-AQ koket var ett utbyte på ca 40 %, ett kappatal runt 30 och en viskositet > 1000 ml/g. Utförde man en förhydrolys som beskrivits ovan följt av ett soda-AQ kok med dessa betingelser: temperatur 160°C, tid ≥ 2 h, EA sats > 21 % och en AQ halt ≥ 1 kg/ton, fick man en dissolvingmassa som uppfyllde kraven.</p><p>Kolhydratanalysen på filtratet visade att mestadels glukomannan brutits ner och lösts ut under förhydrolysen. Däremot skedde det ingen nedbrytning av cellulosa. Utförde man förhydrolysen på ett sådant sätt som beskrivits ovan bröt man ner en hemicellulosa mängd på ca 72 kg/ton flis. Det får ses som en ganska rejäl mängd eftersom man enbart använder vatten under förhydrolysen.</p> / <p>This project was carried out on a request from two companies, Pöyry Sweden AB, Karlstad and Kiram AB. The work was divided in two parts, one literature study and one experimental part. In the literature study different processes for production of dissolving pulp and different processes for viscose preparation were identified. Besides that, some of the lending companies of ionic liquids and some applications of cellulose based products were compiled. The main focus throughout this work has been on processes without sulfur, for an example the use of ionic liquids for dissolving cellulose. In the experimental part, dissolving pulp production by a prehydrolysis followed by a soda-AQ cooking was investigated. The filtrate gained from the prehydrolysis was also examined.</p><p>In the dissolving pulp production different parameters for the prehydrolysis and cooking stage were alternated. For the prehydrolysis the following parameters were varied: time and concentration of anthraquinone and for the cooking stage the parameters time, EA and concentration of anthraquinone. In one experiment the liquid to wood ratio was varied. The conditions that would be used and the target of the experimental work were received from the literature study.</p><p>To reach the target yield of approximately 85 % after an prehydrolysis, with water, the following conditions were required, a temperature of 160°C and a time of 1 hour. The hypothesis that an AQ additive, already in the prehydrolysis, should lowered the yield proved to be wrong. The target for the dissolving pulps after a soda-AQ cooking were a yield of ~ 40 %, a kappa number around 30 and finally a viscosity > 1000 ml/g. A soda-AQ cooking with these conditions: temperature 160°C, time ≥ 2 h, EA > 21 % and an AQ conc. ≥ 1 kg/ton, after a prehydrolysis, mentioned above, resulted in a pulp which achieved the targets.</p><p>The carbohydrate analysis on the filtrate showed that mostly glucomannan was settled out during the prehydrolysis. It also showed that no cellulose was settled out. A result after a prehydrolysis like the one mentioned above was that the amount of hemicellulose was reduced with ~ 72 kg/ton wood.</p>

Detta examensarbete genomfördes från begäran av två företag, Pöyry Sweden AB, Karlstad och Kiram AB. Arbetet var uppdelat i två delar, en litteraturstudie samt en experimentell del. I litteraturstudien kartlades olika processer för framställning av dissolvingmassa och olika processer för beredning av viskosfiber. Utöver det sammanställdes även några av de ledande aktörerna av joniska vätskor samt applikationer för cellulosabaserade produkter. Fokus genom hela arbetet har legat på svavelfria processer som t.ex. användandet av joniska vätskor för upplösning av cellulosa. I den experimentella delen undersöktes det om man via en förhydrolys följt av ett soda-AQ kok, en svavelfri process, kunde producera dissolvingmassa. Utöver produktion av dissolvingmassa undersöktes också filtratet som drogs av efter förhydrolysen. Under den experimentella delen varierades olika parametrar för att se hur det påverkade kvaliteten av massan. De parametrar som varierades vid förhydrolysförsöken var tid och antrakinon (AQ), för soda-AQ koket varierades tid, AQ och effektiv alkali (EA) halt. För ett förhydrolysförsök varierades även vätske/vedförhållandet. Vilka betingelser som skulle användas samt de mål som skulle uppnås fick man fram under litteraturstudien. För att nå målet med ett utbyte på ca 85 % efter förhydrolysen krävdes en temperatur på 160°C och tid på 1 timme för en förhydrolys med enbart vatten. Hypotesen om att en AQ tillsats redan vid förhydrolysen skulle sänka utbytet visades inte stämma, man fick då istället ett ökat utbyte. Målet för massorna efter soda-AQ koket var ett utbyte på ca 40 %, ett kappatal runt 30 och en viskositet &gt; 1000 ml/g. Utförde man en förhydrolys som beskrivits ovan följt av ett soda-AQ kok med dessa betingelser: temperatur 160°C, tid ≥ 2 h, EA sats &gt; 21 % och en AQ halt ≥ 1 kg/ton, fick man en dissolvingmassa som uppfyllde kraven. Kolhydratanalysen på filtratet visade att mestadels glukomannan brutits ner och lösts ut under förhydrolysen. Däremot skedde det ingen nedbrytning av cellulosa. Utförde man förhydrolysen på ett sådant sätt som beskrivits ovan bröt man ner en hemicellulosa mängd på ca 72 kg/ton flis. Det får ses som en ganska rejäl mängd eftersom man enbart använder vatten under förhydrolysen. / This project was carried out on a request from two companies, Pöyry Sweden AB, Karlstad and Kiram AB. The work was divided in two parts, one literature study and one experimental part. In the literature study different processes for production of dissolving pulp and different processes for viscose preparation were identified. Besides that, some of the lending companies of ionic liquids and some applications of cellulose based products were compiled. The main focus throughout this work has been on processes without sulfur, for an example the use of ionic liquids for dissolving cellulose. In the experimental part, dissolving pulp production by a prehydrolysis followed by a soda-AQ cooking was investigated. The filtrate gained from the prehydrolysis was also examined. In the dissolving pulp production different parameters for the prehydrolysis and cooking stage were alternated. For the prehydrolysis the following parameters were varied: time and concentration of anthraquinone and for the cooking stage the parameters time, EA and concentration of anthraquinone. In one experiment the liquid to wood ratio was varied. The conditions that would be used and the target of the experimental work were received from the literature study. To reach the target yield of approximately 85 % after an prehydrolysis, with water, the following conditions were required, a temperature of 160°C and a time of 1 hour. The hypothesis that an AQ additive, already in the prehydrolysis, should lowered the yield proved to be wrong. The target for the dissolving pulps after a soda-AQ cooking were a yield of ~ 40 %, a kappa number around 30 and finally a viscosity &gt; 1000 ml/g. A soda-AQ cooking with these conditions: temperature 160°C, time ≥ 2 h, EA &gt; 21 % and an AQ conc. ≥ 1 kg/ton, after a prehydrolysis, mentioned above, resulted in a pulp which achieved the targets. The carbohydrate analysis on the filtrate showed that mostly glucomannan was settled out during the prehydrolysis. It also showed that no cellulose was settled out. A result after a prehydrolysis like the one mentioned above was that the amount of hemicellulose was reduced with ~ 72 kg/ton wood.

Les pâtes à dissoudre, composées à 95% de cellulose, sont la matière première pour la production de fibres cellulosiques régénérées (viscose, Lyocell…) et de dérivés cellulosiques (ester, éther ou nitrate de cellulose). En tant qu’alternative aux matériaux issus de ressources pétrolières, ces produits connaissent actuellement un fort regain d’intérêt. Ainsi, la production de pâte à dissoudre devrait croître fortement au cours de la prochaine décennie. L’objectif de cette thèse est de proposer des procédés de conversion d’une pâte papetière de résineux en pâte à dissoudre. Pour cela les hémicelluloses présentes dans les pâtes kraft papetières doivent être extraites. Trois méthodes d’extraction d’hémicelluloses ont ainsi été étudiées : (1) une extraction alcaline à froid (CCE) dans des conditions non conventionnelles, (2) un procédé se divisant en deux étapes successives : un stade acide à haute température (150°C) suivie d’une extraction alcaline à chaud (AHCE) et (3) une hydrolyse enzymatique par trois enzymes commerciales (une xylanase, une mannanase, une cellulase). Les deux premières méthodes ont permis de produire des pâtes avec des caractéristiques proches des pâtes à dissoudre commerciales. Cependant, dans les trois voies d’extraction étudiées, l’extraction d’hémicelluloses n’a jamais atteint 100%. Des prétraitements des pâtes (raffinage, explosion à la vapeur, oxydation TEMPO) ont alors été testés pour améliorer l’extraction des hémicelluloses. De nouvelles séquences de purification basées sur la combinaison d’une étape de raffinage suivie d’une extraction alcaline à froid (CCE) peuvent être ainsi imaginées. La dernière partie de ces travaux de thèse s’est intéressée au gonflement des pâtes à dissoudre. Les travaux ont abouti à la création d’une nouvelle méthode simple et rapide de caractérisation du gonflement des fibres de pâte cellulosique. Cette méthode de mesure peut être, dans certaines conditions, considérée comme une mesure alternative de la réactivité des pâtes à dissoudre habituellement caractérisée par le test Fock. / Dissolving pulps, which are composed of 95% cellulose, are the raw materials for the production of regenerated cellulose fibres for textile application and for the production of cellulose derivatives. These products are alternatives to oil based materials. A growing demand in such products is expected in the next decades. Therefore, additional capacities in the production of wood dissolving pulp must be created. The purpose of this work is to develop hemicellulose removal processes with the aim to convert a softwood kraft paper pulp into a dissolving pulp. Three extraction methods were tested: (1) A cold caustic extraction process (CCE) performed under conventional and unconventional conditions; (2) A process consisting in an acid stage at high temperature (up to 150°C) followed by a hot caustic extraction (A-HCE); (3) An enzymatic hydrolysis using xylanase, mannanase, and cellulase. Conversion was quite successful with the two first processes. However, 100% of hemicellulose removal was never reached. In order to improve the hemicellulose extraction efficiency, several pre-treatments were tested (refining, steam explosion, TEMPO oxidation). The addition of a refining stage allows a reduction of the NaOH concentration during CCE extraction without affecting the hemicellulose extraction efficiency. The last part of this thesis work focus on the dissolving pulp swelling. A new and rapid test for the characterization of fibre swelling was developed. This method was used as an approach to the assessment of dissolving pulp reactivity in the viscose process in place of the Fock’s method.

The objective of this study was to evaluate the dissolution of bovine pulp tissue by NaOCl solutions in different concentrations for a similar period to the time of root canal preparation, and chemical and antimicrobial properties of the resulting solution after this dissolution. Fragments of bovine dental pulp were exposed to different solutions (0.5, 1.0, 2.5 and 5.25%) for 10 minutes. Each one minute, the solution was renewed. The reduction of weight of fragment of pulp was measured. The antimicrobial activity of the solutions was evaluated against Enterococcus faecalis by agar diffusion test. Fresh NaOCl solution and the resulting solution of dissolution test were placed into wells prepared agar plates. After the incubation period, the inhibition zones of bacterial growth were measured with the aid of a digital caliper. The concentration of active chlorine initial and final was measured by iodometric titration. The hydrogen potential of the solutions was measured by digital pHmeter. Statistical analysis was performed by ANOVA, test and post hoc Tukey test for paired samples when appropriate (α <0.05). To check the correlation between concentration and rate of dissolution of pulp or percentage of weight reduction of pulp fragments, we employed the Pearson linear correlation. We found a significant association between concentration and dissolution rate of pulp (rPearson=0.9698, p=0.03). There was also a strong correlation between concentration and percentage of weight reduction of the fragments (rPearson=0.9843, p = 0.01). The hypochlorite solution with 5.25% showed the highest inhibition zones, followed by 2.5% NaOCl (p <0.01). There was no statistically significant difference between the concentrations of 0.5% and 1.0%. The inhibition zones reduced after dissolving pulp is not significant for the solution to 1.0% (p=0.1). After dissolving bovine pulp tissue, there was a significant reduction of the pH of the solutions at 0.5%, 1.0% and 5.25%, which kept the concentration of active chlorine dissolution. It is concluded that the higher the concentration of NaOCl, the greater its antimicrobial action against the E.faecalis and its effectiveness in dissolving pulp tissue. Can also be stated that the process of dissolving pulp reduces the antimicrobial effectiveness of sodium hypochlorite, probably due to the consumption of sodium hydroxide during the test. / O objetivo deste estudo foi avaliar a dissolução de tecido pulpar bovino por soluções de NaOCl, em diferentes concentrações, durante período similar ao tempo de preparo do canal radicular; e as propriedades químicas e antimicrobianas da solução resultante após esta dissolução. Fragmentos de polpa dental bovina foram expostos às diferentes soluções de NaOCl (0,5; 1,0; 2,5 e 5,25%) por 10 minutos. A cada 1 minuto, a solução foi renovada. Registrou-se a redução do peso dos fragmentos de polpa. A ação antimicrobiana das soluções foi avaliada frente ao Enterococcus faecalis através do teste de difusão em ágar. Soluções de NaOCl recém manipuladas e as resultantes do teste de dissolução foram colocadas no interior de poços preparados em placas de ágar. Após o período de incubação, os halos de inibição de crescimento bacteriano formados ao redor dos poços foram mensurados com auxílio de paquímetro digital. A concentração de cloro ativo inicial e final foi aferida por titulometria iodométrica. O potencial hidrogeniônico das soluções foi mensurado por pHmetro digital. A análise estatística foi realizada através de ANOVA, teste post hoc de Tukey e teste para amostras pareadas quando apropriado (α<0.05). Para verificação de correlação entre concentração da solução e velocidade de dissolução pulpar ou percentual de redução de peso dos fragmentos pulpares, foi empregado o teste de correlação linear de Pearson. Constatou-se associação significativa entre concentração da solução e velocidade de dissolução pulpar (rPearson=0.9698, p=0,03). Houve, também, forte correlação entre concentração da solução e percentual de redução de peso dos fragmentos (rPearson=0,9843, p=0,01). A solução de hipoclorito a 5,25% apresentou maiores halos de inibição, seguida por NaOCl a 2,5% (p<0,01). Não houve diferença estatisticamente significante entre as concentrações de 0,5% e 1,0%. Os halos reduziram após a dissolução pulpar, não sendo estatisticamente significante para a solução a 1,0% (p=0,1). Após dissolver tecido pulpar bovino, houve redução significativa do pH das soluções a 0,5%; 1,0% e 5,25%, as quais mantiveram a concentração de cloro ativo após dissolução. Conclui-se que, quanto maior a concentração do NaOCl, maior sua ação antimicrobiana frente ao E.faecalis e sua eficácia em dissolver tecido pulpar. Pode-se afirmar também que o processo de dissolução pulpar reduz a eficácia antimicrobiana do hipoclorito de sódio, provavelmente devido ao consumo de hidróxido de sódio durante o período do teste.