<p>The conventional viscose manufacturing process is a mature process that needs to be improved with respect to its environmental impact and its production cost structure. Therefore a research study has been done with the aim to improve the reactivity of the dissolving pulp used, in order to reduce the chemical demand in the viscose process and thus reduce the cost and indirectly the environmental impact.</p><p>The work described in this thesis has shown that it is possible to enhance the pulp reactivity and to use less carbon disulphide in the production of viscose, while maintaining a good quality viscose dope, by two entirely different pretreatment methods, one chemical and one enzymatic.</p><p>The chemical method used pressurized oxygen after the mercerisation step, which increased the reactivity of the alkali cellulose. The viscose dopes produced from the pressurized oxygen treated alkali cellulose had lower filter clogging values, Kw, compared to conventionally produced viscoses. The temperature and the oxygen treatment time of the alkali cellulose were however crucial for the viscose quality.</p><p>The best performing enzyme of several tested was a cellulase of the mono component endoglucanase preparation Carezyme®. This enzymatic treatment was optimized with respect to viscose dope preparation. The study showed that the enzyme treatment could be carried out under industrially interesting conditions with respect to temperature, enzyme dose and reaction time. A re-circulation study of the enzyme showed that it was possible to re-use the spent press water from the enzymatic treatment step several times, and thus lower the production cost. Some of the viscose process stages were modified to properly fit the enzymatically treated dissolving pulp and a comparison between viscose made from enzyme-treated pulp and viscose made from conventional pulp, showed that the enzyme-treated samples had a lower filter clogging value, Kw. This indirectly indicates that the enzyme pretreatment could reduce the carbon disulphide charge in the viscose manufacturing process. An initial study of how the Carezyme® influenced different cellulosic sources was also performed.</p>

The conventional viscose manufacturing process is a mature process that needs to be improved with respect to its environmental impact and its production cost structure. Therefore a research study has been done with the aim to improve the reactivity of the dissolving pulp used, in order to reduce the chemical demand in the viscose process and thus reduce the cost and indirectly the environmental impact. The work described in this thesis has shown that it is possible to enhance the pulp reactivity and to use less carbon disulphide in the production of viscose, while maintaining a good quality viscose dope, by two entirely different pretreatment methods, one chemical and one enzymatic. The chemical method used pressurized oxygen after the mercerisation step, which increased the reactivity of the alkali cellulose. The viscose dopes produced from the pressurized oxygen treated alkali cellulose had lower filter clogging values, Kw, compared to conventionally produced viscoses. The temperature and the oxygen treatment time of the alkali cellulose were however crucial for the viscose quality. The best performing enzyme of several tested was a cellulase of the mono component endoglucanase preparation Carezyme®. This enzymatic treatment was optimized with respect to viscose dope preparation. The study showed that the enzyme treatment could be carried out under industrially interesting conditions with respect to temperature, enzyme dose and reaction time. A re-circulation study of the enzyme showed that it was possible to re-use the spent press water from the enzymatic treatment step several times, and thus lower the production cost. Some of the viscose process stages were modified to properly fit the enzymatically treated dissolving pulp and a comparison between viscose made from enzyme-treated pulp and viscose made from conventional pulp, showed that the enzyme-treated samples had a lower filter clogging value, Kw. This indirectly indicates that the enzyme pretreatment could reduce the carbon disulphide charge in the viscose manufacturing process. An initial study of how the Carezyme® influenced different cellulosic sources was also performed.

<p>In conventional viscose manufacturing, a large amount of carbondisulfide is consumed. This amount has to be decreased to keep the production cost down and to reduce the environmental impact. The purpose with this work was to show if an enzyme treatment of a dissolving pulp could increase the degree of substitution in the viscose so that the amount of carbon disulfide consumed in the process could be decreased. Previous investigations by Kvarnlöf (2007), Engström et.al. (2006) and Henriksson et.al. (2005) has shown that the reactivity of a dissolving pulp (the cellulose raw material) increased when it was pre-treated with endoglucanase (enzyme). Kvarnlöf (2007) also showed that the amount of carbon disulfide that is needed to produce an ordinary viscose (in this work a more viscous viscose has been investigated) could be reduced with one third because of the enzyme treatment.</p><p> </p><p>In this thesis, viscose has been manufactured in a laboratory where the process has been adapted to look like the industrial as far as possible. Analyses were done on the viscose viscosity and degree of substitution. A reference curve was made with the percentage carbon disulfide load versus the viscose gamma number (degree of substitution). Then it was investigated how an enzyme treatment of the dissolving pulp affected the viscose. After the enzyme treatment, the manufacturing process for viscose was done in the exact same way as when the reference tests were done. The enzyme used in this thesis was Carezyme which contents endoglucanase. Then the results from the analyses of the viscose manufactured from enzyme treated dissolving pulp and the reference curve was compared. A positive result would have been that viscose manufactured with enzyme treatment gets a higher gamma number than viscose, with the same load of carbon disulfide, manufactured in the regular way.</p><p> </p><p>The results showed that the degree of substitution had no effect at all; the viscose that has been manufactured from enzyme treated dissolving pulp resulted in gamma numbers on or very close to the reference curve. The only effect that could be shown was a decrease in viscosity, which unfortunately was an unwanted effect. The enzyme treatment has also hampered the process, where shorter fibres among other things have given poorer dewatering properties. Analyses on the viscose manufactured in the laboratory showed that it didn't have the same characteristics as viscose manufactured in a plant.</p> / <p>I den konventionella tillverkningsprocessen för viskos förbrukas stora mängder koldisulfid. Denna mängd behöver minskas, både för att hålla nere produktionskostnaderna men också för att minska miljöpåverkan. Syftet med arbetet var att undersöka om en enzymbehandling av en dissolvingmassa kunde öka substitutionsgraden så att koldisulfid-förbrukningen skulle kunna minskas. Det har i flera tidigare undersökningar av Kvarnlöf (2007), Engström m.fl. (2006) och Henriksson m.fl. (2005) visats att reaktiviteten hos en dissolvingmassa (råvaran i viskosprocessen) ökar när den förbehandlats med endoglukanas (enzym). Kvarnlöf (2007) visade dessutom att mängden koldisulfid som behövdes för att tillverka spinnviskos (i detta examensarbete har en viskösare viskos undersökts) kunde minskas med en tredjedel tack vare enzymbehandlingen.</p><p> </p><p>I detta examensarbete har viskos tillverkats i laboratoriet där processen har anpassats så att den liknar den industriella så mycket som möjligt. Analyser gjordes på viskosens viskositet och substitutionsgrad. En referenskurva tillverkades där den procentuella koldisulfid-satsningen plottades mot viskosens gammatal (substitutionsgraden). Därefter undersöktes hur en enzymbehandling av dissolvingmassan påverkade den färdiga viskosen. Efter enzymbehandlingen av dissolvingmassan utfördes tillverkningsprocessen precis som vanligt för att man skulle kunna se effekterna av enzymet. Enzymet som användes i arbetet var enzympreparationen Carezyme som innehåller endoglukanas. Sedan jämfördes resultaten från analyserna av viskosen tillverkad från enzymbehandlad dissolvingmassa med referensvärdena. Ett positivt resultat hade varit att enzymbehandlad viskos hade ett högre gammatal än viskos tillverkad på vanligt sätt utan enzymförbehandling men med samma koldisulfidsats.</p><p> </p><p>Resultaten visar att substitutionsgraden inte har påverkats alls, dvs. den viskos som tillverkats från enzymbehandlad dissolvingmassa fick gammatal som låg på eller mycket nära referenskurvan. Den enda effekt av enzymet som kunde visas var en viskositetssänkning, vilket inte var något som eftersträvades. Processen har dessutom försvårats av enzymsteget, där kortare fibrer bl.a. gav sämre avvattningsegenskaper. Viskosanalyser har visat att viskosen som tillverkats på laboratoriet inte har samma egenskaper som viskos tillverkad på fabrik.</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.

In conventional viscose manufacturing, a large amount of carbondisulfide is consumed. This amount has to be decreased to keep the production cost down and to reduce the environmental impact. The purpose with this work was to show if an enzyme treatment of a dissolving pulp could increase the degree of substitution in the viscose so that the amount of carbon disulfide consumed in the process could be decreased. Previous investigations by Kvarnlöf (2007), Engström et.al. (2006) and Henriksson et.al. (2005) has shown that the reactivity of a dissolving pulp (the cellulose raw material) increased when it was pre-treated with endoglucanase (enzyme). Kvarnlöf (2007) also showed that the amount of carbon disulfide that is needed to produce an ordinary viscose (in this work a more viscous viscose has been investigated) could be reduced with one third because of the enzyme treatment.   In this thesis, viscose has been manufactured in a laboratory where the process has been adapted to look like the industrial as far as possible. Analyses were done on the viscose viscosity and degree of substitution. A reference curve was made with the percentage carbon disulfide load versus the viscose gamma number (degree of substitution). Then it was investigated how an enzyme treatment of the dissolving pulp affected the viscose. After the enzyme treatment, the manufacturing process for viscose was done in the exact same way as when the reference tests were done. The enzyme used in this thesis was Carezyme which contents endoglucanase. Then the results from the analyses of the viscose manufactured from enzyme treated dissolving pulp and the reference curve was compared. A positive result would have been that viscose manufactured with enzyme treatment gets a higher gamma number than viscose, with the same load of carbon disulfide, manufactured in the regular way.   The results showed that the degree of substitution had no effect at all; the viscose that has been manufactured from enzyme treated dissolving pulp resulted in gamma numbers on or very close to the reference curve. The only effect that could be shown was a decrease in viscosity, which unfortunately was an unwanted effect. The enzyme treatment has also hampered the process, where shorter fibres among other things have given poorer dewatering properties. Analyses on the viscose manufactured in the laboratory showed that it didn't have the same characteristics as viscose manufactured in a plant. / I den konventionella tillverkningsprocessen för viskos förbrukas stora mängder koldisulfid. Denna mängd behöver minskas, både för att hålla nere produktionskostnaderna men också för att minska miljöpåverkan. Syftet med arbetet var att undersöka om en enzymbehandling av en dissolvingmassa kunde öka substitutionsgraden så att koldisulfid-förbrukningen skulle kunna minskas. Det har i flera tidigare undersökningar av Kvarnlöf (2007), Engström m.fl. (2006) och Henriksson m.fl. (2005) visats att reaktiviteten hos en dissolvingmassa (råvaran i viskosprocessen) ökar när den förbehandlats med endoglukanas (enzym). Kvarnlöf (2007) visade dessutom att mängden koldisulfid som behövdes för att tillverka spinnviskos (i detta examensarbete har en viskösare viskos undersökts) kunde minskas med en tredjedel tack vare enzymbehandlingen.   I detta examensarbete har viskos tillverkats i laboratoriet där processen har anpassats så att den liknar den industriella så mycket som möjligt. Analyser gjordes på viskosens viskositet och substitutionsgrad. En referenskurva tillverkades där den procentuella koldisulfid-satsningen plottades mot viskosens gammatal (substitutionsgraden). Därefter undersöktes hur en enzymbehandling av dissolvingmassan påverkade den färdiga viskosen. Efter enzymbehandlingen av dissolvingmassan utfördes tillverkningsprocessen precis som vanligt för att man skulle kunna se effekterna av enzymet. Enzymet som användes i arbetet var enzympreparationen Carezyme som innehåller endoglukanas. Sedan jämfördes resultaten från analyserna av viskosen tillverkad från enzymbehandlad dissolvingmassa med referensvärdena. Ett positivt resultat hade varit att enzymbehandlad viskos hade ett högre gammatal än viskos tillverkad på vanligt sätt utan enzymförbehandling men med samma koldisulfidsats.   Resultaten visar att substitutionsgraden inte har påverkats alls, dvs. den viskos som tillverkats från enzymbehandlad dissolvingmassa fick gammatal som låg på eller mycket nära referenskurvan. Den enda effekt av enzymet som kunde visas var en viskositetssänkning, vilket inte var något som eftersträvades. Processen har dessutom försvårats av enzymsteget, där kortare fibrer bl.a. gav sämre avvattningsegenskaper. Viskosanalyser har visat att viskosen som tillverkats på laboratoriet inte har samma egenskaper som viskos tillverkad på fabrik.

The textile industry is one of the largest industries in the world and it causes up to 10 % of the global greenhouse gas emissions. With large environmental issues of cotton- and oil-based textiles, other options are explored such as man-made fibers producing fibers like viscose and lyocell. Renewcell is a sustaintech company within textile recycling, producing Circulose®. Circulose® is a dissolving pulp made from 100 % recycled cotton material. It can be used to produce man-made fibers such as viscose or lyocell. The viscose process uses chemical modification to make man-made fibers for the textile industry. The process has changed during the years, but the main steps remains the same and was the outline for the method used in this thesis.  The aim of the thesis was to examine the mechanical properties dry tenacity, dry elongation and dry titer and how these change for various viscose filaments made from recycled cotton textile pulp and dissolving wood pulp from softwood. Evaluating the impact that different spinning conditions had on the mechanical properties. Quality of the viscose dope and the viscose filament was analyzed with ball-fall, filterability and microscopic imaging. The purpose was to gain an understanding for the new dissolving pulp made from recycled cotton textile pulp when used to produce viscose dope and viscose filament. By varying the spinning conditions, the impact it had on the mechanical properties for viscose filaments made of recycled cotton textile pulp could be evaluated.  In this thesis, 4 different types of viscose filaments were examined: 100 % dissolving wood pulp; 100 % recycled cotton textile pulp; a blend of 50 % recycled cotton textile pulp and 50 % dissolving wood pulp; and a blend of 70 % recycled cotton textile pulp and 30 % dissolving wood pulp. The filaments were produced by preparing a viscose dope from dissolving pulp, followed by wet spinning. The result showed that good viscose dopes and viscose filaments could be produced from all pulps and blends. Similar mechanical properties was obtained for 100 % dissolving wood pulp and 100 % recycled cotton textile pulp. The tenacity and titer changed with the different blends, and the spinning conditions affected mostly the elongation. The viscose dope’s containing recycled cotton textile pulp eventually had lumps forming and a slight increase in breakage.  The conclusion of this thesis was that viscose filament of 100 % recycled cotton textile pulp and blends with recycled cotton textile pulp was successfully spun, the mechanical properties obtained was promising and showed great possibilities for improvement by altering the spinning conditions. Using a larger amount of recycled cotton textile pulp could lower some sustainability issues regarding the viscose production. Several aspects of the laboratory viscose process can be improved by further research. A focus on optimizing the viscose dope and synthetic fiber handling, analyzing the black particles, lowering lumps and breakage for the viscose containing recycled cotton textile pulp would be optimal. / Textilindustrin är idag en av de största industrierna i världen och orsakar upp till 10 % av de globala växthusgaserna. Det finns stora miljöproblem med bomull och olje-baserade textilier, därför utforskas andra alternativ som till exempel regenererade cellulosafiber som lyocell och viskos. Renewcell är ett sustaintech företag med fokus på textilåtervinning och tillverkar produkten Circulose®. Circulose® är en dissolvingmassa tillverkad av 100 % återvunnet bomullsmaterial, det kan användas för att tillverka regenererade cellulosafiber så som viskos och lyocell. Viskosprocessen använder kemiska modifieringar för att få fram regenererade cellulosafiber som sedan till exempel kan användas i textilier. Viskosprocessen har ändrats under åren men de huvudsakliga stegen kvarstår och har använts som riktlinje för metoden i denna studie.  Målet med detta arbete var att undersöka de mekaniska egenskaperna torr brottstyrka, torr maximal töjning före brott och torr vikt per längdenhet for viskosfilament, samt hur det förändras för olika viskosfilament tillverkade av återvunnen bomullstextilmassa och dissolving vedmassa av barrved. Påverkan som olika spinnförhållanden hade på de mekaniska egenskaperna analyserades. Kvaliteten på viskosdop och viskosfilament att utvärderas med kulfall, filtrerbarhet och mikroskopi. Syftet var att få en ökad förståelse för den nya dissolvingmassan tillverkad av återvunnen bomullstextil när den används för att tillverka viskosdop och viskosfilament. Genom att variera spinnförhållandena kunna utvärdera inverkan på de mekaniska egenskaperna hos viskosfilament av återvunnen bomullstextilmassa.  I detta arbete undersöktes 4 olika typer av viskosfilament, 100 % dissolving vedmassa, 100 % återvunnen bomullstextilmassa, en blandning med 50 % återvunnen bomulls textilmassa och 50 % dissolving vedmassa och en blandning med 70 % återvunnen bomullstextilmassa och 30 % dissolving vedmassa. Filament tillverkades genom framställning av viskosdop från dissolvingmassa följt av våt-spinning. Resultatet visade att bra viskosdop och viskosfilament kunde framställas utifrån alla massor och blandningar. Liknande mekaniska egenskaper uppnåddes för 100 % dissolving vedmassa och 100 % återvunnen bomullstextilmassa. Brottstyrka och vikt per längdenhet varierade för olika blandningar, variationen i spinningförhållande påverkade mestadels maximala töjningen. Mer klumpar och brott uppstod för spinning av viskosdop bestående av återvunnen bomulls textilmassa.  Slutsatsen för detta arbete var att viskosfilament av 100 % återvunnen bomulls textilmassa och blandningar innehållande återvunnen bomullstextilmassa kunde med framgång spinnas, de erhållna mekaniska egenskaperna var lovande och visade på stora förbättringsmöjligheter genom att variera spinningsförhållanden. Att använda en större mängd återvunnen bomullstextilmassa skulle kunna förbättra vissa hållbarhetsaspekter gällande viskosproduktionen. Flera aspekter av laboratorieviskosprocessen kan förbättras genom ytterligare forskning. Ett fokus på att optimera viskosdopar och syntetfiberhantering, undersöka svarta partiklar, minska klumpar och brott för viskos innehållande återvunnen bomullstextilmassa skulle vara optimalt.

The purpose of this thesis is, in collaboration with the Swedish company Innventia, to explore the possibilities of using paper machines to create fabric-like nonwoven materials. As part of a relatively new research-area, it serves as some of the ground knowledge that is needed to drive this field forward. The research of this thesis is born from the increasing need for more environmental friendly textiles, and to find new uses for the paper production facilities and companies that are currently experiencing a decline in paper production. The materials used in the research were produced with the Finnish handsheet former and the StratEx sheet-maker made by Innventia. The research consists of the following tests: Tissue Softness Analysis, (TSA), tensile strength and bending stiffness. The tests are done with different combinations of lyocell, PLA, softwood and dissolving pulp in the tested sheets. It is also tested if the lyocell can be a meaningful substitution for PLA in combination with softwood pulp and dissolving pulp when creating the fabric-like materials. In conclusion of this research it can be said that, compared to benchmarking samples like bedding sheets, table cloths and cotton shirts, the sheets created and tested are competitive alternatives to existing materials when it comes to softness. It also became clear that the tensile strength has to be increased to make fabric-like nonwoven materials applicable on the same level as existing textiles. Even so, it is still evident that there is a potentiality in the use of paper machines in the development and creation of new fabric-like materials.

This thesis forms part of a project with the objective of developing and implementing a novel, wood-based, process for the industrial production of cellulose textile fibres. This new process should not only be cost effective but also have far less environmental impact then current processes. Natural and man-made fibres are usually plagued with problems (e.g. economic and environmental) and are unsuitable in meeting growing demands. The focus of this thesis was therefore to investigate the dissolution of cellulose derived from various pulps in novel aqueous solvent systems.             It was shown that cellulose could be dissolved in a NaOH/H2O solvent at low temperatures (&lt;0°C) and that such an alkaline solvent can be improved regarding the solubility, stability and rheological properties of the cellulose dopes formed if different additives (salts or amphiphilic molecules) are used. The effect of different kinds of pretreatment (individually and combined) and the influence of pulp properties on cellulose accessibility and dissolution were also evaluated. These pretreatments affected, as expected, some characteristic properties of the pulps mainly by reducing the DP but also, for example, changing the composition of the carbohydrates. Not only did the pretreatment affect the solubility it also increased the stability of the cellulose dopes, resembling the effect of chemical additives to the NaOH system. According to multivariate data analysis it was established that, of the pulp properties analyzed, only the composition of carbohydrates and the DP had a significant influence on the solubility of the pulps used in this study. Finally, it was emphasized that the dissolution of cellulose pulps seemed to be controlled by a very complex interaction between both kinetic and thermodynamic parameters. / CelluNova

<p> I viskosprocessens inledande merceriseringssteg behandlas cellulosa (dissolvingmassa) med natriumhydroxid (NaOH) varvid cellulosan omvandlas till alkalicellulosa. Därpå följer en sulfidering med koldisulfid (CS₂) som omvandlar alkalicellulosa till natriumxantogenat. Xantatet löses i en alkalisk lösning och en trögflytande vätska, viskos, bildas. Vid tillverkning av spinnviskos är sista steget i processen en surgörning där koldisulfiden spjälkas av och cellulosan återbildas i form av en tråd. Vid tillverkning av högviskös viskos (Freudenberg HP) sker regenereringen i basisk miljö men vid förhöjd temperatur (100°C), och återbildningen av cellulosa ger då en cellulosabaserad bädd. Genom att öka dissolvingmassans reaktivitet skulle förbrukningen av koldisulfid i sulfideringssteget kunna minskas. Med en ökad reaktivitet menas att fler hydroxylgrupper på cellulosan blir tillgängliga för vidare reaktioner med natriumhydroxid och koldisulfid. Detta skulle kunna möjliggöras med en enzymatisk förbehandling av massan.</p><p>Det första delmålet i projektet var att producera en viskos med hög viskositet i laboratorieskala. Projektets andra mål var att undersöka effekterna av en enzymatisk behandling, med enzymet Carezyme^®, på massans viskositet och reaktivitet.</p><p>En studie gjordes för att se hur olika tider i viskosprocessens andra steg, pressteget, påverkade cellulosahalten och luthalten för alkalicellulosa. Resultaten tydde på att en längre presstid gav en högre cellulosahalt upp till en viss tidpunkt. Vid 195 sekunder avklingade kurvan och effekten av en längre presstid minskade. Resultatet visade också på att mängden lut i alkalicellulosaprovet var relativt konstant och att luthalten inte påverkas nämnvärt av pressningen.</p><p>Vidare genomfördes försök kring viskosprocessens sulfideringssteg. Det fanns under projektets gång stora svårigheter i att uppnå samma höga nivå på gammatalet vid produktion av viskos i laborativ skala (52-58 %) som vid produktion i fabriksskala (68-70 %). Gammatalet är ett mått på hur väl koldisulfid har reagerat med cellulosa under sulfideringen. I ett försök att öka gammatalet satsades en större mängd koldisulfid, med förhoppningen att kunna kompensera för den relativt stora andel koldisulfid som befann sig i gasfas under reaktionen och som därmed inte var aktiv under sulfideringen. Den ökade mängden koldisulfid resulterade dock inte i en ökning av gammatalet. I ett annat försök tillsattes en svag natriumhydroxidlösning direkt till sulfideringskärlet vid avslutad reaktion, utan att någon effekt på gammatalet kunde påvisas. Det undersöktes även om ett ökat förhållande mellan luthalt och cellulosahalt i alkalicellulosan kunde ge någon positiv effekt på gammatalet. Denna förändring gav dock inget ökat gammatal.   </p><p>Dissolvingmassaprover behandlades med enzymet Carezyme^® för att kunna studera dess inverkan på massans reaktivitet och viskositet.  Resultaten visade på en tydlig nedgång i viskositet med högre koncentrationer av enzym. Reaktiviteten på den enzymbehandlade massan ökade i jämförelse med den obehandlade massan. Då viskos producerades med en enzymbehandlad massa kunde ingen effekt av enzymbehandlingen noteras, med avseende på gammatalet.</p><p> </p> / <p>In the first step of the conventional viscose process, called mercerization, cellulose (dissolving pulp) is treated with sodium hydroxide (NaOH) in which the cellulose is converted to alkali cellulose. Alkali cellulose is then treated with carbon disulphide (CS₂) to be converted into a sodium xanthate.  This xanthate is dissolved in an alkali solution and a viscous liquid, called viscose, is formed. The last step in the process is an acidification where the carbon disulphide is splinted off and the cellulose is regenerated in the shape of threads. When producing high viscosity viscose (Freudenberg HP) the regeneration takes place in an alkaline environment and the re-formation of cellulose gives a cellulosic based bed. By increasing the reactivity of the dissolving pulp the amount of carbon disulphide could be reduced, compared at the same degree of substitution. An increase in reactivity means that a larger amount of hydroxyl groups on the cellulose molecule are available to react with sodium hydroxide and carbon disulphide. This could be enabled by an enzymatic pretreatment of the pulp prior to the mercerization step.</p><p>The first aim of this project was to produce a high viscosity viscose in a laboratory scale, comparable to the viscose quality that is produced by Freudenberg HP. The second aim of the project was to investigate the effects of an enzymatic treatment (with the enzyme named Carezyme^®) on the viscosity and reactivity of the dissolving pulp. </p><p>A study was made to examine the influence of the time in the pressing step (after the mercerization) on the cellulose and sodium hydroxide content in the alkali cellulose. The results indicated a linear correlation between the cellulose content and the pressing time up to 195 seconds. At this point the correlation declined and the effects of a longer pressing time decreased. The results also showed that the amount of lye in the alkali cellulose sample was nearly constant and therefore not effected by the pressing time.</p><p>Tests were also carried out concerning the sulphidation step in the process. During the whole project there were difficulties in reaching the same gamma value of the viscose in a laboratory scale (52-58 %) compared to large-scale production (68 - 70%). The gamma value is a measurement of the degree of substitution for carbon disulphide on the cellulose backbone. In one attempt to enhance the gamma value the carbon disulphide charge was increased. The expectation was to compensate for the relatively high amounts of inactive carbon disulphide expected to be found in the gaseous phase in the reactor. However, this did not result in a higher gamma value. In another experiment a weak solution of sodium hydroxide was added directly to the sulphidation vessel after the reaction was completed, but no change in the gamma value was obtained. It was also investigated if an increased relation between the cellulose- and sodium hydroxide content in the alkali cellulose could affect the gamma value positively.  Unfortunately, this modification did not give an increased gamma value.</p><p>Samples of dissolving pulp were treated with the enzyme Carezyme^® to see its impact on viscosity and reactivity of the pulp. The results showed a distinct loss in viscosity with an increased enzyme concentration. The reactivity of the pulp increased compared to the untreated pulp. No effects of the enzymatic treatment could be seen on the final viscose when it was produced from an enzyme treated pulp.</p>

<p>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>