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From the moment of production, paper as a printing substrate is exposed to the process of natural ageing regardless of the type of cellulose fibres in its composition. Accordingly, the prints produced by the various printing techniques are also exposed to several factors that impair the quality of the print i.e. its colour over time. Therefore, it is very important to properly select the printing substrate for achieving a high quality of graphic products. For that purpose, three types of papers with hemp fibres were used as printing substrates which were printed with laboratory hand-operated instrument Esiproof using flexographic cyan (C), magenta (M), yellow (Y) and black (K) water-based inks. Prints were artificially aged in SunTEST XLS+ test chamber according to standard ASTM D 6789-02 for 48 and 96 hours. Based on changes in the reflectance spectra of each printed ink after exposure to electromagnetic radiation it was noticed how composition of printing substrate strongly influence on colour stability of prints due time. An increase of exposure time to electromagnetic radiation leads to a decrease in the value of the reflectance of the printing substrate and cyan, magenta and yellow prints. It was confirmed how electromagnetic radiation have the greatest impact on the reflectance of yellow print, while the black one is the most stabile regardless of the substrate it was printed on.

Aquest treball és la continuació directa del treball de final de grau "Estudi de la viabilitat de la fabricació de panells aïllants tèrmics amb residus de cànem" de l'Andrea Avellaneda Garcia, el qual tenia com a objectiu la realització de prototips reduïts de panells aïllants tèrmics a partir de la combinació de la canemuixa i de fibres papereres d'origen verge. En aquell treball es va produir satisfactòriament una sèrie de provetes amb diferents percentatges de materials, els quals obtenien bons resultats en propietats tant tèrmiques com mecàniques. Així doncs, era viable la fabricació de panells aïllants. És aquí on comença aquest estudi el qual utilitzaria la metodologia més eficaç de fabricació de l'anterior, tot i que en aquest cas no se centri en l'eficàcia dels panells en aïllament tèrmic, sinó que l'estudi es centra en l'obtenció d'un material aïllant acústic. A més a més s'introdueix una nova tècnica de fabricació, que consisteix en el recobriment superficial del material amb resines com són la goma aràbiga i la colofònia diluïdes, amb l'objectiu d'obtenir un material resistent a la humitat. Primerament, es realitza la fabricació de prototips de proves compostos amb canemuixa i un producte paperer totalment verge. Per aquestes proves es fa un assaig acústic per comprovar que el mètode de fabricació usat aconsegueix unes provetes igualment estables i amb uns valors d'aïllament acústic acceptables. Un cop verificada l'eficàcia del mètode de producció de provetes, es decideix substituir el producte paperer verge, per un de reciclat com és el cartó de caixes ja usades. Amb aquest nou material es pretén comprovar si millora en propietats acústiques i mecàniques, com també s'introdueix per donar-li un enfocament encara més fidel a l'economia circular i a la reutilització de materials, que en el cas anterior només s'aplicava en la utilització de la canemuixa. Utilitzant el mateix mètode que en les provetes de canemuixa amb paper, es produeixen una sèrie de provetes amb diferents percentatges de canemuixa i cartó, les quals seran sotmeses a una sèrie de proves de resistència mecànica i aïllament acústic per comprovar l'eficàcia d'aquest nou producte. S'observa que els resultats obtinguts en aquest nou producte són millors tant mecànicament com en termes d'aïllament del so, a més a més d'aconseguir un biomaterial igual d'homogeni i adherència que l'anterior. Un cop aconseguit el nou biomaterial, es procedeix a la fabricació de panells aïllants de dimensions industrials (880x410mm), els quals estaran sotmesos a una prova de flexió per a provar la seva estabilitat dimensional. Els resultats assolits seran satisfactoris, i el panell serà compacte i estable i, per tant, s'arriba a la conclusió que, certament, és possible fer panells aïllants acústics de dimensions industrials, amb residus de cànem i cartó reciclat

El desarrollo y la investigación de nuevos productos que puedan sustituir parcial o completamente materias primas empleadas para la producción de energía, productos químicos de alto valor añadido e incluso la fabricación de papel, ha permitido que el cáñamo industrial (Cannabis sativa L.) se vuelva atractivo como principal materia prima en la reactivación de una economía de base biológica con altas condiciones y capacidades de producción. A partir de lo anterior, el objetivo de este trabajo investigativo es profundizar sobre el potencial del uso de fibra de cáñamo en la industria del papel, soportado por estudios realizados por el Estado Colombiano en lo referente a las disponibilidad de cultivos forestales con fines comercialesque inicialmente se destinan para la siembra y producción de recursos madereros como el pino y eucalipto. Se ha considerado de importancia demostrar que el cáñamo, como fuente de producción primaria, brinda ventajas competitivas económicas, ambientales y sociales frente a los cultivos tradicionales, incluso para las nuevas fuentes de investigación de base biológica. #Cañamo he research and development of new prod-ucts that could partially or completely replace raw materials used for energy production, high value-added chemical products, and even the production of paper, has allowed industrial hemp (Cannabis sativa L.) to become the main raw material for the reactivation of a bio-based economy with high production conditions and capacities. Based on this, the objective of this research is to deepen on the potential use of hemp fiber in the pa-per industry, supported by studies carried out by the Colombian State regarding the availability of forest crops for commercial purposes, which are basically used for planting and the production of wood resources such as pine and eucalyptus. It has been considered important to demonstrate that hemp, as a source of primary production, provides competitive economic, environmental, and social advantages over traditional crops, even for new sources of bio-based research.

In Werkpakket 1 (uitgevoerd door WUR Plant Breeding) is gezocht naar de meest optimale stammen van Ceriporiopsis subvermispora. Hiervoor zijn 30 stammen (20 homokaryons en 10 kruisingen) binnen de soort C. subvermispora onderzocht op hun vermogen om tarwestro en ingekuild bermgras selectief van hemicellulose en lignine te ontdoen. Op basis van de resultaten van Werkpakket 1 blijken C. subvermispora stammen MES15023 (monokaryon), MES15032 (monokaryon) en MES14706 (dikaryon) het meest selectief in de afbraak van lignine in zowel tarwestro als bermgras en is het resultaat van doorgroeien van de substraten met deze stammen een relatieve verrijking in cellulose. In Werkpakket 3 (eveneens uitgevoerd door WUR Plant Breeding) zijn verschillende typen biomassa voorbehandeld met de uit Werkpakket 1 als beste naar voren komende stammen. Er werd daarbij gewerkt met twee mogelijke toepassingen van het op te leveren behandelde materiaal. Deze toepassingen waren biogasproductie (op basis van tarwestro) en productie van vezelmateriaal voor de papier industrie (op basis van Miscanthus, Natuurgras, Lisdodde, Vlaslemen en Hennepscheven). De bovengenoemde materialen werden doorgroeid met 3 C. subvermispora stammen; MES15032 als beste monokaryon in WP1, MES14706 als beste dikaryon in WP1 en MES13094 als referentie uit de eerdere biogas testen. Het met schimmel doorgroeide materiaal werd op verschillende momenten tijdens de kolonisatie door de schimmels bemonsterd en het bemonsterde materiaal werd geanalyseerd op vezelsamenstelling. Stro substraat raakte (evenals in Werkpakket 1, goed doorgroeid met alle drie de schimmelstammen. Ook Miscanthus, vlaslemen en hennepscheven raakten goed doorgroeid met beide geteste schimmelstammen. In tegenstelling tot tarwestro en miscanthus, raakte het natuurgras substraat slechts met moeite doorgroeid. Lisdodde raakte nauwelijks gekoloniseerd door beide geteste schimmelstammen. Uitgaande van de selectieve verrijking van substraten met cellulose (door afbraak van hemicellulose en lignine) bleek vooral na 8 weken incubatie het relatieve gehalte aan cellulose in het tarwestro sterk omhoog te zijn gegaan, ten koste van 19% verlies aan droge stof. Na 12 weken was het relatieve gehalte aan cellulose nog sterker gestegen, maar dit ging ten koste van 35% van de droge stof. In Miscanthus steeg de verhouding cellulose/lignine van 4.4 bij aanvang van de schimmelincubatie gestaag naar 9.8 na 19 weken incubatie met stam MES 15032, maar dit ging ten koste van 20% van de droge stof. Stam MES14706 gaf minder goede resultaten te zien (cellulose/lignine verhouding 6.4 na 19 weken incubatie). Vlaslemen , natuurgras en hennepscheven werden uitsluitend geanalyseerd na 12 weken doorgroeiing met de schimmels. In geval van vlaslemen steeg de verhouding cellulose/lignine van 2.1 bij aanvang naar 6.6 na 12 weken incubatie met stam MES15032. Dit ging echter ten koste van 24% van de droge stof. Bij stam MES14706 steeg de verhouding cellulose/lignine slechts naar een waarde 3.4 na 12 weken incubatie. In natuurgras steeg de verhouding cellulose/lignine niet erg sterk na 12 weken incubatie met de schimmels, maar er verdween wel ongeveer 44% (MES14706) en 49% (MES15032) van de droge stof. In natuurgras bleek de afbraak niet erg selectief; zowel cellulose, hemicellulose als lignine werden allemaal afgebroken. In geval van hennepscheven steeg de verhouding cellulose/lignine bijzonder sterk na 12 weken incubatie met MES15032; van 3.6 bij aanvang naar 18.5 na 12 weken. Dit ging echter ten koste van 50% van de droge stof. Bij incubatie met MES14706 steeg de verhouding cellulose/lignine na 12 weken incubatie naar 7.1 en dit ging ten koste van 37% van de droge stof. Vanwege de slechte kolonisatie van lisdodde door de beide schimmels is besloten om dit substraat niet verder te analyseren. Binnen Werkpakket 5 zijn door CNC Grondstoffen een reeks aan experimenten uitgevoerd gericht op het opschalen van de teelt van C. subvermispora. In de commerciele praktijk wordt een substraat bedoeld voor schimmelkweek gepasteuriseerd door het substraat door eigen microbiele activiteit te laten opwarmen tot waarden rond 60-65oC. De door CNC Grondstoffen uitgevoerde experimenten hebben echter geen van allen succes gehad. In de solid state fermentor bleek het niet mogelijk om de gewenste temperaturen te bereiken. In een experiment waarin gebruik is gemaakt van commercieel beschikbaar substraat op basis van tarwestro bleek echter dat Ceriporiopsis subvermispora niet in staat bleek om dat substraat te koloniseren (terwijl schimmels zoals Pleurotus ostreatus (de oesterzwam) en Lentinula edodes (shiitake) daar in de commerciële praktijk geen enkel probleem mee hebben. Mogelijk heeft C. subvermispora een probleem met de hoge pH van het commerciële substraat. Pogingen om een selectief substraat te maken door tarwestro te verzuren met citroenzuur waren echter eveneens niet succesvol. Het is duidelijk dat de opschaling van het systeem nog enig werk behoeft.

Cotton and oil-based fibre consumption is highly problematic because the growth of these materials often requires fertilisers and toxic pesticides. Less environmentally damaging alternative fibres are urgently required. This study investigates Manila-hemp paper-yarn textile fabrics. Manila-hemp (abacá) is a species of banana grown as a commercial crop in the Philippines, Ecuador, and Costa Rica. Knitted structures of paper, cotton, viscose, and polyester yarns are tested and compared. Tensile strength tests are also performed. Paper yarn shows low shrinkage and no pilling, which are excellent characteristics for use in the textile and clothing industries. However, its poor handleability/knittability, high stiffness, and hard grip must be resolved for the widespread application of paper yarn in the textile industry in the future.

International audience; The hemp plant Cannabis sativa Linn, referring to industrial hemp, is a high-yielding annual industrial crop grown providing fibers from hemp stalk and oil from hemp seeds. Although hemp is a niche crop, hemp production is currently undergoing a renaissance. More than 30 countries grow hemp, with China being the largest hemp producing and exporting country. Europe and Canada are also important actors in the global hemp market. Traditionally, hemp as a fiber plant has been used for the production of apparels, fabrics, papers, cordages and building materials. The hurds, as waste by-product of fiber production, were used for bedding of animals, the seeds for human nutrition, e.g., as flour, and the oil for a wide range of purposes, from cooking to cosmetics. Hemp has also been an important crop throughout human history for medicine. Other more recent applications include materials for insulation and furniture, automotive composites for interior applications and motor vehicle parts, bioplastics, jewelry and fashion sectors, animal feed, animal bedding, and energy and fuel production. Foods containing hemp seed and oil are currently marketed worldwide for both animal and human nutrition. They also find applications in beverages and in neutraceutical products. Hemp oil is also used for cosmetics and personal care items, paints, printing inks, detergents and solvents. It is estimated that the global market for hemp consists of more than 25,000 products. Currently, the construction and insulation sector, paper and textile industries, and food and nutrition domains are the main markets while the cosmetics and automotive sector are growing markets. Innovative applications, e.g., in the medical and therapeutic domains, cosmeceuticals, phytoremediation, acoustic domain, wastewater treatment, biofuels, biopesticides and biotechnology, open new challenges. Hemp is also the object of numerous fundamental studies. This review presents and discusses the traditional and new uses of industrial hemp.

Lignocellulosic crops like kenaf, flax and hemp have been extensively studied the last years with the help of new technology and many new products fabricated with them are ready for the market or have already been marketed. Both the core material and the bast fibers of these crops are ideal feedstocks for the production of yarns and paper of high quality, for rendering flame retardant properties to composites reinforced with them, for the production of energy via a sustainable way without polluting the environment and for use as alternative materials to wood for the manufacturing of panels like particleboards and fiber boards (MDF, HDF, etc.). The investigation of lignocellulosic feedstock as potential source for the sustainable production of materials, products and energy has resulted in promising solutions for the successful replacement of their counterparts made from fossil raw materials. However, the related industries still have some challenges to face, like the cost of materials from lignocellulosic plants in comparison with those derived from fossil sources and the availability of the feedstock throughout the year.

The goal of this study was to prove the feasibility of fiber and paper production from hemp. Experimental tests of the properties of paper obtained from hemp woody core fibers were performed. Fibers from hemp woody core were isolated by a chemical-thermo-mechanical procedure. Sheets of paper were made from thus isolated fibers. The mechanical and optical properties of the paper sheets were also examined. The properties of paper sheets obtained from spruce and beach fibers were examined in the same way for comparison. The obtained results showed that paper produced from fiber isolated from hemp woody core by a chemical-thermo-mechanical procedure had poorer properties than the properties of paper produced from beech and spruce fibers, but it still satisfied conditions for producing low quality newspaper.

Bu araştırmada, buğday sapları, kendir lifleri, iğne yapraklı ağaçlardan kızılçam ve yapraklı ağaçlardan kavak odunu yongalarından modifiye soda-oksijen ve sülfat kağıt hamuru üretim yöntemleriyle optimum üretim koşullarının belirlenmesi amaçlanmıştır.Bu çalışmada, Buğday saplarından sodyum borhidrür(NaBH4) ilaveli soda-oksijen yöntemi ve kızılçam ve kavak odunu yongarı ve kendir liflerinden sülfat-sodyum borhidrür yöntemiyle kağıt hamurları ve kağıtlar üretilmiş ve NaBH4'ün hamur verimi ve elde edilen kağıtların bazı kimyasal, fiziksel ve optik özellikleri üzerine etkisi incelenmiştir. Optimum pişirme parametrelerini belirlemek için her bir hammadde için 1 kontrol 9 normal pişirme deneyleri yapılmıştır. İlave edilen NaBH4 oranına bağlı olarak elenmiş hamur veriminin, hamur viskozitesinin ve polimerizasyn derecesinin arttığı, kappa numarasının azaldığı tespit edilmiştir. Bununla birlikte, NaBH4 oranındaki artışa paralel olarak elde edilen kağıtların parlaklık, opaklık, kopma uzunluğu, patlama indisi ve yırtılma indisi değerleri de artmıştır.Sonuç olarak, soda-oksijen yöntemine göre soda-oksijen-sodyum borhidrür yönteminde buğday sapı hamurlarında verim %6.2, sülfat yöntemine göre sülfat-sodyum borhidrür yönteminde kendir lifi hamurlarında verim %15.66, kızılçam hamurlarında verim %1.6 ve kavak hamurlarında verim %3.41 daha yüksek tespit edilmiştir. In this research, the aim was determination of optimal pulp and paper production conditions with modified soda-oxygen and sulfate methods, from wheat straw, hemp (Cannabis sativa L.)bast fibers, red pine (Pinus brutia Ten.) and poplar (Populus nigra L.) wood.In this study, NaBH4 modified soda-oxygen and sulfate pulping was performed by using wheat straw, hemp bast fibers, red pine and poplar wood and the effects of NaBH4 addition on the some chemical properties of pulps, physical and optical properties of resultant papers were investigated. In order to determine the optimum cooking parameters for each of the raw materials, 1 control and 9 normal different cooking experiments were performed. It was noted that the increasing level of NaBH4 improved the screened pulp yield, pulp viscosity and degree of polymerization, reduced the kappa number. However, the brightness, opacity, breaking length, burst index and tear index of handsheets increased by NaBH4 additions.Consequently, total pulp yields were increased in wheat straw (6.2%) NaBH4 added soda-oxygen pulp those of soda-oxygen one by about, hemp bast fibers (15.66%), red pine wood (1.6%) and poplar wood (3.41%) NaBH4 added sulfate pulp those of sulfate one by about. 126

The aim of this thesis is to elucidate alkaline processing of hemp woody core, supporting the development and optimization of an efficient and non-polluting pulping process. This study has been a constituent of an integral programme to study fibre hemp.It is known that the outer part of the fibre hemp stem can be used for textile and specialty paper purposes. The inner part consists of hemp woody core, which resembles hardwood and might be processed similarly for paper pulp. Literature data and prefeasibility studies show that alkaline processes can be used to produce hemp woody core pulp for papermaking.Alkaline processes, based on sodium hydroxide (NaOH) are used for many wood and non-wood species. The most important process is the kraft process, but alternative NaOH based processes for pulp production have been investigated too. The currently developed alkaline process for high yield hardwood pulping may also be implemented for hemp woody core.Pulp mixes for papermaking can vary, depending on the available fibre sources. The technological developments and the growing market outlet for hardwood fibres increase the possibilities to use hemp woody core for papermaking.In chapter 2 swelling of hemp woody core chips after alkaline (peroxide) impregnation at 70 °C has been studied, as is practised in alkaline peroxide mechanical pulping (APMP) processes. Swelling of hemp woody core chips has been examined in relation to pulp yield and chemical composition of the chips after impregnation.In contrast to wood chips, maximum swelling is attained at 70 °C without chemical treatment, possibly as the result of relatively high porosity of hemp woody core cell walls.Alkaline swelling at 70 °C correlates with the xylan:lignin ratio. Swelling at ambient temperature shows some correlation with acidic group content.Apparent pore size distributions have been examined, using 1H NMR spin-spin relaxation. Several apparent pore size distributions can be distinguished within each sample. Elevated temperature, NaOH and peroxide addition influence the apparent pore size distribution and the total pore volume in different ways.Addition of peroxide results in remark-able increase of the apparent pore sizes. This emphasizes its importance, not only as bleaching chemical in the APMP process, but also promoting fibre flexibility.Alkaline delignification of hemp woody core is studied in chapter 3. Shavings of hemp woody core were delignified isothermally at several temperatures with 1M NaOH in a flow-through reactor. From literature data and from experimental data reported in this chapter, it appears that the initial delignification stage is completed before customary reaction temperatures are reached. Consequently, modelling of alkaline delignification kinetics can be restricted to the bulk and residual delignification stages. This can be described with two simultaneous first order reactions: L/L0 = a2 exp (-k2t) + a3 exp (-k3t), with ki = Ai exp -Eai/(RT).This equation has been solved integrally, calculating a2, a3, Ea2, Ea3, A2 and A3 for the best fit for the experimental data, resulting in an accurate description of the delignification reactions. This kinetic model has also been applied on literature data, supporting its validity for alkaline delignification kinetics in general.This model is also used in chapter 4, to describe the kinetics of alkaline delignification in more detail, and to describe the degradation of xylan and cellulose. Shavings of hemp woody core were impregnated at room temperature with various NaOH concentra-tions (0.25-2.0M) and delignified isothermally at various reaction temperatures (150-180 °C) in a flow-through reactor.Extraction and degradation of xylan from hemp woody core strongly depends on NaOH concentration. Consequently, to attain a certain lignin content, lower NaOH concentrations result in higher pulp yields. Extended pulping diminishes the differences in pulp yields, due to further xylan degradation.The kinetics of lignin, xylan and cellulose degradation are modelled as a function of reaction time, temperature and NaOH concentration. The combined models resulted in a pulp yield model for hemp woody core, suitable for process optimization purposes. Degradation kinetics of perennial wood can be modelled similarly, which was illustrated using literature data on spruce and poplar.In chapter 5 strength and surface properties of test sheets, produced from alkaline hemp woody core pulp were examined. The development of bulk and tear with beating are similar as found for straw pulp; maximum tear strength is attained without beating. Burst and tensile strength, scattering and opacity develop similarly as for hardwood pulps, with less mechanical energy needed. Tear strength is not affected by pulp yield or composition, whereas lower tensile and burst strength are found with decreased yield and lower xylan content.As the paper strength and surface properties of hemp woody core pulp are comparable with those for hardwood and straw pulps, it is conceivable that similar amounts of alkaline hemp woody core pulp can be used in pulp mixes for printing paper grades.The polymerization degree (DP) of hemp woody core pulps has been related to the paper strength properties, and modelled as function of pulping conditions and time.The influence of NaOH concentration on depolymerization and cellulose degradation is much stronger than reported in literature for other pulps. This may be related to the low density of hemp woody core, preventing diffusion effects. Finally, crystallinity has been examined and related to cellulose degradation of alkaline hemp woody core pulp.In chapter 6 the results and conclusions are discussed. It is emphasised that hemp woody core has a lower density than hardwood or softwood. It is suggested that this is the cause for maximal swelling without NaOH addition, the found xylan and yield losses with NaOH impregnation, and the strong dependency of cellulose degradation and depolymerisation on NaOH concentration.In general, it was confirmed that hemp woody core can be delignified similarly as hardwood. The modelling techniques used have been proved to be generally applicable on degradation and depolymerisation kinetics, not only for hemp woody core, but also for hardwood and softwood species. The paper characteristics are comparable both to hardwood and to straw pulp characteristics.

The aim of this thesis is to elucidate alkaline processing of hemp woody core, supporting the development and optimization of an efficient and non-polluting pulping process. This study has been a constituent of an integral programme to study fibre hemp.It is known that the outer part of the fibre hemp stem can be used for textile and specialty paper purposes. The inner part consists of hemp woody core, which resembles hardwood and might be processed similarly for paper pulp. Literature data and prefeasibility studies show that alkaline processes can be used to produce hemp woody core pulp for papermaking.Alkaline processes, based on sodium hydroxide (NaOH) are used for many wood and non-wood species. The most important process is the kraft process, but alternative NaOH based processes for pulp production have been investigated too. The currently developed alkaline process for high yield hardwood pulping may also be implemented for hemp woody core.Pulp mixes for papermaking can vary, depending on the available fibre sources. The technological developments and the growing market outlet for hardwood fibres increase the possibilities to use hemp woody core for papermaking.In chapter 2 swelling of hemp woody core chips after alkaline (peroxide) impregnation at 70 °C has been studied, as is practised in alkaline peroxide mechanical pulping (APMP) processes. Swelling of hemp woody core chips has been examined in relation to pulp yield and chemical composition of the chips after impregnation.In contrast to wood chips, maximum swelling is attained at 70 °C without chemical treatment, possibly as the result of relatively high porosity of hemp woody core cell walls.Alkaline swelling at 70 °C correlates with the xylan:lignin ratio. Swelling at ambient temperature shows some correlation with acidic group content.Apparent pore size distributions have been examined, using 1H NMR spin-spin relaxation. Several apparent pore size distributions can be distinguished within each sample. Elevated temperature, NaOH and peroxide addition influence the apparent pore size distribution and the total pore volume in different ways.Addition of peroxide results in remark-able increase of the apparent pore sizes. This emphasizes its importance, not only as bleaching chemical in the APMP process, but also promoting fibre flexibility.Alkaline delignification of hemp woody core is studied in chapter 3. Shavings of hemp woody core were delignified isothermally at several temperatures with 1M NaOH in a flow-through reactor. From literature data and from experimental data reported in this chapter, it appears that the initial delignification stage is completed before customary reaction temperatures are reached. Consequently, modelling of alkaline delignification kinetics can be restricted to the bulk and residual delignification stages. This can be described with two simultaneous first order reactions: L/L0 = a2 exp (-k2t) + a3 exp (-k3t), with ki = Ai exp -Eai/(RT).This equation has been solved integrally, calculating a2, a3, Ea2, Ea3, A2 and A3 for the best fit for the experimental data, resulting in an accurate description of the delignification reactions. This kinetic model has also been applied on literature data, supporting its validity for alkaline delignification kinetics in general.This model is also used in chapter 4, to describe the kinetics of alkaline delignification in more detail, and to describe the degradation of xylan and cellulose. Shavings of hemp woody core were impregnated at room temperature with various NaOH concentra-tions (0.25-2.0M) and delignified isothermally at various reaction temperatures (150-180 °C) in a flow-through reactor.Extraction and degradation of xylan from hemp woody core strongly depends on NaOH concentration. Consequently, to attain a certain lignin content, lower NaOH concentrations result in higher pulp yields. Extended pulping diminishes the differences in pulp yields, due to further xylan degradation.The kinetics of lignin, xylan and cellulose degradation are modelled as a function of reaction time, temperature and NaOH concentration. The combined models resulted in a pulp yield model for hemp woody core, suitable for process optimization purposes. Degradation kinetics of perennial wood can be modelled similarly, which was illustrated using literature data on spruce and poplar.In chapter 5 strength and surface properties of test sheets, produced from alkaline hemp woody core pulp were examined. The development of bulk and tear with beating are similar as found for straw pulp; maximum tear strength is attained without beating. Burst and tensile strength, scattering and opacity develop similarly as for hardwood pulps, with less mechanical energy needed. Tear strength is not affected by pulp yield or composition, whereas lower tensile and burst strength are found with decreased yield and lower xylan content.As the paper strength and surface properties of hemp woody core pulp are comparable with those for hardwood and straw pulps, it is conceivable that similar amounts of alkaline hemp woody core pulp can be used in pulp mixes for printing paper grades.The polymerization degree (DP) of hemp woody core pulps has been related to the paper strength properties, and modelled as function of pulping conditions and time.The influence of NaOH concentration on depolymerization and cellulose degradation is much stronger than reported in literature for other pulps. This may be related to the low density of hemp woody core, preventing diffusion effects. Finally, crystallinity has been examined and related to cellulose degradation of alkaline hemp woody core pulp.In chapter 6 the results and conclusions are discussed. It is emphasised that hemp woody core has a lower density than hardwood or softwood. It is suggested that this is the cause for maximal swelling without NaOH addition, the found xylan and yield losses with NaOH impregnation, and the strong dependency of cellulose degradation and depolymerisation on NaOH concentration.In general, it was confirmed that hemp woody core can be delignified similarly as hardwood. The modelling techniques used have been proved to be generally applicable on degradation and depolymerisation kinetics, not only for hemp woody core, but also for hardwood and softwood species. The paper characteristics are comparable both to hardwood and to straw pulp characteristics.