Influence on off-gassing during storage of Scots pine wood pellets produced from sawdust with different extractive contents

Off-gassing and self-heating are the major challenges when it comes to transportation and storage of wood pellets. The heat generated due to self-heating poses a fire risk while off-gassing of toxic gasses such as carbon monoxide (CO) and some volatile organic compounds (VOCs) is an environmental and human health risk. With the increase in production volumes of wood pellets which has subsequently increased the amounts of wood pellets in transportation and storage, there is need to find lasting solutions to off-gassing and self-heating of wood pellets. The objective of this study was to test the off-gassing abilities of Scots pine wood pellets produced from sawdust with varying amounts of extractives. The aim is to come up with raw material pre-treatment measures so as to produce wood pellets that are not liable to off-gassing. Six (6) types of sawdust raw materials namely; fresh pine sawdust (FPS), stored pine sawdust (SPS), sawdust plus pine rosin (PRS), sawdust plus linseed oil (LOS), sawdust plus tall oil (TOS) and acetone extracted sawdust (AES) were used to produce the pellets. The produced pellets were then subjected to off-gassing tests under controlled conditions using the ECOM J2KN analyser. The concentrations of carbon monoxide, carbon dioxide and methane increased with storage time but slowed down towards the end of the nine days test period. The formation of these gasses were largely dependent on the type of extractives present in the raw material and not the total extractive content. The formation of methane started later than the other gases and coincided with the time when residual oxygen was depleted

Understanding Off-Gassing of Biofuel Wood Pellets Using Pellets Produced from Pure Microcrystalline Cellulose with Different Additive Oils

Fuel wood pellets have the tendency of undergoing self-heating and off-gassing during storage and transportation. Self-heating can lead to spontaneous combustion and cause fires while toxic gasses such as carbon monoxide and some volatile organic compounds released due to off-gassing are a human health and environmental hazard. Previous research suggests that the self-heating and off-gassing of wood pellets are as a result of the oxidation of wood extractives. The aim of this study was to identify the extractives, i.e., fatty and resin acids that are responsible for the emissions of carbon monoxide, carbon dioxide and methane from wood pellets by testing the off-gassing tendencies of pellets produced from synthetic microcrystalline cellulose and different additive oils. The additive oils were intentionally selected to represent different types of wood extractives (mainly fatty and resin acids) and they included: tall oil, pine rosin, linseed oil and coconut oil. The highest mean concentrations of carbon monoxide, carbon dioxide and methane were recorded from cellulose pellets with added linseed oil. The concentrations of carbon monoxide and methane for the other four pellet types were negligible and there was no carbon dioxide emission. Pellets with added linseed oil had high off-gas emissions due to the high content of unsaturated fatty acids compared to other pellet types

Towards Understanding the Pelletizing Process of Biomass : Perspectives on Energy Efficiency and Pelletability of Pure Substances

The use of fossil resources has to decrease and the use of renewable resources has to increase significantly to mitigate the climate change. In this change towards more renewable resources, biomasses will play an important role, both for energy use and for products. Thus, the utilization of biomasses must be optimized, both linked to which biomass species that are used, as well as the actual production processes. This thesis relates to the production of lignocellulosic biomass pellets, with the purpose to increase the understanding of how a pellet process can be improved.  There are many benefits to pelletize the biomass, such as increased density, more economical transports solutions and increased doseability. However, there is a lack of knowledge on how different biomass species affect the actual pelletizing. This causes pellet producers to strive for a feedstock with a chemical composition that is as uniform as possible, which reduces the possibility of increasing intake of, for example, seasonal or residual products of other kinds. If pellet producers can handle, predict and combine different biomaterials over time without stopping the production, new ways of acquiring raw materials for production would be possible. This will be important for future pellet producers, as the general use of biomasses will increase, so will the competition of the raw material. It will also be of importance in developing countries, which have a greater variation in wood species than today's large pellets producing countries.  This work has been focused on understanding biomasses pelletability, and the method has been to start with components such as, cellulose, hemicellulose, lignin etc. Results shows that there is a significant difference between the hemicelluloses, xylan and glucomannan, in terms of pelletability. During pelletizing, xylan changes its form, generates hard pellets and, correlated to pelletability, xylan are affected by actual moisture content or added water to the process. Glucomannan, however, shows the opposite, a low impact on pelletability and a minimal impact from water during the pelletizing process. A difference that can explain the difference in pelletability, between hardwood and softwood.  Solutions to improve the pelletizing process have also been studied. One result is that adding oxidized starch additive, reduces the energy consumption in the pelletizer and increasing the durability of the pellets, more than native starches. Another result is that a two-stage drying technique, reduces the heat power consumption per tonne of dried materialand at the same time increases the drying capacity. Also, the possibilities for a pellet producer to handle, predict and combine different biomaterials has been studied. Presented results show howbiomasses from Zambia can be used as an single resource or in different resources combinations in a pellet production.  Finally, a recommendation to pellet researchers to include the cellulose material, Avicel, in single pellet studies. By using the same reference material, the methods can be normalized and the pelletability of biomaterials can be validated in a new way. This step would develop the research in the field, and the possibility of increased use of biomass towards the use of more renewable resources in pellet production.För att begränsa klimatpåverkan måste användandet av fossila resurser minska till förmån för förnyelsebara. In denna omställning är och kommer biomassa att bli en mycket viktigresurs att använda tillenergi samt olika produkter. Detta innebär att det är viktigt att både användningen och hanteringen sker resurs- och energieffektivt. Den här avhandlingen handlar om att pelletera lignocellulosisk biomassa med motivet att energieffektivisera pelletsprocessen, samt öka kunskapen om olika biomassors pelleterbarhet.  Det finns många fördelar med att pelletera biomassa, såsom att produkten blir doserbar, lättare att lagra samt att den blir billigare att transporteratack vare högre densitet. Men olika biomassor har olika egenskaper beroende på deras kemiska uppbyggnad, och idag är kunskapen begränsad kring vad som påverkar pelleterbarheten i olika biomassor. Dettamedför att pelletsproduktionen eftersträvarsmå variationer i inkommande råmaterial såsom att bara använda färsk gran, bara lövträd eller en specifik mix. Att förstå och kunna hantera olika biomassors pelleterbarhet skulle innebära att pelletsproducenter kan nyttja ett varierat inflöde, utan att stoppa produktionen. Vilket kommer bli viktigt när omställningen mot mer förnyelsebart ökar konkurrensen om råvaran. En annan aspekt är ett ökat användande av pellets i utvecklingsländer, vilka många har en mycket större variation i träslag än dagens stora pelletsproducerande länder.  Arbetet har inriktats på att förstå hur olika biomaterial påverkar pelleterbarheten. Metoden för detta har varit att utgå från komponenter i biomassan tex. cellulosa, hemicellulosa, lignin m.m. och bygga kunskap därifrån. Resultatet visar att hemicellulosans (i huvudsak xylan och glucomannan) påverkan på pelleterbarhet är större än vad som tidigare varit känt. Xylan under kompression påverkas genom att ändra form vilket resulterar i hårda pellets och starka bindningar, samt att dess påverkan av tillsatt vatten i processen är stor. Glucomannan visar på motsatsen, låg påverkan på pelleterbarhet samt att dess inverkan av tillsatt vatten är liten. Denna skillnad kan förklara olikheterna i att pelletera löv- och barrträd, eftersom xylan är huvudsakliga hemicellulosan i lövträd medan glucomannan är det i barrträd.  Avhandlingen tar även upp hur pelletsprocessens kan effektiviseras. Ett resultat är att oxiderad stärkelse som additiv reducerar energiåtgången i pelletspressen mer än icke oxiderad stärkelse, samtidigt som pelletens hållfasthet förbättras. Ett annat resultat är en tvåstegs-torkteknik som energieffektiviserar torkprocessen samtidigt som torkkapaciteten ökar. Även att kunna hantera olika biomassors pelleterbarhet presenteras, inriktat på hur olika biomassor från Zambia, kan användas för pelletsproduktion. Slutligen finns en rekommendation till pelletsforskare om att inkludera cellulosamaterialet Avicel, i singelpellets-studier. Om alla använder samma referensmaterial, kan metoderna normaliseras och biomassors pelleterbarhet valideras på ett nytt och bättre sätt. Något som utvecklar både forskningen och omställning mot ett ökat nyttjande av förnyelsebara resurser. The use of fossil resources has to decrease and the use of renewable resources has to increase significantly to mitigate the climate change. In this transformation, biomasses will play an important role, and the utilization of biomasses must be optimized.  As a pelletized product the biomass gets increased density, are more economical to transport and the doseability of the product are increased. Thus, as pellets the possibilities to add biomasses in variated application will be both more energy efficient and can be optimized in a better way. Today, there is a lack of knowledge how different biomass species affect the actual pelletizing, and this causes pellet producers to strive for a feedstock with a chemical composition that is as uniform as possible.  In this thesis, it is shown how the pelletizing process can be improved and how a wider utilization of biomasses can be used by an increased understanding about the pelletability when pelletizing pure substances. Results shows that there is a significant difference between the substances within the hemicelluloses. A difference that can explain the difference in pelletability, between hardwood and softwood.The use of fossil resources has to decrease and the use of renewable resources has to increase significantly to mitigate the climate change. In this transformation, biomasses will play an important role, and the utilization of biomasses must be optimized.  As a pelletized product the biomass gets increased density, are more economical to transport and the doseability of the product are increased. Thus, as pellets the possibilities to add biomasses in variated application will be both more energy efficient and can be optimized in a better way. Today, there is a lack of knowledge how different biomass species affect the actual pelletizing. This causes pellet producers to strive for a feedstock with a chemical composition that is as uniform as possible.  This thesis has been focused on understanding biomasses pelletability, and the method has been to start with pure substance such as, cellulose, hemicellulose, lignin etc. In total, thirty-eight different material are included, divided into seventeen biomasses and twenty-one pure substances. Results shows that there is a significant difference between the components within the hemicelluloses, xylan and glucomannan. A difference that can explain the difference in pelletability, between hardwood and softwood. Also, how the pelletizing process can be more energy efficient, with increased drying capacity and increased pellet durability are presented. As well as there are solutions to combined and used a biomass flow as single resources or in combinations without stopping the production line.

Towards Understanding the Pelletizing Process of Biomass : Perspectives on Energy Efficiency and Pelletability of Pure Substances

The use of fossil resources has to decrease and the use of renewable resources has to increase significantly to mitigate the climate change. In this change towards more renewable resources, biomasses will play an important role, both for energy use and for products. Thus, the utilization of biomasses must be optimized, both linked to which biomass species that are used, as well as the actual production processes. This thesis relates to the production of lignocellulosic biomass pellets, with the purpose to increase the understanding of how a pellet process can be improved.  There are many benefits to pelletize the biomass, such as increased density, more economical transports solutions and increased doseability. However, there is a lack of knowledge on how different biomass species affect the actual pelletizing. This causes pellet producers to strive for a feedstock with a chemical composition that is as uniform as possible, which reduces the possibility of increasing intake of, for example, seasonal or residual products of other kinds. If pellet producers can handle, predict and combine different biomaterials over time without stopping the production, new ways of acquiring raw materials for production would be possible. This will be important for future pellet producers, as the general use of biomasses will increase, so will the competition of the raw material. It will also be of importance in developing countries, which have a greater variation in wood species than today's large pellets producing countries.  This work has been focused on understanding biomasses pelletability, and the method has been to start with components such as, cellulose, hemicellulose, lignin etc. Results shows that there is a significant difference between the hemicelluloses, xylan and glucomannan, in terms of pelletability. During pelletizing, xylan changes its form, generates hard pellets and, correlated to pelletability, xylan are affected by actual moisture content or added water to the process. Glucomannan, however, shows the opposite, a low impact on pelletability and a minimal impact from water during the pelletizing process. A difference that can explain the difference in pelletability, between hardwood and softwood.  Solutions to improve the pelletizing process have also been studied. One result is that adding oxidized starch additive, reduces the energy consumption in the pelletizer and increasing the durability of the pellets, more than native starches. Another result is that a two-stage drying technique, reduces the heat power consumption per tonne of dried materialand at the same time increases the drying capacity. Also, the possibilities for a pellet producer to handle, predict and combine different biomaterials has been studied. Presented results show howbiomasses from Zambia can be used as an single resource or in different resources combinations in a pellet production.  Finally, a recommendation to pellet researchers to include the cellulose material, Avicel, in single pellet studies. By using the same reference material, the methods can be normalized and the pelletability of biomaterials can be validated in a new way. This step would develop the research in the field, and the possibility of increased use of biomass towards the use of more renewable resources in pellet production.För att begränsa klimatpåverkan måste användandet av fossila resurser minska till förmån för förnyelsebara. In denna omställning är och kommer biomassa att bli en mycket viktigresurs att använda tillenergi samt olika produkter. Detta innebär att det är viktigt att både användningen och hanteringen sker resurs- och energieffektivt. Den här avhandlingen handlar om att pelletera lignocellulosisk biomassa med motivet att energieffektivisera pelletsprocessen, samt öka kunskapen om olika biomassors pelleterbarhet.  Det finns många fördelar med att pelletera biomassa, såsom att produkten blir doserbar, lättare att lagra samt att den blir billigare att transporteratack vare högre densitet. Men olika biomassor har olika egenskaper beroende på deras kemiska uppbyggnad, och idag är kunskapen begränsad kring vad som påverkar pelleterbarheten i olika biomassor. Dettamedför att pelletsproduktionen eftersträvarsmå variationer i inkommande råmaterial såsom att bara använda färsk gran, bara lövträd eller en specifik mix. Att förstå och kunna hantera olika biomassors pelleterbarhet skulle innebära att pelletsproducenter kan nyttja ett varierat inflöde, utan att stoppa produktionen. Vilket kommer bli viktigt när omställningen mot mer förnyelsebart ökar konkurrensen om råvaran. En annan aspekt är ett ökat användande av pellets i utvecklingsländer, vilka många har en mycket större variation i träslag än dagens stora pelletsproducerande länder.  Arbetet har inriktats på att förstå hur olika biomaterial påverkar pelleterbarheten. Metoden för detta har varit att utgå från komponenter i biomassan tex. cellulosa, hemicellulosa, lignin m.m. och bygga kunskap därifrån. Resultatet visar att hemicellulosans (i huvudsak xylan och glucomannan) påverkan på pelleterbarhet är större än vad som tidigare varit känt. Xylan under kompression påverkas genom att ändra form vilket resulterar i hårda pellets och starka bindningar, samt att dess påverkan av tillsatt vatten i processen är stor. Glucomannan visar på motsatsen, låg påverkan på pelleterbarhet samt att dess inverkan av tillsatt vatten är liten. Denna skillnad kan förklara olikheterna i att pelletera löv- och barrträd, eftersom xylan är huvudsakliga hemicellulosan i lövträd medan glucomannan är det i barrträd.  Avhandlingen tar även upp hur pelletsprocessens kan effektiviseras. Ett resultat är att oxiderad stärkelse som additiv reducerar energiåtgången i pelletspressen mer än icke oxiderad stärkelse, samtidigt som pelletens hållfasthet förbättras. Ett annat resultat är en tvåstegs-torkteknik som energieffektiviserar torkprocessen samtidigt som torkkapaciteten ökar. Även att kunna hantera olika biomassors pelleterbarhet presenteras, inriktat på hur olika biomassor från Zambia, kan användas för pelletsproduktion. Slutligen finns en rekommendation till pelletsforskare om att inkludera cellulosamaterialet Avicel, i singelpellets-studier. Om alla använder samma referensmaterial, kan metoderna normaliseras och biomassors pelleterbarhet valideras på ett nytt och bättre sätt. Något som utvecklar både forskningen och omställning mot ett ökat nyttjande av förnyelsebara resurser. The use of fossil resources has to decrease and the use of renewable resources has to increase significantly to mitigate the climate change. In this transformation, biomasses will play an important role, and the utilization of biomasses must be optimized.  As a pelletized product the biomass gets increased density, are more economical to transport and the doseability of the product are increased. Thus, as pellets the possibilities to add biomasses in variated application will be both more energy efficient and can be optimized in a better way. Today, there is a lack of knowledge how different biomass species affect the actual pelletizing, and this causes pellet producers to strive for a feedstock with a chemical composition that is as uniform as possible.  In this thesis, it is shown how the pelletizing process can be improved and how a wider utilization of biomasses can be used by an increased understanding about the pelletability when pelletizing pure substances. Results shows that there is a significant difference between the substances within the hemicelluloses. A difference that can explain the difference in pelletability, between hardwood and softwood.The use of fossil resources has to decrease and the use of renewable resources has to increase significantly to mitigate the climate change. In this transformation, biomasses will play an important role, and the utilization of biomasses must be optimized.  As a pelletized product the biomass gets increased density, are more economical to transport and the doseability of the product are increased. Thus, as pellets the possibilities to add biomasses in variated application will be both more energy efficient and can be optimized in a better way. Today, there is a lack of knowledge how different biomass species affect the actual pelletizing. This causes pellet producers to strive for a feedstock with a chemical composition that is as uniform as possible.  This thesis has been focused on understanding biomasses pelletability, and the method has been to start with pure substance such as, cellulose, hemicellulose, lignin etc. In total, thirty-eight different material are included, divided into seventeen biomasses and twenty-one pure substances. Results shows that there is a significant difference between the components within the hemicelluloses, xylan and glucomannan. A difference that can explain the difference in pelletability, between hardwood and softwood. Also, how the pelletizing process can be more energy efficient, with increased drying capacity and increased pellet durability are presented. As well as there are solutions to combined and used a biomass flow as single resources or in combinations without stopping the production line.

Effects of moisture content during densification of biomass pellets, focusing on polysaccharide substances

In this study, we pelletized four different pure polysaccharides represented cellulose - Avicel, hemicelluloses - locus bean gum mannan and beech xylan and other polysaccharides - apple pectin, and three woods - pine, spruce and beech. All were pelletized at 100° in a single pellet press unit with different level of moisture content from 0 to 15%. The maximal friction force and work required for compression and friction was analyzed together with the pellet density and hardness. The results showed that xylan pellets completely changed in color at 10% moisture content, and this also occurred to some extent with pectin pellets. The color of both Avicel and locus bean gum pellets were not affected at all. During compression, the results showed that water does not affect compression up to 5 kN, while above 5 kN water decreases the energy need for densification of Avicel, locus bean gum and woods. Above 5 kN the energy needs for compressing xylan and pectin increases with increased moisture content. The hardest pellets were produced from Avicel, while locus bean gum produced the weakest pellets. The study concludes that there is a significant difference in how water affects the two hemicelluloses, glucomannan and xylan, during densification.APC betald 2019.</p

Drifterfarenheter från ett superisolerat flerbostadshus : Kv SEGLET, Karlstad

Seglet är ett 12-vånings punkthus med 44 lägenheter beläget i Karlstad. Byggherre är Karlstads Bostads AB. Huset är byggt med mycket höga ambitioner när det gäller kvalitet och resurshushållning och togs i drift i börjanav 2007. Denna rapport redovisar klimatskalets egenskaper och funktion samt utformningen av installationssystemen för värme, ventilation och tappvatten.Rapporten beskriver också drifterfarenheterna från de första årens drift samt de förbättringsåtgärder som utförts. Seglets lösningar visar att energieffektivisering och inneklimat kan gå hand ihand. Konceptet med en enkel förvärmning av tilluften löser två problem. Dels kan tilluften tillföras lägenheten utan risk för drag och dels saknar det FTX-systemets nackdelar med utökat servicebehov för filterbyten och ökad elanvändning för tilluftsfläkten. Det välisolerade och täta klimatskalet ger en komfortabel inomhusmiljö. Den befarade risken med höga rumstemperaturer sommartid har inte besannats. Tack vare genomtänkta fönsterplaceringar med solskyddsglas där så är befogat samt goda möjligheter till effektiv vädring har lägenheterna samma temperaturnivå sommartid som motsvarande lägenheter i normalisolerade byggnader. Byggnaden är mycket resurseffektiv med låga förbrukningstal på både energi och vatten. Då största delen av värmebehovet täcks med fjärrvärme står sig byggnaden mycket väl i en jämförande miljöbedömning. Nyckeltal för klimatskal och energianvändning Medelvärde för klimatskalets värmeisolering, Um, W/m2,K ca 0,21 Luftläckage, läckflöde vid provtryckning till 50 Pa, l/s,m2Aomg 0,13 Specifik energianvändning, kWh/m2,år 58  

Pelletizing pure biomass substances to investigate the mechanical properties and bonding mechanisms

Solid fuel for heating is an important product, and for sustainability reasons, it is important to replace nonrenewable fuels with renewable resources. This entails that the raw material base for pellet production has to increase. A broader spectrum of materials for pelleting involves variation in biomass substances. This variation, due to lack of knowledge, limits the possibilities to increase the pellet production using new raw materials. In this study, pellets were produced with a single pellet press from 16 different pure biomass substances representing cellulose, hemicellulose, other polysaccharides, protein, lignin, and extractives, and five different wood species, representing softwoods and hardwoods. All pellets were analyzed for the work required for compression and friction, maximum force needed to overcome the backpressure, pellet hardness, solid density, and moisture uptake. The results showed that the hardest pellets were produced from the group of celluloses, followed by rice xylan and larch arbinogalactan. The weakest pellets were from the group of mannans. Conclusions are that the flexible polysaccharides have a greater impact on the pelletizing process than previously known, and that the differences between xylan and glucomannan may explain the difference in the behavior of pelletizing softwoods and hardwoods

Enhanced Strength 3D printed wood and biopolymer laminates, ES3D

Projektet Fiberförstärkta polymerer för 3D-utskrivna laminat (ES3D) var ett samarbete mellan Karlstads universitet och The Wood Region. Syftet var att åstadkomma nya metoder och öka kunskapen kring 3D-utskrivna strukturer med blandningar av termoplaster och sågspån. Genom att öka styrkan i det 3D-utskrivna biobaserade och nedbrytbara materialet kan hållbarhetsmässiga fördelar uppnås. Den enskilda trådens styrka avsågs ökas genom att använda längre spån och rikta dem i utskriftsriktningen. Adhesionen mellan de utskrivna lagren skulle förbättras genom kontrollerad temperatur och s.k. coronabehandling. ES3D har resulterat i en metod för att kunna testa 3D-utskrivna prov i dragprovare för mekanisk karakterisering, som sedankan användas för att jämföra olika materialsammansättningar och tillverkningssätt. Sortering av sågspån, i olika storleksfraktioner, har genomförts med både maskinell rotationssorterare och sållning. Resultatet av den maskinella sorteringen var inte tillräckligt precis för att producera sågspånsfraktioner som kunde användas för ovanstående mål. Ökad adhesion mellan lager med temperaturkontroll eller coronabehandling, har ej kunnat prövas ordentligt, p.g.a. otillräcklig temperaturkontroll, samt att en teknisk lösning för coronabehandling ej fanns

Enhanced Strength 3D printed wood and biopolymer laminates, ES3D

Projektet Fiberförstärkta polymerer för 3D-utskrivna laminat (ES3D) var ett samarbete mellan Karlstads universitet och The Wood Region. Syftet var att åstadkomma nya metoder och öka kunskapen kring 3D-utskrivna strukturer med blandningar av termoplaster och sågspån. Genom att öka styrkan i det 3D-utskrivna biobaserade och nedbrytbara materialet kan hållbarhetsmässiga fördelar uppnås. Den enskilda trådens styrka avsågs ökas genom att använda längre spån och rikta dem i utskriftsriktningen. Adhesionen mellan de utskrivna lagren skulle förbättras genom kontrollerad temperatur och s.k. coronabehandling. ES3D har resulterat i en metod för att kunna testa 3D-utskrivna prov i dragprovare för mekanisk karakterisering, som sedankan användas för att jämföra olika materialsammansättningar och tillverkningssätt. Sortering av sågspån, i olika storleksfraktioner, har genomförts med både maskinell rotationssorterare och sållning. Resultatet av den maskinella sorteringen var inte tillräckligt precis för att producera sågspånsfraktioner som kunde användas för ovanstående mål. Ökad adhesion mellan lager med temperaturkontroll eller coronabehandling, har ej kunnat prövas ordentligt, p.g.a. otillräcklig temperaturkontroll, samt att en teknisk lösning för coronabehandling ej fanns

Improving the understanding of the bonding mechanism of primary components of biomass pellets through the use of advanced analytical instruments

Previous studies have attempted to explain forces holding particles together in densified biomass pellets using theories of forces of attraction between solid particles, forces of adhesion and cohesion, solid bridges and mechanical interlocking bonds including interfacial forces and capillary pressure. This study investigated the bonding mechanism of primary biomass components in densified pellets through the use of advanced analytical instruments able to go beyond what is visible to the naked eye. Data obtained were used to predict how primary biomass components combine to form pellets based on the theory of functional groups and the understanding of structural chemistry. Results showed that hydroxyl and carbonyl functional groups played key roles in helping to identify the type of forces acting between individual particles, at a molecular level. At a microscopic level, morphological examination of the pellet clearly showed solid bridges caused by intermolecular bonding from highly electronegative polar functional groups linked to cellulose and hemicellulose