In this work, nanostructured biocomposite fibers and films with cellulose nanofibers (CNF), cellulose nanocrystals (CNC) and chitin nanocrystals (ChNC) were prepared using solutions mixing followed by electrospinning and melt compounding. The main processing challenges for these materials were to find parameters for: 1) fiber alignment in electrospinning, 2) feeding the nanomaterials into the extruder and 3) dispersion and distribution of the nanomaterials in the polymeric matrix. This thesis consists of three publications, which are summarized below.The first study was about random and aligned cellulose fibers prepared by electrospinning. Cellulose acetate (CA) was used as a matrix and a mixture of acetic acid and acetone (1:1) was used as a solvent. CNC with different concentrations (0–5 wt-%) were used as reinforcement. Microscopy studies showed fibers with smooth surfaces, different morphologies and diameters ranging between 200 and 3300 nm. It was found that the fiber diameters decreased with increased CNC contents. The microscopy studies also indicated well-aligned fibers. Results from dynamic mechanical thermal analysis indicated improved mechanical properties with the addition of CNC. The storage modulus of electrospun CA fibers increased from 81 to 825 MPa for fibers with 1 wt% CNC at room temperature. X-ray analysis showed that the electrospun CA fibers had a crystalline nature and that there was no significant change in crystallinity with the addition of CNC.In the second study, polylactic acid (PLA) and its nanocomposite based on CNF and glycerol triacetate (GTA) were prepared using a co-rotating twin-screw extruder. GTA was used as a plasticizer, a processing aid to facilitate nanofiber dispersion and as a liquid medium for feeding. The optical, thermal and mechanical properties were characterized and the toughening mechanism was studied. The addition of GTA (20%) and CNF (1%) resulted in increased degree of crystallinity and thus decreased optical transparency. Furthermore, these additives showed a positive effect on the elongation at break and toughness, which increased from 2 to 31% and from 1 to 8 MJ/m3, respectively. A combination of nanofiber-matrix interfacial slippage and a massive crazing effect is suggested for PLA toughening. CNF were expected to restrict the spherulite growth and therefore enhance the craze nucleation. In the third study, triacetate citrate plasticized poly lactic acid and its nanocomposites based on cellulose nanocrystals (CNC) and chitin nanocrystals (ChNC) were prepared using a co-rotating twin-screw extruder. The materials were compression molded to films using two different cooling rates. The cooling rates and the addition of nanocrystals (1 wt%) had an impact on the crystallinity as well as the optical, thermal and mechanical properties of the films. The fast cooling resulted in more amorphous materials, increased transparency and elongation to break, (approx. 300%) when compared with slow cooling. Chitin nanocomposites were more transparent than cellulose nanocomposites; however, microscopy study showed presence of agglomerations in both materials. The mechanical properties of the plasticized PLA were improved with the addition of a small amount of nanocrystals resulting in PLA nanocomposites suitable for use in film blowing and thus packaging applications. Summing up, this thesis shows that solution mixing followed by electrospinning can be used to produce reinforced green nanocomposite fibers with random or aligned orientation with, probably, potential to be used in membranes, filters or even in medical applications. It was also shown that PLA-CNF nanocomposites can be prepared using extrusion and liquid feeding and that small amounts of CNF changed the fracture mechanism, resulting in increased toughness. In addition, the cooling rate of the plasticized PLA and its nanocomposite films was found to significantly impact the film properties.

Membrane technology is being extensively used in water purification as an energy efficient and low cost process. Nanostructured (NSM) and nanoenabled (NEM) membranes are favored in this context as nanoscaled entities are expected to provide high surface area, high mechanical properties and versatile surface chemistry as well as provide better control on the pore size and distribution, flux and selectivity of the membrane. Biobased nanoparticles as nanocrystals are expected to have a significant advantage in this context. Thus, the main aim of this work was to explore the use of cellulose nanocrystals as functional entities for the fabrication of nanoenabled composite membranes and apply these fabricated membranes for the removal of dyes and metal ions from polluted water. The first study deals with the isolation of cellulose nanocrystals (CNCBE) from wood using the bioethanol pilot scale setup. Cellulose was prepared from wood by diluted acid treatment in the bioethanol plant followed by dewaxing and bleaching. The cellulose was converted into cellulose nanocrystals by mechanical grinding using lab scale homogenizer. The isolated nanoparticles had a diameter of 5-15 nm and formed a thick gel at 2 wt%. X-ray photoelectron spectroscopy illustrated the presence of O=C-O surface functional groups, directly related to the negative zeta-potential values. Fabricated films of CNCBE denoted good mechanical properties, optical properties and cytocompatibility. Thus, a new isolation route that can be followed to produce nanocrystals in large quantities (600 g/ day) has been developed. In a second study, fully biobased nanocomposite membranes of cellulose nanocrystals and chitosan have been fabricated by freeze-drying and crosslinking with gluteraldehyde in vapor phase. The chitosan bound the CNCSL in a stable and nanoporous membrane network with thickness of 250-270 μm. Homogenous dispersion of CNCSL within chitosan matrix was reported based on scanning electron microscopy (SEM). The Brunauer Emmett and Teller (BET) studies showed a decrease in surface area (3.1 to 2.9 m2/g) and average pore size (17 to 13 nm) after crosslinking. The mechanical performance of composite membranes was low, being 0.98 ± 0.4 and 1.1 ± 0.3 MPa of tensile strength for uncross-linked and cross-linked membranes, respectively. In spite of low water flux (64 L m−2 h−1), the composite membranes successfully removed 98%, 84% and 70% respectively of positively charged dyes like Victoria Blue 2B, Methyl Violet 2B and Rhodamine 6G, from a model wastewater after a contact time of 24 h. In the third study layered membranes containing a highly porous support layer and a dense functional layer has been fabricated following a filtration and hot pressing method. Microsized cellulose fibers from sludge bioresidues was used as the support layer to provide mechanical stability and allow water flow without any hindrance. A nanocomposite system of nanocrystals (CNCSL, CNCBE and PCNCSL) with gelatin as matrix was used as the functional layer. Bubble point measurement confirmed the membrane pore sizes (5-6 m), in microfiltration range, which resulted in high water permeability < 4000 Lh-1m-2 at 1.5 bars. Efficient removal of Ag+, Cu2+ and Fe3+ from industrial wastewater was achieved using these membranes. The removal of metal ions was expected to be driven by the electrostatic attraction between negatively charged nanocellulose and the positively charged metal ions. The work has demonstrated that highly efficient water treatment membranes can be fabricated from nanocellulose via tailoring their ability to interact and selectively adsorb heavy metal ions and dyes.

In the wood industry, determination of the moisture content (mc) with a highaccuracy is of great importance. The green mc is important for optimisation of thewood drying process at sawmills, whereas the mc of dried boards is of interest for thefurther processing and final use of the boards. In the first publication in this thesis,which is a technical report written in Swedish, different measuring techniques withtheir own pros and cons are discussed. A total of 13 different measurement principlesare discussed, focusing on the ability to measure mc in the range of 7-18%. The resultsuggests that mc-meters that use electromagnetic waves in the radio- and microwaveranges have the greatest potential to become the next generation mc-meters for driedboards.The second publication, which is presented in this thesis, investigates the possibilityof measuring the green sapwood mc in pine logs by combining industrial X-rayscanners and 3D-scanners. The method is shown to be suitable for identifying batchesof logs in which the sapwood has begun to dry prior to sawing, rather than predictingthe sapwood mc with high accuracy at the level of individual logs.In a single board, one would ideally like to measure the mc profile over the entirecross section to determine the mc gradient. However, the measured result is affectedin the vicinity of the board edges. In the third publication, the existence of thisproblem is identified, and it is shown that it can be decreased by using correlationfunctions generated by finite element simulations of the measurement system.The fourth publication considers the potential to increase the measurement accuracyof the mc of single boards by combining different measurement techniques.Microwaves, X-rays and visual sorting into different wood quality classes are used. Itis shown that the measurement accuracy is increased by the addition of both the Xraymeasurements and the visual sorting. This result is interesting because visualsorting is usually already present in the final sorting of large sawmills. This is alsowhere the mc measurement preferably is to be performed.

The research is presented as a composite thesis containing a theoretical explanatory review based on four scientific articles. The thesis covers the investigation of wood modification methods, which in the future could possibly be developed further to enhance the performance of wood products in an efficient and economical way. The target applications for the studied methods were non-structural wooden materials for outdoor exposure, such as cladding, facades and decking. Therefore, weather resistance, appearance and durability were the qualities to be studied.The methods were based on the combination of heat and impregnation with liquid preservatives. The following methods were included in the study: heat treatment in steam, heat treatment in oil with subsequent oil impregnation of heat treated wood and impregnation with artificial chemicals (copper, furfuryl alcohol and phenol formaldehyde) enhanced by preheating the wood. All the treatments were performed mainly on Scots pine, but also on Norwegian spruce and European varieties of ash, aspen, birch and beech. The first article covers the investigation of methods for oil heat treatment and oil impregnation of wood. The oil treatments were designed and performed at laboratory scale. The second and third articles cover studies concerning the behaviour of steam heat treated, oil heat treated and oil impregnated wood boards in terms of their resistance to cyclical climate conditions and brown rot fungi. The climate conditions were recreated in laboratory by letting the samples to soak in water, freeze in a freezer and absorb heat from an infrared lamp. The fourth article covers the study of impregnation of preheated wood with copper-based, furfuryl alcohol and phenol formaldehyde solutions; phenol formaldehyde treated wood was tested in the accelerated weathering test in order to find out if the treatment blocks wood resin coming out from the knots.The results showed that degradation processes within wood during oil heat treatment were similar to the degradation processes during heat treatment in steam, but with the difference of a small oil uptake when heat treating in oil. When heated wood is directly placed to cool down in oil at room temperature, then it absorbs significantly more oil than during the process of heat treatment in oil; similarly, impregnation with copper-based preservative after preheating was deeper compared to impregnation without preheating. However, oil seems to be rather unstable inside wood. After the samples were impregnated with oil in the experiments, the oil migrated throughout the wood and leached out when exposed to water and heat. By visual observation it was found that colour degraded to a certain extent in all untreated and treated species exposed to the cyclical weather conditions used in the study. It could also be noticed that the method used to create the cyclical weather conditions (mentioned above), in which the wood was exposed to periods of soaking, freezing and warming, showed to be an effective method to test the wood for outdoor applications. It was observed that both heat treatment and oil impregnation improved durability of wood against brown rot fungi. However, the oil impregnation method needs, probably, to be further developed to protect wood in the long term due to oil leakage from the wood. It was found that the phenol formaldehyde treatment using hot-and-cold bath process significantly reduced the migration of resin and extractives through knot in painted wood panels.

With population expansion and industrialization, heavy metal has become one of the biggest and most toxic water pollutants, which is a serious problem for human society today. The aim of this work is to explore the potential of nanopolysaccharides including nanocellulose and nanochitin to remove metal ions from contaminated water. The above nano-polysaccharides are of interest in water purification technologies due to their high surface area, high mechanical properties, and versatile surface chemistry. Silver, copper and iron are the main metal ions targeted in the study, due to their abundance in industrial effluents. The first study shows that the effect of pH conditions, surface charge and nature of surface functional groups on native nanocellulose and nanochitin on silver ion adsorption. The highest Ag+ ion removal efficiency observed for cellulose nanocrystals (CNC), was 64 % followed by chitin nanocrystals (ChNC, 37%) and cellulose nanofibers (CNF, 27%). Wavelength dispersive X-ray analysis (WDX) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of silver ions on the surface of the nanocellulose and nanochitin after adsorption. This study showed that the adsorption performance of cellulose nanofibers was inferior to cellulose nanocrystals and to enhance the adsorption capacities of nanofibers, surface functionalization of nanofibers was explored in the following study.In the second study, cellulose and chitin nanofibers functionalized with carboxylate entities have been prepared by chemically modifying the industrial residues, by TEMPO mediated oxidation followed by mechanical disintegration. The increase in copper adsorption on the nanofibers correlated both with the pH and carboxylate content and reached maximum values of 135 mg g-1 and 55 mg g-1 for highly oxidized cellulose and chitin nanofibers, respectively. Furthermore, the metal ions could be easily recovered from the contaminated nanofibers through a washing procedure in acidic water. The adsorption capacity of oxidized cellulose nanofibers for other metal ions, such as Nickel (II), Chromium (III) and Zinc (II), was also demonstrated. In the third study, the adsorption selectivity and removal efficiency of metal ions (Ag+, Cu2+ and Fe3+) from model water and industrial effluents by adsorption onto native and enzymatically phosphorylated nanocelluloses were studied. Phosphorylation significantly improved the functionality and sorption behaviour of nanocellulose. The removal efficiency is considered as being driven by the nature and density of functional group on the nanocellulose surface. Generally, when the mixture of metal ions are present in water the metal ion selectivity was in the order Ag+ > Fe3+ > Cu2+, irrespective of the surface functionality of nanocellulose. Nanocelluloses showed efficient adsorption in case of industrial effluent from mirror making industry and above 99% removal of Cu2+ and Fe3+ by phosphorylated nanocellulose was observed. The work has demonstrated that nano-polysaccharides, especially after surface modification are highly promising biosorbents for capturing heavy metal ions from water and of great industrial relevance and may enable next-generation water purification technologies.

The production of fully degradable nanocomposites with biopolymers as matrix and cellulose nanofibrils with high aspect ratios as reinforcement is still a challenging task. Also, due to the large amount of hydroxyl groups on the surface of these nanofibrils, they tend to irreversibly agglomerate during drying. This process, known as hornification, decreases the aspect ratio of the nanofibrils. Consequently, their reinforcing potential in nanocomposites is lowered. Thus, the objective of this PhD project is to produce novel biopolymer composites that are reinforced by functionalised cellulose nanofibrils in powder form. A successful preparation of such bio-based composites could open up ways to new applications in e.g. medicine, bio-packaging or horticulture. In order to induce an optimal compounding of the fibrils with different biopolymers, good fibril/matrix embedding is required. Therefore, the cellulose nanofibrils have to be modified appropriately to match the hydrophilic or hydrophobic nature of the polymer matrix.The production of fully degradable nanocomposites with biopolymers as matrix and cellulose nanofibrils with high aspect ratios as reinforcement is still a challenging task. Also, due to the large amount of hydroxyl groups on the surface of these nanofibrils, they tend to irreversibly agglomerate during drying. This process, known as hornification, decreases the aspect ratio of the nanofibrils. Consequently, their reinforcing potential in nanocomposites is lowered. Thus, the objective of this PhD project is to produce novel biopolymer composites that are reinforced by functionalised cellulose nanofibrils in powder form. A successful preparation of such bio-based composites could open up ways to new applications in e.g. medicine, bio-packaging or horticulture. In order to induce an optimal compounding of the fibrils with different biopolymers, good fibril/matrix embedding is required. Therefore, the cellulose nanofibrils have to be modified appropriately to match the hydrophilic or hydrophobic nature of the polymer matrix. In the first study, water-redispersible, nanofibrillated cellulose (NFC) in powder form was prepared from refined, bleached beech pulp (RBP) by carboxymethylation and mechanical disintegration. The sequence of the treatments influenced the stability of the final products in water. When carboxymethylation was applied first, enhanced disintegration of RBP into its sub-structural elements was observed. The prepared powder of this route formed a stable gel in water without sedimentation after 20 h. SEM images affirmed a significant reduction of cellulose nanofibrils agglomeration compared to unmodified NFC. The results suggest that NFC in dry form could be used as an alternative to conventional NFC in aqueous suspensions used as starting material for derivatization and compounding with biopolymers.

The hygro-thermal processes that wood is exposed to during drying and heat treatment lead to different reactions or responses in the wood material. The objective of this thesis has been to study the impact of different drying and heat-treatment strategies on various responses, such as strength, sorption/desorption behaviour, dimensional stability and colour changes. A decrease of shear strength along grain direction was found for high- temperature dried pine that was dried at temperatures exceeding 100°C, compared to boards dried at lower temperatures. No unambiguous decrease of surface hardness, cleavage strength or toughness was found for clear wood samples when high-temperature dried material was compared to material dried at lower temperatures. A decrease of hygroscopicity for wood exposed to increased temperatures was found. The higher the temperature, the greater was the decrease in equilibrium moisture content, EMC. The desorption isotherm of dried pine wood compared to initial desorption isotherm for fresh, green wood also showed lower EMC. Noticeable colour-change responses to heat treatment were found when different wood constituents such as pine and spruce sap and extractives from pine heartwood were heat-treated separately. Colour changes increased with time and temperature. An accelerated colour change was found for pine sap and extractives at temperatures exceeding 70°C. Studies of material properties such as extractive content and its influence on diffusivity show that density has greater influence than extractive content on diffusivity in pine and spruce. Pine shoved lower diffusivity than spruce, but when extractives were removed from pine heartwood, no difference was found in diffusivity compared to pine sapwood or spruce heartwood in a comparison of average levels between unpaired groups. The relation between diffusion coefficients in tangential, radial and axial direction in solid pine sapwood were found to be 1:1.8:7 respectively. Phenomena within the area of process dynamics were also studied. Calculations of thickness of a thin, dry outer shell formed in pine sapwood boards early in the capillary phase of drying were done based on temperature and mass flux measurements. Comparison with dry shell thickness analysed in a computer tomography scanner showed fairly good agreement. / Godkänd; 2005; 20061214 (haneit)

LCA was used to compare the environmental impacts of two different passenger tubs being designed for the GO-4 vehicle. Based on the results, the adoption of biomaterials clearly displays many benefits. / May 2017

Mycelium-composites has been emerging commercially as an environmentally sustainable alternative to conventional materials. By utilizing the fungal mycelium’s ability to bond with lignin and cellulose fibers of plants, mycelium-composites can be made that are recyclable and renewable. Mycelium therefore has the potential to contribute to creating more sustainable options in material selection for product designers. However, the visual appearance of mycelium materials might pose a challenge when it comes to their adaption into society. Case-studies have indicated a negative reaction to the mycelium-composites aesthetics which are characterized by imperfections and irregularities with an off-white coloring. Using theories surrounding aesthetics, materials experience and emotional design, the purpose of this study was to further develop the visual and/or aesthetical aspects of a mycelium-composite through a material driven design process The results of material development is presented in a product concept that displays the insight that can assist designers create mycelium-based products that are more accepted by a broader market.

In this study the properties of composites made of wood flour and thermoplastics have been investigated. In order to improve the interfacial adhesion between hydrophobic and nonpolar thermoplastics and hydrophilic and polar wood flour different additives have been used as compatibilizers in composites systems. The interaction between a wood filler and thermoplastic matrix, with and without compatibilizers, has been studied using conventional mechanical testing, impact testing, dynamic mechanical thermal analysis (DMTA), electron microscopes and infrared spectroscopy. Tests of mechanical properties, such as maximum tensile strength, tensile modulus and impact strength have shown that maleic anhydride grafted styrene-ethylene/butylene-styrene triblock copolymer (SEBS-MA) acts as a compatibilizer in the composite system. The SEBS-MA improves the stress transfer from the matrix to the wood particles and forming an flexible interphase around the wood particle and therefore improves the impact properties. The DMTA measurements indicated that there is an interaction between the wood surfaces and the maleic anhydride part of the SEBS-MA copolymer, and also between PS and wood. Morphological studies with SEM and TEM showed that the addition of SEBS-MA improved the adhesion between the wood particles and polymer matrix and that the compatibilizer is located at the interphase region between them. An infrared spectroscopy study indicated that the MA in the SEBS may react with the wood by forming hydrogen- and esterbonds and also possibly interaction between PS and wood. / Godkänd; 1997; 20061128 (haneit)