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  • 1.
    Alander, B.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials.
    Capezza, A.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymeric Materials. Department of Plant Breeding, The Swedish University of Agricultural Sciences, Box 101, Alnarp, Sweden.
    Wu, Q.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Johansson, E.
    Olsson, Richard T.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Hedenqvist, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    A facile way of making inexpensive rigid and soft protein biofoams with rapid liquid absorption2018In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 119, p. 41-48Article in journal (Refereed)
    Abstract [en]

    A novel and facile method to produce inexpensive protein biofoams suitable for sponge applications is presented. The protein used in the study was wheat gluten (WG), readily available as a by/co-product, but the method is expected to work for other cross-linkable proteins. The foams were obtained by high-speed stirring of pristine WG powder in water at room temperature followed by drying. Glutaraldehyde was used to crosslink the foam material in order to stabilize the dispersion, reduce its tackiness and improve the strength of the final foam. The foams were of medium to high density and absorbed readily both hydrophobic and hydrophilic liquids. The foam structure, consisting primarily of an open pore/channel system, led to a remarkably fast capillary-driven (pore-filling only) uptake of a hydrophobic liquid (limonene). Essentially all uptake occurred within the first second (to ca. 90% of the dry weight). In a polar liquid (water), the rapid pore-filling occurred in parallel with a more time-dependent swelling of the foam matrix material. Further improvement in the foam strength was achieved by making a denser foam or adding TEMPO-oxidized cellulose nanofibres. Soft foams were obtained by adding glycerol.

  • 2.
    Aminzadeh, Selda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lauberts, M.
    Dobele, G.
    Ponomarenko, J.
    Mattsson, T.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Membrane filtration of kraft lignin: Structural charactristics and antioxidant activity of the low-molecular-weight fraction2018In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 112, p. 200-209Article in journal (Refereed)
    Abstract [en]

    Lignin, which is the second most abundant biomass component and has carbon-rich phenolic content, is a promising renewable raw material for multiple applications, such as carbon fibers, adhesives, and emulsifiers. To use lignin efficiently, it is important to ensure its purity and homogeneity. As a result, the separation of lignin into fractions with high purity and narrow molecular-weight distributions is likely a prerequisite for several applications. Ultrafiltration using ceramic membranes has many advantages, including enabling direct lignin extraction from Kraft pulp cooking liquors without pH and temperature adjustment. One challenge with membrane filtration using such a system is the potential for reduced membrane performance over time, which is associated with fouling. In this study, LignoBoost Kraft lignin was fractionated using a ceramic membrane with a molecular weight cut-off of 1 kDa. The separation behavior during ultrafiltration fractionation was investigated and the antioxidant properties of the recovered low-molecular-weight (low-MW) lignin samples were evaluated. Using this model system, the permeate fluxes were unstable during the 100 h of membrane operation. However, a decrease in the average MW in the permeate over time was observed. The shift in MW was most pronounced for virgin membranes, while a more stable MW distribution was evident for membranes subjected to multiple cleaning cycles. According to 2D NMR analysis, low-MW lignin that was recovered after 100 h of operation, consisted of smaller lignin fragments, such as dimers and oligomers, with a high content of methoxy-groups. This was confirmed using the size exclusion chromatography method, which indicated an weigh average molecular weight in the range of 450–500 Da. 31P NMR spectroscopy showed that, despite the lower total content of phenolic OH groups, the low-MW sample had a higher proportion of non-condensed phenolic OH groups. The results of the antioxidant tests demonstrated the strong potential of lignin and its low-MW fraction as a natural antioxidant, particularly for lipid-containing systems. The low-MW lignin fraction showed better antioxidant activity than the non-fractionated LignoBoost lignin in the kinetic oxygen radical absorbance capacity (ORAC) test and demonstrated three-fold stronger inhibition of the substrate (fluorescein) than the reference antioxidant Trolox (a water-soluble derivative of vitamin E).

  • 3.
    Antonsson, Stefan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindström, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Low Mw-lignin fractions together with vegetable oils as available oligomers for novel paper-coating applications as hydrophobic barrier2008In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 27, no 1, p. 98-103Article in journal (Refereed)
    Abstract [en]

    Lignin residues are available in large amounts as kraft lignin from chemical pulping processes. This lignin is mainly incinerated in recovery boilers. The recovery boilers are often the bottle-necks in the overall pulping process when pulp production increases are desired. Through cross-flow nano-filtration of the black liquor from kraft pulping, a low-molecular weight lignin fraction can be removed thus decreasing the organic load on the recovery boilers. The low-molecular weight lignin fraction furthermore exhibit different characteristics compared to other commercial kraft lignins and represents a new raw material source in novel applications.

    The low-molecular weight lignin was used together with a vegetable oil to produce a new hydrophobic lignin derivative similar to suberin. The lignin and the lignin derivative was analysed with FT-IR, UV-vis and SEC. The ability of the product to make paper surfaces hydrophobic was also evaluated.

    The results demonstrate the possibility to make a suberin-like lignin derivative that is potentially of interest in paper-coating applications due to its capability to interact well with wood fibres and make paper hydrophobic.

  • 4.
    Areskogh, Dimitri
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Structural modification of commercial lignosulphonates through laccase catalysis and ozonolysis2010In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 32, no 3, p. 458-466Article in journal (Refereed)
    Abstract [en]

    Lignosulphonates are by-products from the sulphite pulping process, in which lignin is separated from cellulose by the addition of sulphonic acid groups to the alpha-position of lignin, thereby increasing the solubility of lignin in water. The predominant industrial utilisations of lignosulphonates are as dispersants, plasticisers and water-reducing agents in concrete preparation. The ability of lignosulphonates to function as a good plasticisers and water reducers is intimately linked with the purity of the lignosulphonate, its molecular weight and the number of charged groups present in the macromolecule. Currently, lignosulphonates are outrivaled by synthetic plasticisers termed superplasticisers due to their superior properties when used as additives to high-strength concrete. If lignosulphonates are to successfully compete with these superplasticisers, significant modifications are required. This paper describes a two-stage treatment of lignosulphonates in which the molecular weight is increased through laccase oxidation and carboxylic groups are introduced through ozonolysis. The technical significance of the results is also discussed.

  • 5.
    de Carvalho, Danila Morais
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Moser, Carl
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Wood Chemistry and Pulp Technology.
    Impact of the chemical composition of cellulosic materials on the nanofibrillation process and nanopaper properties2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 127, p. 203-211Article in journal (Refereed)
    Abstract [en]

    This paper investigated the impact of the amounts of lignin and hemicelluloses on cellulose nanofibers (CNFs). Birch and spruce wood were used to prepare holocellulose and cellulose samples by classical methods. To better assess the effect of the chemical composition on the CNF performance and simplify the process for CNF preparation, no surface derivatization method was applied for CNF preparation. Increased amounts of hemicelluloses, especially mannans, improved the defibration process, the stability of the CNFs and the mechanical properties, whereas the residual lignin content had no significant effect on these factors. On the other hand, high lignin content turned spruce nanopapers yellowish and, together with hemicelluloses, reduced the strain-at-break values. Finally, when no surface derivatization was applied to holocellulose and cellulose samples before defibration, the controlled preservation of residual lignin and hemicelluloses on the CNFs indicate to be crucial for the process. This simplified method of CNF preparation presents great potential for forest-based industries as a way to use forestry waste (e.g., branches, stumps, and sawdust) to produce CNFs and, consequently, diversify the product range and reach new markets.

  • 6.
    Deshpande, Raghu
    et al.
    MoRe Research, SE-89122 Örnsköldsvik, Sweden.
    Giummarella, Nicola
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Wallenberg Wood Science Center.
    Henriksson, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Wallenberg Wood Science Center.
    Germgård, Ulf
    Karlstad University, SE-65188 Karlstad, Sweden.
    Sundvall, Lars
    MoRe Research, SE-89122 Örnsköldsvik, Sweden.
    Grundberg, Hans
    Domsjö Fabriker, SE-89186 Örnsköldsvik, Sweden.
    Lawoko, Martin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    The reactivity of lignin carbohydrate complex (LCC) during manufacture of dissolving sulfite pulp from softwood2018In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 115, p. 315-322Article in journal (Refereed)
    Abstract [en]

    The presence of covalent bonds between lignin and polysaccharides was investigated in dissolving pulps made with one-stage and two-stage acidic sulfite pulping for 100% pine heartwood raw material. The covalent bonds between lignin and pulp polysaccharides occurred mainly to xylan and glucomannan and were of the phenyl glycosides and γ–esters types. The α-ethers that are common in wood were missing in the studied pulp samples. Based on these findings and known lignin reactions during sulfite pulping, a mechanism explaining the absence of the α-ethers is discussed. It is suggested that the lignin carbohydrate bonds may play a vital role in lignin recalcitrance.

  • 7.
    Du, Xueyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lindström, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Modification of industrial softwood kraft lignin using Mannich reaction with and without phenolation pretreatment2014In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 52, p. 729-735Article in journal (Refereed)
    Abstract [en]

    The amination of industrial softwood kraft lignin was conducted using the Mannich reaction to modify the lignin structure for value-added applications. To understand the reaction mechanism and to quantify the amount of amine groups that were introduced, different types of NMR analyses were performed. The lignin was also pretreated by phenolation to increase its reactivity and the amount of the amine groups that were introduced. The Mannich reaction was very selective at the C-5 position of the guaiacyl units and complete under acidic conditions with similar to 11-fold amounts of reagents of dimethylamine and formaldehyde over either model lignin (4-hydroxy-3-methoxyacetophenone, HMAP) or industrial spruce kraft lignin (LignoBoost lignin, LBL). For LBL, 28 amine groups were introduced over 100 aromatic rings. By weight, the nitrogen content was 2.5%. The animated lignin was found to possess a higher molecular mass, reaching a Mp of 4.9 x 10(3) Da compared to the original 319 x 10(3) Da, and with a considerably increased dispersibility, especially in a dilute aqueous solution of hydrochloric acid (pH = 3), namely 5.2 mg/ml. With a preceding phenolation treatment, which increased the amount of phenolic aromatic rings available for the Mannich reaction, an introduction of 42 amine groups over 100 aromatic rings, or a nitrogen content of 4.8%, was obtained, which caused a further increase of the molecular mass to 5.1 x 10(3) Da (Mp) and of dispersibility in the aqueous solution of hydrochloric acid up to 32.0 mg/ml. The aminated lignins with or without the phenolation pretreatment formed very stable colloidal suspensions in water, with large particle sizes (391 and 39 nm), high zeta potentials (31.6 and 27.2 mV), and large charge densities (1.6 and 1.2 x 10(-7) equiv./ml, respectively). The potential value-added applications of these modified lignins with high amine contents include use as surfactant chemicals, polycationic materials and slow-release fertilisers, among others.

  • 8.
    Ezekiel, Ngesa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ndazi, Bwire
    Nyahumwa, Christian
    Karlsson, Sigbritt
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Effect of temperature and durations of heating on coir fibers2011In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 33, no 3, p. 638-643Article in journal (Refereed)
    Abstract [en]

    Biocomposites derived from polymeric resin and lignocellulosic fibers may be processed at temperatures ranging from 100 degrees C to 230 degrees C for durations of up to 30 min. These processing parameters normally lead to the degradation of the fiber's mechanical properties such as Young's modulus (E), ultimate tensile strength (UTS) and percentage elongation at break (%EB). In this study, the effect of processing temperature and duration of heating on the mechanical properties of coir fibers were examined by heating the fibers in an oven at 150 degrees C and 200 degrees C for 10,20 and 30 min to simulate processing conditions. Degradation of mechanical properties was evaluated based on the tensile properties. It was observed that the UTS and %EB of heat treated fibers decreased by 1.17-44.00% and 15.28-81.93%, respectively, compared to untreated fibers. However, the stiffness or E of the fibers increased by 6.3-25.0%. Infra red spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to elucidate further the influence of chemical, thermal and microstructural degradation on the resulting tensile properties of the fibers. The main chemical changes observed at 2922, 2851, 1733, 1651, 1460, 1421 and 1370 cm(-1) absorption bands were attributed to oxidation, dehydration and depolymerization as well as volatization of the fiber components. These phenomena were also attributed to in the TGA, and in addition the TGA showed increased thermal stability of the heat treated coir fibers with reference to the untreated counterparts which was most probably due to increased recrystallization and cross linking. The microstructural features including microcracks, micropores, collapsed microfibrils and sort of cooled molten liquid observed on the surface of heat treated coir fibers from the scanning electron microscope (SEM) could not directly be linked to the effect of temperature and durations of heating although such features may have largely account for the lower tensile properties of heat treated coir fibers with reference to untreated ones.

  • 9.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Softwood kraft lignin: Raw material for the future2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 77, p. 845-854Article in journal (Refereed)
    Abstract [en]

    Large quantities of kraft lignin are formed in the pulp industry. Although the vast majority is used for internal energy production at mill sites, modern pulping technology allows for a partial outtake of lignin without disturbance of the energy balance in the mill. At present, lignin from softwood pulping is available in commercial quantities and it can be assumed that this amount will rapidly increase in the future. Therefore, development of material systems based on softwood kraft lignin should be beneficial for the future sustainable society and add value to a renewable resource. In this review, the formation, structure, and properties of softwood kraft lignin is summarized and it is suggested that, depending on final use, an optimization of lignin properties is done through selected fractionation and purification.

  • 10. Gordobil, O.
    et al.
    Moriana, Rosana
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Zhang, Liming
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Labidi, J.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Assesment of technical lignins for uses in biofuels and biomaterials: Structure-related properties, proximate analysis and chemical modification2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 83, p. 155-165Article in journal (Refereed)
    Abstract [en]

    The potential of organosolv and kraft eucalyptus and spruce lignin as feedstock for polymeric materials and biofuel applications was assessed. Proximate analysis was used to predict the heating values and char formation. Chemical modification, based on the esterification reaction with methacryloyl chloride, was applied to introduce vinyl groups into the lignin macromolecules for enhanced reactivity. Kraft eucalyptus and spruce lignins had a more condensed structure than organosolv lignins, which resulted in greater thermal stability for these lignins. For different species within the same process, the thermal parameters showed a correlation with certain structural and compositional parameters (ash and sugars content, molecular weight and degree of condensation). Organosolv spruce lignin produced the highest heating value of 24. MJ/Kg, which is suitable for biofuel applications. The content of phenolic OH groups was higher for kraft lignins and especially higher for softwood lignins, both organosolv and kraft. The degree of methacrylation, estimated from the content of vinyl groups per C9 lignin unit, was significantly greater for organosolv lignins than for kraft lignins despite the higher OH-groups content in the latter.

  • 11. Halvarsson, Soeren
    et al.
    Edlund, Hakan
    Norgren, Magnus
    Properties of medium-density fibreboard (MDF) based on wheat straw and melamine modified urea formaldehyde (UMF) resin2008In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 28, no 1, p. 37-46Article in journal (Refereed)
    Abstract [en]

    Wheat straw was investigated as a raw material for manufacturing of medium density fibreboard (MDF) in a fully equipped pilot-plant. Commercial urea melamine formaldehyde (UMF) and a mixture of UMF-resin and urea melamine phenol formaldehyde (UMPF) adhesives were used as binders in manufacturing of high performance MDF. The study evaluated the quality of MDF produced of straw (i.e., SMDF). Different qualities of wheat straw and different resin contents (14-17%) were used. Moreover, the SMDF was produced at different thicknesses of 9 and 16 mm and densities of 750-1000 kg/m(3). The properties of the resulting SMDF were evaluated by analysing mechanical and water absorption (anti-swelling) properties as a function of density. internal bond (IB), modulus of rupture (MOR), modulus of elasticity (MOE), thickness swelling (TS), and water absorption (WABS) were the properties analysed. SMDF-panels produced with densities above 780kg/m(3) and resin contents above 14% met the requirements for wood-based MDF standard EN 622-5:1997.

  • 12. Halvarsson, Sören
    et al.
    Edlund, Håkan
    Norgren, Magnus
    Manufacture of non-resin wheat straw fibreboards2009In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 29, no 2-3, p. 437-445Article in journal (Refereed)
    Abstract [en]

    Wheat straw was used as raw material in the production of fibreboards. The size-reduced straw was pretreated with steam, hot water and sulphuric acid before the defibration process to loosen its physical structure and reduce the pH. No synthetic binder was added. Adhesive bonding between fibres was initiated by activation of the fibre surfaces by an oxidative treatment during the defibration process. Fenton's reagent (ferrous chloride and hydrogen peroxide) was added. Two different levels of hydrogen peroxide (H2O2), 2.5% or 4.0% were used. The resulting fibres were characterized in terms of fibre length distribution, shive content, pH and pH-buffering capacity. The properties of finished fibreboards were compared with medium-density fibreboard (MDF) with density above 800 kg/m(3) produced from straw and melamine modified UF resin. The modulus of rupture (MOR), modulus of elasticity (MOE) and internal bond (IB) were lower than those of conventional manufactured wheat straw fibreboards but close to the requirements of the MDF standard (EN 622-5: 2006). The water absorption properties for the H2O2 activated straw fibreboards were relatively high, but were reduced by 25% with the addition of CaCl2 into the defibrator system as a water-repelling agent. Increased levels of hydrogen peroxide improved the mechanical and physical properties of the straw fibreboard. Crown

  • 13.
    Jose Villaverde, Juan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ligero, Pablo
    Ek, Monica
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    de Vega, Alberto
    Mild peroxyformic acid fractionation of Miscanthus x giganteus bark. Behaviour and structural characterization of lignin2012In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 35, no 1, p. 261-268Article in journal (Refereed)
    Abstract [en]

    Miscanthus x giganteus bark was subjected to mild fractionation with peroxyformic acid by a two stage process. A factorial experimental design was used to study and quantify the effect of the variables (formic acid concentration (80-90%), hydrogen peroxide concentration (0.2-0.4%), temperature of the first stage (60-80 degrees C), and treatment time of the second stage (60-120 min)) on the main parameters of fractionation: pulp yield, remaining lignin and total polysaccharides in pulp. The dependence of lignin precipitation rate on hydrogen peroxide concentration in liquor was also studied. Hydrogen peroxide concentrations inferior to 0.5% seems to be suitable to recover high percentages of lignin. The isolated lignin was analysed by 2D-HSQC, (13)C- and (31)P NMR spectroscopy, FTIR spectroscopy, size-exclusion chromatography and chemical analysis. The most important chemical modifications taken place in the lignin during the fractionation were identified: beta-O-4' cleavage and hydrolysis of LC-bond structures. The C9-formula was also determined: C(9)H(6.81)O(2.90)(OCH(3))(0.68)(COOH)(0.07)(OH(Ph))(0.38)(OH(Al))(0.33) .

  • 14.
    Keyoumu, Ayiguli
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Sjödahl, Ragnar
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Henriksson, Gunnar
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Ek, Monica
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Gellerstedt, Göran
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Lindström, Mikael E.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Continuous Nano- and Ultrafiltration of Kraft Pulping Black Liquor with Ceramic Filters: A method for lowering the load on the recovery boiler while generating valuable side-products2004In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 20, no 2, p. 143-150Article in journal (Refereed)
    Abstract [en]

    Ceramic membranes coated with ZrO2 were used for the continuous separation of a well-defined low molecular weight lignin from softwood and hardwood kraft black liquors on a pilot scale. The membranes used had M-w cut-offs of 1000, 5000, and 15,000 Da, respectively. The flux (permeate flow) through the different membranes measured as L/(m(2 .)h) was studied by varying the inlet pressure and temperature. The black liquor lignins in the permeate from the filters were isolated and studied with GPC and UV spectroscopy. The low molecular weight lignin fraction was highly phenolic and could be polymerised by one-electron oxidation.

  • 15.
    Khosravi, Sara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Khabbaz, Farideh
    Casco Adhesives AB Analyscentrum, Stockholm, Sweden.
    Nordqvist, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Protein-based adhesives for particleboards2010In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 32, no 3, p. 275-283Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to elucidate the possibilities of using soy protein isolate (SPI) and wheat gluten (WG) as binders for particleboards. One-layer particleboards were produced in laboratory scale. Parameters regarding the formulation of the adhesive and the gluing process were investigated, while the press parameters were kept constant. The considered factors were: the use of protein as a dispersion and/or as a dry protein powder, the temperature during the preparation of the dispersion, the time for preparing the dispersion, the storage time of dispersion prior to gluing, and the use of dried core particles or green particles. The board properties evaluated were: internal bond (IB), thickness swelling (TS) and water absorption (ABS). The results were statistically evaluated and SIMCA-P+ software was employed as a multivariate analyzing tool. The results show that protein adhesives can work as adhesive for particleboard. The results also reveal that it is preferable to use the dispersion as a binder rather than the dry protein. Furthermore, in the case of the SPI, the time for preparing the dispersion is a significant parameter: it appears that longer dispersion time results in enhanced board properties. According to the results, the temperature during the preparation does not seem to have any impact on the gluing properties of the SPI dispersions. On the other hand, in the case of WG dispersions, the temperature has an impact on the properties of the adhesive, favouring lower temperature, while the time is insignificant. Additionally, if the dispersion has been stored for more than 1 day before it is used, it results in boards with poorer mechanical and water resistance properties. The utilization of the green chips, instead of the dried core particles, is clearly a disadvantage, especially regarding the water resistance of the particleboards. It appears that SPI is superior to WG when it comes to the water resistance as well as the mechanical properties of the boards. However, it is not possible to compare these two proteins explicitly, since SPI contains a higher percentage of protein. Additionally, WG contains more starch, which is known to give poorer water resistance properties.

  • 16.
    Khosravi, Sara
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Nordqvist, Petra
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Khabbaz, Farideh
    AkzoNobel, Casco Adhesives AB, Stockholm, Sweden.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Protein-based adhesives for particleboards - effect of application process2011In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 34, no 3, p. 1509-1515Article in journal (Refereed)
    Abstract [en]

    The main purpose of this study was to investigate wheat gluten (WG) dispersions as adhesives for particleboard. The effect of the dispersion concentration and two application methods were studied. When application method 1 was employed all the dispersion was added to the particles in one step, the particles were dried after the gluing. When using application method 2, the dispersion was added in two steps with drying of the glued chips between the first and the second addition of the dispersion. The amount of dry wheat gluten on dry particles was kept constant for all the experiments as was the pressing conditions. The performance of the wheat gluten dispersions were evaluated based on the following board properties: internal bond (IB), thickness swelling (TS) and water absorption (ABS). The experiments were conducted according to a factorial screening design and SIMCA-P+ was employed as a multivariate analyzing tool. The results reveal that application method 2 seems to be  beneficial. Furthermore, it appears as, regarding the IB of the boards, the preferable dispersion concentration depends on the employed application method. When application method 1 is used a higher concentration seems to be better, in contrast for application method 2 a lower concentration of the dispersion may be beneficial. The improved properties obtained using application method 2 is proposed to be due to a more optimal penetration of the dispersion into the wood particles.

     

  • 17.
    Li, Jiebing
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Improved lignin properties and reactivity by modifications in the autohydrolysis process of aspen wood2008In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 27, no 2, p. 175-181Article in journal (Refereed)
    Abstract [en]

    Autohydrolysis of aspen wood breaks down lignin beta-O-4 linkages via both acidolysis and homolytical cleavage. A simultaneous repolymerization by lignin-lignin condensation is the major reason for the low degree of delignification and the poor lignin reactivity. Modification of the autohydrolysis reaction by the addition of either NaOH or 2-naphthol changes the mechanism such that less acidolysis and fewer lignin-lignin condensation reactions take place, and an almost complete delignification can be achieved. The resulting isolated lignins have a low M., a light color and still contain some of the native beta-O-4 linkages. Lignin from autohydrolysis in the presence of NaOH possesses more carboxylic acid groups, while the addition of 2-naphthol results in a lignin with a large amount of phenolic hydroxyl groups and incorporated naphthalene rings. These types of change are beneficial since the lignin structure becomes much more homogeneous with a greater potential for further upgrading and use.

  • 18.
    Li, Jiebing
    et al.
    KTH. Research Institutes of Sweden RISE, Drottning Kristinas väg 61, 11486 Stockholm, Sweden.
    Wang, Miao
    KTH. Research Institutes of Sweden RISE, Drottning Kristinas väg 61, 11486 Stockholm, Sweden.
    She, Diao
    Zhao, Yadong
    KTH.
    Structural functionalization of industrial softwood kraft lignin for simple dip-coating of urea as highly efficient nitrogen fertilizer2017In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 109, p. 255-265Article in journal (Refereed)
    Abstract [en]

    Urea coating was conducted using polylactic acid (PLA) blended with industrial softwood kraft lignin after applying a dip-coating technique. The lignin was pre-functionalized via esterification that increased coat layer hydrophobicity or via amination that created an organically bound nitrogen structure. The PLA film reference had many pores, while the film from the PLA-lignin derivative complex was highly homogeneous and had no pores. The coat thickness was generally adjustable by repeating the coating process reaching up to 81% weight against the urea core. After coating, urea release in water was largely delayed, 20-30 and 6-10 times as long as that of uncoated urea or PLA-coated urea respectively. The coated urea will be a highly effective nitrogen fertilizer due to the controlled release after coating, the slow release from the organically bound nitrogen structure, and the expectedly extra stability against urease hydrolysis and microorganism nitrification after using the lignin structure.

  • 19.
    Li, Tao
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials. Nanjing Forestry University, China.
    Cheng, D. -L
    Wålinder, Magnus E. P.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Materials.
    Zhou, D. -G
    Wettability of oil heat-treated bamboo and bonding strength of laminated bamboo board2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 69, p. 15-20Article in journal (Refereed)
    Abstract [en]

    In order to improve the interface properties of bamboo in laminated board applications for severe outdoor environment, bamboo sheets were heat treated in soybean oil and post oil extracted in this paper. Following oil heat treatment at 180 degrees C for 2 h, bamboo specimens were either removed from the oil immediately or left in the oil until they were cooled to room temperature. Contact angle measurements before and after oil heat treatment showed a significant increase in the hydrophobicity of bamboo, and these changes differed based on the process parameters. Results from scanning electron microscopy and Fourier transform infrared spectroscopy indicated that these phenomena may be due to the combination effect of the change of chemical composition and the surplus oil on the surface of modified bamboo. Then, the ethanol extraction process was subsequently applied to remove the surplus oil. Finally, the results of bonding strength tests on laminated bamboo boards prepared from oil heat-treated samples which thereafter had been subjected to ethanol extraction showed acceptable interface properties, although lower than the reference.

  • 20.
    Moraisde Carvalho, Danila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. Univ Fed Vicosa, Dept Forestry Engn, Pulp & Paper Lab, BR-36570900 Vicosa, MG, Brazil.
    Sevastyanova, Olena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Penna, Lais Souza
    da Silva, Brunela Pereira
    Lindstrom, Mikael E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Colodette, Jorge Luiz
    Assessment of chemical transformations in eucalyptus, sugarcane bagasse and straw during hydrothermal, dilute acid, and alkaline pretreatments2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 73, p. 118-126Article in journal (Refereed)
    Abstract [en]

    The impact of hydrothermal, dilute acid, and alkaline pretreatments on the chemical structure of eucalyptus, sugarcane bagasse, and straw were compared with a view to their subsequent bioconversion into ethanol. Sugarcane bagasse and straw contain high amounts of extractives (15.0% and 12.2%, respectively), ash (2.3% and 7.9%, respectively), and silica (1.4% and 5.8%, respectively). If not properly corrected, the presence of silica would lead to the overestimation of the lignin, while high amounts of extractives would cause the overestimation of the content of sugars in biomass. Applying a novel approach through the use of complete mass balance, bagasse and straw were proven to contain lower amounts of lignin (18.0% and 13.9%, respectively) than previously reported for these raw materials, and certainly a much lower amount of lignin than eucalyptus (27.4%). The syringyl to guaiacyl units ratio (SIG) for lignin in bagasse and straw (1.1 and 0.5, respectively) was lower than that for eucalyptus (2.7), indicating a different reactivity during chemical pretreatments. The xylan content in sugarcane bagasse and straw was much higher than that in eucalyptus, with a significantly lower degree of substitution for uronic acids and acetyl groups. The sugarcane straw showed the highest mass loss during the investigated pretreatments, especially under alkaline conditions, with a total biomass yield of only 37.3%. During the hydrothermal and dilute acid treatments, mostly hemicelluloses were removed, followed by the formation a significant amount of pseudo-lignin structures, while the alkaline pretreatment affected the lignin content. With eucalyptus, the formation of structures similar in their behavior to extractives (i.e., soluble in toluene and ethanol, subsequently referred to as "pseudo-extractives") was observed during all three pretreatments, with 12.4% for hydrothermal, 18.9% for dilute acid, and 8.7% for alkaline pretreatment. This information, combined with actual yields, should be taken into account when assessing the impact of pretreatments on the chemical composition and structure of biomass.

  • 21. Newson, W. R.
    et al.
    Prieto-Linde, M. L.
    Kuktaite, R.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Gällstedt, M.
    Johansson, E.
    Effect of extraction routes on protein content, solubility and molecular weight distribution of Crambe abyssinica protein concentrates and thermally processed films thereof2017In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 97, p. 591-598Article in journal (Refereed)
    Abstract [en]

    To understand if and how extraction conditions influence properties of molded protein films, Crambe abyssinica protein concentrates were produced from deoiled seed meal under various extraction conditions. Properties of the resulting hot compression molded films were evaluated through the molecular weight distribution, protein polymerization behavior and tensile tests. Precipitated protein concentrates demonstrated higher protein content and a pronounced shift to higher molecular weight distributions and reduced solubility on heating, indicating increased protein polymerization compared to those from lyophilized supernatants. Thermally processed films from isoelectrically precipitated protein concentrates show a high resistance to extraction with a combination of reducing agent and denaturant, indicating the presence of non-disulfide covalent cross linking. Also, tensile strength was higher in concentrates from precipitated proteins compared to those from supernatants. The protein concentrates resulting in thermally processed films with a high protein content, the highest levels of protein-protein interaction and high tensile strength were based on alkaline extraction and isoelectric precipitation. Therefore, a combination of alkali extraction and isoelectric precipitation is recommended to produce protein concentrates for molded film production.

  • 22.
    Nordqvist, Petra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Johansson, E.
    Khabbaz, F.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Characterization of hydrolyzed or heat treated wheat gluten by SE-HPLC and 13C NMR: Correlation with wood bonding performance2013In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 51, p. 51-61Article in journal (Refereed)
    Abstract [en]

    Wheat gluten, being an abundant and relatively inexpensive protein source, is an attractive raw material for sustainable wood adhesives. Mild enzymatic hydrolysis (degree of hydrolysis: 0-5.5%) or heat treatment (50, 70, or 90°C for 15min-24h) was used to improve the bonding performance of wheat gluten. Size exclusion high performance liquid chromatography (SE-HPLC) and nuclear magnetic resonance (13C NMR) were used to correlate the obtained changes in bonding performance with the structural changes of wheat gluten.The protein structures of the samples heated at 50°C or 70°C were mainly unfolded as interpreted from the SE-HPLC results, however, without improvement in bonding performance. The 13C NMR results indicate that the extent of unfolding at 50°C or 70°C is too low to result in improved bond strength. Generally, heat treatment at 90°C or lower levels of hydrolysis (0-0.6%) resulted in similar improvements in bond strength and water resistance. The results indicate that the improvements in bonding performance are due to a combination of unfolding and polymerization for the samples heated at 90°C, while it is due to unfolding of the protein structure for the hydrolyzed samples. Higher levels of hydrolysis (≥1.3%) resulted in impaired bond strength and water resistance, most likely due to the decreased molecular size of the proteins. Carbohydrates, normally strongly associated with the proteins, were liberated during the hydrolysis, possibly contributing to the reduced bond strength for these samples.

  • 23.
    Nordqvist, Petra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Lawther, Mark
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Khabbaz, Farideh
    Adhesive properties of wheat gluten after enzymatic hydrolysis or heat treatment - A comparative study2012In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 38, no 1, p. 139-145Article in journal (Refereed)
    Abstract [en]

    Wheat gluten, among other plant proteins, constitutes an attractive raw material for sustainable alternatives to today's petroleum-based wood adhesives. Nevertheless, the bonding performance, and especially the water resistance, of these plant proteins need to be improved to turn them into competitors equal in merit to today's petroleum-based products. The aim of this study was to investigate if mild hydrolysis or heat treatment of wheat gluten will improve its adhesive properties. Wheat gluten was hydrolyzed with the enzyme Alcalase (degree of hydrolysis 0.3-5.5%), or heat treated at different temperatures (50, 70, and 90 degrees C) and varying time intervals (15 min to 24 h). Alkaline water dispersions of these modified wheat gluten samples were used as adhesives to bond together wood substrates of beech at a press temperature of 110 degrees C and a press time of 15 min. The tensile shear strengths of the substrates were measured for comparison of bond strength and resistance to cold water. The substrates were evaluated according to a slightly modified version of the European Standard EN 204. Lower levels of hydrolysis (0.3-0.6%) and most of the heat treatments at 90 degrees C resulted in improved bond strength and water resistance. Nevertheless, the adhesive properties, especially the water resistance, need to be further improved to fulfill today's requirements for wood adhesives.

  • 24.
    Nordqvist, Petra
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Nordgren, Niklas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Khabbaz, Farideh
    AkzoNobel, Casco Adhesives AB.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Plant proteins as wood adhesives: Bonding performance at the macro- and nanoscale2013In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 44, p. 246-252Article in journal (Refereed)
    Abstract [en]

    Soy protein isolate and wheat gluten were studied to evaluate their wood bonding performance. A multiscale approach was employed, combining tensile shear strength measurements, optical microscopy, and adhesion measurements at the nanoscale using atomic force microscopy. Tensile shear strength measurements were performed on beech wood substrates bonded with either dispersions of soy protein isolate or wheat gluten to investigate bond strength and water resistance. The results reveal a significant difference in bond strength between the plant proteins. Soy protein isolate is superior to wheat gluten, especially regarding water resistance, both under acidic and alkaline conditions. Cross sections of the wood substrates were examined by optical microscopy to study protein penetration and bond line thickness. The results indicate that a proper bond can be obtained using lower amount of soy protein isolate than wheat gluten. Atomic force microscopy in colloidal probe mode was used to investigate nanoscale adhesion between cellulose and solvent cast protein films. The results show that adhesion between the plant proteins and the wood component is important for the bonding performance. Further, it is shown that the results from atomic force microscopy and tensile shear strength measurements display the same trend demonstrating that the bonding properties translates well spanning regimes from the macro- to the nanoscale. The presented multiscale approach is shown to have great potential and may be used in the future to predict properties at different length scales in the design and formulation of new bioadhesives.

  • 25.
    Norström, Emelie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Fogelström, Linda
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Nordqvist, P.
    Khabbaz, F.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Gum dispersions as environmentally friendly wood adhesives2014In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 52, p. 736-744Article in journal (Refereed)
    Abstract [en]

    Today, wood adhesives are mainly prepared from petroleum-based polymers. There is an ambition to decrease the utilization of petroleum-based raw materials and introduce bio-based polymers instead. However, the utilization of bio-based polymers is often limited due to insufficient properties in terms of water resistance or heat resistance. In this study bio-based dispersions have been prepared of locust bean gum, guar gum, xanthan gum and tamarind gum and evaluated as wood adhesives. Due to the high viscosity of the dispersions, a low dry solids content of 6. wt% was used. The film forming properties have been investigated and contact-angle measurement have been performed to obtain an indication of water resistance. Wood substrates have been bonded together and the bonding performance has been evaluated with different techniques. The gum dispersions have been compared with a commercial poly(vinyl acetate)-based wood adhesive and the results demonstrate that gums can be used as binders for wood adhesives. Locust bean gum dispersions show remarkable results - comparable to the commercial wood adhesive - even though the dry solids content is very low. The locust bean gum dispersion fulfills the D2 and WATT 91 requirements for wood adhesives according to the European Standard EN 204 and European Standard EN 14257.

  • 26. Rasheed, Faiza
    et al.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Kuktaite, Ramune
    Plivelic, Tomas S.
    Gallstedt, Mikael
    Johansson, Eva
    Mild gluten separation - A non-destructive approach to fine tune structure and mechanical behavior of wheat gluten films2015In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 73, p. 90-98Article in journal (Refereed)
    Abstract [en]

    Despite the increasing production of wheat gluten (WG) for industrial use, minor attention has been given to the impact of the separation procedure on the gluten quality. The purpose of the present study was to probe the effect of the separation treatments (harsh vs mild) on gluten structure, morphology, and performance in bio-based films. The harshly separated industrial WG showed aggregated and pre-cross linked structure in the starting material most likely due to shear forces during gluten separation from flour and heat effect during the drying procedures. Further, when the harshly separated WG was processed into films the pre-crosslinked starting material restricted new crosslinks formation and structural rearrangements at nano-scale. The mechanical integrity of the film was also affected resulting in films with low Young's modulus and strength. WG (from cultivars Diskette, Puntari, and Sleipner) recovered from mild separation showed relatively "native" non-destructed crosslinking pattern and not previously observed structural morphology at nano-scale. When processed into films the mildly separated WG showed well polymerized intimately crosslinked proteins both with disulfide and other covalent crosslinks. The nano-scale morphology showed lamellar and hexagonal arrangements, not reported so far in any study. The structural rearrangements among films from mildly separated WG resulted in materials with improved mechanical integrity as compared to films from harshly separated WG. The present study showed that the quality of WG is significantly affected by the separation procedure which also affects protein polymerization, nano-scale morphology, and tensile properties of films.

  • 27. Rombouts, I.
    et al.
    Lagrain, B.
    Delcour, Jan A.
    Leuven Food Science and Nutrition Research Centre (LFoRCe), KULeuven, Belgium.
    Türe, Hasan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Johansson, E.
    Kuktaite, Ramune
    Crosslinks in wheat gluten films with hexagonal close-packed protein structures2013In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 51, p. 229-235Article in journal (Refereed)
    Abstract [en]

    Wheat gluten/glycerol (WGG) films were extruded with aqueous ammonia/salicylic acid or urea to investigate the reactions contributing to their hexagonal close-packed protein structures and material properties. The addition of aqueous ammonia and salicylic acid increased the pH, which, in turn, increased the level of intermolecular disulfide and lanthionine cross-links in the WGG films. Increased protein cross-linking reactions resulted in higher material strength and tensile modulus. These cross-linking reactions and the resulting material properties were similar for WGG films with 7.5% and 10% aqueous ammonia. Added urea into WGG film partially degraded into cyanate and ammonium. Cyanate subsequently reacted with lysine and cysteine to ε-carbamyllysine and S-carbamylcysteine, respectively. Even though these reactions resulted in a more alkaline reaction environment, hereby favoring disulfide bond formation and decreasing protein extractability, they also prevented the involvement of cysteine and lysine in protein cross-linking. The alkylation of these reactive amino acids, together with the plasticizing effect of urea, led to lower material strength and elastic modulus with increasing levels of urea.

  • 28. Stenberg, C.
    et al.
    Svensson, M.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Study of the drying of linseed oils with different fatty acid patterns using RTIR-spectroscopy and chemiluminescence (CL)2005In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 21, no 2, p. 263-272Article in journal (Refereed)
    Abstract [en]

    The oxidative drying of two different linseed oil coatings with either high content of linoleic or linolenic fatty acids have been studied. The curing performance has been followed by a combination of two different analytical techniques, real-time infrared (RTIR) spectroscopy and chemiluminescence (CL) at different temperatures. The effect of a metal drier on the drying process has also been evaluated. The purpose was to reveal how structural variations can improve the drying performance and film properties for oxidative drying linseed oil coatings. The reaction rate is increased for both oils with increased temperature as expected. The oil rich in linolenic acid reacts more rapid and exhibits shorter induction times compared to the oil rich in linoleic acid. The addition of a metal drier further accelerates the drying but in a different manner for the different oils. The oil high in linolenic acid oxidizes so rapidly that a skin layer, acting as a diffusion barrier to atmospheric oxygen, is formed. The through drying rate is then strongly reduced, leaving high levels of residual unsaturation in the film. As a consequence, this will generate poor ageing properties. The oil richness in linoleic acid shows, much better through drying properties even when the reaction is accelerated by both the use of a metal drier and high temperatures. The consequence is that the linseed oil high in linoleic acid can be cured rapidly with good through drying and low levels of residual unsaturations. The combination of the two analytical techniques gives complementary information of the drying mechanisms of the linseed oils. The techniques are shown to be very useful when following oxidative drying of thin films.

  • 29.
    Svärd, Antonia
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Brännvall, E.
    Edlund, Ulrica
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Modified and thermoplastic rapeseed straw xylan: A renewable additive in PCL biocomposites2018In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 119, p. 73-82Article in journal (Refereed)
    Abstract [en]

    Xylan extracted from rapeseed straw was chemically modified to gain hydrophobic and thermoplastic properties via macroinitiator formation followed by a free radical grafting-from polymerization with octadecyl acrylate. Biocomposites were then prepared by incorporation of 5 or 20% (w/w) rapeseed straw xylan into a poly(epsilon-caprolactone) (PCL) matrix by melt extrusion. The grafted xylan was homogeneously distributed within the biocomposite and reinforced the PCL matrix while at the same time preserving the ability to elongate to tensile strains > 500%. Analogous biocomposites made from unmodified xylan in a PCL matrix resulted in heterogeneous mixtures and brittle tensile properties.

  • 30.
    Tagami, Ayumu
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Gioia, Claudio
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Lauberts, Maris
    Latvian State Inst Wood Chem, 27 Dzerbenes Str, LV-1006 Riga, Latvia..
    Budnyak, Tetyana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Moriana, Rosana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Lindström, Mikael
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Sevastyanova, Olena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Solvent fractionation of softwood and hardwood kraft lignins for more efficient uses: Compositional, structural, thermal, antioxidant and adsorption properties2019In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 129, p. 123-134Article in journal (Refereed)
    Abstract [en]

    This work summarizes the impact of solvent fractionation on the chemical structure, antioxidant activity, heating values, and thermal and adsorption properties of industrial hardwood and softwood kraft lignins. The aim of the research was to develop a simple approach for obtaining lignin fractions with tailored properties for applications in certain materials. Four common industrial solvents, namely, ethyl acetate, ethanol, methanol and acetone, in various combinations, were found to be efficient for separating spruce and eucalyptus kraft lignins into fractions with low polydispersities. The ethanol fraction of spruce and the ethyl acetate fraction of eucalyptus afforded the highest yields. Gel-permeation chromatography analysis was used to evaluate the efficiency of the chosen solvent combination for lignin fractionation. The composition and structure of the lignin material was characterized by elemental analysis, analytical pyrolysis (Py-GC/MS/FID) and P-31 NMR spectro-scopy. The thermal properties of the lignin samples were studied using thermogravimetric analysis. Proximate analysis data (ash, volatile components, organic matter and fixed carbon) was obtained through the direct measurement of weight changes in each experimental curve, and the high heating values (in MJ/kg) were calculated according to equations suggested in the literature. The adsorption properties of fractionated kraft lignins were studied using methylene blue dye. The correlations observed between molecular weight, composition and functionality and the thermal, radical scavenging and adsorption properties of the lignin fractions provides useful information for selecting the appropriate solvent combinations for specific applications of lignin raw materials (including their use as antioxidants, biofuels or sorbents in water treatment processes).

  • 31.
    Türe, Hasan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Gällstedt, M.
    Johansson, E.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Wheat-gluten/montmorillonite clay multilayer-coated paperboards with high barrier properties2013In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 51, p. 1-6Article in journal (Refereed)
    Abstract [en]

    This study presents the oxygen-barrier properties of paperboards with a wheat gluten (WG)/montmorillonite clay (MMT) multilayer coating, in which MMT was sandwiched between two layers of WG. Urea was added to the WG to facilitate the coating procedure and the clay was applied as an aqueous dispersion. With a coating thickness of ~20μm, oxygen transmission rates were 8-10cm3/(m2dayatm) at 50% RH, which meant that the oxygen barrier was ca. 25 times better than that given by a single-layer WG-coated paperboard (uncoated paperboard showed infinite values). The water vapor transmission rate (WVTR) was 28-39g/(m2day) using a 50-0% RH gradient, which was 6- to 8-fold lower than the value for uncoated paperboard. Tensile tests revealed small, if any, mechanical effects when the paperboard was coated. A protein solubility analysis indicated that urea-containing WG films were slightly more intermolecularly cross-linked than urea-free WG films. X-ray diffraction revealed that the MMT layer consisted of unswollen tactoids similar to those observed in the MMT powder. The Cobb60 data showed that both WG and clay increased the water absorbency.

  • 32.
    Wu, Qiong
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lindh, Vilhelm H.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Johansson, E.
    Olsson, Richard T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Freeze-dried wheat gluten biofoams; scaling up with water welding2017In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 97, p. 184-190Article in journal (Refereed)
    Abstract [en]

    This paper presents a simple and rapid wet welding technique that enables the scaling up of freeze-dried protein (wheat gluten (WG)) biofoams for e.g. thermal insulation applications. The welding occurred by first wetting faces of foam cubes in water and then pressing them together for a limited time period. The water plasticized thin cell-walls of the two foams formed a dense weld when the plasticized cells collapsed under the drying step. The welds were always stronger and stiffer than the surrounding cellular structure. Based on three-point bending, it was shown that welded specimens (four-cube samples) were 7 times stronger than specimens produced directly as one piece with similar total size. This illustrated the problem of freeze-drying larger products; by instead assembling smaller foams into a large object the overall foam structure became more homogeneous. In addition, the dense welds become “walls” that limit gas convection in the mainly open cell structure, beneficial for thermal insulation. This is the first report on combined freeze-drying and water welding. It shows the sustainable potential of the technique for foam production, since only water is used as a foaming/welding agent.

  • 33.
    Zikeli, Florian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Technische Universität Wien, Austria.
    Ters, T.
    Fackler, K.
    Srebotnik, E.
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wheat straw lignin fractionation and characterization as lignin-carbohydrate complexes2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 85, p. 309-317Article in journal (Refereed)
    Abstract [en]

    Alkaline extracted and untreated wheat straw were ball-milled with liquid nitrogen cooling rendering them completely soluble in the solvent system dimethylsulfoxide-aqueous tetrabutylammonium hydroxide for subsequent fractionation into two lignin-carbohydrate complex fractions termed glucan-lignin and xylan-lignin according to their preferred association with glucan or arabinoxylan, respectively. This is the first description using this fractionation protocol for wheat straw. Eventually, acidolysis lignins were prepared from both lignin-carbohydrate complexes and structurally characterized using wet chemistry and NMR spectroscopy methods. Using the novel procedure we could reveal differences regarding wheat straw lignin association with polysaccharides, p-hydroxycinnamic acids and tricin as well as in their monomer composition. In glucan-lignin the lignin moiety was found to be linked mainly to glucan but also to branched arabinoxylan. Xylan-lignin, however, was rich in structures creating cross-links between lignin and linear arabinoxylan via ether-ester bridges by bi-functional ferulic acid. Inter-molecular ether-ester-linkages by ferulic acid connecting the lignin moieties of the two LCC fractions glucan-lignin and xylan-lignin were proposed. Alkaline extraction of the straw resulted in a strikingly lower recovery of xylan-lignin in the subsequent fractionation which was attributed to cleavage of ester linkages between ferulic acid and arabinoxylan. Structural characteristics indicated glucan-lignin and xylan-lignin deriving from different morphological origins of the cell wall.

  • 34. Zikeli, Florian
    et al.
    Ters, Thomas
    Fackler, Karin
    Srebotnik, Ewald
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Fractionation of wheat straw Dioxane lignin reveals molar mass dependent structural differences2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 91, p. 186-193Article in journal (Refereed)
    Abstract [en]

    Dioxane lignin was isolated from ball-milled wheat straw by neutral dioxane-water extraction and subsequently molar-mass-fractionated by flash chromatography in dimethylformamide. The eluted lignin containing material was pooled into six distinct molar mass fractions that were in turn structurally characterized in detail by wet chemistry and NMR spectroscopy methods. Fractions of higher molar mass were found to be enriched in p-hydroxyphenyl units and contained more p-hydroxycinnamic acid units. They were found mainly associated with linear arabinoxylan, while in low-molar-mass fractions additional glucan contributions were found. Fractions of lower molar mass consisted of relatively more guaiacyl units and showed exclusive association with tricin units. One distinct lignin fraction with lower lignin content supposedly contained high ratios of arabinoxylan chains esterified by ferulic acid and cross-linked via ferulic acid dimerization, structures which were considered to represent lignin nucleation sites. High abundance of dibenzodioxocin type structures in this fraction indicated that they could be involved in cross-linking hemicelluloses networks with lignin moieties.

  • 35.
    Zikeli, Florian
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Vienna University of Technology, Austria.
    Ters, Thomas
    Fackler, Karin
    Srebotnik, Ewald
    Li, Jiebing
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Successive and quantitative fractionation and extensive structural characterization of lignin from wheat straw2014In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 61, p. 249-257Article in journal (Refereed)
    Abstract [en]

    A unique process for the fractionation of lignin from wheat straw is proposed: Ball milling for 8 h, followed by a direct and an acidolysis-assisted dioxane-water extraction. Four distinctly different lignin structures were thus obtained: (1) one free non-core lignin, which is a cellulose-lignin with lowest molar mass and highest contents of p-hydroxycinnamic acids, condensed phenolic hydroxyl groups and tricin moieties, and with a detectable amount of cinnamyl alcohols; (2) two core xylan-lignins differing in their degree of branching as indicated by their xylose/arabinose ratios of >4 and similar to 2, respectively; (3) one core cellulose-lignin which is the residual fraction resistant to all extractions. Based on the mass balance of Klason lignin the yields of these four fractions are 13.8%, 18.1%, 37.5% and 12.5%, respectively, thus accounting for 82% of the total KL in wheat straw. Therefore, the isolated lignin fractions could be considered as highly representative allowing a good insight into the different features of wheat straw lignin.

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