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  • 101.
    Bäckström, Marie
    et al.
    RISE, Innventia.
    Melander, Erik
    KTH Royal Institute of Technology, Sweden.
    Brännvall, Elisabet
    KTH Royal Institute of Technology, Sweden.
    Study of the influence of charges on refinability of bleached softwood kraft pulp2013In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, no 4, p. 588-595Article in journal (Refereed)
    Abstract [en]

    To investigate how the number of charged groups affects the refinability of pulp, different levels of fibre charge were introduced to fully bleached softwood kraft pulp by bulk carboxymethylation. The chemical compositions of the fibres thus remained similar and the effect of the charge could be evaluated. The pulps were refined in a PFI-mill. The introduction of additional charges clearly resulted in a higher refinability in terms of a higher WRV for a given energy input. However, the increase in swellability was not accompanied by a corresponding increase in tensile index. The highly charged pulps suffered severe damage to the fibre wall during refining, showing that the combination of high charge levels and mechanical forces cause destruction of the fibre wall, which inhibits paper strength development. 

  • 102.
    Bäckström, Marie
    et al.
    RISE, Innventia.
    Tubek-Lindblom, Anna
    RISE, Innventia.
    Wågberg, Lars
    RISE, Innventia.
    Studies of the influence of deflocculants and flocculants on the refining efficiency on a pilot scale2009In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 3, p. 319-326Article in journal (Refereed)
    Abstract [en]

    The objective of the present investigation was to study the influence of flocculants and deflocculants on refining efficiency. The refining was performed with the aid of a conical refiner at EuroFEX, and the refining response was evaluated as the change in fibre properties and in the mechanical properties of handsheets. Using the same furnish, an unbleached neverdried softwood pulp, the effect of fibre dimensions on floc strength was excluded as much as possible. The degree of flocculation was changed by addition of APAM, CPAM, guar gum and CMC. The floc strength was characterized using a parallel plate rheometer. The added chemicals, except for APAM, affected the relation between power input and gap clearance. To reach a certain power the fibres treated with guar gum, CMC or CPAM required a narrower gap clearance than the reference pulp or when APAM was added to the fibres. Refining at a narrower gap clearance increased the refining efficiency in terms of WRV and paper property development, as long as fibre length reduction could be avoided.

  • 103. Carlsson, A.
    et al.
    Håkansson, K.
    Kvick, M.
    Lundell, F.
    RISE, Innventia.
    Söderberg, L.D.
    RISE, Innventia.
    Evaluation of steerable filter for detection of fibers in flowing suspensions2011In: Experiments in Fluids, ISSN 0723-4864, E-ISSN 1432-1114, no 4, p. 987-996Article in journal (Refereed)
  • 104. Carlsson, A.
    et al.
    Söderberg, L. Daniel
    RISE, Innventia.
    Lundell, F.
    Fibre orientation measurements near a headbox wall2010In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 25, no 2, p. 204-212Article in journal (Refereed)
    Abstract [en]

    Experimental results on the fibre orientation in a laboratory scale headbox are reported. Images containing fibres in approximately 1 mm thick slices parallel to the wall were captured at different wall distances. A steerable filter was used to determine the orientation of bleached and unbeaten birch fibres, suspended in water, at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only dilute suspensions were studied. It is shown that the fibre orientation distribution varies with the distance from the wall. Sufficiently far upstream in the headbox a more anisotropic distribution is found closer to the wall.

  • 105.
    Carlsson, Linn
    et al.
    KTH Royal Institute of Technology, Sweden.
    Ingverud, Tobias
    KTH Royal Institute of Technology, Sweden.
    Blomberg, Hanna
    KTH Royal Institute of Technology, Sweden.
    Carlmark, Anna
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Malmström, Eva
    KTH Royal Institute of Technology, Sweden.
    Surface characteristics of cellulose nanoparticles grafted by surface-initiated ring-opening polymerization of ε-caprolactone2015In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 2, p. 1063-1074Article in journal (Refereed)
    Abstract [en]

    In this study, surface-initiated ring-opening polymerization has been employed for the grafting of e-caprolactone from cellulose nanoparticles, made by partial hydrolysis of cellulose cotton linters. A sacrificial initiator was employed during the grafting reactions, to form free polymer in parallel to the grafting reaction. The degree of polymerization of the polymer grafts, and of the free polymer, was varied by varying the reaction time. The aim of this study was to estimate the cellulose nanoparticle degree of surface substitution at different reaction times. This was accomplished by combining measurement results from spectroscopy and chromatography. The prepared cellulose nanoparticles were shown to have 3.1 (±0.3) % of the total anhydroglucose unit content present at the cellulose nanoparticle surfaces. This effectively limits the amount of cellulose that can be targeted by the SI-ROP reactions. For a certain SIROP reaction time, it was assumed that the resulting degree of polymerization (DP) of the grafts and the DP of the free polymer were equal. Based on this assumption it was shown that the cellulose nanoparticle surface degree of substitution remained approximately constant (3–7 %) and seemingly independent of SI-ROP reaction time. We believe this work to be an important step towards a deeper understanding of the processes and properties controlling SI-ROP reactions occurring at cellulose surfaces.

  • 106.
    Carrick, Christopher
    et al.
    KTH Royal Institute of Technology, Sweden.
    Lindström, Stefan B.
    Linköping University, Sweden.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars Göran
    KTH Royal Institute of Technology, Sweden.
    Lightweight, highly compressible, noncrystalline cellulose capsules2014In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 26, p. 7635-6744Article in journal (Refereed)
    Abstract [en]

    We demonstrate how to prepare extraordinarily deformable, gas-filled, spherical capsules from nonmodified cellulose. These capsules have a low nominal density, ranging from 7.6 to 14.2 kg/m3, and can be deformed elastically to 70% deformation at 50% relative humidity. No compressive strain-at-break could be detected for these dry cellulose capsules, since they did not rupture even when compressed into a disk with pockets of highly compressed air. A quantitative constitutive model for the large deformation compression of these capsules is derived, including their high-frequency mechanical response and their low-frequency force relaxation, where the latter is governed by the gas barrier properties of the dry capsule. Mechanical testing corroborated these models with good accuracy. Force relaxation measurements at a constant compression rendered an estimate for the gas permeability of air through the capsule wall, calculated to 0.4 mL μm/m2 days kPa at 50% relative humidity. These properties taken together open up a large application area for the capsules, and they could most likely be used for applications in compressible, lightweight materials and also constitute excellent model materials for adsorption and adhesion studies.

  • 107.
    Carrick, Cristopher
    et al.
    KTH Royal Institute of Technology, Sweden.
    Ruda, Marcus C.
    SweTree Technologies AB, Sweden.
    Pettersson, Bert
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE, Innventia. Wallenberg Wood Science Centre, Sweden.
    Wågberg, Lars Göran
    Wallenberg Wood Science Centre, Sweden.
    Hollow cellulose capsules from CO2 saturated cellulose solutions: Their preparation and characterization2013In: RSC Advances, ISSN  2046-2069, no 7, p. 2462-2469Article in journal (Refereed)
    Abstract [en]

    A new material consisting of mm-sized hollow cellulose spheres, for biomedical applications or for the preparation of low weight porous materials has been prepared by a unique solution precipitation (SP) method. The technique is based on three separate steps. In the first step, high molecular mass, non-modified cellulose is dissolved in a suitable solvent. This cellulose solution is then saturated with a suitable gas (CO2 or N2 in the present work) and finally this gas-saturated solution is drop-wise added to a water reservoir. In this step, the cellulose is precipitated and a gas bubble is nucleated in the center of the cellulose sphere. When stored in water, the hollow center is filled with water, indicating that the capsule wall is porous in nature. This was also supported by BET-area measurements as well as by high resolution SEM-images of broken capsule walls. The internal void volume of a capsule was about 5 μl and the wall volume was about 8 μl. It was also established that the properties of the cellulose capsules, i.e. wall and void volume, the specific surface area, the average pore size of the capsule wall, the wall density, and the compressive load capacity could be tuned by the choice of cellulose concentration in the solution before precipitation. The capsule wall volume and void volume were also affected by the choice of gas, the gas pressure and the gas dissolution time during the gas saturation step. The response of the cellulose wall of the prepared capsules to changes in pH and ion concentration in the surrounding solution was also investigated. The swelling-shrinking behavior was further investigated by introducing more charges to the capsule wall, via carboxymethylation of the cellulose. This was achieved by using carboxymethylated cellulose which increased the swelling-shrinking effect. The results show a typical polyelectrolyte gel behavior of the capsule wall and the wet modulus of the cellulose wall was determined to be between 0.09-0.2 MPa depending on the charge of the cellulose in the capsule wall. Furthermore, the freeze dried cellulose spheres had a modulus of 1.9-7.4 MPa, depending on the cellulose concentration during the preparation of the spheres. These cellulose capsules are suitable both for the preparation of porous materials, where these larger spheres are joined together in 3D-shaped materials, and for controlled release where the interior of the capsules is filled with active substances and these substances are released by controlling the pores in the capsule walls.

  • 108.
    Carvalho, Lara
    et al.
    Luleå university of technology, Sweden.
    Furusjö, Erik
    Luleå university of technology, Sweden.
    Kirtania, Kawnish
    Luleå university of technology, Sweden.
    Wetterlund, Elisabeth
    Luleå university of technology, Sweden.
    Lundgren, Joakim
    Luleå university of technology, Sweden.
    Anheden, Marie
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Wolf, Jens
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy. RISE, Innventia.
    Techno-economic assessment of catalytic gasification of biomass powders for methanol production2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 237, p. 167-177Article in journal (Refereed)
    Abstract [en]

    This study evaluated the techno-economic performance and potential benefits of methanol production through catalytic gasification of forest residues and lignin. The results showed that while catalytic gasification enables increased cold gas efficiencies and methanol yields compared to non-catalytic gasification, the additional pre-treatment energy and loss of electricity production result in small or no system efficiency improvements. The resulting required methanol selling prices (90–130 €/MWh) are comparable with production costs for other biofuels. It is concluded that catalytic gasification of forest residues can be an attractive option as it provides operational advantages at production costs comparable to non-catalytic gasification. The addition of lignin would require lignin costs below 25 €/MWh to be economically beneficial.

  • 109. Celaya, J.
    et al.
    Bridgwater, A.V.
    Toven, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Fast pyrolysis bio-oil production from Scandinavian forest residues2012Conference paper (Refereed)
  • 110. Celaya, J.
    et al.
    Bridgwater, A.V.
    Toven, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Fast pyrolysis bio-oil production from Scandinavian forest residues2012Conference paper (Refereed)
  • 111.
    Celaya Romeo, Javier
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Wernersson Brodin, Fredrik
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Toven, Kai
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Re-homogenization of phase separated forest residue pyrolysis oil by blending2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 163, p. 60-66Article in journal (Refereed)
    Abstract [en]

    The wood processing industry generates large amounts of forest residues like branches and tops which represent a significant unexploited resource for sustainable biofuel production. A feasible thermochemical route to valorise these residues is fast pyrolysis. However, the main product of this technology, pyrolysis oil or bio-oil, shows several disadvantages in comparison with conventional fuels. One of the main drawbacks of bio-oil is its instability which results in liquid phase separation in many cases. The purpose of this study is to verify whether homogenous single-phase heating fuels for district heating etc. can be formed from aged, phase separated forest residue pyrolysis oils by blending. Aged, phase separated pyrolysis oils were blended with either methanol or 1-butanol and the amount of alcohol needed to form homogeneous and storage stable fuel blends was evaluated. Homogeneity of the fuel blends was analysed by water concentration profile analysis and image analysis. Storage stability was analysed by analysing homogeneity as function of storage time. Essential fuel characteristics were analysed. The results revealed that phase separated forest residue pyrolysis oil can be homogenized by adding moderate amounts of alcohol and that some of the blends are stable longer than two months. Alcohol addition also improves essential product properties for pyrolysis oils as heating fuels. This work forms part of the ReShip Project partly funded by the Research Council of Norway (The ENERGIX programme).

  • 112. Cervin, N.T.
    et al.
    Aulin, C.
    RISE, Innventia.
    Larsson, P.T.
    RISE, Innventia.
    Wågberg, L.
    Ultra porous nanocellulose aerogels as separation medium for mixtures of oil/water liquids2012In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, no 2, p. 401-410Article in journal (Refereed)
  • 113. Chacha, N.
    et al.
    Toven, K.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Mtui, G.
    Katima, J.
    Mrema, G.
    Steam pretreatment of pine (Pinus patula) for fuel ethanol production in Tanzania2011Conference paper (Refereed)
  • 114. Chacha, N.
    et al.
    Toven, K
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Mtui, G
    Katima, J
    Mrema, G
    Steam Pretreatment of Pine (Pinus patula) wood residue for the production of reducing sugars2011In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 45, p. 495-501Article in journal (Refereed)
  • 115.
    Chang, Shan-Shan
    et al.
    Université Montpellier, France.
    Salmen, Lennart
    RISE, Innventia.
    Olsson, Anne-Mari
    RISE, Innventia.
    Clair, Bruno
    Université Montpellier, France.
    Deposition and organisation of cell wall polymers during maturation of poplar tension wood by FTIR microspectroscopy2014In: Planta, ISSN 0032-0935, E-ISSN 1432-2048, Vol. 239, no 1, p. 243-254Article in journal (Refereed)
    Abstract [en]

    To advance our understanding of the formation of tension wood, we investigated the macromolecular arrangement in cell walls by Fourier transform infrared microspectroscopy (FTIR) during maturation of tension wood in poplar (Populus tremula x P. alba, clone INRA 717-1B4). The relation between changes in composition and the deposition of the G-layer in tension wood was analysed. Polarised FTIR measurements indicated that in tension wood, already before G-layer formation, a more ordered structure of carbohydrates at an angle more parallel to the fibre axis exists. This was clearly different from the behaviour of opposite wood. With the formation of the S2 layer in opposite wood and the G-layer in tension wood, the orientation signals from the amorphous carbohydrates like hemicelluloses and pectins were different between opposite wood and tension wood. For tension wood, the orientation for these bands remains the same all along the cell wall maturation process, probably reflecting a continued deposition of xyloglucan or xylan, with an orientation different to that in the S2 wall throughout the whole process. In tension wood, the lignin was more highly oriented in the S2 layer than in opposite wood.

  • 116.
    Chedid, Fadia
    et al.
    RISE, Innventia.
    Aldaeus, Fredrik
    RISE, Innventia.
    Jacobs, Anna
    RISE, Innventia.
    Lignin molecular mass determined using size-exclusion chromatography and MALDI-TOF mass spectrometry2014Conference paper (Refereed)
  • 117.
    Chen, Fei
    et al.
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE, Innventia.
    Olsson, Richard T.
    KTH Royal Institute of Technology, Sweden.
    Gedde, Ulf W.
    KTH Royal Institute of Technology, Sweden.
    Hedenqvist, Mikael S.
    KTH Royal Institute of Technology, Sweden.
    Unusual effects of monocarboxylic acids on the structure and on the transport and mechanical properties of chitosan films2015In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 132, p. 419-429, article id 10041Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to study the transport of monocarboxylic acids in chitosan films, since this is important for understanding and predicting the drying kinetics of chitosan from aqueous solutions. Despite the wealth of data on chitosan films prepared from aqueous monocarboxylic acid solutions, this transport has not been reported. Chitosan films were exposed to formic, acetic, propionic and butyric acid vapours, it was found that the rate of uptake decreased with increasing molecular size. The equilibration time was unexpectedly long, especially for propionic and butyric acid, nine months. A clear two-stage uptake curve was observed for propionic acid. Evidently, the rate of uptake was determined by acid-induced changes in the material. X-ray diffraction and infrared spectroscopy indicated that the structure of the chitosan acetate and buffered chitosan films changed during exposure to acid and during the subsequent drying. The dried films previously exposed to the acid showed less crystalline features than the original material and a novel repeating structure possibly involving acid molecules. The molar mass of the chitosan decreased on exposure to acid but tensile tests revealed that the films were always ductile. The films exposed to acid vapour (propionic and butyric acid) for the longest period of time were insoluble in the size-exclusion chromatography eluent, and they were also the most ductile/extensible of all samples studied.

  • 118.
    Chen, Fei
    et al.
    KTH Royal Institute of Technology, Sweden.
    Monnier, Xavier
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE, Innventia.
    Gedde, Ulf Wiel
    KTH Royal Institute of Technology, Sweden.
    Hedenqvist, Mikael Stefan
    KTH Royal Institute of Technology, Sweden.
    Wheat gluten/chitosan blends: A new biobased material2014In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 60, p. 186-197Article in journal (Refereed)
    Abstract [en]

    Wheat gluten and chitosan are renewable materials that suffer from some poor properties that limit their use as a potential replacement of petroleum-based polymers. However, polymer blends based on wheat gluten and chitosan surprisingly reduced these shortcomings. Films were cast from acidic aqueous or water/ethanol solutions of wheat gluten and chitosan. Wheat gluten was the discontinuous phase in the 30-70 wt.% wheat gluten interval investigated. The most homogeneous films were obtained when reducing agents were used (alone or together with urea or glycerol). They consisted mainly of 1-2 μm wheat gluten particles uniformly distributed in the continuous chitosan phase. Slightly smaller particles were also observed in the water/ethanol solvent system, but together with significantly larger particles (as large as 200 μm). Both small and large particles were observed, albeit in different sizes and contents, when surfactants (both with and without a reducing agent) or urea (without a reducing agent) were used. The particles were often elongated, and preferably along the film, the most extreme case being observed when the glyoxal crosslinker was used together with sodium sulfite (reducing agent), showing particles with an average thickness of 0.6 μm and an aspect ratio of 4.2. This film showed the highest transparency of all the blend films studied. For one of the most promising systems (with sodium sulfite), having good film homogeneity and small particles, the mechanical and moisture solubility/diffusivity properties were studied as a function of chitosan content. The extensibility, toughness and moisture solubility increased with increasing chitosan content, and the moisture diffusivity was highest for the pristine chitosan material. It is noteworthy that the addition of 30 wt.% wheat gluten to chitosan reduced the moisture uptake, while the extensibility/toughness remained unchanged.

  • 119.
    Chen, Fei
    et al.
    KTH Royal Institute of Technology, Sweden.
    Nilsson, Fritjof
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE, Innventia.
    Hedenqvist, Mikael Stefan
    KTH Royal Institute of Technology, Sweden.
    Chitosan extrusion at high solids content: An orthogonal experimental design study2014In: Polymers from Renewable Resources, ISSN 2045-1377, Vol. 5, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    For economic reasons and to save time there is a need to shorten the drying operation associated with the production of chitosan materials. Hence it is of interest to extrude chitosan at as high a solids content as possible. This is, to our knowledge, the first systematic study of the extrusion of chitosan at high solids content (60 wt%). An orthogonal experimental design was used to evaluate the effect of processing conditions and material factors on the extrudability of chitosan. This, together with the examination of the evenness and surface finish of the extrudate, made it possible to determine the best conditions for obtaining a readily extrudable high quality material. It was observed that a 1/1 ratio of chitosans with molar masses of 12 and 133 kDa, a process liquid containing 30 wt% acetic acid and 70 wt% water, and extrusion at 50 rpm and 50°C were the optimal material and processing conditions. Materials processed under these conditions were evaluated mechanically at different times after extrusion (stored at 50% RH) in order to see when the properties stabilized. Most mass loss occurred within the first three days after extrusion and this governed the mechanical properties (stiffness and extensibility), which also exhibited the largest changes within these three days (an increase in modulus from 18 to 830 MPa and a decrease in elongation at break from 17 to 3%).

  • 120.
    Chen, Z. -Q.
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Abramowicz, K.
    Umeå University, Sweden.
    Raczkowski, R.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Ganea, S.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Wu, H. X.
    SLU Swedish University of Agricultural Sciences, Sweden; CSIRO Commonwealth Scientific and Industrial Research Organisation, Australia.
    Lundqvist, Sven-Olof
    RISE, Innventia.
    Mörling, T.
    SLU Swedish University of Agricultural Sciences, Sweden.
    De Luna, S. S.
    Umeå University, Sweden.
    Garci­a Gil, M. R.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Mellerowicz, E. J.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Method for accurate fiber length determination from increment cores for large-scale population analyses in Norway spruce2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 9, p. 829-838Article in journal (Refereed)
    Abstract [en]

    Fiber (tracheid) length is an important trait targeted for genetic and silvicultural improvement. Such studies require large-scale non-destructive sampling, and accurate length determination. The standard procedure for non-destructive sampling is to collect increment cores, singularize their cells by maceration, measure them with optical analyzer and apply various corrections to suppress influence of non-fiber particles and cut fibers, as fibers are cut by the corer. The recently developed expectation-maximization method (EM) not only addresses the problem of non-fibers and cut fibers, but also corrects for the sampling bias. Here, the performance of the EM method has been evaluated by comparing it with length-weighing and squared length-weighing, both implemented in fiber analyzers, and with microscopy data for intact fibers, corrected for sampling bias, as the reference. This was done for 12-mm increment cores from 16 Norway spruce (Picea abies (L.) Karst) trees on fibers from rings 8-11 (counted from pith), representing juvenile wood of interest in breeding programs. The EM-estimates provided mean-fiber-lengths with bias of only +2.7% and low scatter. Length-weighing and length2-weighing gave biases of-7.3% and +9.3%, respectively, and larger scatter. The suggested EM approach constitutes a more accurate non-destructive method for fiber length (FL) determination, expected to be applicable also to other conifers.

  • 121.
    Chen, Zhiqiang
    et al.
    SLU Swedish University of Agricultural Sciences,Sweden.
    Gil, Maria Rosario García
    SLU Swedish University of Agricultural Sciences,Sweden.
    Karlsson, Bo
    Skogforsk, Sweden.
    Lundqvist, Sven Olof
    RISE, Innventia.
    Olsson, Lars
    RISE, Innventia.
    Wu, Harry Xiaming
    SLU Swedish University of Agricultural Sciences, Sweden; CSIRO, Australia.
    Inheritance of growth and solid wood quality traits in a large Norway spruce population tested at two locations in southern Sweden2014In: Tree Genetics & Genomes, ISSN 1614-2942, E-ISSN 1614-2950, Vol. 10, no 5, p. 1291-1303Article in journal (Refereed)
    Abstract [en]

    Unfavorable genetic correlations between growth and wood quality traits are one of the biggest challenges in advanced conifer breeding programs. To examine and deal with such correlation, increment cores were sampled at breast height from 5,618 trees in 524 open-pollinated families in two 21-year-old Norway spruce progeny trials in southern Sweden, and age trends of genetic variation, genetic correlation, and efficiency of selection were investigated. Wood quality traits were measured on 12-mm increment cores using SilviScan. Heritability was moderate (~0.4-0.5) for wood density and modulus of elasticity (MOE) but low (~0.2) for microfibril angle (MFA). Different age trends were observed for wood density, MFA, and MOE, and the lower heritability of MFA relative to wood density and MOE in Norway spruce contrasted with general trends of the three wood quality traits in pine. Genetic correlations among growth, wood density, MFA, and MOE increased to a considerably high value from pith to bark with unfavorable genetic correlations (−0.6 between growth and wood density, −0.74 between growth and MOE). Age-age genetic correlations reached 0.9 after ring 4 for diameter at breast height (DBH), wood density, MFA, and MOE traits. Early selections at ring 10 for diameter and at ring 6 or 7 for wood quality traits had similar effectiveness as selection conducted at reference ring 15. Selection based on diameter alone produced 19.0 % genetic gain in diameter but resulted in 4.8 % decrease in wood density, 9.4 % decrease in MOE, and 8.0 % increase in MFA. Index selection with a restriction of no change in wood density, MOE, and MFA, respectively, produced relatively lower genetic gains in diameter (16.4, 12.2, and 14.1 %, respectively), indicating such index selection could be implemented to maintain current wood density. Index selection using economic weights is, however, recommended for maximum economic efficiency

  • 122.
    Chen, Zhi-Qiang
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Karlsson, Bo
    Skogforsk, Sweden.
    Lundqvist, Sven-Olof
    RISE, Innventia.
    Garci­a Gil, María Rosario
    SLU Swedish University of Agricultural Sciences, Sweden.
    Olsson, Lars
    RISE, Innventia.
    Wu, Harry X.
    CSIRO Commonwealth Scientific and Industrial Research Organisation, Australia.
    Estimating solid wood properties using Pilodyn and acoustic velocity on standing trees of Norway spruce2015In: Annals of Forest Science, ISSN 1286-4560, E-ISSN 1297-966X, Vol. 72, no 4, p. 499-508Article in journal (Refereed)
    Abstract [en]

    Key message: Strong genetic correlations were observed between Pilodyn measurement and wood density, and between acoustic velocity and MFA. Combination of Pilodyn penetration and acoustic velocity measurements from standing trees can provide reliable prediction of stiffness of Norway spruce for breeding selection.

    Context: Traditional methods for the estimation of solid wood quality traits of standing tree such as wood density, microfibril angle (MFA), and modulus of elasticity (MOE) are time-consuming and expensive, which render them unsuitable for rapidly screening a large number of trees in tree breeding programs.

    Aim: This study aims to evaluate the suitability of using Pilodyn penetration and acoustic velocity (nondestructive evaluation) to assess wood density, MFA, and MOE for Norway spruce.

    Methods: Pilodyn penetration and Hitman acoustic velocity, as well as wood density, MFA, and MOE using benchmark SilviScan were measured on 5618 standing trees of 524 open-pollinated families in two 21-year-old Norway spruce (Picea abies) progeny trials in southern Sweden.

    Results: Strong genetic correlations were observed between Pilodyn measurement and wood density (rg = −0.96), and between acoustic velocity and MFA (rg = −0.94). Combination of Pilodyn penetration and Hitman acoustic velocity measurements (Formula presented.) obtained from standing trees showed a genetic correlation with benchmark MOE of 0.99. This combined MOE(Formula presented.) had higher selection efficiency for benchmark MOE (92 %) compared to 58–60 % using acoustic velocity alone and 78 % using Pilodyn penetration alone.

    Conclusion: Combination of Pilodyn penetration with Hitman acoustic velocity provided very high selection efficiency for the three most important quality traits for wood mechanical properties in Norway spruce.

  • 123.
    Chen, Zhi-Qiang
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Karlsson, Bo
    Skogforsk, Sweden.
    Mörling, Tommy
    SLU Swedish University of Agricultural Sciences, Sweden.
    Olsson, Lars
    RISE, Innventia.
    Mellerowicz, Ewa J.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Wu, Harry X.
    SLU Swedish University of Agricultural Sciences, Sweden; CSIRO Commonwealth Scientific and Industrial Research Organisation, Australia.
    Lundqvist, Sven-Olof
    RISE, Innventia.
    Gil, María Rosario García
    SLU Swedish University of Agricultural Sciences, Sweden.
    Genetic analysis of fiber dimensions and their correlation with stem diameter and solid-wood properties in Norway spruce2016In: Tree Genetics & Genomes, ISSN 1614-2942, E-ISSN 1614-2950, Vol. 12, no 6, article id 123Article in journal (Refereed)
    Abstract [en]

    Adverse genetic correlations between growth traits and solid-wood, as well as fiber traits are a concern in conifer breeding programs. To evaluate the impact of selection for growth and solid-wood properties on fiber dimensions, we investigated the inheritance and efficiency of early selection for different wood-fiber traits and their correlations with stem diameter, wood density, modulus of elasticity (MOE), and microfibril angle (MFA) in Norway spruce (Picea abies L). The study was based on two large open-pollinated progeny trials established in southern Sweden in 1990 with material from 524 families comprising 5618 trees. Two increment cores were sampled from each tree. Radial variations from pith to bark were determined for rings 3–15 with SilviScan for fiber widths in the radial (RFW) and tangential (TFW) direction, fiber wall thickness (FWT), and fiber coarseness (FC). Fiber length (FL) was determined for rings 8–11. Heritabilities based on rings 8–11 using joint-site data were moderate to high (0.24–0.51) for all fiber-dimension traits. Heritabilities based on stem cross-sectional averages varied from 0.34 to 0.48 and reached a plateau at rings 6–9. The “age-age” genetic correlations for RFW, TFW, FWT, and FC cross-sectional averages at a particular age with cross-sectional averages at ring 15 reached 0.9 at rings 4–7. Our results indicated a moderate to high positive genetic correlation for density and MOE with FC and FWT, moderate and negative with RFW, and low with TFW and FL. Comparison of several selection scenarios indicated that the highest profitability is reached when diameter and MOE are considered jointly, in which case, the effect on any fiber dimension is negligible. Early selection was highly efficient from ring 5 for RFW and from rings 8–10 for TFW, FWT, and FC.

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  • 124.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Advanced biomaterials based on nanofibrillated cellulose: from nanopapers to nanomedicine2014Conference paper (Refereed)
    Abstract [en]

    Nanofibrillated cellulose (NFC) offers a wide range of interesting opportunities and advantages, being biodegradable, renewable and thus environmentally sound. Extensive research has been performed on the effective production and application of NFC. The proposed applications extend from being a component in paper, coatings and composite materials to being applied in bio-medicine as part of wound dressings or in drug delivery systems. Some of the major advantages of NFC are the dimensions and the structural and chemical composition of nanofibrils, which lead to the formation of dense networks with optimized optical and mechanical properties. In this respect, the concept of nanopaper has been introduced. Nanopapers are strong structures, with high light transmittance and smooth surfaces. These characteristics open for novel applications, including the formation of smooth substrates for printing functionality. A recently explored example is the printing of bioactive biomacromolecules and conductive structures on tailor-made nanopapers, which could form the basis for novel biosensors. Additionally, nanobarriers are most promising in novel packaging applications where the self-assembly properties of the material facilitate the formation of dense structures with high barrier against oxygen. However, NFC alone does not seem to be sufficient for the formation of adequate nanobarriers due to the brittle and hygroscopic characteristics of the material. Novel biocomposite concepts need thus closer attention, where the strong and high barrier properties of NFC could be complemented with adequate bioplastics and additives for the formation of ductile films, suitable for conversion processes. From the biomedical point of view, NFC offers several advantages. Depending on the structural and chemical composition of the material and the cross-linking with adequate polymers and particles, micro-porous and elastic gels can be formed. Such gels can hold a considerable amount of water, thus being an excellent material for keeping a moist environment during wound healing and for facilitating the regeneration process of human tissue. Additionally, NFC gels based on oxidized nanofibrils can have pH-sensitive characteristics, a property with potential in drug delivery. With the intention of giving an extensive description of NFC and its modern applications, this presentation will be divided into three main sections; i) production and definition, ii) characterization including structural, chemical and biological aspects and iii) novel applications of NFC from nanopapers to biomedical devices.

  • 125.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose fibres, nanofibrils and microfibrils: The morphological sequence of MFC components from a plant physiology and fibre technology point of view2011In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 6Article in journal (Refereed)
  • 126.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Complementary microscopy techniques for surface characterisation of uncoated and mineral pigment coated paper2012In: Current microscopy contributions to advances in science and technology / [ed] Méndez-Vilsa A., Formatex Research Center, 2012, p. 1448-1455Chapter in book (Refereed)
  • 127.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Complementary Microscopy Techniques for Surface Characterisation of Uncoated and Mineral Pigment Coated Paper2012In: Current Microscopy Contributions to Advances in Science and Technology, Formatex Research Center , 2012, , p. 8Chapter in book (Refereed)
  • 128.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Microscopy and computerized image analysis of wood pulp fibres multiscale structures2010In: Microscopy: Science, technology, applications and education / [ed] Méndez-Vilas A., Formatex Research Center, 2010, p. 2182-2189Chapter in book (Refereed)
  • 129.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Optical methods for the quantification of the fibrillation degree of bleached MFC materials2013In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 48, p. 42-48Article in journal (Refereed)
    Abstract [en]

    In this study, the suitability of optical devices for quantification of the fibrillation degree of bleached microfibrillated cellulose (MFC) materials has been assessed. The techniques for optical assessment include optical scanner, UV-vis spectrophotometry, turbidity, quantification of the fiber fraction and a camera system for dynamic measurements. The results show that the assessed optical devices are most adequate for quantification of the light transmittance of bleached MFC materials. Such quantification yields an estimation of the fibrillation degree. Films made of poorly fibrillated materials are opaque, while films made of highly fibrillated materials containing a major fraction of nanofibrils are translucent, with light transmittance larger than 90%. Finally, the concept of using images acquired with a CCD camera system, for estimating the fibrillation degree in dynamic conditions was exemplified. Such systems are most interesting as this will widen the applicability of optical methods for quantification of fibrillation degree online in production lines, which is expected to appear in the years to come.

  • 130.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Aasrød, Kenneth
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Leinsvang, Berit
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Bouveng, Mikael
    RISE, Innventia.
    Johansson, Per-Åke
    RISE, Innventia.
    Structural effects on print-through and set-off2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 3, p. 596-603Article in journal (Refereed)
    Abstract [en]

    In this study the effect of paper structure on ink transfer and cold-set print quality was assessed. A factorial experiment involving 5 factors with two levels was designed. Several sheet structures were constructed. The sheets were made from three basic pulps, thermomechanical pulp (TMP), de-inked pulp (DIP) and stone groundwood (SGW). The designed structures were homogeneous and layered to verify the effect of sheet structure and fines content on print quality. A comprehensive multiscale characterisation of the sheet structures was performed. The analyses comprised scanning electron microscopy (SEM) and mercury porosimetry for bulk structure assessment. Parker Print Surf (PPS), laser profilometry and field-emission scanning electron microscopy (FE-SEM) were applied for giving a detailed description of the surface structure affecting ink transfer. The study revealed that the surface structure affects the ink demand and set-off. Increasing the micro-roughness leads to an increment of ink demand in order to achieve a given print density. The bulk pore structure affects the light scattering coefficients. Small pores are positive for increasing the light scattering and thus for reducing the print-through level. This was confirmed by SEM and mercury porosimetry measurements.

  • 131.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Averianova, Natalia V.
    Kazan National Research Technological University, Russia.
    Gibadullin, Marat R.
    Kazan National Research Technological University, Russia.
    Petrov, Vladimir A.
    Kazan National Research Technological University, Russia.
    Leirset, Ingebjörg
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Micro-structural characterisation of homogeneous and layered MFC nano-composites2013In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 44, no 1, p. 331-338Article in journal (Refereed)
    Abstract [en]

    The complementary capabilities of various characterisation methods for micro-structural assessment are demonstrated. The assessed structures were composed of unbleached microfibrillated cellulose (MFC) in combination with bleached and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) pre-treated MFC materials. The biodegradable nano-composites were thus characterised in detail, including laser profilometry, scanning electron microscopy (SEM) in high and low vacuum modes, and field-emission SEM. The distribution of the unbleached MFC materials was assessed by staining the unbleached MFC with osmium tetroxide (OsO4), which reacts with CC double bonds encountered in lignin. In addition, some properties of the MFC nano-composite films were tested, i.e. tensile properties, water wettability and oxygen permeability. In general, the group of characteristics of the nano-composite MFC films was better than the properties of the films made of the neat MFC qualities. This indicates that mixing complementary MFC qualities could give synergetic effects that are not exploited completely when using the MFC qualities separately. The study thus confirms the suitability of unbleached MFC materials as a component in multilayer structures, for example biodegradable packaging applications.

  • 132.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Averianova, Natalia V.
    Kazan National Research Technological University, Russia.
    Kondalenko, Olga
    Kazan National Research Technological University, Russia.
    Garaeva, Milyausha
    Kazan National Research Technological University, Russia.
    Petrov, Vladimir A.
    Kazan National Research Technological University, Russia.
    Leinsvang, Berit
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Karlsen, Trond
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of residual fibres on the micro-topography of cellulose nanopaper2014In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 56, p. 80-84Article in journal (Refereed)
    Abstract [en]

    Nanopaper is a new material concept composed of nanocellulose, which has been proposed for a series of applications. Recently, the surface of nanopapers has also been emphasized as an important structure to control. This is due to the potential of nanopaper structures as a substrate for printing functionality, which could expand the applicability of nanopaper as a functionalized biomaterial. In this study, we demonstrate how the roughness of nanopaper is affected by the fraction of residual fibres that were not fibrillated into nanofibrils after a homogenization procedure. The topography and morphology were assessed with laser profilometry, atomic force microscopy and scanning (transmission) electron microscopy. The results show a linear correlation between the estimated fraction of residual fibres and the roughness of the assessed nanopapers. Furthermore, the fraction of residual fibres can be reduced by fractionating the nanocellulose, which is demonstrated in the present work. Such knowledge will be valuable for designing nanopaper surfaces with specific structural characteristics.

  • 133.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Brodin, Malin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Karlsen, Trond
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Wood pulp fibres and nanocellulose: Characterization and application in biocomposite materials2014Conference paper (Refereed)
    Abstract [en]

    A composite can be defined as a material composed of two or more components having distinct morphology and chemistry, and giving synergetic effects. In this paper the term biocomposite is used, referring to i) a material having at least one bio-component (e.g. wood pulp fibres and nanofibrils) or ii) biomaterials intended for biomedical applications. The utilization of wood pulp fibres in composite materials has gained major interest during the last years. There are various wood pulp fibres that can be used as reinforcement in composites, e.g. thermo-mechanical pulp (TMP), chemi-thermo-mechanical pulp (CTMP) and kraft pulp fibres. Depending on the pulping process (TMP, CTMP or kraft pulp), the pulp fibres differ greatly with respect to the fibre morphology and chemistry. Kraft pulp fibres have been one of the most used raw materials for producing nanocellulose. Nanocellulose from wood refers to various cellulose nano-materials such as cellulose nanocrystals and nanofibrillated cellulose. Nanofibrillated cellulose is composed of a major fraction of structurally homogeneous nanofibrils having typical widths in the nanometre scale and lengths in the micrometre scale. Wood pulp fibres and nanofibrils have been proposed as reinforcement in composite materials. Some of the major motivations have been the potential improvements by using fibres and nanofibrillated materials with respect to e.g. strength, biodegradability and functionality. The purpose of the present work is to review some advances in biocomposite research and development, including three focus areas; structured biocomposites, flexible biocomposites and biomaterials.

  • 134.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Kirsebom, H.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Designing nanocellulose qualities for wound dressings2013Conference paper (Refereed)
  • 135.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Kuznetsova, Nina V.
    Kazan National Research Technological University, Russia.
    Garaeva, Milyausha
    Kazan National Research Technological University, Russia.
    Leirset, Ingebjörg
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Galiullina, Guzaliya
    Kazan National Research Technological University, Russia.
    Kostochko, Anatoliy V.
    Kazan National Research Technological University, Russia.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Bleached and unbleached MFC nanobarriers:: Properties and hydrophobisation with hexamethyldisilazane2012In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, no 12, article id 1280Article in journal (Refereed)
    Abstract [en]

    This study explores the production and surface modification of microfibrillated cellulose (MFC), based on unbleached and bleached Pinus radiata pulp fibres. Unbleached Pinus radiata pulp fibres tend to fibrillate easier by homogenisation without pre-treatment, compared to the corresponding bleached MFC. The resulting unbleached MFC films have higher barrier against oxygen, lower water wettability and higher tensile strength than the corresponding bleached MFC qualities. In addition, it is demonstrated that carboxymethylation can also be applied for production of highly fibrillated unbleached MFC. The nanofibril size distribution of the carboxymethylated MFC is narrow with diameters less than 20 nm, as quantified on high-resolution field-emission scanning electron microscopy images. The carboxymetylation had a larger fibrillation effect on the bleached pulp fibres than on the unbleached one. Importantly, the suitability of hexamethyldisilazane (HMDS) as a new alternative for rendering MFC films hydrophobic was demonstrated. TheHMDS-modifiedfilmsmade of carboxymethylated MFC had oxygen permeability levels better than 0.06 mL mm m-2 day-1 atm-1,which is a good property for some packaging applications.

  • 136.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Miettinen, A.
    Hendriks, C. L. L
    Gamstedt, K.
    Kataka, M.
    Structural characterisation of kraft pulp fibres and their nanofibrillated materials for biodegradable composite applications2011In: Nanocomposites and Polymers with Analytical Methods, InTech , 2011Chapter in book (Refereed)
  • 137.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Powell, L.C
    Cardiff University School of Dentistry, UK; Swansea University, UK.
    Khan, S
    Cardiff University, UK.
    Hill, K.E
    Cardiff University UK.
    Thomas, D.W
    Cardiff University, UK.
    Wood nanocellulose: Characterization and potential application as barrier against wound bacteria2014Conference paper (Refereed)
    Abstract [en]

    Wood nanocellulose is a novel biomaterial for wound dressing applications. Wood nanocellulose was produced from never-dried P. radiata pulp fibres. The applied pre-treatment was 2,2,6,6-tetramethylpiperidinyl-1-oxyl  (TEMPO) mediated oxidation. To characterise bacterial growth, P. aeruginosa PAO1 biofilms were grown in Mueller Hinton broth on air-dried films. Various microscopy techniques, including atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM) and field-emission scanning electron microscopy (FESEM), were applied to characterise the nanocellulose material and the bacterial-nanocellulose interactions.   Multiscale assessments, including FESEM and AFM, revealed the effective fibrillation of the fibre wall structure, yielding nanofibrils with diameters less than 20 nm and lengths in the micrometre-scale. Importantly, we have demonstrated that the growth of PAO1 was inhibited in the presence of the nanocellulose suspensions when compared to the control. Additionally, SEM imaging revealed distinct clusters of PAO1 cells growing on the surfaces of nanocellulose films. This work highlights the potential usefulness of novel nanocellulose materials in wound dressings with optimized characteristics.

  • 138.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Powell, L.C
    Cardiff University School of Dentistry, UK; Swansea University, UK.
    Nordli, H.R
    NTNU Norwegian University of Science and Technology, Norway.
    Khan, S
    Cardiff University, UK.
    Hill, K.E
    Cardiff University, UK.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Thomas, D.W
    Cardiff University, UK.
    Nanocellulose from wood as a biomaterial for biomedical applications2014Conference paper (Refereed)
    Abstract [en]

    During the last decades major efforts have been made to produce nanocellulose from wood, where the cellulose fibres are disintegrated into individualized nanofibrils with diameters < 20 nm and lengths in the micrometre scale. Production procedures include various pre-treatments, which yield nanocelluloses with varying chemical and structural properties. One important area of research is nanocellulose as a biomaterial with potential applications within the health sector. As an example, the superior mechanical properties, good moisture retention capability and the ability to form elastic macro-porous structures are advantageous properties for utilizing nanocellulose substrates for wound dressings. However, the utilization of nanocellulose as a substrate for wound dressings requires a thorough assessment of the biocompatibility of the material.  In this respect, it has been demonstrated in-vitro that nanocellulose does not exert acute toxic phenomena on fibroblast cells. However, in addition to in-vitro cytotoxicity testing, in-vivo testing of nanocellulose and the ability of nanocellulose to resist bacterial colonization need a closer attention. This presentation will give an overview of the current research on nanocellulose as a biomaterial for wound dressing applications, considering the morphology of nanocellulose structures, mechanical properties, moisture absorption, cytotoxicity tests and nanocellulose-bacteria interactions.

  • 139.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Solheim, Olav
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Lenes, Marianne
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Larsen, Åge G.
    SINTEF, Norway.
    A method for estimating the fibre length in fibre-PLA composites2013In: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 250, no 1, p. 15-20Article in journal (Refereed)
    Abstract [en]

    Wood pulp fibres are an important component of environmentally sound and renewable fibre-reinforced composite materials. The high aspect ratio of pulp fibres is an essential property with respect to the mechanical properties a given composite material can achieve. The length of pulp fibres is affected by composite processing operations. This thus emphasizes the importance of assessing the pulp fibre length and how this may be affected by a given process for manufacturing composites. In this work a new method for measuring the length distribution of fibres and fibre fragments has been developed. The method is based on; (i) dissolving the composites, (ii) preparing the fibres for image acquisition and (iii) image analysis of the resulting fibre structures. The image analysis part is relatively simple to implement and is based on images acquired with a desktop scanner and a new ImageJ plugin. The quantification of fibre length has demonstrated the fibre shortening effect because of an extrusion process and subsequent injection moulding. Fibres with original lengths of >1 mm where shortened to fibre fragments with length of <200 μm. The shortening seems to be affected by the number of times the fibres have passed through the extruder, the amount of chain extender and the fraction of fibres in the polymer matrix.

  • 140.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose nanofibrils: production, characterization and applications2011In: Fine Structure of Papermaking Fibres, Swedish University of Agricultural Sciences , 2011, , p. 13Chapter in book (Refereed)
  • 141.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    On the porosity and oxygen barrier properties of cellulose nanofibril-based films2011Conference paper (Refereed)
  • 142.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    On the structure and oxygen transmission rate of biodegradable cellulose nanobarriers2012In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 7Article in journal (Refereed)
  • 143.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Pretreatment-dependent surface chemistry of wood nanocellulose for pH-sensitive hydrogels2014In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 3, no 29, p. 423-432Article in journal (Refereed)
    Abstract [en]

    Nanocellulose from wood is a promising material with potential in various technological areas. Within biomedical applications, nanocellulose has been proposed as a suitable nano-material for wound dressings. This is based on the capability of the material to self-assemble into 3D micro-porous structures, which among others have an excellent capacity of maintaining a moist environment. In addition, the surface chemistry of nanocellulose is suitable for various applications. First, OH-groups are abundant in nanocellulose materials, making the material strongly hydrophilic. Second, the surface chemistry can be modified, introducing aldehyde and carboxyl groups, which have major potential for surface functionalization. In this study, we demonstrate the production of nanocellulose with tailor-made surface chemistry, by pre-treating the raw cellulose fibres with carboxymethylation and periodate oxidation. The pre-treatments yielded a highly nanofibrillated material, with significant amounts of aldehyde and carboxyl groups. Importantly, the poly-anionic surface of the oxidized nanocellulose opens up for novel applications, i.e. micro-porous materials with pH-responsive characteristics. This is due to the swelling capacity of the 3D micro-porous structures, which have ionisable functional groups. In this study, we demonstrated that nanocellulose gels have a significantly higher swelling degree in neutral and alkaline conditions, compared to an acid environment (pH 3). Such a capability can potentially be applied in chronic wounds for controlled and intelligent release of antibacterial components into biofilms.

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  • 144.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Tobjörk, Daniel
    Åbo Akademi University, Finland.
    Österbacka, Ronald
    Åbo Akademi University, Finland.
    Inkjet-printed silver nanoparticles on nano-engineered cellulose films for electrically conducting structures and organic transistors:: concept and challenges2012In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, no 11, article id 1213Article in journal (Refereed)
    Abstract [en]

    This study explores the suitability of microfibrillated cellulose (MFC) films as a substrate for printing electrically conductive structures and multilayer electronic structures such as organic field effect transistors. Various MFC qualities were tested, including mechanically produced MFC, 2,2,6,6-tetramethylpiperidinyl- 1-oxyl pre-treated MFC and carboxymethylated- MFC. The films differed significantly with respect to the surface structure. In addition, the carboxymethylated-MFC films were surface modified with hexamethyldisilazane (HMDS) to reduce the water-wettability of the films, and thus, improve the print resolution of the inkjet-printed silver (Ag) nanoparticles. The Ag-particles (diameter>50 nm) were printed on the HMDS-modified films, which were mainly composed of nanofibrils with diameters >20 nm. The effect of surface roughness and surface chemical characteristics on the ink spreading and print resolution of the Ag-structures was explored. It was demonstrated that organic transistors operating at low voltages can be fabricated on nano-engineered MFC films.

  • 145.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Yu, Y.
    Diserud, O.
    Quantitative Electron Microscopy of Cellulose Nanofibril Structures from Eucalyptus and Pinus Radiata Kraft Pulp Fibres2011In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 17Article in journal (Refereed)
  • 146.
    Cho, Sung-woo
    et al.
    KTH Royal Institute of Technology, Sweden.
    Blomfeldt, Thomas O.J.
    KTH Royal Institute of Technology, Sweden.
    Halonen, Helena
    RISE, Innventia.
    Gällstedt, Mikael
    RISE, Innventia.
    Hedenqvist, Mikael Stefan
    KTH Royal Institute of Technology, Sweden.
    Wheat gluten-laminated paperboard with improved moisture barrier properties: A new concept using a plasticizer (glycerol) containing a hydrophobic component (oleic acid)2012In: International Journal of Polymer Science, ISSN 1687-9422, E-ISSN 1687-9430, article id 454359Article in journal (Refereed)
    Abstract [en]

    This paper presents a novel approach to reduce the water vapor transmission rate (WVTR) and water absorbance of wheat gluten/paperboard laminates by introducing a hydrophobic component (oleic acid (OA)) into the hydrophilic plasticizer (glycerol). Whereas the paperboard showed immeasurably high WVTR, the laminate with gluten/glycerol yielded finite values. More importantly, by incorporating 75 wt.% OA into the plasticizer, the WVTR and water absorbance were reduced by, respectively, a factor of three and 1.5-2. Of particular interest was that the mechanical properties were not changing dramatically between 0 and 50 wt.% OA. The results showed clear benefits of combining a gluten film with paperboard. Whereas the paperboard provided toughness, the WG layer contributed with improved moisture barrier properties. In addition, WVTR indicated that the paperboard reduced the swelling of the outer gluten/glycerol layer in moist conditions; a free standing gluten/glycerol film would yield infinite, rather than finite, WVTR values. 

  • 147. Cho, S.-W.
    et al.
    Gällstedt, M.
    RISE, Innventia.
    Johansson, E.
    Hedenqvist, M.S.
    Injection-molded nanocomposites and materials based on wheat gluten2011In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, no 1, p. 146-152Article in journal (Refereed)
  • 148. Cho, S.-W.
    et al.
    Gällstedt, Mikael
    RISE, Innventia.
    Hedenqvist, M.S.
    Effects of glycerol content and film thickness on the properties of vital wheat gluten films cast at pH 4 and 112010In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 117, no 6, p. 3506-3514Article in journal (Refereed)
    Abstract [en]

    This study deals with the optical properties and plasticizer migration properties of vital wheat gluten (WG) films cast at pH 4 and 11. The films contained initially 8, 16, and 25 wt % glycerol and were aged at 23°C and 50% relative humidity for at least 17 weeks on a paper support to simulate a situation where a paper packaging is laminated with an oxygen barrier film of WG. The films, having target thicknesses of 50 and 250 Όm, were characterized visually and with ultraviolet/visible and infrared spectroscopy; the mass loss was measured by gravimetry or by a glycerol-specific gas chromatography method. The thin films produced at pH 4 were, in general, more heterogeneous than those produced at pH 11. The thin pH 4 films consisted of transparent regions surrounding beige glycerol-rich regions, the former probably rich in gliadin and the latter rich in glutenin. This, together with less Maillard browning, meant that the thin pH 4 films, in contrast to the more homogeneous (beige) thin pH 11 films, showed good contact clarity. The variations in glycerol content did not significantly change the optical properties of the films. All the films showed a significant loss of glycerol to the paper support but, after almost 9 months, the thick pH 11 film containing initially 25 wt % glycerol was still very flexible and, despite a better contact to the paper, had a higher residual glycerol content than the pH 4 film, which was also more brittle.

  • 149. Cho, S.-W.
    et al.
    Gällstedt, Mikael
    RISE, Innventia.
    Hedenqvist, M.S.
    RISE, Innventia.
    Properties of wheat gluten/poly(lactic acid) laminates2010In: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 58, no 12, p. 7344-7350Article in journal (Refereed)
    Abstract [en]

    Laminates of compression-molded glycerol-plasticized wheat gluten (WG) films surrounded and supported by poly(lactic acid) (PLA) films have been produced and characterized. The objective was to obtain a fully renewable high gas barrier film with sufficient mechanical integrity to function in, for example, extrusion-coating paper/board applications. It was shown that the lamination made it possible to make films with a broad range of glycerol contents (0-30 wt %) with greater strength than single unsupported WG films. The low plasticizer contents yielded laminates with very good oxygen barrier properties. In addition, whereas the unsupported WG films had an immeasurably high water vapor transmission rate (WVTR), the laminate showed values that were finite and surprisingly, in several cases, also lower than that of PLA. Besides being a mechanical support (as evidenced by bending and tensile data) and a shield between the WG and surrounding moisture, the PLA layer also prevented the loss of the glycerol plasticizer from the WG layer. This was observed after the laminate had been aged on an "absorbing" blotting paper for up to 17 weeks. The interlayer adhesion (peel strength) decreased with decreasing glycerol content and increasing WG film molding temperature (130 °C instead of 110 °C). The latter effect was probably due to a higher protein aggregation, as revealed by infrared spectroscopy. The lamination temperature (110-140 °C) did not, however, have a major effect on the final peel strength.

  • 150. Chunilall, V.
    et al.
    Bush, T.
    Larsson, Per Tomas
    RISE, Innventia.
    Iversen, Tommy
    RISE, Innventia.
    Kindness, A.
    A CP/MAS 13C-NMR study of cellulose fibril aggregation in eucalyptus dissolving pulps during drying and the correlation between aggregate dimensions and chemical reactivity2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 6, p. 693-698Article in journal (Refereed)
    Abstract [en]

    Changes in supramolecular properties of cellulose I, namely its lateral fibril aggregate dimension (LFAD), in bleached hardwood acid bisulphite pulp during drying was studied using cross-polarization/magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C-NMR) in combination with spectral fitting. A significant change in aggregate dimensions was noticed when each of the pulp grades were oven dried. The effect of drying was further investigated with pulp samples subjected to different drying methods. A comparison of a harsh oven drying, mild and rapid air drying, and a very mild and slow condition drying showed that the LFAD of the material decreases in the following order: oven drying &gt; air drying &gt; condition drying. The correlation between the total extractable material S10 (%) and LFAD and also the LFAD increment (ΔLFAD in %) are presented and shown to be intimately related. This means that the method of drying influences the size of the fibril aggregate dimensions and depends on the presence of extractable material within the fibre cell wall. Reactivity studies were carried out based on the acetylation of cotton linters and commercial 96α pulp. Results indicate that the initial reaction rate is proportional to the specific surface area of the two cellulose pulp samples. Accordingly, the specific surface area is directly related to initial reactivity of the performed acetylation. We demonstrated that it is possible to control the LFAD and hence specific surface area in laboratory-produced pulps 91α, 92α, and 96α by the drying method. Thus controlling LFAD can probably be one viable route for controlling the initial reactivity of dissolving pulp towards acetylation.

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