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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 29 (1995), S. 467-479 
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary A new high-yield pulping process based on ethanol pretreatment and steam cooking was studied. The effect of processing conditions (cooking temperature at six levels and ethanol concentration at five levels) was determined. Optimum results appeared at 30% ethanol concentration and with cooking at 195 °C. The cooking liquor was analyzed by GC-MS and low-molecular lignin fragments were identified. Alcohol in alkaline medium destroys the three-dimensional lignin structure by cleavage of ether bonds, increases the penetration of the impregnation solution (higher sulfonation) and solubilizes lignin. Ethanol treatment facilitates fiber separation in the middle lamella. Pulp prepared under optimal conditions has higher flexibility, conformability and better bonding ability when compared with other samples. Higher concentrations of ethanol (above 30%) might cause precipitation of lignin on the fiber surface.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 30 (1996), S. 463-475 
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary The effect of various forms of treatment — chemical, thermal and pressure — on the tensile properties of wood was investigated. Spruce was impregnated in water, sodium sulfite and/or sodium bicarbonate, and heated at temperatures ranging from 20 to 190 °C. At the end of cooking (190 °C), decompression was applied both slowly and suddenly. A rise in temperature, an increase in heating time, from 4 to 10 min. at 190 °C, as well as fast pressure release influenced the tensile strength. The chemical treatment resulted in lignin sulfonation while carboxylation produced fiber swelling and, consequently, tensile strength decreased.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 20 (1988), S. 137-141 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The oxidation of chemithermomechanical (aspen) pulp with ruthenium tetroxide followed by peroxidation with hydrogen peroxide was performed to study the graft copolymerization of methacrylic acid, epoxypropyl acrylate and epoxypropyl methacrylate. For epoxy monomers, lower pH (i.e. 〈 5) is more favorable due to the participation of the epoxy group in the grafting reaction in acidic medium. Moreover, the grafting of epoxy monomers appeared more efficient than methacrylic acid.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 2517-2526 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hardwood pulp (birch: Betula Papyfera Marsh, and aspen: Populus Tremolides Michx) has been copolymerizeed with acrylamide using the xanthate grafting method. Grafting has been initiated using a redox system of ferrous ion and hydrogen peroxide. The effect of operating conditions on grafting parameters was also investigated. The factors studied were initial pH, time, and concentrations of hydrogen peroxide and acrylamide. When birch was used as a substrate, grafting parameters were as follows: grafting efficiency 82%, degree of conversion 35%, and polymer loading 60%. In the case of aspen, the maximum level of grafting efficiency, i.e., 87%, was reached with a polymer loading of 60%. Nevertheless, as in the case of birch, the conversion reached a rather low-level reading, i.e., 50%. Finally, some mechanical properties of paper sheets obtained through grafted pulps (dry and wet breaking lengths, dimensional stability, modulus, and extension at break) are compared to those of standard paper sheets.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 184 (1991), S. 157-166 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Misch- und Spritzgießbedingungen (Temperatur, Zeit und Druck) für die Verarbeitung von mit chemithermomechanischem Espenzellstoff (CTMP) verstärktem Polystyrol wurden optimiert. Die Verarbeitungsbedingungen wirkten sich wesentlich auf die mechanischen Eigenschaften des Verbundmaterials aus. Außerdem wurde der Einflußeiner zusätzlichen Faserverkapselung mit Polystyrol auf die mechanischen Eigenschaften untersucht, die im Vergleich zu den Verbunden ohne Faserverkapselung bessere Werte ergaben. Mit dem verkapselten CTMP konnte eine Verbesserung der mechanischen Eigenschaften bei einem Fasergehalt von bis zu 36 Vol.-% erreicht werden.
    Notes: Optimization of mixing and molding conditions (e.g. temperature, time and pressure) of aspen chemithermomechanical pulp (CTMP)-polystyrene composites was carried out. Compounding conditions showed a substantial effect on the mechanical properties of the composites. The effect of fiber encapsulation with polystyrene on the mechanical properties of the composites was also evaluated. Compared to non-encapsulated ones, the mechanical properties of composites showed superior results when encapsulated CTMP fibers were used. After encapsulation of wood fibers, and optimization of mixing and molding conditions, composites with up to 36% of fiber volume fraction could be incorporated in polystyrene with improved mechanical properties.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 38 (1989), S. 841-848 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The present paper examines the influence of various reaction parameters (e.g., pH, type, and concentration of peroxide, reaction time, oxygen as well as reaction medium) on the graft copolymerization of methacrylic acid, butyl methacrylate, epoxypropyl acrylate, and epoxypropyl methacrylate onto chemithermomechanical pulps, initiated by the xanthate method. The optimum concentration of H2O2 changes with the monomer used. Among the peroxides investigated, H2O2 offered the best performance. Oxygen and organic solvents, e.g., acetone and vegetable oil, inhabited grafting reaction. In addition, epoxy monomers showed better results compared to other monomers; this may be due to the participation of epoxy groups in the polymerization reaction
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 1-12 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Secondary Ion Mass Spectrometry (SIMS), a new surface analysis technique, has begun to be applied to the studies of organic macromolecule surface either for chemical imaging and functional group analysis or for the determination of molecular weight distribution. The instrumental conditions that are critical for obtaining a meaningful spectrum are discussed for polymers which have properties similar to lignocellulosic materials, i.e., they are thermally fragile and electrically insulating. Examples are given for qualitative and quantitative analyses. Possible uses of SIMS for characterization of lignocellulosic materials are suggested. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Paper properties of the thermochemical pulp modified by ozonation and grafting with styrene, acrylamide or their mixtures have been studied. Paper sheets, prepared by hot pressing from ozonated and grafted pulps showed improvement in: wet breaking length; dry breaking length; burst and dimensional stability.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 6 (1985), S. 261-271 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Wood fibers of aspen in the form of chemithermomechanical pulp (CTMP) has been used as reinforcement in polyethylene (PE). The secant modulus, tensile strength, energy, and elongation at yield were measured. It was found that the mechanical properties of the composite were higher than those of PE by a factor of 2.6 for modulus, 2.3 for stress, and 2.1 for energy at yield. Compared to glass fiber composites, the CTMP composites showed higher elongation, about 100 percent higher energy, 106 percent higher stress, and 75 percent higher modulus. Note that the cost of treated wood fibers is several times lower than that of treated glass fibers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Hardwood fibers of aspen in the form of chemithermo-mechanical pulp (CTMP) have been used as reinforcement in linear low density polyethylene (LLDPE). The effect of composite treatment (immersion in boiling water, heat exposure at 105°C for seven days or at a temperature of -40°C) on resulting mechanical properties were evaluated. The grafted aspen CTMP composites showed by far the best results with regard to secant modulus, tensile strength, energy, and strain when compared to those of wood flour, mica or glass-fiber filled LLDPE, as well as to virgin LLDPE. Finally, the dimensional stability of CTMP aspen-filled LLDPE composites immersed for four hours in boiling water was better than that of mica or glass-fiber filled LLDPE.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
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