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  • 1
    Electronic Resource
    Electronic Resource
    Cellulose: a random walk along its historical path (1994)
    Springer
    Cellulose 1 (1994), S. 1-25 
    Details
    ISSN: 1572-882X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Cellulose as a material has been widely used for centuries in all kinds of practical applications. However, its chemical composition, structure and morphology were also unknown for centuries. The modern history of cellulose chemistry actually began in 1837 when Anselme Payen chemically identified cellulose from plants. Since then, the establishment of its chemical and physical structures has undergone multitudinous periods of struggle. Until the early 1920s, many scientists believed that cellulose was made up of a few small molecules of glucose or cellobiose. Very few scientists accepted the premiss that it was a polymer. The controversial debates were continued for over ten years. Eventually, substantial experimental data provided proof that cellulose is a covalently linked, high-molecular-weight macromolecule. This fact also provided the foundation for the establishment of polymer science. Some of the historical development of chemistry and structures are briefly reviewed, and recent approaches to studying cellulose structures with new instrumentation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00818796
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  • 2
    Electronic Resource
    Electronic Resource
    Thermoplasticization of wood. I. Benzylation of wood (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 2457-2482 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of converting wood into thermoplastic materials was undertaken to develop a new technique in effective utilization of wood wastes. Thermoplasticizatoin of wood carried out by means benzylation. Various reaction parameters, such as alkalinity of reaction media, reaction temperature, and time were taken into account to produce benzylated wood with different degrees of substitution (based on weight gain) FTIR, DSC, DMTA, SEM and x-ray crystallography were used to characterize the chemical and mechanical properties of benzylated wood. Experimental data showed that preswelling and reaction temperature had critical effects on benzylation reaction. Lignin in wood appeared to inhibit benzylation but extractives had little effect. Different species showed some variation in reaction rates. The thermoplasticized wood exhibited good melting properties and were readily molded into bulk materials or extruded into films and sheets. A wide range of glass transition temperatures from 66 to 280°C for the benezylatedwoods was achieved, and they were larely dependent on the weight gain. The molded and extruded products exhibited acceptable mechanical strength for structural engineering applications. The property and structure relationship for the thermoplasticized wood were discussed
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270725
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  • 3
    Electronic Resource
    Electronic Resource
    Thermoplasticization of wood. II. Cyanoethylation (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 4143-4160 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyanoethylation was attempted to convert wood into thermoplastic material as a means to utilize low quality wood species as well as wood waste materials. Cyanoethylation reaction was conducted with control of the alkalinity of the reaction media, reaction temperature and time, and wood-to-acrylonitrile ratio. Cyanoethylated wood was purified and its nitrogen content and weight gain were determined. Fourier transform infrared (FTIR) spectroscopy was used to monitor the absorption peak of cyano group. Thermoproperties of cyanoethylated wood were analyzed by means of a differential scanning calorimeter (DSC) and a dynamic mechanical thermal analyzer (DMTA). Reaction mechanisms and chemistry influencing the thermoproperties of cyanoethylated wood were discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080271221
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  • 4
    Electronic Resource
    Electronic Resource
    Composites from benzylated wood and polystyrenes: Their processability and viscoelastic properties (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 7-11 
    Details
    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: Utilization and conservation of raw materials are two of the main thrusts of our research. Several plasticized woods have been prepared from sawdust in our laboratory. They possess unique thermal, mechanical, and viscoelastic properties. In this study, benzylated wood was used to blend with polystyrene to prepare a wood/plastic composite. Its dynamic processability and viscoelastic properties were evaluated. The mixtures with different blending ratios (benzylated wood/polystyrene) were prepared by mixing them in an intensive mixing device. The specific energy required to do the processing work decreased with the increase of benzylated wood in the composite. The mixture can be molded or extruded easily. The study of the viscoelasticity of the compression-molded composite products using a dynamic mechanical thermal analyzer (DMTA) revealed, regardless of the mixing ratios, a single damping peak (tan δ). This suggested good compatibility between the two polymers. The glass transition temperature and the storage modulus of these composites decreased as the amount of benzylated wood increased. A composite with comparable mechanical properties of polystyrene was obtained from those composites with mixing ratios (benzylated wood/polystyrene) ranging from 0.4 to 0.6. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070500102
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  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of microcrystalline cellulose. I. Changes in ultrastructural characteristics during preliminary acid hydrolysis (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 483-488 
    Details
    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: Several microcrystalline celluloses prepared from viscose staple, bagasse, ramie, and cotton were evaluated by viscosimetry, X-ray diffraction and scanning and transmission electron microscopies. The changes in crystallinity, size of crystallites, grain-size distribution, morphological features, and degree of polymerization were found to be dependent on and greatly limited by the polymorphic conformations of cellulose. These changes were more conspicuous in cellulose II than in cellulose I. The coexistence of a two-phase system still remains in all the specimens of microcrystalline cellulose powders. Combining the findings with respect to the extent of the changes in the size of crystallites, it appears inevitable that recrystallization in some of the defective crystallites and degradation in the disordered areas of cellulose occurs simultaneously in the preliminary hydrolysis process during the production of microcrystalline cellulose. © 1996 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Formation and behavior of mechanoradicals in pulp cellulose (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 1487-1499 
    Details
    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 mechanical degradation of pulp cellulose fiber was studied at ambient temperature and at 77°K. ESR findings reveal that mechanical degradation occurs via free-radical routes. Three types of mechanoradicals contributing singlet, doublet, and triplet ESR signals are identified. The singlet signals are derived from the alkoxy radicals at C4 positions as a consequence of the cleavage of glucosidic bonds, the radical pairs generated at C1 positions contributing the doublet signals. Triplet signals are derived from the C2 and C3 positions due to the cleavage of C2 and C3 bonds. Of these radicals, alkoxy radicals are the most stable at ambient temperature. Carbon radicals are capable of interacting rapidly with oxygen molecules to produce peroxy radical intermediates, where alkoxy radicals are inert toward oxygen molecules. ESR study also reveals that cellulose mechanoradicals are capable of initiating vinyl polymerization. MMA propagating radicals are identified when the monomers are in contact with cellulose mechanoradicals. The ability of mechanoradicals to initiate graft copolymerization from cellulose fiber is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230519
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  • 7
    Electronic Resource
    Electronic Resource
    ESR studies of the photodegradation of cellulose graft copolymers (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 3591-3600 
    Details
    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: Ultraviolet light induced free radicals in cellulose and cellulose graft copolymers were studied by means of ESR spectroscopy. At least six kinds of free radicals were formed in cellulose when the polymer was irradiated with ultraviolet light. Polystyrene and poly(methyl methacrylate) are more resistant to ultraviolet light than cellulose; however, the cellulose graft copolymers of polystyrene and poly(methyl methacrylate) were degraded by ultraviolet light. ESR studies revealed that photoinduced free radicals in cellulose graft copolymers were formed at the grafting branches of the copolymers rather than the cellulose backbone. The mechanisms of light stabilization and energy transfer reactions of cellulose and cellulose graft copolymers are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070231215
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  • 8
    Electronic Resource
    Electronic Resource
    Mechanochemical process in cotton cellulose fiberCorrected proofs received October 22, 1982 (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 1-10 
    Details
    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: Mechanical processing of cotton cellulose by means of a fiber cutter resulted in the disaggregation and defiberation of fiber bundles, shortening of fiber length, and loss of degree of polymerization. It is evident that the mechanical energy supplied by shear forces is sufficient to cause homolytic scission of cellulose main chains. Mechanoradicals formed in the interim were verified by ESR studies. The crystallinity of cellulose was not influenced by mechanical treatments, but accessibility of the polymer was substantially increased due to the creation of new surfaces. The mechanically treated fiber inclined to proceeded oxidative chain reaction during aging. Regardless of their treatment conditions, cellulose fiber reached its limiting lower molecular weight after 100 days of aging.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280101
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  • 9
    Electronic Resource
    Electronic Resource
    ESCA study of oxidized wood surfaces (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 2777-2784 
    Details
    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: Results of a preliminary study of the surface of wood exposed to outdoor weathering as well as to UV irradiation showed that ESCA provides valuable information and insight into the manifestation of weathering and photooxidation. From the ESCA spectra, the increase in signal intensities of carbon-oxygen bonds and oxygen-carbon-oxygen bonds (or unsaturated carbon oxygen bond) and oxygen-to-carbon ratio, and the decrease in carbon-carbon and carbon-hydrogen bonds of weathered and UV-irradiated wood surfaces suggested that wood surface was oxidized. Nevertheless, it was a superficial effect. Only a slow oxidation was observed at 100 μm under the exposed wood surfaces. From the oxygen-to-carbon ratio data, it revealed that weathered wood surface was rich in cellulose, poor in lignin. The leached-away degradation products from weathered wood surface accounted for the discrepancy between the ESCA line shapes of UV-irradiated and weathered wood surfaces.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070290908
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  • 10
    Electronic Resource
    Electronic Resource
    Protection of wood surfaces against photooxidation (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 1429-1448 
    Details
    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: Protection of wood surfaces against photoinduced oxidative degradation can be achieved by using effective coating agents. Several penetrating chemical agents, such as triol-G 400, PEGG 400, and 1-octadecanol, were shown to provide good protection for wood surfaces against discoloration during ultraviolet irradiation. In addition, wood surfaces coated with clear film-forming finishes, such as homo- and copolymers of 2-hydroxy-4 (3-methacryloxy-2-hydroxy-propoxy) benzophenone, exhibited outstanding performance into inhibiting discoloration and surface deterioration. Infrared and ultraviolet absorption spectra and scanning electron microscopy studies revealed that the clear polymeric coatings containing an internal UV absorber were very stable and resistant to photooxidation. Possible chemistry and mechanisms of protection of wood surfaces provided by these polymeric coating systems are discussed.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300410
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