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  • 1
    Electronic Resource
    Electronic Resource
    Mechanical properties of solvolysis lignin-derived polyurethanes (1991)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 41-47 
    Details
    ISSN: 1042-7147
    Keywords: Polyurethane ; Solvolysis lignin ; Tensile properties ; Diphenylmethane diisocyanate ; Crosslinking ; 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
    Notes: In order to study the tensile properties of solvolysis lignin polyurethanes, polyurethane (PU) films were prepared from the solvolysis lignin (SL)-polyethylene glycol (PEG)-diphenylmethane diisocyanate (MDI) system, and in addition to this further PU films were also prepared from the SL-MDI system. In the SL-PEG-MDI system, the SL content, the molecular weight of PEG and the NCO:OH ratio were varied in order to control the physical properties. The tensile stress and Young's modulus of the PUs of the SL-PEG-MDI type increased with increasing SL content and NCO:OH ratio. The tensile properties of the PUs from the SL-MDI system showed no NCO:OH ratio dependency; i.e. the mechanical properties of PUs are not influenced by the change in crosslinking. It is possible to control the tensile properties of PUs of the SL-PEG-MDI type by changing the content of PEG and SL at a constant NCO:OH ratio.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1991.220020106
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  • 2
    Electronic Resource
    Electronic Resource
    Kraft lignin in polyurethanes. II. Effects of the molecular weight of kraft lignin on the properties of polyurethanes from a kraft lignin-polyether triol-polymeric MDI system (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1819-1832 
    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: Polyurethane films were prepared by solution casting using a three-component system consisting of polymeric MDI, a propylene oxide-based polyether triol and kraft lignin fractions of different molecular weights. The polyether triol was used as soft segment. The composition of the polyurethanes was varied whereas the NCO/OH ratio was kept constant. The crosslink density increased with increasing molecular weight of the kraft lignin fraction used, which is a result of an increase in functionality of the kraft lignin with increasing molecular weight. Polyurethanes prepared from low molecular weight kraft lignin were found to be more flexible than those prepared from medium and high molecular weight kraft lignin (at lignin contents below 30%). At kraft lignin contents higher than about 30% (which at the NCO/OH ratio used corresponds to a hard segment content of about 70%), rigid and glassy polyurethanes were obtained regardless of the molecular weight of the kraft lignin fraction used.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070401102
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamic viscoelasticity of isoprene rubber reinforced with short cellulose fibers (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 657-667 
    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 dynamic viscoelasticity was investigated for isoprene rubber (IR) composites filled with untreated and chemically treated cellulose fibers. Mercerization and benzylation were employed as chemical treatments. Bleached kraft pulp and cellulose powder were used as cellulose fillers. By mixing cellulose fillers, the dynamic modulus E′ of IR composites was improved, especially above the glass transition temperature. Benzylation of cellulose fibers reduced E′ of IR composite, while mercerization increased it. A tan δ peak was observed at about -33°C at 110 Hz along with a shoulder peak at about -16°C for the IR composites. The intensity of the tan δ peak decreased when mixed with cellulose fillers. The shoulder peak next to the main peak could be separated assuming a Gaussian type equation; log E″ = D exp { -C[(1sol;T) - (1/T0)]2} where D is the maximum value of log E″ vs. 1/T curve, T0 is the maximum temperature, and C is a parameter to determine the width of the Gaussian function. From the Arrhenius plot of the frequencies against 1/T0, the apparent activation energies were calculated as 220-235 kJ/mol for the shoulder peak (α1 process) and ca. 180 kJ/mol for the main peak (α2 process). The α2 process is caused by the glass transition of the rubber matrix. The α1 process is assigned as the molecular motion of the rubber matrix strongly restricted by the fiber element.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400503
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  • 4
    Electronic Resource
    Electronic Resource
    Kraft lignin in polyurethanes. III. Effects of the molecular weight of PEG on the properties of polyurethanes from a kraft lignin-PEG-MDI system (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 39-50 
    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: Polyurethane (PU) films were prepared by solution casting using a three-component system consisting of a low molecular weight fraction of softwood kraft lignin (KL), polyethylene glycol (PEG) of various molecular weights, and crude diphenylmethane diisocyanate (MDI) as starting materials. All films were prepared using a constant NCO/OH ratio. The effects of KL content, PEG content, and molecular weight of PEG on the tensile, thermal, and swelling properties of the PUs were studied. The results showed that the crosslink density Tg and tensile properties were essentially unaffected by variations in the sequence length of the soft segment at a given PEG content. The properties of the PUs were found to depend mainly on the soft/hard segment ratio. The behavior of the glass transition temperature upon changes in the PU composition indicated that the soft and hard segments were extensively mixed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410105
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  • 5
    Electronic Resource
    Electronic Resource
    Studies on absorbed water in cellulose by broad-line NMR (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1749-1759 
    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: Nuclear magnetic resonance absorption spectra of linter cellulose containing various amounts of water were studied to clarify the relation between the amount of absorbed water in cellulose fiber and the molecular motion in such a cellulose-water system. An amorphous cellulose sample was used for the sake of comparison. The changes in line width and second moment of the spectra were measured at various temperatures. From the variation with temperature of the first-derivative curves and the second moments, it has been inferred that the proton movement of absorbed water changes markedly over the approximate range 180°-200°K and that the absorbed water lowers the glass transition temperature of cellulose to room temperature.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160712
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of hydrogen bond formation on dynamic mechanical properties of amorphous cellulose (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 3221-3231 
    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 temperature dependence of the dynamic modulus (E′) and the mechanical loss tangent (tanδ) of amorphous cellulose prepared from cellulose triacetate by saponification was measured and compared with that of cellophane, recrystallized cellulose obtained by immersing amorphous cellulose in water, and cellulose triacetate. The E′ of amorphous cellulose decreased initially with increasing temperature and then began to increase at about 70°C with a maximum at 80°C, decreasing again at about 100°C. Another decrease in E′ was observed at 220°C accompanied by a discontinuity at 155°C. In the tan δ-versus-temperature curve, a medium peak at 60°C a shoulder peak at 146°C, and a broad peak at 200°C were observed. It was found that the transition at about 60°C was related to hydrogen bond formation by free OH groups. The transition at about 150°C was attributed to a recrystallization process by heating, and the relaxation at 200°C, to the glass transition of the polymer. The decrement in E′ observed at about 100°C was attributed to the cooperative motion of an individual pyranose ring in amorphous cellulose, juding from the E′ and tan δ assignment of other cellulose materials. The change in E′ was also measured isothermally as a function of time in the temperature range between 40°C and 80°C, where a maximum in tan δ and an increment in E′ were observed as the temperature dependence of the dynamic viscoelasticity. The change in E′ with elapsed time was analyzed kinetically, and an activation energy of 2.6 kcal/mole was calculated. This value is the expected activation energy of hydrogen bond formation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070201203
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  • 7
    Electronic Resource
    Electronic Resource
    Graft copolymerization of vinyl monomers on cellulose using peroxyacetic acid-ferrous ion redox initiator system (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1119-1129 
    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: Graft copolymerization of vinyl monomers such as methacrylate, acrylamide, and acrylic acid on cellulose using the peroxyacetic acid-ferrous ion redox initiator system was studied. Filter paper was chosen as cellulosic material. The effect of the experimental conditions on grafting ratio, grafting efficiency, total conersion and number of branches, and other factors was studied by varying the concentration ratio of peroxyacetic acid to ferrous salt, reaction time, reaction temperature, the addition of disodium ethylenediaminetetraacetate (EDTA), pH, and so on. It was found that there is an optimum range of initiator concentration, that at a higher temperature the copolymerization proceeds more rapidly and more efficiently, and that the addition of EDTA enables the copolymerization to proceed at a higher pH.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270402
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of bound water on structural change of regenerated cellulose (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1875-1884 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phase transition of water sorbed in regenerated cellulose (II), for water contents ranging from 0 to 1,0 (water/dry cellulose, g/g), was investigated by differential scanning calorimetry (DSC). It was found that the amount of water bound to each glucose unit is ca. 3 mol considering that water diffuses only into the amorphous region of cellulose. The increase of this amount by adding excess water to cellulose suggests that the amorphous region of cellulose II increases in the presence of water. The transient state, at a water content ranging from 0,4 to 0,6, where the intermolecular distance expands, is reflected in an intermediate crystallization at a temperature between the crystallization of free water and freezing bound water. Mechanical properties of cellulose II under moist conditions were related to the results obtained by DSC. Further, the strength at break of cellulose II was compared with that of natural cellulose (I). The strength of cellulose II decreases in presence of bound water, whereas that of cellulose I increases. Based on the comparison of the results of DSC and mechanical properties of cellulose I and II, the difference is attributed to the structural change of the amorphous region when water molecules are bound to the hydroxyl groups of cellulose. The defect or internal strain of the amorphous region of cellulose I decreases and the molecular chain is transformed into a more regular arrangement when water molecules break hydrogen bonds. On the other hand, the amorphous chain of cellulose II takes a more released and expanded arrangement in presence of water molecules which break hydrogen bonds in the crystalline region of cellulose II. The decrease of crystallinity was observed by x-ray diffraction.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880811
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  • 9
    Electronic Resource
    Electronic Resource
    Structural change of amorphous cellulose by water- and heat-treatment (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1655-1668 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Strips of amorphous cellulose film were conditioned under wet atmospheres of 80 and 100% relative humidity or heated at 393 K in vacuo for different time intervals. The structural change of these samples was investigated using differential scanning calorimetry (DSC), IR spectrometry, x-ray diffractometry (x-ray), and the density-gradient column method. In the initial stage of conditioning of cellulose samples at a wet atmosphere, it was found that the thermally determined relative volume fraction (α) of the amorphous part of cellulose stays constant while the diffusion coefficient (Dod), calculated from the rate of H → D exchange of OH groups observed in IR, decreases rapidly. This fact seems to show that the rearrangement of cellulose molecules does not occur as a whole but only partly in the vicinity of the OH groups which affect the process of H → D exchange. If large amounts of water are supplied, however, cellulose molecules rearrange freely and provide a crystalline structure, as observed clearly by x-ray. On the other hand, during the heat-treatment of amorphous cellulose, the decrease of α and Dod can be clearly observed by DSC and IR from the initial stage of treatment. Judging from the change of α and Dod, it was inferred that the hydrogen bond formation occurs step by step simultaneously with the rearrangement of cellulose molecules by heat-treatment.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820606
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  • 10
    Electronic Resource
    Electronic Resource
    Differential scanning calorimetric studies on bound water in 1,4-dioxane acidolysis lignin (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1265-1274 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The amounts of three different types of water adsorbed on hydrolyzed lignin, which was obtained by acid hydrolysis of softwood meal in 1,4-dioxane containing trace amounts of hydrochloric acid (in the following called DL), and on its derivatives, i.e., methylated and acetylated lignins, were determined by differential scanning calorimetry (DSC). The first type of water is non-freezing water, the glass transition of which was detected by DSC. The second type of water corresponds to a kind of bound water which was detected from a crystallization peak in the vicinity of 225 K (peak II). This peak appeared when the water content exceeded a critical amount of non-freezing water. The third type of water is free water, the crystallization peak (peak I) of which was found at the same temperature as that of pure water. From the enthalpies of crystallization of the above two types of water and the known weight of sorbed water, the amount of bound water in DL was determined to be 0,10 (weight of bound water/weight of dry sample). Furthermore, it was found that bound water breaks hydrogen bonds in DL and decreases its glass transition temperature (Tg) from 425 K to 330 K. The amount of hydroxyl groups, which varies with the degree of methylation or acetylation, was also found to affect the bound water content and inevitaby to decrease T g.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840616
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