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  • 1
    Electronic Resource
    Electronic Resource
    Defects in plasma-deposited hydrogenated amorphous silicon prepared under visible light illumination (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2561-2567 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental studies have been made on the defects in undoped plasma-deposited hydrogenated amorphous silicon prepared with visible light illumination on a growing surface. This material (referred to as illuminated GD a-Si:H) has a broad defect band around midgap (Ec −1.4 eV〈E〈[SB:E:c]−0.8 eV) that is composed of two types of defect states (ST1 and ST2). The type 1 defect state (ST1) that lies in the higher energy side (Ec −E〈1.2 eV) of the band is a neutral Si dangling bond (D0). Increase in the density of ST1 of the illuminated GD a-Si:H induced by long exposure to light after the growth was smaller than that of GD a-Si:H deposited in the same run without the illumination. The energy position of the Si D0 state measured from a valence band edge is almost independent of optical band gap. The density of the type 2 defect state (ST2) that lies on the lower energy side (Ec−E〉1.2 eV) of the defect band does not increase with long exposure to light. One probable candidate for the origin of ST2 is a Si dangling bond coupled with another Si dangling bond or with residual impurities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348664
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  • 2
    Electronic Resource
    Electronic Resource
    Formation of nanocrystallites governed by the initial stress in the ultrathin hydrogenated amorphous silicon films (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 1067-1069 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spectroscopic ellipsometry identified E1 transitions at a lower energy than that for c-Si (3.38 eV). These transitions are generated from the Si paracrystallites or disordered crystallites in the ultrathin silicon films (2–10 nm) deposited by thermal chemical vapor deposition. During the growth of the film, paracrystallites expand gradually; disorder in the paracrystallites increases. Finally, a completely disordered Si network, i.e., the amorphous network, is generated. The presence of disorder crystallites in the ultrathin Si films acts as a constraint for the crystallization of the ultrathin films by rapid thermal annealing. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1377299
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  • 3
    Electronic Resource
    Electronic Resource
    Fine crystalline grain model for the determination of the morphology of ultrathin amorphous silicon films (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1159-1161 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To obtain the morphology of ultrathin hydrogenated amorphous silicon (a-Si:H) films with thicknesses of 2–10 nm grown by thermal chemical-vapor deposition, we have utilized spectroscopic ellipsometry and introduced a model, called the fine crystalline grain model. This model resolves that the growth of the amorphous silicon matrix starts with the formation of dense deformed crystallites or paracrystallites. A better fit to the experimental data has been obtained with this model when the a-Si:H film thickness is below 20 nm. The fine grain component gradually decreases with the film growth. It has been clarified that the presence of deformed crystallites in the starting a-Si:H films acts as a constraint for their crystallization by rapid thermal annealing. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1450046
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  • 4
    Electronic Resource
    Electronic Resource
    Polymer distribution in the cell wall of a wood-polyethylenimine composite (1991)
    Springer
    Wood science and technology 25 (1991), S. 215-224 
    Details
    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 light microscopic (LM) visual technique to determine the polyethylenimine (PEI) distribution in a wood-PEI composite was studied by the adsorption of acid red or the circulation of Cu(II) ion with PEI in the composite. The amount of the adsorbed dye or Cu(II) on the composite increased linearly with an increase in the PEI content of the wood-PEI. The dyed composites were observed with LM under monochromatic light, corresponding to their absorption maxima at 560 nm for acid red and at 640 nm for copper chelate. The microscopic image was photographically recorded and the negative was subjected to densitometric analysis. At a polymer content lower than 4% in the composite, about 70% of total polymer was located in the middle lamella region, leaving only 30% in the secondary wall. With increasing PEI content of the composite, the concentration in the secondary wall increased, and about 80% of the polymer was located in the secondary wall at a PEI content of 27%. There were no noticeable differences between the amount of polymer detected by dyeing with acid red and by chelating with Cu(II). From the results of the line analysis of the intensity of the characteristic X-ray of uranium, the distribution of the PEI in the cell wall agreed closely with that determined by the LM method. It was concluded that the LM visual technique to determine the PEI location in the wood-PEI composite by dyeing with acid red or by chelating with Cu(II) is a simple and reliable method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223472
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  • 5
    Electronic Resource
    Electronic Resource
    Flory polymer-polymer interaction parameter between hemicellulose and lignin from hardwood (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 133-142 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The interaction parameter between hemicellulose and lignin from beech wood was evaluated from vapor pressure osmometric measurements on solvent-polymer and solvent-polymer-polymer solutions. Dimethyl sulfoxide (DMSO) was used as a solvent. The interaction parameters between hemicellulose and DMSO (χ01) and between lignin and DMSO (χ02) increase with increasing temperature, and the change with temperature is proportional to inverse temperature. It was found for both polymers that DMSO becomes a “poor solvent” at higher temperature. This result was also derived from the free energy of dilution. The interaction parameter between hemicellulose and lignin (χ12) was evaluated as a function of temperature from the activity of solvent in a solution of the three components. At 60°C, χ12 is positive; it decreases with increasing temperature and becomes negative at 70-80°C where a minimum is found. Above 80°C, χ12 increases again to become positive at 90°C. Thus, hemicellulose and lignin attract each other at 70-80°C, but there is repulsion between the polymers at higher and lower temperatures.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021930113
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  • 6
    Electronic Resource
    Electronic Resource
    Thermoplastic behavior of lignin with various synthetic plasticizers (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 2799-2810 
    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 thermoplasticization of thiolignin (TL) and dioxane lignin (DL) with various synthetic plasticizers has been investigated. The thermal softening temperatures Ts of the lignin-plasticizer systems were measured applying the flow tester technique which is useful for investigating the thermal properties of polymers. It was found that the Ts of the lignins were lowered considerably as the solubility parameters (after Hildebrand) of the plasticizers approach close to that of lignin, namely, around 11. The lowering in the Ts of the lignins with the plasticizers was described by a linear equation with respect to the plasticizer concentration which ranged up to 20 wt-%. The sorption of the limited amounts (〈 5%) of water to the lignins also considerably decreased the Ts, however, the extent of lowering in the Ts by water sorption is less than that by the plasticizer addition at their contents over about 15%. The relationship of Ts to water content (up to about 30%) was curved, not linear. It was clearly shown that a combined use of the plasticizer and water brought about the most effective plasticizing for the lignins compared with the use of either of those alone.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070191015
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  • 7
    Electronic Resource
    Electronic Resource
    Phase separation state in hemicellulose and lignin blends analyzed by contact angle measurements (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 177-183 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The phase separation states of hemicellulose and lignin in their blends were investigated by means of contact angle measurements. The hysteresis behavior in dynamic contact angles suggested that a phase separation of cluster-state type (not of random dispersion type) took place at hemicellulose-rich and lignin-rich mixing ratios. It may be caused by the low cohesive force between hemicellulose and lignin molecules. Further, the total surface tension, and the balance between dispersion and polar forces in the total surface tension were evaluated from the equation of Wu. It was found that in the region of a hemicellulose-rich mixing ratio, the polar and dispersion forces of the surface tension of the solid were reduced and raised, respectively, and in contrary to this, in the lignin-rich region, the former were raised and the latter were reduced. The polymer-polymer interaction parameter of Flory between hemicellulose and lignin depends on the mixing ratio as reported previously; this may be ascribed to a difference of the balancing of polar-dispersion forces.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021970114
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of corona discharge treatment on cellulose prepared from beech wood (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1695-1706 
    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: Cellulose prepared from beech wood (Fagus crenata Blume) was treated in a corona discharge. The chemical changes produced by the treatment were investigated by use of infrared spectrum, Schiff's reaction, adsorption of methylene blue and Orange II, and intrinsic viscosity. Infrared absorption bands at 1382 and 1715 cm-1 were formed. The color reaction with Schiff's reagent indicated that the 1715 cm-1 absorption was due to the aldehyde group and not to the carboxyl group. The intrinsic viscosity was decreased by the air corona treatment, but was not affected by nitrogen corona treatment. The adsorption of methylene blue was not increased by corona treatment, indicating that no acidic groups were formed. Adsorption of Orange II indicated that some basic groups were formed by the nitrogen corona after a long treatment time. Low molecular weight fractions showing the 1382 cm-1 infrared absorption band were formed by corona treatment. These fractions were removed from cellulose by washing with water, and they increased with an increase in the treatment time. The absorption band at 1382 cm-1 was assigned to the symmetric carbon-hydrogen bending of methyl group.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410728
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  • 9
    Electronic Resource
    Electronic Resource
    Enhancement of miscibility between hemicellulose and lignin by addition of their copolymer, the lignin-carbohydrate complex (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 2827-2837 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The miscibility between hemicellulose and lignin from beech wood was investigated from observation of their glass transition temperature, along with the effect of addition of their copolymer, the lignin-carbohydrate complex (LCC). The binary and ternary blend systems of hemicellulose, lignin and LCC change from immiscible to miscible by increasing the temperature. This behavior shows that this blend system has an upper critical solution temperature (UCST). The binodal temperature decreases with increasing amount of LCC added. This behavior was analyzed by the temperature and composition dependence of the Flory polymer-polymer interaction parameter (χ12). The value of χ12 estimated from the phase diagrams indicates that χ12 decreases with an increase in both the lignin content and the temperature.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021950814
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanical and dielectric properties of cyanoethylated wood (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1757-1769 
    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 properties and dielectric properties of film specimens from cyanoethylated wood (CE-wood) which is a mixture of CE-(cellulose, hemicellulose, and lignin) were investigated and compared with those of cyanoethylated cellulose (CEC). From the dynamic mechanical measurement for CE-wood, it was observed distinctively that the segmental motions of the main chains were restrained by lignin. But these restraints were released with chlorination of CE-wood. The dynamic behavior for chlorinated CE-wood was similar to that for CEC. It was found that the CE-wood was plasticized effectively by blending with cyanoethylated poly(vinyl alcohol) (CE-PVA). The dynamic and static modulus of CE-wood decreased with increasing the CE-PVA fraction in the blended film, and the change of tensile strength at break for the CE-wood polyblends showed a maximum value at the CE-PVA fraction of ca. 40%. It was found that CE-wood which contained lignin showed very high values of dielectric constant comparable to those of CEC which was well known to be a high-performance dielectric materials. These dielectric properties were attributed to the segmental motion of the side chains, and it was tough that the behavior of the side chain was not so much influenced by the lignin as that of the main chain. CE-wood film specimens could be drawn to threefold the initial length in acetone aqueous solution. The degree of orientation measured by optical method increased rapidly at the early stage of drawing. The Young's modulus and the tensile strength at break of the high-drawn specimen increased to as much as three or four times those of the undrawn one, and the elongation at break changed little.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400929
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