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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of the reverse Diels-Alder reaction of dicyclopentadienecarboxylate groups on cotton cellulose (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 1169-1178 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cotton cellulose in the form of fabric has been esterified with dicyclopentadienecarboxylic acid to a degree of substitution of 0.44. The kinetics of the reverse Diels-Alder reactions of the dicyclopentadienyl groups of the resulting cellulose ester in the presence of trapping agents and of swelling and nonswelling liquids have been measured with the differential scanning calorimeter. Fiber width measurements indicate that the esterified cotton fibers are swollen in the presence of the trapping agents dibutyl maleate, N-phenylamaleimide, and N-phenylmaleimide in tetraglyme solution, and in the presence of the nonreactive swelling agents tetraglyme and glycerol. The activation parameters for the dissociations in the swollen fibers are: Ea = 28-33 kcal/mole and ΔS* = -5 to +5 e.u. These kinetic parameters are similar to those previously found for the dissociation of methyl dicyclopentadienecarboxylate in solution. Fiber width measurements indicate that the esterified cotton fibers are collapsed in the dry state and in the presence of paraffin oil, deposited Carbowax 6000, or deposited glyceryl tristearate. The activation parameters for the dissociations in the collapsed fibers are Ea = 18-24 kcal/mole and ΔS* = -20 to -30 e.u. The kinetics are discussed in terms of the state of the cellulose matrix in the swollen and in the collapsed fibers.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.150070413
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  • 2
    Electronic Resource
    Electronic Resource
    Gel permeation properties of cellulose. I. Preliminary comparison of unmodified and crosslinked, decrystallized cotton cellulose (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 2563-2578 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Decrystallized cotton cellulose was found to be have gel permeation properties comparable to those of the highly crosslinked dextran and polyacrylamide gels used in chromatography. Partial separations of pairs of sugars, ranging in molecular weight from 120 to 738, were studied by determining the optical rotations of fractions eluted from chromatographic columns, employing a sensitive automatic polarimeter. The elution volumes of individual sugars of known molecular weights provide a quantitative measure of changes produced in the cellulose polymer structure by crosslinking. A significant difference was found between unmodified cellulose and the same material crosslinked by formaldehyde treatment; although crosslinking reduced permeability to larger molecules, the crosslinked material was found to be more permeable than the untreated cellulose to compounds having molecular weights below approximately 1000.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150051009
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  • 3
    Electronic Resource
    Electronic Resource
    Selective reactivities and accessibilities of the hydroxyl groups in cotton cellulose based on equilibrium data from a reversible chemical reactionPresented at the 24th Annual Southwest Regional Meeting of the American Chemical Society, Austin, Texas, December 4-6, 1968. (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 1225-1235 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to determine the relative equilibrium constants for reactions of the hydroxyl groups at C2, C3, and C6 of the D-glucopyranosyl units, methyl vinyl sulfone was reacted with cellulose dissolved in benzyltrimethylammonium hydroxide. The reaction was carried to constancy in distribution of substituents between the 2-0- and 6-0-positions. The distributions of substituents in the D-glucopyranosyl units were measured by gas-liquid chromatographic analysis of the products from hydrolysis of the modified cellulose. Relative equilibrium constants were then evaluated, assuming complete accessibility of all three types of hydroxyl groups of the cellulose in solution. For determination of the relative accessibilities of the individual types of hydroxyl groups in heterogeneous reactions of cotton cellulose with methyl vinyl sulfone, the reactions were carried to equilibrium distributions in media of various normalities of sodium hydroxide (i.e., media of various swelling strength). The distributions of substituents in the D-glucopyranosyl units were measured. From these values and the ratio of equilibrium constants, the relative accessibilities of the hydroxyl groups at C2 versus those at C6 were calculated. Apparent accessibilities of the hydroxyl groups at C2 are approximately double those at C6 when the reaction is carried out in 1N sodium hydroxide and about triple those at C6 when the reaction is carried out in 0.5N sodium hydroxide.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.150070503
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  • 4
    Electronic Resource
    Electronic Resource
    Assessment of the state of order of hydroxyl groups and of molecular segments in hydrocellulose (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 1623-1633 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Through a study of the selective distribution of substituents introduced into hydrocellulose from reaction with N,N-diethylaziridinium chloride, the change in selective availability of hydroxy groups at C-2, C-3, and C-6 has been followed as a function of duration of hydrolysis to form the hydrocellulose. The hydrocellulose formed at a particular duration of hydrolysis showed maximum selective availability of hydroxyl groups; this was found to coincide with minimum moisture regain and minimum breadth at half height for 101, 101, and 002 peaks in x-ray diffractograms. These points are discussed in terms of the structures of the hydrocelluloses at various stages of hydrolysis and in terms of the sequence of changes which is now associated with the conversion of fibrous cotton to “exemplar hydrocellulose,” i.e., the hydrocellulose having the highest degree of crystalline order, and subsequently, to less highly ordered hydrocelluloses.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090613
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  • 5
    Electronic Resource
    Electronic Resource
    Structures of reagent residues resulting from reactions of divinyl sulfone with cotton cellulose (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 1677-1683 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cotton cellulose in fabric form was crosslinked with divinyl sulfone by catalysis with solutions of sodium hydroxide of normalities ranging from 0.1 to 4.0. The molecular chains of cellulose were hydrolyzed with sulfuric acid to yield hydrolyzates from which simple substituted glucoses (i.e., those bonded to a single unit of DVS), the simple crosslinked glucoses (i.e., those joined together by a single unit of DVS), and complex structures (i.e., those substituted or crosslinked with more than one unit of DVS in the chain) were isolated and measured. The fractions of the reagent residues in the forms of the structures noted above were found to change substantially with the concentration of base employed to catalyze the reaction. The constitution of the reagent residues resulting from reaction in 0.1N base was remarkably simple: 82% of the DVS residues in the form of simple crosslinks and 18% in the form of simple substituents. Complex structures accounted for as much as 70% of the DVS residues under other conditions of reaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090617
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  • 6
    Electronic Resource
    Electronic Resource
    Availability and state of order of hydroxyl groups on the surfaces of microstructural units of crystalline cotton cellulose (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 1431-1440 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relative accessibilities of the hydroxyl groups of the D-glucopyranosyl units of hydrocellulose have been studied by means of the reaction of N,N-diethylaziridinium chloride, which produces 2-(diethylamino)ethyl cellulose. The deviation in the distribution of substituents among the 2-O-, 3-O-, and 6-O-positions of the D-glucopyranosyl residues in a hydrocellulose from that in a disordered cellulose in which the three types of hydroxyl groups are equally accessible is the basis for estimating the selective accessibilities of the hydroxyl groups in the crystalline cellulose. A particular hydrocellulose, lying within the range of leveling-off degree of polymerization, was studied in detail; this hydrocellulose, designated EHC (“Exemplar Hydrocellulose”), was formed from fibrous cotton by hydrolysis for 0.67 hr in 2.5N hydrochloric acid at reflux. EHC exhibited higher selective accessibility (larger deviation from equal accessibility) of the hydroxyl groups at C-2, C-3, and C-6, than samples of hydrocellulose formed in shorter or longer periods of hydrolysis. This selective accessibility is discussed in terms of intra- and intermolecular hydrogen bonding on the surfaces of crystalline microstructural units in EHC.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090523
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  • 7
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    Martian lavas: Three complementary remote sensing techniques to derive flow properties (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Several remote sensing techniques have been developed to determine various properties of lava flows. We are currently focusing on three such techniques to interpret Martian lava flows on Alba Patera, which are based on measurements of distal flow lobe widths which can be used to infer silica content; convolution of flow margins which can distinguish between pahoehoe and a'a types of basaltic flows; final flow field dimensions which can be combined with ground slope to derive effusion duration and average effusion rate. These methods are extremely complementary and together provide a more significant and complete understanding of extra-terrestrial lava flows. However, each of these techniques have specific and distinct data requirements.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 2: G-M; p 899-900
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Emplacement of Long Lava Flows on Mauna Loa (hawaii) and Alba (mars) (1985)
    In:  CASI
    Details
    Publication Date: 2014-10-08
    Description: Spacecraft images revealed that extremely long lava flows (more than 200 km long) exist on the surface of Mars and Io. Compared to terrestial volcanic eruptions, the occurrence of these long flows is very unusual, and may hint at a different style of either magma production or eruption. Attempts to model the emplacement of the long flows on other planets, using a Bingham rheological model, were only partially successful. The objective is to conduct field measurements on long lava flows in Hawaii (where individual flows such as those of 1859 and 1881 exceed 40 km in length) in order to document and interpret their flow characteristics. In this way, a better understanding of the formation of long lava flows is sought as well as a determination of whether the Mauna Loa flows are terrestrial analogs to the long flows seen on Mars and Io.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA, Washington Repts. of Planetary Geol. and Geophys. Program; p 248-250
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  • 9
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    Fractal analysis: A new remote sensing tool for lava flows (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Many important quantitative parameters have been developed that relate to the rheology and eruption and emplacement mechanics of lavas. This research centers on developing additional, unique parameters, namely the fractal properties of lava flows, to add to this matrix of properties. There are several methods of calculating the fractal dimension of a lava flow margin. We use the 'structured walk' or 'divider' method. In this method, we measure the length of a given lava flow margin by walking rods of different lengths along the margin. Since smaller rod lengths transverse more smaller-scaled features in the flow margin, the apparent length of the flow outline will increase as the length of the measuring rod decreases. By plotting the apparent length of the flow outline as a function of the length of the measuring rod on a log-log plot, fractal behavior can be determined. A linear trend on a log-log plot indicates that the data are fractal. The fractal dimension can then be calculated from the slope of the linear least squares fit line to the data. We use this 'structured walk' method to calculate the fractal dimension of many lava flows using a wide range of rod lengths, from 1/8 to 16 meters, in field studies of the Hawaiian islands. We also use this method to calculate fractal dimensions from aerial photographs of lava flows, using lengths ranging from 20 meters to over 2 kilometers. Finally, we applied this method to orbital images of extraterrestrial lava flows on Venus, Mars, and the Moon, using rod lengths up to 60 kilometers.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst., Twenty-Third Lunar and Planetary Science Conference; p 4-6
    Format: text
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