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  • 11
    Electronic Resource
    Electronic Resource
    Ultrastructure of acid- and enzyme-modified cross-linked potato starch (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 265-276 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Purified potato starch, cross-linked with epichlorohydrin (65-5.4 anhydroglucose units per cross-link) by an iterative method that preserved the native crystalline structure of the starch granule, was exposed to enzymic (B. subtilis α-amylase at 50°C) and acidic (3 N HCl at 40°C) hydrolysis. The stability of the granules to digestion by enzymes, as measured by their weight loss after incubation with the enzyme solution, increased with the degree of cross-linking; by contrast, the stability to acid attack decreased as a function of the degree of cross-linking. The morphology of these samples was studied by scanning electron microscopy. A lamellar structure, which was most evident after enzyme treatment, was observed in samples that had a weight loss of greater than 50%. The results reflect differences in accessibility, which are interpreted in terms of a statistical model of the ultrastructure with correlated fluctuations in density in the radial direction.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140203
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  • 12
    Electronic Resource
    Electronic Resource
    Enzymatic depolymerization of lamellar single crystals of nigeran (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1069-1080 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lamellar single crystals of the α-glucan: nigeran have been subjected to controlled enzymic degradation as an approach to understanding polysaccharide organization in these crystals. Analysis of both reactant and products by various methods argues that a situation exists where the crystals are inaccessible at 20°C but become increasingly accessible as the temperature approaches that of solution for the crystals in water. One has to conclude that chain folds are inaccessible to enzymes at 20°C and become increasingly accessible as one approaches the “melting temperature.” This could be due to increased mobility of the surface chains as temperature is raised, which produces large dynamic loops and makes enzyme degradation possible. The general conclusion is that nigeran single-crystal surfaces are disordered and increasingly mobile close to their dissolution temperature in water.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190510
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  • 13
    Electronic Resource
    Electronic Resource
    Conformations of the hydroxymethyl group in crystalline aldohexopyranoses (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2369-2374 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180925
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  • 14
    Electronic Resource
    Electronic Resource
    Enzymatic degradation of β(1 → 4) xylan single crystals (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2459-2464 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enzymatic degradation of β(1 → 4) xylan single crystals with xylanases was investigated by electron microscopy and electron diffraction. The enzyme attack takes place at the edge of the crystals and progresses towards their centers. This is consistent with an endo-enzyme mechanism, where the enzyme interacts essentially with the accessible xylan chains located at the crystal periphery.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360181007
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  • 15
    Electronic Resource
    Electronic Resource
    The ball-milling of cellulose fibers and recrystallization effects (1959)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 1 (1959), S. 313-322 
    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: A study has been made of the effect of fine structure on the decrystallization process which results from the ball-milling of cellulose. The rate of decrystallization is sensitive to the type of fine structure and is accelerated by the presence of moisture. The extent of chain degradation was greater in air atmosphere than in carbon dioxide, suggesting that mechanically induced free radical degradation occurs along with other chain-breaking processes. A study of the density and moisture regain of the samples after various times of milling showed that a linear relation between regain and density held over the entire range studied. The relation was the same for native and regenerated cellulose. The process of recrystallization of the ball-milled samples was studied under various conditions and compared to the hydrolytically induced recrystallization of rayons. The type of lattice which develops on recrystallization was found to depend on the original lattice, the extent of ball-milling and the conditions of recrystallization. A highly ball-milled sample could be made to recrystallize as cellulose I, II, or IV depending on the conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1959.070010308
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  • 16
    Electronic Resource
    Electronic Resource
    Isomorphism in the poly(3,3-bis-hydroxymethyloxetane) family and copolymers: Poly (3,3-bis-hydroxymethyloxetane-co-3-methyl-3-hydroxymethyloxetane) (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 749-758 
    Details
    ISSN: 0887-6266
    Keywords: isomorphism ; poly (3,3-bis-oxetane) ; fiber diffraction ; solid state NMR ; copolymers ; co-polyoxetanes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers of 3,3-bis-hydroxymethyloxetane, BHMO, 3-metyl-3-hydroxymethyloxetane, MHMO, or with 3-ethyl-3-hydroxymethyloxetane, EHMO, monomer units were characterized by x-ray fiber diffraction, differential scanning calorimetry and 13C solid-state nuclear magnetic resonance (NMR). The copolymers are statistically random and crystalline throughout the range of compositions. Both P(BHMO) and P(MHMO) appear to crystallize in the same crystal form. The fiber repeat indicates a planar zigzag backbone conformation, c(fiber axis) = 4.77 ± 0.03 Å. Similarities in the x-ray fiber diagrams as well as a linear dependence of Tm with composition of copolymer with no change in fiber diagrams indicates isomorphism, a phenomenon in which the random substitution of MHMO monomeric units into the crystalline lattice of P(BHMO) occurs without hindering crystallization of the resulting copolymer. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320416
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  • 17
    Electronic Resource
    Electronic Resource
    Precipitation of ferrites in Nafion® membranes (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 1073-1086 
    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: Iron oxide particles were precipitated in Nafion® 117 perfluorinated ion-exchange membranes using four different methods. Precipitated ferrites yielded magnetically responsive nanocomposite films and probed structural variations in the membrane. Optical microscopy, transmission electron microscopy, vibrating sample magnetometry (VSM), and Mössbauer spectroscopy were used to characterize the materials. Microscopy showed that the ferrites were distributed unevenly across the films with a dense skin making up the surface layers. Higher temperature enhanced accessibility to iron and increased ferrite loadings were obtained for these samples. Nanosize particles of magnetite (Fe3O4) were present as disks or as clusters of disks in all the treated films. Needles and bundles of needles of maghemite (γ-Fe2O3) were produced in the films that were reacted at the boil. All the samples exhibited superparamagnetic response by VSM. Due to the shorter time scale of the Mössbauer measurement (∼ 10-7 s), ferrimagnetic response was detected for boiled and autoclaved samples. © 1996 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Local chain motions of poly(β-hydroxyoctanoate) in the bulk. 13C NMR relaxation study (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 33 (1995), S. 367-378 
    Details
    ISSN: 0887-6266
    Keywords: NMR relaxation ; local chain motion ; PHO ; temperature dependence ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Variable-temperature 13C NMR spin-lattice relaxation times (T1) and Nuclear Overhauser Enhancements (NOE) at two magnetic fields have been used to study the dynamics of the amorphous part of a semicrystalline sample (33% of crystallinity) of poly(β-hydroxyoctanoate) (PHO). The interpretation of the relaxation data of the backbone carbons was made by employing a number of motional models. Among these, the DLM model offered the best interpretation of the relaxation data in terms of conformational transitions and librational motions of the backbone C—H vectors, and proved to be superior to unimodal distribution functions. The interpretation of temperature- and frequency-dependent T1 and NOE data of the carbon nuclei in the n-pentyl side chain was made by employing a newly developed composite spectral density function for multiple internal C—C bond rotations of restricted amplitude and chain segmental motion. The temperature dependence of the linewidths of the various protonated carbon resonances of PHO has been discussed in terms of the semicrystalline character of this polymer. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1995.090330304
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  • 19
    Electronic Resource
    Electronic Resource
    13C and 1H amorphous linewidths in semicrystalline poly(4-hydroxybutyrate) and poly(3-co-4-hydroxybutyrate) above Tg by high resolution and solid-state NMR experiments (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1777-1788 
    Details
    ISSN: 0887-6266
    Keywords: Spin-spin relaxation ; C-13 linewidth ; poly(hydroxyalkanoate)s ; solid state NMR ; semicrystalline polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The high-resolution 13C and 1H nuclear magnetic resonance (NMR) linewidths of semi-crystalline poly(4-hydroxybutyrate), P4HB, and poly(3-hydroxybutyrate-co-4-hydroxybutyrate), (P3/4HB-18, 18% 4HB units) in the amorphous phase and in the melt are studied as a function of temperature and magnetic field strength. Measurements of the 13C spin-spin relaxation times under the same experimental conditions show that the natural line-width is a minor contributor to the line-broadening observed in the 13C spectra of the solid polymers. A variety of coherent averaging solid-state NMR methods are used to examine possible contributions from various line-broadening mechanisms. It is shown that magnetic susceptibility and chemical shift dispersion are the major factors for the broadening of the proton and carbon resonances of P4HB in the amorphous phase and the melt, respectively. Incomplete motional narrowing due to a slow motional mode restricted in amplitude by the presence of crystallites and/or chain constraints was found to be the major line-broadening factor for P3/4HB-18 in the amorphous phase. Correlations between crystalline morphology, physical and mechanical properties, and polymer chain dynamics are discussed, along with the way these factors affect the NMR linewidth data presented. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Preparation of a microporous composite: Encapsulation of paper by polyethylene (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 2025-2037 
    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: A rapid polymerization method for in situ synthesis of polyethylene in a typical paper matrix of cellulose fibers is described. The unique properties of this double matrix, polyethylene in cellulose, are the result of performing the polymerization in a nonsolvent such that simultaneous polymerization and crystallization takes place yielding a nascent morphology. The morphology has been studied by scanning electron microscopy and was found to be different from what is usually obtained for melt crystallized polyolefins. Optical microscopy shows the polyethylene to be present as a complementary matrix with respect to the basic fiber construct. Mechanical, optical, and other properties of encapsulated filter paper have been measured using standard TAPPI tests. The results show a general improvement in physical properties for a range of “add ons” from 0 to 27%. Wet-strength and opacity undergo major changes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180711
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