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  • Polymer and Materials Science  (3,303)
  • LUNAR AND PLANETARY EXPLORATION
  • 1980-1984
  • 1970-1974  (1,973)
  • 1960-1964  (1,336)
  • 1945-1949
  • 1925-1929
  • 1970  (1,973)
  • 1963  (1,336)
Collection
Keywords
Publisher
Years
  • 1980-1984
  • 1970-1974  (1,973)
  • 1960-1964  (1,336)
  • 1945-1949
  • 1925-1929
Year
  • 1
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    Mars biological analysis by gas chromatography (1963)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: N. Am. Aviation Proc. of the 12th Lunar and Planetary Exploration Colloq., Vol. 3, No. 2; p 29-36
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    NASA TECHNICAL REPORTS
  • 2
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    Simple vidicon microscopy (1963)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: N. Am. Aviation Proc. of the 12th Lunar and Planetary Exploration Colloq., Vol. 3, No. 2; p 47-48
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Moon: Old and New (1970)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This video presents the moon as studied by man for more than 20 centuries. It reviews the history of lunar studies before the first moon landing, the major things learned since Apollo 11, and closes with a resume of lunar investigations scientists would like to undertake in the future.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-110511 , NASA-JSC-554 , NONP-NASA-VT-95-42155
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    NASA TECHNICAL REPORTS
  • 4
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    Experimental organic cosmochemistry: The formation of biochemical compounds (1963)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: N. Am. Aviation Proc. of the 12th Lunar and Planetary Exploration Colloq., Vol. 3, No. 2; p 9-28
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Post Apollo manned lunar program (1970)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-114032 , B70-09075
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Apollo 14: Shepard Hitting Golf Ball on Moon (1970)
    In:  Other Sources
    Details
    Publication Date: 2019-08-16
    Description: Live footage of astronaut Alan Shepard hitting a golf ball on the Moon is featured on this video.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-TM-110638 , VJSC-1207 , NONP-NASA-VT-95-56871
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    NASA TECHNICAL REPORTS
  • 7
    Electronic Resource
    Electronic Resource
    High molecular weight poly-L-proline: Synthesis and physical-chemical studiesThis is “Polypeptides. XLI.” For the preceding paper in this series see A. J. Alder, G. D. Fasman, and E. R. Blout, J. Am. Chem. Soc., in press.This work has been supported by the Office of the Surgeon General, Department of the Army.Presented in part at the 132 Meeting of the American Chemical Society, New York, New York, September 1957. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 3-14 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly-L-proline in the molecular weight range 50,000-90,000 has been synthesized from L-proline-N-carboxyanhydride. The molecular weight obtained is dependent on the initiator concentration. The rate constants for the polymerization have been determined by measuring the CO2 evolution. By observation of rotation during the polymerization, it is possible to deduce the conformation of the polymer in the polymerization solution. It is concluded that the immediate product of the polymerization is neither pure form I nor pure form II. The differences between form I and form II of poly-L-proline have been further characterized by measurements of their ultraviolet rotatory dispersion and their ultraviolet spectra.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360010103
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  • 8
    Electronic Resource
    Electronic Resource
    Modification of the reactivity of a small molecule by reversible association with a synthetic polymer. Inhibition of the hydrolysis of cationic esters by polyanionsAbstracted in part from a Ph.D. thesis to be submitted by J. A. Shafer to the Graduate School, Polytechnic Institute of Brooklyn, in June 1963. Financial support of this work by the Office of Naval Research and the National Institutes of Health is gratefully acknowledged. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 71-77 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The base-catalyzed hydrolysis rate of the cationic esters obtained by quaternization of N,N,N′,N′-tetramethylethylenediamine with phenylbromoacetate was studied in buffers and in solutions of partially neutralized polymeric acids. The polyanions were found to be powerful inhibitors of the reaction. This effect was interpreted as due to the association of the ester with the polyanion, from which the catalytically active hydroxyl groups are repelled. It is shown that kinetic data may be interpreted by a procedure similar to the Lineweaver-Burk plot to yield the reactivity of the bound ester and the dissociation constant of the polymer-ester complex.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360010108
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  • 9
    Electronic Resource
    Electronic Resource
    Copolymers of L-proline and sarcosine: Synthesis and physical-chemical studiesThis is “Polypeptides. XLIII.” For the preceding paper in this series see E. R. Blout, J. P. Carver, and J. Gross, J. Am. Chem. Soc., 85 (1963).Presented in part at the 132 Meeting of the American Chemical Society, New York, September 1957.This work supported by the Office of the Surgeon General, Department of the Army. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 99-109 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of high molecular weight copolypeptides of L-proline and sarcosine have been synthesized. Experimental evidence is presented which indicates that the products are true copolymers rather than mixtures of homopolymers. In contrast to poly-L-proline I, a copolymer of L-proline-sarcosine I containing approximately 50% sarcosine is soluble in water. Two molecular conformations of the copolymers, similar to those found for polyproline, have been characterized by means of infrared spectroscopy and optical rotatory dispersion. The residue rotation of L-proline has been obtained from the copolymers and is -250°.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360010202
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  • 10
    Electronic Resource
    Electronic Resource
    Ionic polysaccharides. IV. Free-rotation dimensions for disaccharide polymers. Comparison with experiment for hyaluronic acid (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 811-824 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The root-mean-square end-to-end distance has been calculated for a model allowing free rotation about glycoside bonds for the general case of polysaccharides having a disaccharide repeating unit. Numerical estimates are given for several naturally occurring structures based on an idealized pyranose unit in the C1 chair conformation. Extrapolation procedures which make use of the intrinsic viscosity [η] in good solvents to obtain unperturbed dimensions do not represent, data for hyaluronic acid very well, especially at low molecular weights. However, order-of-magnitude estimates suggest that this polymer behaves similarly to other polysaccharides, and probably has stiffer local structure than typical non-ionic synthetic polymers. A double logarithmic plot of the product of [η] and M̄w, the weight-average molecular weight, against the degree of polymerization in the range for M̄w of 104 to 2 × 104 permits a straight-line fit of available data for all the glycosaminoglycans, including heparin and the chondroitin sulfates, as well as sodium carboxymethyl cellulose. This result suggests similarity of short-chain hydrodynamic behavior of these polymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090707
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  • 11
    Electronic Resource
    Electronic Resource
    The 4th Jerusalem symposium (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 875-875 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090711
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  • 12
    Electronic Resource
    Electronic Resource
    Masthead (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090801
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  • 13
    Electronic Resource
    Electronic Resource
    Diffusional boundary spreading in the ultracentrifuge (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 865-874 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A common approximation for deriving solutions to the Lamm equation is to neglect diffusion. This paper presents a singular perturbation technique that allows one to estimate the band spreading due to nonzero diffusion coefficient. We illustrate the general mathematical technique by its application to sedimentation when pressure effects are important. Comparison of the approximate solution with accurate numerical solutions shows that the relative errors are of the order of 1% both for concentration and concentration gradient for parameters of chemical interest.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090710
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  • 14
    Electronic Resource
    Electronic Resource
    Role of pH in charging of glycogen (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 891-896 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glycogen acquires a negative charge in both alkaline and acidic solutions and can move in an electrical field, its mobility being related to the degree of alkalinity or acidity. There is a slight increase in relative viscosity at both ends of the pH spectrum. These effects and the changes in nuclear magnetic resonance as a function of pH are interpreted.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090803
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  • 15
    Electronic Resource
    Electronic Resource
    Studies on the viscosity of solutions of bovine liver glutamate dehydrogenase and on related hydrodynamic models; effect of toluene on enzyme association (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 877-889 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The viscosity of bovine liver glutamate dehydrogenase solutions was studied at 10 and 20° C in 0.2.M sodium phosphate buffer at pH 7, in the concentration range 0.1-8 mg/ml. A method for the study of the viscosity of very dilute solutions of associating enzymes is described. It was found that the reduced specific viscosity ηsp/c of glutamate dehydrogenase continuously increases with increasing enzyme concentration, from about 4 ml/g at the lowest concentrations to about 16 ml/g at 8 mg/ml. In the presence of 10-3M GTP and 10-3M NADH the viscosity increase is much smaller and the results can be extrapolated to zero enzyme concentration to yield an intrinsic viscosity [η] = 3.2. The values of ηsp/c in phosphate buffer alone apparently extrapolate to the same value of [η], or to a value close to it. We also observe that, in the presence of toluene ηsp/c increases very much more with enzyme concentration: ηsp/c already equals 16 ml/g at a concentration of 0.75 mg/ml. These observations are in good agreement with the hypothesis that the active oligomer of glutamate dehydrogenase (MW = 312,000) associates with increasing enzyme concentration to form linear rodlike polymers of indefinite length. This association is strongly diminished by the addition of 10-3M GTP, 10-3M NADH. Toluene, on the other hand, promotes reversible association to linear polymers of very high molecular weight. The transverse and axial rotary frictional coefficients of macroscopic bodies, similar to a physical model for the structure of glutamate dehydrogenase recently advanced, were determined. Assuming that the viscosity of the model is equal to that of an ellipsoid of rotation with identical frictional coefficients, we calculate [η] = 3.26 ml/g according to Kuhn and 3.20 ml/g according to Simha, for the glutamate dehydrogenase oligomer, in good agreement with the result derived from the study of enzyme solutions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090802
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  • 16
    Electronic Resource
    Electronic Resource
    Surface chemistry of poly(β-beiizyl L-aspartate) (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 911-922 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular monolaycrs of poly(β-benzyl L-aspartate) spread at. an air-water interface have been studied. The results obtained both by direct observations on the monlayer and from examination of collapsed films with polarized infrared spectroscopy and electron diffraction are consistent with the presence of right handed α-helices in the mono-layer when the molecular weight is high. When 1% (v/v) isopropanol is present in the subphase the right-handed helix prevails, provided that the monolayer is first spread on water. Monolayers of low molecular weight polymer appear to form the crossed-β structure. Orientated collapsed films of high molecular weight polymer can be converted to the left-handed α-helical and to the ω-conformation, and the mechanisms are discussed. The surface chemistry of this polymer is compared with that of related polymers and a consistent pattern of behavior emerges.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090805
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  • 17
    Electronic Resource
    Electronic Resource
    Characterization of acid-denatured DNA by low-angle light scattering (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1017-1028 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Low-angle light scattering results reported previously demonstrated that measurements on high molecular weight native DNA must be made at angles below 30° in order to obtain correct molecular weights. Earlier light-scattering data obtained on denaturated DNA at angles above 30° showed no change in molecular weight upon denaturation, even though other techniques clearly showed that strand separation occurred. This paper reports low-angle measurements on solutions of calf thymus and T7 DNA denatured under acidic conditions. The results demonstrate that a halving of molecular weight consistent with strand separation is detected by light scattering only when low-angle data are used to obtain correct molecular weights for native material. As expected from theoretical considerations, the scattering from denatured DNA is a linear function of sin2(θ/2), where θ is the angle of observation. This result shows that anticipated experimental artifacts have no significant effect on the low-angle measurements and demonstrates that the curvature in the scattering envelope observed for native DNA below 30° is an inherent property of the native molecule.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090905
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  • 18
    Electronic Resource
    Electronic Resource
    Kinetics for the transition between cis- and trans-helices in poly-L-prolineA preliminary report of this work was presented at the 156th National Meeting of the American Chemical Society, Atlantic City, New Jersey, September 1968. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1001-1016 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics for the cis-trans isomerization of long-chain poly-L-proline has been studied as a function of pressure, temperature, and solvent composition in the acetic acid + n-propanol solvent system. Our complete kinetic curves were fitted by Monte Carlo techniques, and rate constants for nucleation, growth, and termination were estimated. It was found that for the formation of a cis-helix, high pressure, low temperature, and increased acetic acid content of the solvent, lowered the rate of nucleation relative to growth. The inverse seems to be t rue for the formation of a trans-helix. Molecular models suggest that this behavior of the kinetic constants can be due to the exposure of peptide units to solvent in the transition state for trans nucleation, and the burying of peptide units in the transition state for cis nucleation. It is further suggested from our analysis of complete kinetic curves that at least one of the assumptions usually made in the analysis of relaxation kinetics is invalid for poly-L-proline.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090904
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  • 19
    Electronic Resource
    Electronic Resource
    X-Ray diffraction of ethylenediamine-amylose complex (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1039-1047 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solutions of amylose in ethylenediamine yield a crystalline film complex upon evaporation of solvent. The x-ray analysis indicates the presence of a tetragonal-shaped cell with a symmetry approximating that of space group P212121. The amylose sixfold helix has a diameter of 13.3 Å and a translation period of 8.0Å. Chemical and physical analyses support a complexing ratio of one ethylenediamine molecule to every two glucose units. The structure is nearly identical to any amylose-dimethyl sulfoxide complex previously examined. The square mode of packing arrangement appears to result from complexation between amylose chains. Such complexing indicates a much greater degree of amylose interaction than is observed in amylose complex structures having a hexagonal close-packing arrangement.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090907
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  • 20
    Electronic Resource
    Electronic Resource
    Potentiometric titration of poly-S-carboxymethyl-L-cysteine in aqueous NaCl solution (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1049-1058 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: pH titration measurements of poly- S-carboxymethyl-L-cysteine were undertaken in the aqueous Nacl solution in relation to the β form-random coil transition. The titration curves show a marked molecular weight dependence because of the shortened chain length of materials. Comparison of the optical rotatory dispersion parameter a0 with the titration curve reveals that the titration curve apparently reflects a β structure-random coil transition. The β form of this polymer is assumed to be an intramolecular β form, rather than a β structure stabilized by an intermolecular hydrogen bond, at least in the polymer concentration range considered here. The standard free energy change per amino acid residue for the transition from un-ionized random coil to un-ionized β form is estimated to be about -750 cal/mole residue in the range of 0.005-0.2M NaCl concentration.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1970.360090908
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  • 21
    Electronic Resource
    Electronic Resource
    Oligonucleotide interactions. III. Circular dichroism studies of the conformation of deoxyoligonucleolides (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1059-1077 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism (CD) spectra of the four usual deoxymononucleosides, all sixteen deoxydinucleotides, and a number of trinucleotides have been measured. The dimer spectra are quite different from the sum of the spectra of their constituent monomers. This indicates the presence of base-stacked conformations analogous to those found for ribonucleoside diphosphates. The CD spectra of several deoxytrinucleotide diphosphates and single-strand f 1 DNA can be calculated fairly well by using a semi-empirical nearest-neighbor approach. There is little or no effect of terminal phosphate or of salt concentration on the optical properties of most deoxy oligomers. The possibility of simultaneous analysis of mixtures of deoxypurine or deoxypyrimidine sequence isomers has been examined. This seems to be a viable approach for the analysis of purine runs but cannot promise much success for pyrimidine runs.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1970.360090909
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  • 22
    Electronic Resource
    Electronic Resource
    Oligonucleotide interactions. IV. Conformational differences between deoxy- and ribodinucleoside phosphates (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1079-1103 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism spectra of all 16 ribodinudeoside phosphates containing the bases adenine, uracil, cytosine, and guanine have been measured at room temperature and neutral pH. These results are compared with the circular dichroism spectra of the corresponding deoxy compounds. From the optical properties it is clear that the geometry of the base-stacked conformation of ribo compounds must differ substantially from that of deoxy compounds. Because of this, it is not possible to draw firm conclusions about the relative extent of stacking in most ribo and deoxy compounds. The optical rotatory dispersion of about a dozen deoxy and ribodinucleoside phosphates has been studied as a function of temperature. These results confirmed the conclusions drawn earlier from measurements at a single temperature. Several dinucleoside phosphates containing a 2′ → 5′ phosphodiester bond have also been examined. These compounds have a substantial degree of base stacking at room temperature. The geometry of the stacked conformation is different from that of either the normal ribo dimer or the deoxy dimer. The role of the 2′-hydroxyl group in stabilizing base stacked geometries has been examined by studies on C-2′-O-methyl-pC. This compound has optical properties almost identical to those of CpC. This suggests that the effect of the 2′ hydroxyl is felt indirectly through its perturbation of the geometry of the sugar ring rather than directly by hydrogen bonding. It is not possible at present to identify precise conformational differences among deoxy-, ribo-and 2′ → 5′ ribodinucleoside phosphates.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1970.360090910
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  • 23
    Electronic Resource
    Electronic Resource
    Aggregation of poly-L-proline II (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1119-1124 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1970.360090912
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  • 24
    Electronic Resource
    Electronic Resource
    The influence of single-strand breaks on the kinetics of denaturation of DNA (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1349-1360 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of single-strand breaks on the kinetics of the relaxation of DNA in a solution of low ionic strength has been investigated by a temperature jump method. The relaxation of DNA after a jump of 0.7 °C in the melting region has been monitored by measuring the extinction at 260 nm. For essentially monodisperse T4 DNA (M = 130 × 106) two distinct relaxation times have been observed, that depend markedly on the initial extent of denaturation 1 - θ. The larger relaxation time decreases from 450 sec to about 300 sec, the smaller one from 55 see to 30 when 1 - θ increases from 0.03 to about 0.8. The dependence of these relaxation times on the average number of single-strand breaks per molecule (p) appears to be very small up to p = 100. However, the relative contribution of the slow process decreases sharply when p increases from 0.6 to 30 and remains nearly constant for larger p. The observations are discussed in the light recent theories of the kinetics of denaturation.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1970.360091105
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  • 25
    Electronic Resource
    Electronic Resource
    Electro-optic scattering studies on deoxyribonucleic acid (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1361-1372 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements have been made of the intensity of light scattered from aqueous solutions of calf thymus DNA with and without the application of electric fields. For fields approaching 150 V/cm and frequencies below 2.5 KHz, changes (ΔI) of up to 10% in the residual scattered intensity were observed. In agreement with previous dielectric and electric birefringence measurements, a low frequency dispersion of ΔI was observed, from which a rotary diffusion constant (D) of 1200 s-1 was determined. Interpreting the electric field data in terms of the classical dipolar orientation theory led to values of 2.4 × 10-25 cm (7.4 × 10-14 esu) and 4.3 × 10-25 cm (13 × 10-14 esu) for the permanent dipole moment and the anisotropy of the electric polarisabilities respectively. Furthermore the permanent dipole moment was along the major molecular axis and the particles orientated in the field as rigid entities. The zero field data indicated a molecular shape which was not rodlike but corresponded to the Kratky-Porod “stiffness” parameter of x = 24 for the wormlike coil model. Although curved, the molecules appeared to orientate in low-intensity electric fields as rigid, but not rodlike molecules. The implications of this on recent discrepancies in D determined by two or more dynamic relaxation methods is briefly discussed.
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    Buoyant density and solvation of magnesium DNA (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1391-1402 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The buoyant density of T-4 DNA was determined by equilibrium sedimentation in a density gradient, of mixed solutions of cesium and magnesium chlorides and bromides. The preferential hydration was calculated from these data, allowing appropriately for the exchange equilibrium of DNA with Cs+ and Mg++ ions. The charge and intrinsic solvation of the counterions were found to have no appreciable effect on the hydration of the DNA, the extent of solvation depending only on the thermodynamic, activity of the water. Various reasonable hypotheses are discussed to account for these results.
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    Studies on bacteriophage MS2. VIII. Evidence for dimer formation of MS2 RNA by reaction with formaldehyde at acidic pH (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1373-1389 
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    Notes: Reaction of 27 SMS2 RNA with formaldehyde normally results in an unfolded, 13.4 S form. At acidic pH, however, and under the proper ionic conditions, a compact component sedimenting at 36-40 S was obtained. The molecular weight of this species corresponds to a dinner. The formaldehyde concentration was not critical, and approximately the same number of base pairs had been opened in the compact and in the unfolded form. Presumably dimers, which had been specifically formed under defined conditions, were stabilized by formaldehyde-induced crosslinks. Similar dimers were formed by 16 S and by 23 S ribosomal RNA, but not by tRNA.
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    Editorial (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 1-1 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 29
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    Theory of the helix-coil transition in DNA considered as a copolymer (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 25-32 
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    Notes: The grand-partition-function theory of the preceding paper is used to derive expressions for the number of base pairs bonded in DNA with explicit consideration of the copolymeric nature of the DNA. The following features of the DNA molecule are taken into account: (1) the DNA's from different sources have different ratios of a-t and g-c pairs; (2) the a-t pair is weaker than the g-c pair; (3) the nearest-neighbor frequencies of the two kinds of base pairs are nonrandom; (4) the stacking energies (nearest-neighbor energies) of the various combinations of pairs may be different. An ensemble is constructed in which the features (1) through (4) are introduced by means of statistical weights on the various pairs and combinations of pairs, and an expression for the corresponding partition function is written. Expressions are derived for the number of bonded base pairs and the number of helical sequences.
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    Masthead (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963) 
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    Keywords: Chemistry ; Polymer and Materials Science
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    URL: http://dx.doi.org/10.1002/bip.360010201
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    The presence in collagen of γ-glutamyl peptide linkagesSupported by grants from the National Institutes of Health, U. S. Public Health Service, A-3172, H-4762, H-3838, M-2565, M-2562. The material in this paper is taken from a thesis submitted by Carl Franzblau in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Sue Golding Graduate Division of Medical Sciences, Albert Einstein College of Medicine, Yeshiva University. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 79-97 
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    Notes: A method is described for formation of hydroxamic acids by direct coupling, in aqueous medium, of hydroxylamine hydrochloride and the sodium salt of a carboxylic acid. The reaction is mediated by a water-soluble carbodiimide, 1-cyclohexyl-3-[2-morpholinyl-(4)-ethyl]-carbodiimide metho-p-toluene sulfonate. Using model compounds, the production of α-, β- and γ-acyl hydroxamic acids was studied. Hydroxamic acid derivatives of α-polyglutamic and γ-polyglutamic acids were also prepared. Dinitro-phenylhydroxamate derivatives were prepared and subjected to Lossen rearrangement, and the reaction mixtures hydrolyzed. Analysis showed that α-polyglutamic acid yielded as many molecules of α,γ-diaminobutyric acid as there had been glutamic acid residues in the form of the dinitrophenylhydroxamate, and gave rise to no ammonia and succinic semialdehyde. In contrast, γ-polyglutamic acid yielded exactly twice the molar quantity of ammonia as there had been glutamic acid residues in the form of dinitrophenylhydroxamate, and also gave rise to significant quantity of succinic semi-aldehyde but no α,γ-diaminobutyric acid. Since production of the latter is characteristic of α-glutamyl hydroxamates and production of the former is associated with γ-glutamyl hydroxamates, the results indicated that the side-chain carboxyl groups of either polymer retained their identities during formation of the hydroxamic acid derivative, and no interchange had occurred between α- and γ-carboxyl groups. These methods were then used to establish that gelatin of ichthyocol contains (per 1000 total residues) at least 20 residues of glutamic acid in γ-peptide linkage. Due to the incomplete dinitrophenylation of the hydroxamic acid derivative of the protein, gelatin of calf skin collagen gave a lower figure of 10 such linkages per 1000 total amino acid residues-a value which must be considered a minimum value. These results show that γ-glutamyl peptide bonds exist in collagen.
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    Theory of helix-coil transitions involving complementary poly- and oligo-nucleotides. I. The complete binding caseThis investigation was supported in part by Research Grant A-4283 from U. S. Public Health Service.Based upon a portion of a Ph.D. thesis to be submitted by W. S. M., Jr., to Brown University. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 133-143 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A statistical thermodynamic treatment of thermally induced helix-coil transitions is formulated with the matrix method for an (ensemble) of system(s) in which one strand of a double helix consists of a homopolymeric polynucleotide and the other strand comprises a number of complementary oligonucleotides. Each oligonucleotide is considered to be completely bound to the longer chain when in the helical configuration and completely free from it when in the randomly coiled configuration. The case of partial binding; i.e., “dangling,” is treated in a later paper. Taken into account in both cases are intrachain “stacking” interactions between nearest neighbor residues and interchain hydrogen bonding.An approximate treatment of the characteristic equation of the formulation indicates that the reciprocal of the transition temperature (1/T0) is a linear function of the reciprocal of the degree of polymerization (D.P.) of the oligonucleotides. In the same approximation, 1/T0 is also a linear function of the negative logarithm of the absolute activity of the oligonucleotides. Transition curves obtained by exact calculation on a computer are presented for various degrees of polymerization of both the oligo- and polynucleotides. These curves show a sharpening of the transition with increasing D.P. of the long chain and the aforementioned reciprocal D.P. dependence of 1/T0.
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    Dielectric dispersion of polyglutamic acid solution (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 171-182 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The dielectric dispersion of polyglutamic acid (PGA) was studied in the pH range of 4-9.8. Three different dispersion curves were obtained. Above pH 6.0, where PGA has a random coil configuration, the dielectric dispersion is characterized by a large dielectric increment (ca. 450) and a relaxation time of 10-12.7 × 10-6 sec. Between pH 6.0 and 5.0, where PGA is in a transitional state with small viscosity, a dispersion curve with very small dielectric increment and also small relaxation time was observed. Below pH 5.0, where PGA has a helical configuration, the dispersion is characterized by a relaxation time of 10-12 × 10-6 sec. and a dielectric increment of about 120. The dipole moment of coil and helical forms of PGA were calculated by using Allgen's equation, and qualitative discussions of these dielectric properties are presented.
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    Absorption spectra of nucleotides, polynucleotides, and nucleic acids in the far ultraviolet (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 193-208 
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    Notes: Ultaviolet absorption spectra down to 185 mμ are presented for a number of nucleic acids and synthetic polynucleotides in the helical and random forms, and of their constituent mononucleotides, as well as the corresponding nucleosides and free bases. A short wavelength absorption band is in all cases observed with a maximum varying between about 187 and 201 mμ. These bands are more intense than those near 260 mμ. The helical polymers show a hypochromic effect in this region of a somewhat similar magnitude to that in the 260 mμ region. Other spectral phenomena accompanying denaturation and degradation are described.
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    The inactivation of soluble ribonucleic acid by formaldehyde (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 209-229 
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    Notes: The inactivation of sRNA by reaction with formaldehyde has been reported as it occurs under various conditions giving differing amounts of secondary structure. The theory of inactivation of an active macromolecule by a chemical reaction is developed. Results obtained with a partially melted out secondary structure show that formaldehyde inactivates sRNA by a single reaction at any one of about ten sites, while reaction at other sites does not affect the activity of the sRNA. In the presence of Mg++ at neutral pH, a large proportion of the active molecules are completely protected against inactivation. From the correlation between the amount of secondary structure and the difficulty of inactivation, it is shown that at least a portion of the secondary structure of sRNA is essential to its amino acid acceptor ability. A comparison of results of various workers shows that formaldehyde does not alter RNA as drastically as other reagents and thus enables more discrimination between sites of reaction which are essential and those which are not essential to biochemical activity.
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    Editorial (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 295-295 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Infrared spectra and molecular conformations of D,L-copoly-γ-benzylglutamates (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 297-317 
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    Notes: Infrared absorption and x-ray diffraction measurements have been made of D,L-copoly-γ-benzylglutamate fibers (cast from dioxane solutions) with various D/L ratios and with various degrees of polymerization. It was found that each chain of these copolymers consists of a random coil portion and an α-helix portion and that the conformation of the latter is similar to the α-helix of pure poly-γ-benzyl-L-glutamate. It was also found that the fraction of the α-helix portion increases with the degree of polymerization of the copolymer. A simplified polymerization mechanism has been proposed for mixtures of D- and L-amino acid N-carboxyanhydrides. A model of the molecular conformation of the D,L-copolypeptide chains derived from this proposed polymerization mechanism is in good agreement with infrared, x-ray, and other measurements. Based on the results of these observations, we discuss the number of L- or D-residues linked in succession that is required for initiating the formation of an α-helix during the course of polymerization.
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    Optical properties of the poly-L-proline and collagen helicesThis research was supported in part by U.S. Public Health Service grants A5852 and 9202. Contribution No. 232 of the Graduate Department of Biochemistry, Brandeis University, Waltham 54, Massachusetts. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 319-330 
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    Notes: Poly-L-proline I and II, polyphydroxy-L-proline II, polysarcosine, and collagen, as well as two model amides have been examined by far ultraviolet spectrophotometry. Absorption spectral data are presented. Neither in solution nor in oriented films of poly-L-proline I and II is there any indication of excition resonance splitting of the peptide absorption band. In collagen there is some, in the poly-L-prolines only minimal, hypochromicity. These observations, at least in poly-L-proline II, run counter to theory. Optical rotatory dispersion measurements in the ultraviolet indicate simple dispersion in collagen and poly-L-proline II down to at least 232 mμ. The Cotton effect (trough at 233 mμ) observed in α-helical polypeptides and proteins is absent. The implications of these findings are discussed.
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    Dilatometric and refractometric studies of the helix - coil transition of poly-L-glutamic acid in aqueous solutionThis work was supported by grants from the U. S. Public Health Service (GM-K3-3441, GM-10880, HE-06285). (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 359-370 
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    Notes: The helix - coil transition of poly-L-glutamic acid (PGA) in aqueous solutions was followed by volume changes, ΔV, and also differential refractive indices, Δn. The increase in ΔV or decrease in Δn upon mixing the sodium salt of PGA with dilute HCl gave three straight lines between pH 7 and 4, the two breaks corresponding to the transition zone observed by other physical methods. For the reaction: —COO- + H+ → —CO-OH, ΔV per mole of H+ bound was 11.4 and 11.1 ml. in 0.01 and 0.2M NaCl solutions, respectively. An additional conformational change of about 0.5-1 ml. per amino acid residue was observed for the reaction: coil → helix, after taking electrostatic interaction into consideration. This was probably due to the release of the water of hydration at the amide linkages when the polypeptide coil is converted into the α-helix, or even the occurrence of voids in the polypeptide chain as a result of imperfect packing of the atoms, although the origin of this volume change is still not fully understood at the present time. The volume changes as calculated from Δn by assuming a constant polarizability of the polymer was found to be higher for the association reaction than those mentioned above. On the other hand, the calculated ΔV for the transition was in fair agreement with those by direct measurements.
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    Optical properties of chromophore-macromolecule complexes: Absorption and fluorescence of acridine dyes bound to polyphosphates and DNAThe work described in this paper was sponsored in part by the U. S. Atomic Energy Commission and in part by the Department of Chemistry, University of California, Berkeley, California. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 401-417 
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    Notes: Dye-macromolecule complexes provide good models for the study of the effects of coupling between chromophores. In addition to modifications of the visible and UV absorption spectra of the dyes at small interchromophore distances, very efficient energy transfer has been demonstrated at longer distances. The probability of nonradiative transition increases with the number of excitation transfers so that an array of oscillators close to one another becomes nonfluorescent. The insertion of a dye molecule, acting as a trap for the excitation energy, in the highly ordered system of chromophores constituted by the purine and pyrimidine bases of native DNA has given results supporting the intercalation model of Lerman and providing an experimental approach to the problem of the path length of energy migration in the DNA molecule. The average excitation path length seems to be of the order of only ten base pairs, a result which can explain the lack of fluorescence of the DNA.
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    Sedimentation and diffusion of polyelectrolytes. Part II. Experimental studies with poly-L-lysine hydrohalides (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 473-495 
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    Notes: The sedimentation, diffusion, and osmotic behavior of poly-L-lysine hydrochloride is examined over a wide range of ionic strengths and in solutions which range in relative composition from a swamping excess of added salt (suppression of charge effect) to salt-free solutions (maximum effect). The charge effect is found to essentially obey the theoretical treatment proposed in Part I of this work. The frictional coefficient of the macroion in salt-free solutions is comparable to that of the fully stretched chain. In excess of salt the friction is appreciably smaller, its magnitude not varying greatly with ionic strength. The molecular weight is determined osmotically and also from diffusion-sedimentation, with the charge effect suppressed by addition of salt or eliminated through the use of non-ionized forms of the polymer; a reasonable agreement is obtained between the methods. The influence of small ions on sedimentation is also examined. The secondary salt effect is found to be much smaller than that predicted theoretically; on the other hand, the substitution of different counterions in the absence of secondary salt effect gives rise to changes of the expected magnitude.
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    The initial reaction in strong-base catalyzed polymerizations of α-amino acid N-carboxyanhydrides (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 500-502 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Properties of poly-β-hydroxybutyrate. I. General considerations concerning the naturally occurring polymerPortions of this work were taken from a thesis by R. Alper submitted to the Graduate School, Syracuse University in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Presented before the Polymer Division at the 145th National American Chemical Society Meeting, New York, September 1963. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 545-556 
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    Notes: Poly-β-hydroxybutyric acid has been isolated from two bacterial sources by two different procedures. Molecular weight and intrinsic viscosity for the two samples were vastly different. This was blamed on degradation occurring during polymer isolation. An optical rotatory dispersion curve for the high molecular weight sample showed a sharp increase in specific rotation at wavelengths less than 450mμ. From this fact and the reported optical activity of the monomer it is concluded that the polymer is stereo-regular. X-ray examination of the “native” and “regenerated” polymer yielded the same crystalline pattern. Electron diffraction and x-ray data on single crystals of the polymer indicate a fiber repeat of 5.9 A. The value can only be reconciled with some kind of helical conformation in the solid state.
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    Studies of the conformation of amylose in solutionPaper presented in part before the Division of Carbohydrate Chemistry, 140th Meeting of the American Chemical Society, Chicago, September 1962. This work was supported by a Grant from the Corn Industries Research Foundation. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 527-544 
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    Notes: It has been suggested previously that water is a nearly indifferent solvent for amylose on the basis that the exponent a of the Mark-Houwink equation is very nearly 0.50 and the second virial coefficient A2 is extremely small. It is shown that such solutions do not show the expected precipitation on cooling and the temperature coefficient of the intrinsic viscosity is small and negative. It is suggested that water is both an indifferent and a nearly athermal solvent for this polymer. Various lines of evidence suggest the polymer to exist as a very stiff coil in this and in other solvents. Variations in the intrinsic viscosity and radius of gyration in various solvents show the importance of skeletal effects in addition to the usual osmotic effects. Application of the Porod-Kratky wormlike coil model leads to unreasonably short persistence lengths if the contour length is based on a fully extended conformation but large and reasonable values of the order 40-70 A. if it is assumed that the basic conformation is the helical one observed in various amylose complexes in the crystalline state. As was previously known, the specific optical rotation decreases sharply in aqueous solutions above approximately pH 12. Accompanying this change in rotation there is first a decrease, then an increase in intrinsic viscosity. This later behavior is strikingly reminiscent of the known behavior of polyglutamic acid in the pH-dependent transition from helix to coil. It is concluded that the conformation is that of a stiff coil with essentially helical backbone contour in neutral solution, and the decrease in rotation and in intrinsic viscosity at high pH results from a partial breakdown of the helical structure with a concomitant increase in backbone flexibility. The increase in viscosity and radius of gyration in extreme alkaline solution is probably due to a polyelectrolyte expansion of the polymer coil. Some other miscellaneous observations which are in accord with this model are also pointed out.
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    Masthead (1963)
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    Biopolymers 1 (1963) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Effect of hydrophobic bonding on the stability of poly-L-alanine helices in water (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 419-429 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The Lifson-Roig theory for the helix-random coil transition in polyglycine has been modified to take side-chain interactions into account. The modified theory is developed specifically for poly-L-alanine which probably contains a β1-α4 hydrophobic bond. A conditional probability, expressing the strength of such a hydrophobic bond, is evaluated from the Nemethy-Scheraga data for the free energy of formation of the bond. This, together with the conditional probabilities for the states of the backbone chain, permit an evaluation of the partition function and properties of the helix-random coil transition. It is seen that the hydrophobic bond renders the poly-L-alanine helix much more stable than the corresponding polyglycine one, in agreement with data obtained by Gratzer and Doty.
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    Polynucleotides. VI. Molecular properties and conformation of polyribouridylic acidThe last paper in this series was by J. R. Fresco and J. Massoulié, J. Am. Chem. Soc., 85, 1352 (1963).This investigation was supported by grants from the National Science Foundation, the United States Public Health Service, and the American Heart Association. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 431-446 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Optical, hydrodynamic, and titration properties of polyribouridylic acid (poly U) were investigated in 0.2M Na+, pH 6. Above 15°C., poly U was shown to be a randomly coiled single chain, devoid of secondary structure. There is no shear rate dependence of viscosity; molecular weight is independent of ionic strength; there is virtually no conformationally dependent hypochromicity; no anomalous optical rotatory dispersion; and no anomalous titration behavior. The dependence of the sedimentation constant and intrinsic viscosity on molecular weight was determined. Poly U was shown to be the most highly expanded of all synthetic and naturally occurring randomly coiled polynucleotides.
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    Masthead (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Synthesis of poly-L-lysine and poly-L-lysyl albumin via ∊,N-trifluoroacetyl-α,N-carboxy-L-lysine anhydrideThis investigation was supported in part by research grants (AI-04715 and 235103) from the National Institutes of Health, United States Public Health Service. (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 517-525 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Free poly-L-lysine base has been synthesized from ∊,N-trifluoroacetyl-α,N-carboxy-L-lysine anhydride via poly-∊,N-trifluoroacetyl-L-lysine (IV). No racemization occurred during the removal of trifluoroacetyl groups from IV with 1M piperidine. Measurements of optical rotatory dispersion suggest that IV exists in methanol in a helical form. The synthesis of poly-L-lysyl rabbit serum albumin is also described.
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  • 50
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    Volume changes accompanying thermal denaturation of deoxyribonucleic acid. II. Denaturation at alkaline pH (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 445-457 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The change in apparent molal volume φ of DNA on thermal denaturation in carbonate buffer at pH 11.0 has been determined by the dilatometric method. It was found that φ increases sigmoidally during the helix-coil transition. Several methods, including a colorimetric technique that closely simulates the conditions used in the dilatometric experiments, were employed to estimate the protons lost by the DNA during the transition. These measurements indicated that the extent of the proton loss depends on the counterion present, increasing in the order Li+ 〈 Na+ 〈 K+ 〈 Cs+. The major part of the volume changes observed during the denaturation is due to the volume changes expected to accompany the transfer of protons from the bases guanine and thym ne to carbonate ions. As has been previously reported for the denaturation of DNA at neutral pH, the volume change directly due to the change in shape of the polymer molecules is so small as to be experimentally undetectable.
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    Location of proline derivatives in conformational space. II. Theoretical optical activity (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 569-588 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The coupling of theoretical optical calculations with experimental data provides a check of the validity of the theory or provides conformational information. The theory was validated by studies in which the approximate conformation was located independently. These studies have shown that a theory restricted to the two lowest energy transitions for each chromophore gives qualitative agreement with experiment. On the other hand, for some of the proline derivatives, the theoretical treatment allows detailed conformational assignments. Both successes and failures in correlating theory with experiment are discussed. The results presented provide a basis for assessing the prospects for relating protein and polypeptide optical activity to their conformations.
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    Ethidium bromide-DNA complex: Wavelength dependence of pyrimidine dimer inhibition and sensitized fluorescence as probes of excited states (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 639-653 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Ethidium bromide inhibits the formation of ultraviolet-induced pyrimidine dimers in DNA. The efficiency of dimer inhibition increases with increasing energy of the exciting photons. The efficiency of energy transfer from the DNA singlet to the dye singlet, as monitored by sensitized fluorescence, is independent of wavelength. The efficiency of singlet-singlet transfer agrees with that for dimer inhibition at photon energies corresponding to excitation of the lowest singlet state of DNA. Our results support a model in which dimers are formed both directly from the singlet state and also from the triplet state, with triplets arising from higher vibrational levels of the singlet.
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    Testing of A size criterion for DNA-hydrocarbon binding (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 689-696 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The intercalation model of DNA-hydrocarbon binding appears reasonable, but rests on indirect evidence only. To test the model, a size criterion for binding has been proposed. The size criterion is based on the assumption that hydrophobic forces play a major role in the binding of hydrocarbons to DNA. It states that hydrocarbons which are small enough to intercalate into DNA and be well protected from contact with the medium, will be found to bind to DNA; those that are too large will not. We report results on the binding of fourteen polycyclic aromatic hydrocarbons to DNA. Predictions based on the size criterion were found to be valid in all cases tested.
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    Cooperative binding of adenosine by polyuridylic acid: A further analysis (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 697-715 
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    Notes: The dialysis data of Huang and Ts'o for the cooperative binding of adensine to polyuridylic acid are analyzed here using a grand-partition function Ising model method similar to that originally employed for polyelectrolytes by Rice and Nagasawa. An appropriate modification permitting the treatment of the sliding degeneracy of the two polyuridylic acid strands is also included. In addition to the previously estimated stacking energy of about -6 kcal/mole one also obtains the free energy change F̄ for the transfer of a single adenosine molecule from a fixed site in solution to a fixed site on the polyuridylic acid. This binding energy falls in the range F̄ = -140 to +620 cal/mole, indicating that binding in the 1:2 (purine: pyrimidine) complex is either very weak or repulsive. The absence of any comparable cooperative stacking of adenosines in solution at the same concentration together with the likely repulsive character of the binding implies that the stacking energy must contain a significant contribution from other processes than simple stacking of adenosines. A generalization of the theory to treat multicomponent binding and longer-range interactions is effected, and the form applicable to simultaneous binding of both adenosine and guanosine by polyuridylic acid is presented.
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    PMR chemical shifts of TFA in poly(γ-benzyl L-glutamate) solutions (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 739-744 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The present communication describes a new way of studying helix-random coil transformations of polypeptide, poly-(γ-benzyl L-glutamate), in benzene-trifluoracetic acid (TFA) and chloroform-TFA systems. The difference between the PMR chemical shift of TFA with and without the polypeptide, measured as Δ, may be used to follow the conformational transition. This technique is particularly useful for concentrated solutions, where the PMR peaks of the polymer are so broad that no valuable information may be derived. As the TFA content increases in the system (at constant polymer concentration), Δ decreases normally whether the polymer is helical or random. However, Δ changes in a different way in the helix-random coil transition region, and actually increases with increasing TFA content. This peculiar behavior is explained in terms of the solvation of the helix and random coil structures.
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    NMR study of the slowly exchanging hydrogens of 640 Å steerskin collagen (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 745-748 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    Solution properties of synthetic polypeptides. VI. Helix-coil transition of poly-N5-(3-hydroxypropyl)-L-glutamine (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 717-738 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A new procedure for evaluating u and σ characterizing σ-helix-forming polypeptides in solution was derived from Nagai's theory for the helix-coil transition of such polymers. Here u is the activity for helix formation from random coil, and σ is the helix initiation parameter. The necessary data are the helical content fN at fixed solvent and temperature as a function of N, where N is the degree of polymerization of the polypeptide sample. Such data were obtained from ORD measurements on a number of fractionated samples of poly-N5-(3-hydroxypropyl)-L-glutamine (PHPG) in mixtures of water and methanol covering the complete range of composition and at various termperatures (5-40°C). When analyzed in terms of the proposed procedure, they yielded values of σ which were in the range (3.2 ± 0.6) × 10-4, substantially independent of solvent composition and temperature. These values were much larger than those obtained recently for σ of poly(β-benzyl-L-aspartate) in m-cresol and in a mixture of chloroform and DCA. The data for [η] and s0 (limiting sedimentation coefficient) as functions of molecular weight indicated that the molecular shape of PHPG in pure methanol is essentially rodlike, whereas that in pure water is not entirely randomly coiled but rather may be regarded as an interrupted helix. These indications were consistent with the results from ORD measurements. When plotted against the corresponding values of fN, the values of [η] and [s0] for PHPG in mixtures of water and methanol of various compositions and temperatures formed smooth composite curves, and we attributed these phenomena to the fact that σ of PHPG was nearly constant under these solvent conditions. Here [s0] stands for a reduced limiting sedimentation coefficient which is equal to the inverse friction factor of the solute molecule.
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    Masthead (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Interaction of nucleic acids. VI. Interaction of purine with nucleic acids (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 765-782 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The interaction of purine with DNA, tRNA, poly A, poly C, and poly A. poly U complex was investigated. In the presence of purine, the nucleic acids in coil form (such as denatured DNA, poly A and poly C in neutral solutions, or tRNA) have lower optical rotations. In addition, hydrodynamic studies indicate that in purine solutions the denatured DNA has a higher viscosity and a decreased sedimentation coefficient. These findings indicate that through interaction with purine, the bases along the poly-nucleotide chain are unstacked and are separated farther from each other, resulting in increased assymmetry (and possibly volume) of the whole polymer. Thus, the de-naturation effect of purine reported previously can be explained by this preferential interaction of purine with the bases of nucleic acids in coil form through a hydrophobic-costacking mechanism. Results from studies on optical rotation and helix-coil transition show that the interaction of purine is greater with poly A than with poly C. The influence of temperature, Mg++ concentration, ionic strength, and purine concentration on the effect of purine on nucleic acid conformation has also been investigated. In all these situations the unraveling of nucleic acid conformation occurs at much lower temperatures (20-40°C lower) in the presence of purine (0.2-0.6M).
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    Configurational statistics of polysaccharide chains. Part II. CelluloseContribution No. 286 from Centre of advanced study in physics, University of Madras, India. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 783-790 
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    Notes: The characteristic ratio of unperturbed cellulose chain was computed as a function of the angle τ at, the bridge oxygen atom and the degree of polymerization. Very high values of the order of 40 or more, depending on the angle at the bridge oxygen atom, have been obtained for this ratio, indicating that cellulose chains are highly extended. The average dimensions of cellulose chains are found to be sensitive even for small changes in the angle at the bridge oxygen, and these chains attain the character of a random coil in very high molecular weight range (degree of polymerization greater than 2000). The large differences in the unperturbed dimensions of cellulosic chains observed in different solvents have been attributed to the possible small changes in the angle τ caused by specific solvent, interactions.
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    Effect of side-chain hydrophobic bonding on the stability of homopolyamino acid α-helices: Conformational studies of poly-L-leucine in waterPresented before the Division of Biological Chemistry at the 154th National Meeting of the American Chemical Society, Chicago, Illinois, September 1967. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 749-764 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The conformational properties of block copolymers of poly-L-leucine in water have been examined. The degree of polymerization of the poly-L-leucine block was 11 and 21, respectively, for samples prepared by the Merrifield procedure, and 56 for a sample prepared by the polymerization of leucine N-carboxyanhydride. The optical rotatory dispersion parameter b0 was used to obtain the helix content θh at various temperatures. Application of the Lifson-Roig theory gave the following parameters for the transition of a residue from a coil to a helical state: v = 0.05-0.011, ΔH = +100 cal/mole, ΔS = +0.70-1.00 e. u. These parameters, as well as those for other polyamino acids, are accounted for by hydrophobic bonds involving the nonpolar side chains in the helical and randomly coiled forms. From the data for poly-L-alanine and theoretical values of the thermodynamic parameters for hydrophobic bond formation, the parameters for formation of a polyglycine helix are computed. By separating the contributions of the backbone, it is possible to obtain a set of thermodynamic parameters for the side-chain contributions of a number of polyamino acids. Increased size of the nonpolar side chain (with a larger contribution from hydrophobic bonding) makes a larger contribution to the stability of the α-helix which is reflected, among other ways, in a higher helix content at given temperature.
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    Polymerization of amino acid derivatives by polymer catalysts. V. Polymerization of DL-β-phenylalanine N-carboxyanhydride by several poly(N-alkylamino acid) diethylamides (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 791-797 
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    Notes: The polymerization of DL-β-phenylalanine N-carboxyanhydride (NCA) initiated by poly(N-benzylglycine)diethylamide (DEA) and poly(N-methyl-DL-alanine)DEA has been investigated. As previously reported, polysarcosine DEA, poly-N-ethylglycine DEA, and poly-N-n-propylglycine DEA showed marked accelerations in the polymerization of DL-β-phenylalanine NCA as compared with the polymerization initiated by low molecular weight, amines having similar base strength. However, this phenomenon (the chain effect) was not observed with the two polymer catalysts studied in the present investigation With poly-N-methyl-DL-alanine DEA, adsorption of DL-β-phenylalanine NCA onto the polymer chain takes place, though not so effectively as with other polypeptides, so the absence of chain effect was ascribed to a reduced flexibility of the polymer chain. With poly(N-benzylglycine)DEA, the reactivity of terminal base group was found to be much lower than that of other polymer catalysts. However, the absence of the chain effect would be attributed to the rigidity of polymer chain of poly-N-benzylglycine DEA due to the bulkiness of the N-benzyl group.
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    Ionic polysaccharides. III. Dilute solution properties of hyaluronic acid fractions (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 799-810 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Molecular weights by osmometry (M̄n), light scattering (M̄w), and sedimentation-diffusion (MsD) were determined for selected fractions and unfractionated samples of hyaluronic acid in the molecular weight range 3 × 104-1.7 × 106. For the determination of MsD from the sedimentation coefficient s, a calibration procedure based on the data of Laurent, Ryan, and Pietruszkiewicz gave the following relations in 0.2M NaCl: log (s-1)0 = 14.681 - 0.413 log MsD and log D0 = -3.828 - 0.568 log MsD, where subscript, zero refers to zero concentration and D is the diffusion coefficient. The average Mandelkern-Flory parameter β in 0.2M NaCl is 3.0 × 106. Data for the intrinsic viscosity [η] may be fitted for M 〉 105 by [η] = K′Ma, where K′, a are in 0.2M NaCl, 0.0228, 0.816; in 0.5M NaCl, 0.0318, 0.777; in 0.1 M HCl, 0.0279, 0.763, respectively. Below M = 105, [η] appears to fall below the values calculated, possibly due to non-Gaussian behavior of short chains. The second virial coefficient A2 in 0.5M NaCl approaches the ideal Donnan value, decreasing slightly with increasing molecular weight. The friction parameter P is about 20% smaller than that of uncharged polymers of similar dimensions. The flexible coiling nature of this polymer is confirmed.
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    Sedimentation of ribosomal ribonucleic acid from ribonuclease treated and untreated ribosomes (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 843-864 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The formation of a slowly sedimenting form of 23-S ribosomal RNA from E. coli has been investigated by analytical ultracentrifugation and thermal denaturation in aqueous solution and in formamide. Evidence is presented that the slow form of 23-S arises as a result of nucleate damage to the RNA in the 50-S ribosome. The 30-S ribosome (and 16-S RNA), is unaffected. The slow form of 23-S RNA cannot be demonstrated under conditions of complete denaturation in formamide, but only by partial denaturation in aqueous solution of low ionic strength (〈 0.01M Na). Apparent maintenance of the integrity of 23-S RNA in formamide after nuclease treatment suggests that this may not be a simple linear molecule. An alternative model is suggested containing a circular element in the structure.
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    Mechanochemical study of wet-spun lithium-DNA fibers (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 825-842 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Uniform LiDNA fiber specimens of nearly 20 m length have been prepared with a wet-spinning method developed by the author. Samples immersed in the spinning bath (80% ethyl alcohol containing 0.4M LiCl) have been subjected to mechanochemical study involving stretching, relaxation, and contraction measurements. A special technique was developed to transfer the sample from the Teflon-coated cylinder used in spinning to the sample column of the mechanochemical apparatus without stretching or removing the sample from the spinning bath. Force-strain curves of samples consisting of two fiber bundles showed an initial region of low slope followed by a region of high slope and a second region of low slope up to rupture. Some thicker specimens showed an aging effect which abolished the initial low-slope region and was interpreted as indicative of crystallization. Force-strain curves of two-bundle samples showed a strong influence of temperature with a complete loss of tensile strength of the LiDNA fibers in the spinning bath at about 55°C. Furthermore, samples at zero strain exhibited a contractile force when subjected to temperatures above about 40°C; the contractile process was pronounced with samples kept above 48°C. On contraction these samples obtained a zero-force length 20-30% of the original. These data are taken as evidence for a helix-to-coil transition occurring in the DNA, the low melting temperature being caused by the chemical influence of the ambient aqueous alcohol-LiCl bath.
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    Low-angle light-scattering studies on alkali- and heat-denatured DNA (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1029-1038 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The molecular weight of native DNA is shown to decrease by at least a factor of two on denaturation by heat or alkali. This result is obtained only if low-angle (〈30°) light-scattering measurements are used. High-angle measurements (〉30°) do not reveal a decrease in molecular weight on denaturation due to the incorrect value for native DNA. The dn/dc value for both native and denatured DNA is 0.166 ml/g ± 0.003 ml/g. Methods are described for the clarification of native and denatured DNA solutions for light scattering by the use of membrane filters.
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    Electric dichroism studies: Interaction of trifluoroacetic acid with poly(gamma;-benzyl L-glutamate) (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 991-1000 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Electric dichroism studies on poly(γ-benxyl L-glutamate) show that the addition of small amounts (up to 5%) of trifluoroacetic acid causes complete disappearance of dichroism in contrast to the electric birefringence, which drops to an observable plateau at 20% of its initial value. This loss of dichroism cannot be explained simply by a decrease in the effective dipole moment of the benzyl ester side chains, and the nature of this interaction is explored by nuclear magnetic resonance and infrared spectral studies. Theories of the helix-coil transition which require an initial protonation of the helix backbone to form a more flexible rod consisting of helical segments interrupted by regions of random coil are shown to be inadequate to describe the changes in poly(γ-benzyl L-glutamate) effected by small amounts of trifluoroacetic acid. Rather, trifluoroacetic acid in small amounts interacts with the ester carbonyl oxygen in the side chain, either by hydrogen bonding or protonation, before there is evidence of any effect on the backbone or of loss of helix content.
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    Raman spectra of poly-L-lysines (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1229-1237 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Raman spectra of poly-L-lysine hydrochloride and poly-∊-carbobenzoxy-L-lysine in the solid state have been obtained and are consistent with the presence of an α-helical structure. The Raman spectrum of poly-L-lysine in aqueous solution suggests the presence of random coil structures.
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    Backbone and side-chain conformations of amino acids and amino acid residues in peptidesContribution No. 288 from the Centre of Advanced Study in Biophysics, University of Madras, Guindu Campus, Madras-25, India. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1249-1252 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1970.360091005
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    Masthead (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1970.360091101
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    Conformational studies of linear β-D-1,4′-mannan and galactanContribution No. 289 from the Centre of Advanced Study in Physics, University of Madras, Madras, India. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1239-1247 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nonbonded interaction energy of disaccharides, mannobiose and galactobiose and polysaccharides mannan and galactan have been computed as a function of dihedral angles (φ,ψ). The conformation (40°, -20°) has been preferred for the mannan chain from nonbonded interaction energy considerations. The O5…O3′ type of intramolecular hydrogen bond has been found to be possible in the above conformation. Comparison of the allowed region of mannan with those of cellulose and xylan indicates that the monomer unit, in mannan chain has slightly higher freedom of rotation than that of cellulose and less than that of xylan. As in cellulose and mannan, the freedom of rotation of the monomer units in β-1,4′ galactan is highly restricted. Unlike mannan (which prefers an extended conformation) the β-1,4′ galactan prefers a helical conformation similar to amylose. Just as in amylose the O2…O3′ type hydrogen bond between contiguous residues is also possible in β-1,4′ galactan.
    Additional Material: 7 Ill.
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    Perspectives report: Melting of DNA: Its study and application as a research methodWe are delighted to include this article in Biopolymers since it includes the important Russian literature in this area. The Editors. (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1253-1306 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 23 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1970.360091102
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    Critical comparison of the experimental optical activity of helical polypeptides and the predictions of the molecular exciton model (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1475-1502 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The predictions of the presently accepted molecular exciton model for the optical activity of helical polypeptides are in reasonable agreement with experimental spectra in the accessible wavelength range. However, crucial verification requires the detect of a significant negative rotatory hand just below the accessible range. A computer-oriented method is utilized to obtain information concerning the inaccessible range. Optical rotatory dispersion computed by evaluation of the Kronig-Kramers integral transform from the experimentally determined circular dichroism of several helical homopolypeptides in solution are compared with the experimentally determined optical rotatory dispersion. Computed and experimental curves are congruent within an uncertainty approaching that of the experimental technique, whatever the polypeptide sample lot, side chains, and solvent. It is shown that t his agreement is not a computational or experimental artifact. These results can be interpreted in two ways: (1) that the predicted band does not exist, and (2) that the perturbation of the predicted band is being negated by other inaccessible bands in the vacuum ultraviolet. Arguments are presented to show that the first of these two possibilities is more probable.
    Additional Material: 10 Ill.
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    Electrophoretic charge of a cylindrical macroion in aqueous 1 : 1 electrolyte (1970)
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 1511-1530 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potential problem is formulated for rodlike macroions and reduced to a single dimensionless equation with appropriate boundary conditions. A method of solution based on piecewise linearization of the potential equation is detailed and compared with two other approaches. It is suggested that the present method yields improved estimates of macroion charges. Some numerical results are included, and the relation between electrophoretic charge and macroion charge is considered.
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    Preparation of long-chain paraffins from nitric acid degradation products of polyethylene; some consequences for polymer crystal structure studies (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 19-34 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is demonstrated that dicarboxylic acids of uniform lengths, obtained by degrading chain-folded polyethylene single crystals, can be converted to paraffins via the intermediate diiodide by means of the procedure of Barton et al. Thus we are now in the position of obtaining uniform paraffins of chain lengths longer than hitherto available for the study of the crystallization of oligomeric chains. Measurements of melting points and heats of fusion revealed major differences between the paraffins and the corresponding parent dicarboxylic acids. It follows that such measurements on the unmodified products of the nitric acid degradation cannot be used directly for the assessment of the chain traverse length and the degree of crystallinity. It was found further, that the intermediate diiodide is a sufficiently close approximation to the paraffin for the purposes just quoted.
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    Universal calibration in GPC: A study of polystyrene, poly-α-methylstyrene, and polypropylene (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 89-103 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theoretical justification for using M[η], or a similar quantity, as a universal calibration parameter in GPC is reviewed. The equation based on this parameter is applied to transform the primary calibration curve, obtained by means of polystyrene samples, into calibration curves for poly-α-methylstyrene, polypropylene, and linear polyethylene. The Mark-Houwink equations for these polymers, as they are used in the transformation, are discussed. The resulting GPC calibration curves are compared with molecular weights and peak elution volumes of fractionated poly-α-methylstyrene and polypropylene. The same comparison is made with samples of polypropylene and polyethylene having very broad molecular weight distributions. The agreement lies within experimental error.
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    Calibration of gel-permeation columns with unfractionated polymers (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 148-152 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/pol.1970.160080112
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    Addition polymers: Formation and characterization. D. A. SMITH, ed., Plenum Press, New York, 1968. pp. 492. $22.00 (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 482-482 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    URL: http://dx.doi.org/10.1002/pol.1970.160080314
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    Precipitation chromatography theory (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 207-224 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A discussion is given of the behavior of a mathematical model chosen to approximate conditions during precipitation chromatographic fractionation of polymer (Baker Williams fractionation). With only one molecular weight species of polymer a complete solution of the mathematical model was obtained. With more than one species it was necessary to use a computer solution. Curves showing the movement of polymer containing one and two species of polymer are given for a variety of conditions of operation. It was found that the degree of fractionation of polymer approaches a limiting value with increasing length of column. Under some conditions the degree of fractionation may go through a maximum with length of column. The equilibrating distance (distance of travel of the liquid phase required to establish equilibrium of polymer between the liquid and the bed) was found to be very important in determining the fractionation.
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    Dynamic and steady-shear melt rheology of and ethylene-methacrylic acid copolymer and its salts (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 277-287 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Studies have been made on the dynamic and steady-shear melt rheology of an ethylene-methacrylic acid copolymer and two of its salts obtained by partial neutralization with sodium and with calcium bases. Measurements were made with a Weissenberg rheogoniometer over a broad range of shear rates and frequency in the temperature interval mainly from 100 to 160°C. The temperature coefficients of dynamic and steady shear viscosity are evaluated at both constant shear rate and constant stress. Likewise, complex dynamic viscosities and apparent high steady-flow viscosities and intercompared at equivalent frequencies and shear rates. The un-ionized acid copolymer shows good correlation between the frequency dependence of the complex viscosity and the shear rate dependence of the apparent viscosity. This is not true for either the sodium salt or the calcium salt. These results are consistent with the two-phase structural model for these materials, i.e., a matrix of hydrocarbon in which are embedded ionic domains.
    Additional Material: 12 Ill.
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    Effect of diluents on the melt viscosity of branched polybutadienes (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 305-310 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enchanced low-shear melt viscosity of branched polybutadienes is shown to be sensitive to dilution with low molecular compounds. The viscosity of branched polymers falls more rapidly with dilution than that of linear polymers, i.e., branched polymers show increased response to plasticization. At least one instance is demonstrated in which the viscosity ratio ηbr/ηlin reverses from a value greater than unity to less than one in passing from dry polymer to rubber extended with relatively large quantities of oil.
    Additional Material: 3 Ill.
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    Normal stress and shear stress in a viscoelastic liquid under oscillatory shear flow (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 371-381 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Normal stress and shear stress of concentrated polystyrene solutions in a chlorinated diphenyl were measured under steady flow and oscillatory shear flow in a Weissenberg rheogoniometer. The normal stress difference was observed to oscillate at double the frequency of the applied shear strain with amplitude proportional to the square of the applied amplitude, while the shear stress was found to oscillate at the same frequency with amplitude proportional to the applied amplitude. A theoretical relation between the displacement of the oscillatory normal stress difference from zero level and the dynamic modulus derived by Lodge and other investigators was confirmed experimentally, and the theoretical predictions of Coleman and Markovitz concerning the relation among steady-flow normal stress difference and dynamic modulus were also confirmed. However, the theoretical predictions of Lodge, of Spriggs, Huppler and Bird, and of Williams on the relation between the amplitude and phase of oscillatory normal stress and those of oscillatory shear stress did not agree with experimental results.
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    Single crystals of high polymers by film formation (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 47-59 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple method of preparing thin uniform films of high polymers has been examined for growing single crystals from solution. Single crystals of polyethylene, polypropylene, polybutene-1, polyacrylonitrile, and cellulose triacetate have been obtained by this method. Different stages of growth reveal different growth features that are also obtained from solutions of these polymers by changing temperature and concentration.
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    Isomorphic interactions of ethylenic polymers and paraffin wax (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 81-87 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The high degree of flexibility of blends containing minor amounts of partly crystalline copolymers of ethylene and vinyl acetate in paraffin wax seems to be a manifestation of some type of interaction. Low-angle x-ray diffraction of such blends showed a new long spacing intermediate in length between the polymer long spacing and the c axis length of the wax unit cell. This new long spacing appears to be a consequence of isomorphism involving cocrystallization of polymeric ethylene sequences and wax molecules. A lesser type of isomorphic interaction, epitaxy, occurs in polyethylene-wax blends: wax overgrows crystals of already crystallized polyethylene in the same orientation without a change in its c axial dimension.
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    Thermoluminescence in hydrocarbon polymers (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 143-147 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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    Yield condition and propagation of Lüders' lines in tension-torsion experiments on poly(vinyl chloride) (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 893-901 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have derived from the Eyring theory of non-Newtonian flow a yield condition which is valid for an arbitrary state of stress. Experimental data obtained in simple axial compression tests show the influence of the hydrostatic stress on the yielding of poly(vinyl chloride). This fact confirms the proposed condition and disproves the von Mises criterion. Tension-torsion tests performed on thin tubes lead to results which fit our condition fairly well. The pattern of Lüders' lines appearing on the surface of thin tubes subjected to simple tension, simple shear, and tension-torsion are parallel to the direction where the value of the normal stress is equal to the hydrostatic stress.
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    Fusion of homopolymers and ordered copolymers containing ethylene sebacate structural units (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 957-967 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The melting temperatures of homopolymers of poly(ethylene sebacate) possessing a most probable molecular weight distribution and ordered copolymers of ethylene sebacate/propylene adipate were studied by slow heating processes and by the analysis of the dependence of the melting temperature on the crystallization temperature utilizing rapid heating rates. For the ordered copolyesters, where the composition of the crystallizing co-units ranged from 0.8 to 0.2 mole fraction the latter method gave results which were similar to those that have been obtained for the other polymer systems that have been studied. Extrapolated equilibrium melting temperatures could be obtained in a straightforward manner and were found to be independent of the copolymer composition in accord with theoretical expectations. On the other hand, a unique set of results were obtained for the homopolymers. A plot of the relationship between the melting temperature and the crystallization temperature for all the molecular weights studied gave a slope close to unity. This made it operationally impossible to extrapolate to the equilibrium melting temperature for this system.
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    Internal motion in organosilicon polymers. II. Dimethylpolysilazanes crosslinked through silicon (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 999-1010 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An investigation of the internal motion in organosilicon polymers by wideline nuclear magnetic resonance has been extended to a pair of dimethylpolysilazanes crosslinked through trifunctional silicon. The data suggest that there is considerable internal motion in all silazanes at 77°K. Evidence is presented for the presence of C3 rotation of the methyl groups, as well as rotation or torsional oscillation of the Si(CH3)2 groups about the polymer backbone. Upon warming the NMR line is seen to narrow, and this is associated with the onset of additional motion, including chain translation and chain flexing or bending. Crosslinking through silicon increases the barrier to chain translation while decreasing the barrier to chain flexing or bending.
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    Structure and properties of poly-2,5-distyrylpyrazine (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1027-1037 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly-2,5-distyrylpyrazine (poly-DSP) was investigated by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and measurements of dynamic viscoelastic and electrical properties. From DTA and TGA studies it was confirmed that poly-DSP melts at 321°C and depolymerizes rapidly to the monomer at temperatures between 335°C and 345°C in helium. The polymer is affected by oxygen above 200°C. The E′ value from dynamic viscoelasticity measurements on amorphous film is 2 × 1011 dyne/cm2 at room temperature. It decrease abruptly in the temperature range 140-150°C; but the net decrease of E′ within this temperature range is relatively small. The electrical properties of amorphous poly-DSP are characterized by a small temperature dependence of the dielectric constant between room temperature and 100°C. The dielectric loss tangent was observed to be small, and the dc conductivity was extremely small. It is concluded that rotation of the phenyl branches in the polymer occurs above -30°C and the glass transition occurs at about 150°C. These properties are discussed in some detail in relation to the polymer structure.
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    Comonomer and stereosequence distributions in high polymers (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1111-1126 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Comonomer and stereosequence distributions in linear high polymers are considered from the point of view of the general theory of stationary random sequences. Although the discussion is centered about binary polymerizations which may be regarded as stationary Markov processes of low order, attention is paid to distinguish results valid for any stationary random process including stationary non-Markov processes from those special to a particular Markov process. Alternative derivations of copolymer composition equations are given along with a corrected version of a previously suggested scheme of relating conditional probabilities of different orders. The nature and relative merits of the several measures proposed in the literature to characterize comonomer and stereosequence distributions are also discussed in some detail.
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    Dielectric absorption in oriented poly(vinylidene fluoride)Paper presented in part at the 16th Annual Meeting, Society of Polymer Science of Japan, Tokyo, 1967. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1177-1186 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The loss peak caused by molecular motion of the molecules in crystalline regions appears at about 70°C (110 Hz) (α1 absorption) for the α form, and at about 110°C (110 Hz) (α2 absorption) for the β form. Orientation significantly affects the magnitude of the β absorption which appears at about -40°C. The very high value of the dielectric constant for stretched film is believed to be due to the orientation effect. The γ absorption, which is assumed to be local-mode absorption, is not so much affected by orientation. An additional loss peak has been found at around 0°C in dynamic mechanical measurements, but the molecular mechanism is unknown.
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    A dynamic approach to diffusion and permeation measurements (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 467-479 
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    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A dynamic method for investigating the mechanism of permeation and diffusion through polymers has been explored. The permeation cell consists of two compartments separated by the membrane. The permeant (gas, vapor, or liquid) is introduced into one compartment; a carrier gas (helium) flows at constant rate through the other and sweeps the permeant which diffuses through the membrane to the thermal conductivity detector. Both compartments are at atmospheric pressure; thus no or little membrane support is required, and leakage problems are minimal. Moreover, the same membrane can be used over a wide temperature range and for diverse permeants. The detector signal is at any instant proportional to the permeation rate. A simple mathematical formalism for deriving the diffusion coefficient from the transient permeation rates has been developed. The measured diffusion and permeability coefficients of CO2, O2, and N2 through low-density polyethylene closely agree with literature values. Permeation of hexane and benzene through polyethylene follows a complex diffusion law, and the rate depends on the thermal history of the system. The dynamic method is particularly suited to the study of transitions in polymers. Changes in permeation rates, usually occurring at transition points, can easily be discovered by slow temperature scanning of the system.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080312
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    Statistical mechanics of chain molecules. PAUL J. FLORY, Wiley (Interscience), New York, 1969, 432 pp. $17.50. (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 487-487 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080317
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  • 94
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    Multiple melting transitions in fractions of partially isotactic poly(propylene oxide) (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 519-528 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three transitions are detected dilatometrically when partially isotactic poly(propylene oxide) melts. One transition, the temperature of which is independent of the crystallization temperature over a wide range below 60°C, is ascribed to the melting of lamellar crystallites which are limited in thickness by the average isotactic sequence length alone. The other two transitions, the temperatures of which vary with the crystallization temperature, are ascribed to the melting of lamellar crystallites with thickness determined predominantly by three- and two-dimensional primary nucleation acts. The theory of Flory is adapted and applied quantitatively to the melting points of three crystalline fractions of poly(propylene oxide), obtained from a polymer produced via the zinc diethyl and water catalyst system. This method leads to a thermodynamic melting point of isotactic poly(propylene oxide) near 82°C.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080404
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  • 95
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    Fracture surface of polystyrene: Mackerel pattern (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 583-594 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Characteristic markings of concentric bands are formed on the fracture surface of tensile specimens under certain loading conditions. The marking form in the fast crack growth region of the mirror area of fracture. Optical and electron optical microscope techniques have been used to study the morphology of the markings. It is shown that in this region the crack propagates along the interface between the craze, in which the crack nucleated, and the bulk material. The mackerel pattern is caused by the crack jumping from one craze-matrix interface to the other.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080409
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  • 96
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    Tensile properties and equilibrium swelling of plasticized amorphous polyurethane rubbers (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 605-624 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Incorporation of plasticizers or other inert, liquid diluents causes a profound weakening of rubbers. The modulus of elasticity and tensile strength decrease approximately with the square of the gel fraction v0 of rubber which was present at the time of formation of the three-dimensional network. Equlibrium swelling of plasticized rubbers is well represented by v2m = kv0, where v2m is the volume fraction of rubber network in the swollen state, at equlibrium, and k a constant equal to v2m for the unplasticized rubber. This swelling law is independent of the way in which v0 is obtained; inert liquid diluents, comprising molecularly dispersed compounds, as well as suspensions of insoluble liquids, gases, and chemically inert, solid fillers yield the same relation. Further, it is independent of the chemical nature of solvent and rubber. It appears that also the mechanical properties of foams, liquid-filled foams, and plasticized elastomers containing the same volume fraction of network rubber are very similar.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080411
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  • 97
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    Multiple melting in isotactic polystyrene (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 649-652 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080415
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  • 98
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    Viscoelastic and relaxation properties of a polystyrene melt in axial extension (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 657-678 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: On axial extension of polymer melts at constant deformation rates, the development of high-elastic deformation is of predominant importance during the initial period. High-elastic deformation is accompanied by a rise in viscosity and in the modulus of high-elasticity and by retardation of the relaxation processes in the region of large relaxation times. At relatively low deformation rates, the rise in viscosity and high-elasticity modulus and the retardation of relaxation processes may give way to a decrease in viscosity and high-elasticity modulus and acceleration of relaxation processes, so that stationary flow regimes are attained. The transition from strain regimes with increasing viscosity and modulus of high elasticity to those with a decrease of these quantities corresponds to an increase in the rate of accumulation of irreversible deformation. Accordingly, a competing influence due to the orientation effect and to destruction of the network of intermolecular bonds becomes evident while stationary flow is being attained. The orientation effect must be responsible for the retardation of the relaxation processes, whereas rupture of the intermolecular network bonds results in structural relaxation accelerating relaxation processes. In contrast to shearing, during extension the orientation effect is of predominant importance. Hence in stationary flow regimes the viscosity may not only remain independent of the rate of strain, but even increase with it. In this case the contribution of the large relaxation times to the relaxation spectrum increases with increasing stress in stationary flow regimes. The fact that the longitudinal viscosity and the modulus of high elasticity are independent of the stress in stationary flow regimes does not guarantee linearity of the mechanical properties of the polymer in the prestationary stage of deformation when complex changes occur in its relaxation characteristics. At high deformation rates the viscosity and the modulus of high elasticity keep rising with increasing deformation until rupture occurs. Determination of the strength of polystyrene samples vitrified after extension showed that it is due not to the entire degree of extension, but only to the value of accumulated high-elastic deformation. The strength of the vitrified samples is to a first approximation independent of the rate at which the melt was extended.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080501
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  • 99
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    Dielectric relaxation in ethylene-methacrylic acid copolymers and their salts (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 727-738 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric relaxation data have been obtained for two ethylene-methacrylic acid copolymers (containing about 4 mole-% methacrylic acid units and about 8 mole-% methacrylic acid units, respectively) and the lithium, sodium, and calcium salts prepared by partial neutralization of the polyacids. The frequency range employed was from 50 Hz to 10 kHz and the temperature range was from -130°C to 100°C. Attention is focused on three dielectric loss regions labeled β, β and α in order of increasing temperature. The β′ process (-10°C at 100 Hz in the salts only) correlates with a mechanical loss process previously reported and is attributed to microbrownian motion taking place in an amorphous hydrocarbon phase. The β′ process (20°C at 100 Hz) has also been observed mechanically and is attributed to the same mechanism as the β process. The higher temperature of this relaxation compared to the β relaxation is attributed to the presence of acid groups which form crosslinks composed of interchain hydrogen bonds. The α process (〉50°C at 100 Hz in the salts only) correlates with dielectric and NMR data previously reported for a sodium salt and is assigned to motions within ionic domains formed by the clustering of salt groups.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080506
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  • 100
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    Molecular weight distribution functions for styrene-acrylonitrile copolymers (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 807-811 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080513
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