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  • General Chemistry  (4,448)
  • Cell & Developmental Biology  (817)
  • Polymer and Materials Science  (440)
  • Limnology
  • 1945-1949  (1,686)
  • 1930-1934  (4,019)
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  • 1
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The inhibitor and initiator action of 33 compounds on the bulk polymerization of pure isoprene has been studied. Picric acid was found to be the most powerful inhibitor at 100°C. The conclusion reached in Part I, that the initiator activity of diazoaminobenzene is superior to all other compounds has been found to be valid also between 100-150°C. The heat polymerization of isoprene between 100-150°C. in the presence of picric acid leads only to the formation of dimers. Three of the four possible isomers have been separated. The solid complex compound of diprene (I) with silver nitrate has been used to separate it from dipentene (II) and the hydrocarbon of Lebedew (III, IV) has been identified as a monochloride. The relative yields (I): (II): (III+IV) = 16:1:2 are in agreement with the relative availability and localization of π-electrons in isoprene. Observations on the properties of polyisoprene are in agreement with the more extensive work by d'Ianni. Some remarks on polymers from bulk polymerization are added. Isoprene acts as a powerful inhibitor on the polymerization of vinylidene chloride. This effect is independent of the method of polymerization.
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  • 2
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Natural rubber and GR-S synthetic rubber have been vulcanized to varying degrees of cross linking through the use of disazodicarboxylates. These compounds react readily with the above unsaturated polymers in a manner which assures the formation of one cross linkage for each molecule of the disazo compound. Elastic properties of the vulcanizates so produced are similar to those of rubber specimens vulcanized in the conventional manner with sulfur and an accelerator. Their stress-strain curves deviate from the form prescribed by the statistical theory of rubber elasticity in the same manner as observed by Gee for sulfur vulcanizates. The equilibrium force of retraction at 100% elongation has been measured over a 30-fold range in the degree of cross linking; equilibrium swelling measurements extend over an 80-fold range. The magnitude of the force of retraction over most of the range covered agrees remarkably well with the explicit predictions of the statistical theory. The significance of the deviations which are observed is discussed.
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  • 3
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    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 273-287 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It has been shown that subdivision of certain homogeneous polymerizing systems into droplets of diameter 10-4 to 10-5 cm. will entail a probability of finding only one active chain in each particle if the kinetics of the reaction remained otherwise unaffected. Some cases of polymerization in compartmentalized systems have been considered, and it has been shown that, where active centers are generated singly within completely isolated drops, the effect of increasing subdivision would be to increase the rate of reaction and chain length. On the other hand, with the formation of active chains in pairs, the opposite effect is to be anticipated, namely a decreasing rate of reaction with increasing subdivision. These conclusions are briefly considered in relation to the problem of dispersion polymerization, and it is shown that the theory of compartmentalization could account for the occurrence of high rates of reaction and chain lengths in the emulsion process, as compared with a bulk system. On the other hand, there is no evidence showing that the reaction rate is ever reduced in finely dispersed systems.
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  • 4
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 289-307 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A practical and simple method, with perfectly reproducible results, has been studied for the determination of chain-length repartition of cellulose samples from different wood pulps. By this method, it shall be possible to understand the influence of different factors governing the manufacture and the mechanical properties of our end products.
    Notes: Nous avons étudié une méthode pratique et simple, dont les résultats soient parfaitement reproductibles, de détermination de la répartition des longueurs de chaînes de la cellulose provenant de pâtes de bois différentes. Cette méthode nous permettra de mieux comprendre l'influence des différents facteurs de fabrication sur les qualités mécaniques de nos produits finis.
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  • 5
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By means of chain transfer agents such as dodecyl mercaptan, polyisoprenes whose number-average molecular weights range between 300-1200 and which are liquid at room temperature have been prepared. The structure and physical properties of these substances have been investigated. Vulcanization of these liquids to rubberlike materials at room temperature and above is described.
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  • 6
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The recently developed x-ray method of crystallinity determination is applied to products of heterogeneous acid hydrolysis of cellulose fibers. Upon treatment of viscose rayon fibers with boiling 2.5 N sulfuric acid, the crystalline fraction is increased from 39 to 49% within half an hour, and remains constant upon prolonged treatment. Ramie does not show any change in percentage crystallinity when subjected to the same treatment. Its crystalline fraction is, however, transformed into cellulose IV. The observed changes in moisture regain of the hydrolyzed products are in line with the x-ray results.
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  • 7
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 323-336 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The construction of a thermostated osmometer of the Fuoss-Mead pattern is described. The technique of preparation of bacterial cellulose membranes for osmotic measurements on high polymer systems is given. The permeability of such membranes may be controlled by growth to a thickness of 4-5 mm., drying in contact with a stainless steel surface, and reswelling in water or alcohol-water mixtures. The degree of reswelling required to give membranes suitable for use with polymers of a range of molecular weights is given. The factors affecting the behaviour of the membranes in the osmometer are discussed.
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  • 8
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 337-350 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bacterial cellulose membranes have been used successfully to measure the osmotic pressures of a number of high polymer-solvent systems. The dynamic method of Fuoss and Mead has been used in most cases, but for polyvinylxylene in benzene the rate curves are not symmetrical since the solvent passes through the membrane faster from the solution side. The molecular weight values for two polyvinyl acetates agree well with the calculated kinetic values, and for polyethyl sebacate the value obtained agrees with that found by endgroup titration. Values of the Huggins “constant” μ are given for various systems.
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  • 9
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 359-376 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization reaction which occurs when butene vapor is mixed with boron trifluoride gas has been studied under various conditions. It has been found that this polymerization occurs only if a third component, or cocatalyst, is present. The function of the cocatalyst has been investigated, and the mechanism of the polymerization reaction is discussed.
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  • 10
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Refractive index-temperature and volume-temperature data for polyvinyl acetate and polybutyl acrylate have been determined and used to calculate the specific refractivity as a function of temperature by the Lorentz-Lorentz and the Eyckman equations. The results show a variation of specific refractivity with temperature which exceeds experimental error. The variation is evident as an increase of specific refractivity with temperature above Tm and suggests experiments which will show the increase more clearly. A theoretical justification for the increase of specific refractivity with temperature in polymers is discussed.
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  • 11
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 399-400 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 12
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 401-403 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 13
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The osmotic pressures of two samples of poly-4-vinyl-N-n-butylpyridonium bromide (average D. P. 730 and 1900) were measured in 93% ethanol in the concentration range 0.02-0.20 g./100 cc. The osmotic pressures were higher than those of the corresponding parent polymers, due to partial dissociation of bromide ions. Because of the low dielectric constant ( ε′ = 28) of the solvent and the high concentration of positive charge in the polycations, however, a large fraction of the bromide ions (≥ 95%) were bound by electrostatic attraction to the cations and contributed neither to osmotic pressure nor to conductance. Unlike neutral polymers, the ratio (osmotic pressure over concentration) increases with dilution, due to increasing dissociation with dilution. Addition of an excess of a simple one-one electrolyte (lithium bromide) almost completely suppressed the dissociation of the polysalt and gave osmotic pressures of the same order of magnitude as those of the neutral polymers. The resulting curves were linear, with a considerably smaller slope than for the parent polymer. Combining the results on osmotic pressure with conductance data, the transference numbers of the polycations were estimated to be 0.28 and 0.52 for degrees of polymerization 730 and 1900 respectively. The conductance of lithium bromide is decreased by the addition of these polyelectrolytes, possible due to the association of an excess of anions to the polycations under the influence of their electrostatic fields.
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  • 14
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 473-482 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: It is easiest to calculate the mean quadratic distance between the chain ends of a macromolecule when all rotations are free. This condition, however, is generally not realized; in this paper are discussed the results obtained by introducing a symmetric repartition function for the position of each atom of the chain on the circle of the basis of the valential cone. We have compared the formulas proposed here graphically with their results (Figs. 2 and 3). This comparison shows that the Kuhn and Taylor formulas are only an approximation of the formula established in an earlier paper; the formula of these authors has a restricted validity. The extent of this validity increases with the number of units in the chain molecule. By using the repartition functions proposed by Taylor, we represent the value of the mean quadratic distance as a function of the interaction energy. It is possible that this energy has the value calculated from the vapors of normal aliphatic hydrocarbons; but it is the sum of several terms and must vary with the number of units and the temperature. The established formula permits the prediction of two different aspects of the precipitation of the polymers, by decreasing the temperature or by addition of a precipitant. Finally, if the atoms of the chains must in their rotations pass over potential barriers, it is possible to predict anomalies in their comportment.
    Notes: Le cas le plus simple pour calculer l'écart quadratique moyen entre les extrémités d'une chaǐne macromoléculaire est celui oùtoutes les rotations sont libres. Mais cette condition n'est généralement pas réalisée, aussi avons nous examiné dans cet article les résultats obtenus en introduisant une fonction de répartition symétrique pour les positions de chaque atome de la chaîne sur le cercle de base du cǒne de valence. Nous comparons les formules proposées jusqu'ici en représentant graphiquement leurs résultats (figs. 2 et 3). Cette comparaison montre que la formule de Kuhn et Taylor (8,9) est une approximation de celle que nous avons établié dans un article précédent (7) et a, de ce fait, un domaine de validité plus restreint. Ce domaine augmente avec le nombre des chaǐnons de la chaîne. En utilisant les fonctions de répartition proposées par Taylor nous représentons les valeurs de l'écart quadratique moyen en fonction de l'énergie d'interaction (figs. 6 et 7). Nous montrons ensuite que cette énergie d'interaction ne peut avoir la valeur calculée pour les vapeurs de carbures aliphatiques normaux mais est la somme de plusieurs termes et doit varier avec la nombre de chaǐnons et la température. Les formules établies permettent de prévoir deux aspects différents de la précipitation suivant qu'elle est effectuée par abaissement de la température ou adjonction d'un précipitant. Enfin, lorsque dans leurs rotations les atomes de la chaîne doivent passer par dessus des barrières de potentiel on peut prévoir des anomalies dans son comportement.
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  • 15
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Tensile strengths of natural rubber samples quantitatively crosslinked with decamethylene dis-methyl azodicarboxylate have been determined. The proportion of the azo vulcanizing agent was varied 80-fold, the fraction p of cross-linked units in the products ranging from 0.10x 10-2 to 8.0 x 10-2. In spite of the small dimensions of the test specimen (cross section 0.10 in. by about 0.005 in.), the average error for a single observation is similar to that obtained in conventional testing procedures applied to specimens vulcanized with sulfur and accelerators. Deviations from the mean for 262 tests on 15 different cures are well represented by a Gaussian error function; a slight intimation of skewness is evident only at the extremities of the distribution of deviations. These results are incompatible with the commonly held view that rupture of the sample takes place at the “weakest link” in the series of flaws inevitably occurring along the specimen. It would appear that the ability to withstand tensile stress (applied in a specified manner) is an inherent characteristic of the bulk material. The rapid increase in tensile strength with the degree of crosslinking p for small values of this quantity is consistent with the conclusion, previously reached in the investigation of the physical properties of butyl rubber (6) that the tensile strength is directly related to the fraction of the structure which is permanently oriented by stretching. At higher degrees of cross-linking (at ρ x 100 = 1.0 to 1.5, depending on the molecular weight of the rubber) the tensile strength passes through a maximum and then declines steadily to quite low values for higher ρ's. This adverse effect of higher degrees of cross-linking is believed to result from the diminished elongation at which crystallization sets in and, hence, the smaller fraction of the network elements sufficiently oriented to participate in crystallite formation. Modification of up to 7% of the isoprene units of the rubber with the monofunctional compound, ethyl azodicarboxylate, depresses the tensile strength of the disazo vulcanized rubber relatively little. Evidently, the limited extent to which these modified (or copolymer) chains may enter into crystallization is adequate to bring about high tensile strength. Lack of direct correlation between modulus and tensile strength for rubbers vulcanized with various sulfur-accelerator combinations can only be explained by assuming that conventional vulcanization processes are accompanied to varying degrees by chain scission reactions. When vulcanized rubber is “over-cured,” or heat aged, chain scission becomes excessive.
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  • 16
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The equilibrium swelling of the gum stocks of twelve different rubber vulcanizates has been measured in thirteen organic solvents. The results are in good agreement with the theory of Flory and Rehner. Values of the internal pressure (cohesive energy density) and the average molal volume between cross-linkages Vc have been determined for the rubbers. The molal volume Vc is shown to agree closely with that obtained from measurement of the elastic modulus. An analysis of earlier data on the swelling of polybutadiene shows the number of cross-linkages to be directly proportional to the sulfur content.
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  • 17
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The quantum yield of inactivation of chymotrypsin was found to be independent of variations in conditions of irradiation including light intensity, concentration of the irradiated solution, rate of stirring and the presence or absence of oxygen. The quantum yield for inactivation is at a minimum at the isoelectric point (pH 5.4). An explanation is offered for the variation of the quantum yield with pH in terms of an internal Franck-Rabinowitch mechanism. The absorption spectra of the enzyme was also studied as a function of pH, as was that of an amino acid mixture whose composition corresponded to that of chymotrypsin. Evidence is presented for the existence of bound, un-ionizing tyrosine in the native enzyme and of unbound tyrosine in alkali-denatured enzyme. The significance of changes in the absorption spectra accompanying irradiation is discussed.
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  • 18
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymers of 2-ethyl-, 2-isopropyl-, and 2-n-amyl-1,3-butadiene alone, and their copolymers with styrene and with butadiene have been prepared and characterized. These monomers give the same ratio of 1,2 to 1,4 addition as has been noted for isoprene. Much less mercaptan must be used with these monomers than is required for butadiene to give soluble polymers. All these monomers copolymerize with styrene readily but have higher Wall α values than butadiene. The stress-strain properties and Gehman low-temperature properties of all of the new polymers have been determined by the Government Laboratories, University of Akron, and are included in this report. There appear to be no unusual properties to be noted.
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  • 19
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 4 (1949), S. 597-604 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Information concerning monomer reactivity in copolymerization has been obtained for thirteen copolymerization systems. The influence of substituents and chain length in vinyl polymerization is discussed in the light of this and preceding data. Unsaturated acid behavior in copolymerizations is discussed for the first time.
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  • 20
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    Journal of Polymer Science 4 (1949), S. 619-628 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By applying hydrochloric acid solution at different temperatures to various fibrous cellulose samples and following the per cent loss in weight with time, hydrolysis-time curves have been obtained. These plots have been resolved into a straight line and a curve, representing the rate of removal of difficultly and easily removable components, respectively. Under the experimental conditions applied, the ratedetermining reaction in the removal of the difficultly accessible components from the fibers is essentially a kinetically zero-order reaction. This was borne out by the results of hydrolyses of hydrocellulose preparations. Within the experimental range the temperature coefficient of this rate is independent of the representative fibrous materials and is relatively high, corresponding to an energy of activation of 28-29 kcal./mol. The easily and difficultly accessible regions, assessed by resolving the rate plots, are different with the same fibers, depending on the experimental conditions. The reactivity of both the easily and difficultly hydrolyzable constituents varies with different cellulose fibers. The complex nature of the kinetics of removal (hydrolysis) of the easily accessible components is discussed.
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  • 21
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    Journal of Polymer Science 4 (1949), S. 1-12 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The production of monomer during degradation of polystyrene in vacuo below 310°C. has been investigated. A mechanism has been proposed which explains the dependence of monomer formation on the initial breaks in the chain. The degradation in presence of oxygen has been studied. A mechanism for this reaction has been proposed which accounts for the type of curves obtained experimentally. The role of antioxidants has been briefly indicated. The elementary steps for the degradation in vacuo and in the presence of oxygen have been discussed.
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  • 22
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    Journal of Polymer Science 4 (1949), S. 629-637 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An extension of the kinetic analysis of the generalized reaction mechanism for copolymerization given in Part I has been carried out to obtain the functions for molecular weight distribution and number and weight-average molecular weights.
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  • 23
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    Journal of Polymer Science 4 (1949), S. 638-638 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 24
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    Journal of Polymer Science 4 (1949), S. 665-666 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 25
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    Journal of Polymer Science 4 (1949), S. 639-664 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Samples of polyisobutene, polyisoprene, polybutadiene, GR-S, and polyethylene, weighing about 25 to 50 mg., were pyrolyzed in a vacuum of about 10-6mm. of mercury in a specially designed apparatus at temperatures ranging between 300 to 475°C. The volatile products of pyrolysis were separated into four fractions: (IV) gaseous, volatile at -196°; (IIIA) liquid, at -75°, (IIIB) liquid, at 25°; and (II) waxlike fraction, volatile at the temperature of pyrolysis. The gaseous fraction was analyzed in the mass spectrometer and was found to consist in all cases of CH4. The liquid fraction, IIIA, was analyzed similarly and was found to give a mass spectrum characteristic for any given polymer. A molecular weight determination of the waxlike fraction by the micro freezing point-lowering method, showed it to vary from 543 to 739, depending on the polymer from which the fraction was obtained. It is shown that the method of pyrolytic fractionation of high molecular weight polymers, in conjunction with mass spectrometer analysis of the more volatile fractions, can serve as a means of identifying the polymers.
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  • 26
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    Journal of Polymer Science 4 (1949), S. 669-670 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 27
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    Journal of Polymer Science 4 (1949), S. 667-668 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 28
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    Journal of Polymer Science 4 (1949), S. 671-672 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 29
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    Journal of Polymer Science 4 (1949), S. 673-688 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The significance of the water content to the physical properties of phenol-formaldehyde resins at various stages of preparation is briefly discussed. Available methods for the determination of water in such resins were found to be either unreliable or too elaborate for process control. It was undertaken to develop a simple, rapid, relative method for the continuous measurement of water content which can be used to follow the follow the process of dehydration and to indicate the end-point which will result in the best dispersion of water in the cured resin. In order to standardize or calibrate such a relative method, it was necessary also to develop an absolute method for the analysis of water in the resol.The composition of a homogeneous mixture of liquids is reflected by its vapor pressure-temperature relationships. During dehydration at 80°C., the vapor pressure of the resol decreases about 350 mm. of mercury. A very sharp increase in the slope of the vapor pressure curve occurs at approximately the proper degree of dehydration. At this stage a slight decrease in water content causes a very large decrease in vapor pressure. The sharp inflection in the curve is attributed to the existence of both “free” and “bound” water in the resin.During the process of vacuum dehydration of the resin, while the “free” water decreases to approximately one-eighth of its original content, the “bound” water remains substantially constant. The binding of water is attributed to the methylol groups of the resol molecules and its release during the cure or hardening of the resin is considered to result from the conversion of these groups to methylene linkages.
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  • 30
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    Journal of Polymer Science 4 (1949), S. 152-152 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Polymer Science 4 (1949), S. 183-202 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism presented constitute proposals made in attempts to portray the role that electrophilic halides play in catalyzing the polymerization of unsaturated hydrocarbons. All of these halides require the presence of a Friedel-Crafts catalyst in the reaction mixture and differ primarily in the interpretation of what constitutes the active factor in the initiation, propagation, and cessation steps. Mechanisms involving a thermal activation and dehydrohalogenation are discussed briefly and rejected as rather improbable. On the other hand, mechanisms involving a cationoid complex intermediate and a carbonium ion are extensively reviewed, especially in light of the recent findings of British investigators regarding the function of the so-called third component or cocatalyst. Attention is called to the rather marked specificity of reactions involving water or other polar cocatalysts, and, in addition, it is pointed out that, although cocatalysts appear to be necessary prerequisities for activation in a number of cases, the phenomenon is not a general one, since systems exist in which proton-supplying cocatalysts have not been proved necessary to initiate growth. To date, no single mechanism seems to satisfy all of the qualitative observations and known data. It is intended that the present discussion summarize available facts in terms of possible mechanisms, and, in addition, evaluate their plausibility in the light of present knowledge.
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  • 32
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    Journal of Polymer Science 4 (1949), S. 215-218 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science 4 (1949), S. 221-223 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science 4 (1949), S. 247-263 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The discrepancies in the published work on the interaction of acetone and cellulose nitrate are discussed and explained. Vapor phase adsorption isotherms for the adsorption of acetone by cellulose nitrate have been determined with an adsorption balance. They have been shown to be independent of the crystalline-amorphous ratio of the polymer but dependent upon its nitrogen content. In cellulose nitrates which are completely soluble in acetone, no limiting adsorption has been found. Adsorption analysis (a modification of chromatography) has been applied to the determination of the liquid phase adsorption by cellulose nitrate of acetone from mixtures with petroleum ether. In terms of the liquid mixture concentrations, there appears to be limited adsorption, but this is shown to be due to the nonideal nature of the solutions of acetone and petroleum ether. When allowance is made for this, the liquid and vapor phase isotherms are the same within experimental error and do not support the existence of compounds of acetone and cellulose nitrate.
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  • 35
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    Notes: Some experiments on the polymerization of 2,3-dimethyl-1,3-butadiene and its copolymerization with butadiene are reported. This monomer requires very little modifier as compared to butadiene.
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  • 36
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    Notes: The infrared and ultraviolet absorption spectra of Koresin are very similar to those of an acid-catalyzed p-tert-butylphenol-acetal- dehyde polymer. This is believed to be evidence that Koresin has Structure I. A variety of phenol-aldehyde resins have been prepared for comparison with Koresin. The ratings of some of these materials as tackifiers have been reported. These furnish further evidence that the molecular weight of a phenol-aldehyde resin is important in its tackifying action. An alkaline-catalyzed condensation product of acetylene and p-tert-butylphenol shows no tackifying action and has no free hydroxyl in the polymer as judged by its infrared pattern.
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  • 37
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    Notes: o-Hydroxystyrene did not copolymerize with styrene and butadiene in GR-S-type systems. A terpolymer of these three monomers was obtained by copolymerizing o-acetoxystyrene, styrene and butadiene in carbon tetrachloride solution by the action of stannic chloride followed by hydrolysis of the acetate groups in the polymer with dilute hydrochloric acid in dioxane solution. The polymer thus obtained did not improve the tack of GR-S.
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  • 38
    ISSN: 0022-3832
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    Notes: The paper deals with a tentative plan to extend quantitative x-ray measurements for determining the degree of crystallinity of polymers (as used earlier in cellulose determinations), to the investigation of rubber, polythene, and a polyamide. Strictly monochromatized copper radiation was used. The results show that further work along these lines may be promising. The raw rubber sample used was identical with one of those investigated by Goppel and by Arlman. It yielded a crystallinity figure higher than that reported by Goppel, but conformed with that found by Arlman. The figures obtained for polythene at different temperatures are compared with those derived from density and heat capacity measurements by other workers. The degree of crystallinity of polythene at room temperature is found to be ∼ 55%, and in samples of polyhexamethylene sebacamide, previously treated in different ways, figures between ∼50 and 70% are obtained. It is shown that the possibility of using the background intensity as a measure of the disordered fraction is confined to not too high angles of diffraction. A method is described (and experimentally checked) allowing for reducing the curves of intensity distribution as a function of 2θ as observed in various polymers to a comparable scale. It is further emphasized that, in polymers where hydrogen bonds play a decisive role in intermolecular cohesion, the x-ray results suggest that the “crystalline” or ordered fraction may to a considerable extent involve states of two-dimensional order.
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  • 39
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    Journal of Polymer Science 4 (1949), S. 725-733 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The strong ultraviolet absorption in the wave-length region 280-330 mμ shown by copolymers of acenaphthylene with styrene or methyl methacrylate is due to acenaphthylene residues. The spectra of samples of copolymer containing a small percentage of acenaphthylene are different from the spectrum of polyacenaphthylene. As a result of the comparison of the spectra of these copolymers with the spectra of acenaphthene and with the two forms of 1,1′-biacenaphthyl it is concluded that spectra of the copolymers can be explained as arising from the presence of pairs of acenaphthylene groups. Finally it is shown that the spectra can be used to estimate the acenaphthylene contents of the copolymers.
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  • 40
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  • 41
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    Notes: Bis-isopropyl xanthogen (“dixie”) is a poor promoter, but an effective modifier, in the GR-S recipe, as was concluded from unreported intrinsic viscosity measurements. High molecular mercaptans are good promoters but very poor modifiers. In recipes containing mercaptans as promoters, dixie acts like a retarder until a conversion of 30% is attained. After this conversion the rate becomes normal. It is found that at a conversion of 30% most of the dixie has been dissipated. Bis-isopropyl xanthogen can be determined polarographically. A procedure is given for the polarographic determination of dixie and the determination by amperometric titration of mercaptan when both dixie and mercaptan are present in a GR-S latex. Disappearance curves of dixie and of mercaptans are given when both modifiers are present in the original charge.
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    Journal of Polymer Science 4 (1949), S. 749-749 
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    Journal of Polymer Science 4 (1949), S. 773-774 
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    Journal of Polymer Science 4 (1949), S. 775-775 
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  • 45
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    Notes: Quantum yields for the inactivation of crystalline swine pepsin have been determined as a function of pH at 2537 A. The quantum yield is near a minimum at pH 4.08, at which point a value of 0.0019 was found, rises rapidly above pH 6, and shows a slight maximum near pH 2.7. The maximum is more pronounced with polychromatic light. The quantum yield (at pH 2.01) was found to be the same with either hemoglobin or casein as a substrate. Urea had no effect on the quantum yield although urea alone, 7 M, inactivates pepsin at an appreciable rate. Urea and light denaturation do not modify the absorption spectrum of pepsin in the same way. The data of Gates has been recalculated; it shows an increase of quantum yields with decreasing wave length. It has been concluded, from experiments with model substances, that inactivation can occur by the absorption of a quantum by any aromatic group in pepsin.
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    Journal of Polymer Science 4 (1949), S. 75-82 
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    Notes: Photochemical reactions of trimeric and tetrameric phosphonitrilic chlorides with some hydrocarbons are described. Soluble and insoluble photoreaction products are formed. From the soluble fraction, distillable phenyl- and decahydronaphthyl-phosphonitrilic chlorides were separated; the indistillable and deposit fractions were also found to contain high percentages of carbon and hydrogen. This shows that successive substitution of the chlorine atoms by radicals, R, of the solvents, R—H, had taken place.
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    Journal of Polymer Science 4 (1949), S. 93-96 
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    Journal of Polymer Science 4 (1949), S. 96-96 
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  • 49
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    Notes: The conductance of a series of salts made by the addition of n-butyl bromide to 4-vinylpyridine-styrene copolymers (1.5 to 90 mole per cent vinylpyridine) has been measured in dioxane (∊′ = 2.2), ethylene dichloride (∊′ = 10.2), and a series of nitromethane-dioxane mixtures (16.0 ≤ ∊′ ≤ 39.4). Three independent arguments deduced from the data show that ionic association under the influence of interionic electrostatic forces must occur in solutions of polyelectrolytes in such a way that a certain average fraction of the counter ions accompany the large polycation and contribute nothing to conductance. First, the conductance at fixed copolymer composition and fixed salt concentration decreases with decreasing dielectric constant of the solvent medium. Second, at a given counter ion concentration in a given solvent, the conductance decreases with increasing pyridonium content of the chain. Third, for a given salt and solvent, the conductance decreases with increasing salt concentration at a rate much slower than that characteristic of simple electrolytes.
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    Notes: A series of copolymers, of 4-vinylpyridine and styrene, covering the range 1.5 to 100% vinylpyridine were prepared in 20% toluene solution at 80°. Strong electrolytes were then made by the addition of n-butyl bromide in nitromethane solution. The salts with high vinylpyridine content were soluble in water, alcohols, nitromethane, and other polar solvents. Viscosities of the parent copolymers in methyl ethyl ketone were in the range 0.15-0.20; osmotic pressures gave molecular weights in the range 50,000-80,000. The polyelectrolytes in nitromethane and nitromethane-dioxane mixtures gave viscosity-concentration curves which were strongly concave upwards: at 1 mg./100 cc., the reduced viscosity of the salt of polyvinylpyridine in nitromethane was 6.0. The salts of the different copolymers did not differ much in their viscosities at concentrations above a few tenths of a gram per 100 cc., a fact which shows a high degree of ionic association; only as zero concentration is approached, can the detailed polymer structure be seen. The extent of association at a given concentration is controlled by the amount of vinylpyridine in the copolymer and by the dielectric constant of the solvent. Addition of simple one-one electrolytes, such as tetrabuty lammonium bromide, suppresses the electrostatic increase in viscosity which otherwise appears at low concentrations. The following empirical equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ {{\eta _{{\rm sp}} } \mathord{\left/ {\vphantom {{\eta _{{\rm sp}} } {\rm C}}} \right. \kern-\nulldelimiterspace} {\rm C}} = {{\rm A} \mathord{\left/ {\vphantom {{\rm A} {\left( {1 + {\rm B}\sqrt {\rm C} } \right)}}} \right. \kern-\nulldelimiterspace} {\left( {1 + {\rm B}\sqrt {\rm C} } \right)}} + {\rm D} $$\end{document} was found to fit the data for the different systems studied. The constant A depends on copolymerization ratio and probably on molecular weight; it is a measure of the extent to which the polymer coil can spread out at infinite dilution as a consequence of the intramolecular Coulomb repulsion between charges attached to the chain. It is roughly several orders of magnitude larger than the intrinsic viscosity of the parent polymer. The constant B is a measure of the electrostatic forces and increases with decreasing dielectric constant of the solvent.
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    Journal of Polymer Science 4 (1949), S. 153-182 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The approximations implicit in the use of the Gaussian network model for soft rubber are discussed. It is shown that the form of the stress-strain curve can be derived for this model simply, and without special assumptions about the form or behavior of the network. The common assumption that the network junctions are fixed, or can be treated as fixed, is discussed. It is shown that this picture of the situation is unrealistic: the junctions have a Brownian motion comparable to that of any portion of the intervening molecular segments. The introduction of this assumption is not generally admissible, but it will not affect the outcome of certain types of calculation; in particular, one can foresee that it need not affect the calculated form of the stress-strain curve. A particularly simple and straightforward calculation of the network entropy on this basis is given. Wall's the ory of rubber is analysed. It is shown that Wall's postulates are not consistent with the network structure of rubber, and in general lead to different results.
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    Journal of Polymer Science 4 (1949), S. 219-220 
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    Journal of Polymer Science 4 (1949), S. 224-224 
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    Notes: Various mechanisms which have been proposed for the reaction between ferrous iron and hydrogen peroxide are reviewed. Two of these mechanisms appear equally satisfactory on the basis of present evidence: that of Bray and Gorin, involving formation of tetravalent (ferryl) iron, and that of Haber and Weiss, involving formation ofhydroxyl and perhydroxyl radicals. Mechanisms involving these intermediates have been developed for the ferric iron-catalyzed decomposition of hydrogen peroxide; the mechanism of Bray and Gorin appears satisfactory, while that of Haber and Weiss leads to certain inconsistencies. A mechanism with ferrous iron and hydroxyl and perhydroxyl radicals as intermediates is presented, which accounts for the experimental observations in the ferric iron-catalyzed decomposition of hydrogen peroxide. The reaction between hydrogen peroxide and ferrous iron induces the reaction between hydrogen peroxide and various organic compounds; this induced reaction (termed a Fenton reaction) is a chain reaction which is initiated by the active intermediates (ferryl iron or hydroxyl radical) formed in the primary reaction. The determination of hydrogen peroxide by reaction with ferrous iron, if carried out in the presence of various organic compounds (termed promoters), gives incorrect results, due to induced oxidation of the promoters; other compounds, termed suppressors, reduce the extent of this induced oxidation of promoters. It appears that both types of compounds react with ferryl iron or hydroxyl radical to form radicals, which if formed from promoters, reduce ferric iron or hydrogen peroxide, while the radicals formed from suppressors oxidize ferrous iron. These considerations are of particular importance in the determination of organic hydroperoxides. The reaction between hydrogen peroxide or organic peroxides and ferrous iron can induce, or initiate, the polymerization of vinyl monomers; this is an example of redox polymerization, which is of considerable practical importance at present.
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    Journal of Polymer Science 4 (1949), S. 404-404 
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    Journal of Polymer Science 4 (1949), S. 405-407 
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    Journal of Polymer Science 4 (1949), S. 408-408 
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    Journal of Polymer Science 4 (1949), S. 408-408 
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    Journal of Polymer Science 4 (1949), S. 409-410 
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    Journal of Polymer Science 4 (1949), S. 411-412 
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    Journal of Polymer Science 4 (1949), S. 415-416 
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    Journal of Polymer Science 4 (1949), S. 417-434 
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    Notes: During recent years attempts have been made to formulate a viscosity-concentration relationship. The method of Huggins, in introducing a factor k′ as a hydrodynamic correction factor is examined, and in particular the attempts to draw conclusions relating k′ to the thermodynamic properties of the solution. An explanation is offered to correlate the experimental viscosity-concentration relationship and the change of solvent. A possible method for the actual calculation of concentration effects has been applied to the case of a suspension of spherical particles, for which, as a first approximation, a value of 10.6 for the coefficient of the c2 term has been obtained.
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    Journal of Polymer Science 4 (1949), S. 483-513 
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    Journal of Polymer Science 4 (1949), S. 515-522 
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    Notes: The effect of increasing and decreasing temperature on the light transmission of polythene has been measured. On raising the temperature of a sheet of polymer the light transmitted increases steadily at an increasing rate until the sample becomes glass clear at the melting point (ca. 112°C.). On cooling from the melt the specimen becomes very opaque a few degrees below the melting point, then becomes much more transparent and thereafter the light transmission decreases as temperature falls, the transmission-temperature curve approximating to the curve for rising temperature. Changes in the spherulite structure of polythene film on heating and cooling have been observed under the microscope and recorded on a cinéfilm. Decay of spherulites on heating is seen not to occur by the reverse of the process by which they are formed from the melt, and the light transmission results are discussed in relation to the spherulitic structure of the polymer.
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    Journal of Polymer Science 4 (1949), S. 527-529 
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    Journal of Polymer Science 4 (1949), S. 531-532 
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    Journal of Polymer Science 4 (1949), S. 533-537 
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    Journal of Polymer Science 4 (1949), S. 538-538 
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    Journal of Polymer Science 4 (1949), S. 539-541 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science 4 (1949), S. 542-542 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science 4 (1949), S. 543-544 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science 4 (1949), S. 545-554 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Legumin of green peas and horse beans was dissolved in solutions of several salts and the viscosity and reducing capability of these solutions was determined. The amounts of iodine required for titration (reducing capability) are dependent on the pH of the solution and on the temperature; between pH 5.0 to 5.8 and +5° to +25° the titration values are almost constant. By comparing several neutral salts it was found that in the cases of sodium chloride, potassium bromide, potassium iodide, calcium chloride and magnesium nitrate the reducing capability and intrinsic viscosity of legumin both are low; however, in the case of potassium thiocyanate both values are high. No denaturation takes place in solutions containing 2-30% ethyl- or propylic alcohol and calcium chloride or like salts. Sodium salicylate causes denaturation; the intrinsic viscosity and reducing capability of legumin in these solutions is high. Sodium dodecylbenzene sulfonate has a strong peptizing action on legumin and denaturates it. After a mild deamination of legumin with nitrous acid only slight differences in viscosity and reducing capability could be observed. The solutions containing much propylic alcohol and salt grew in time more and more viscous, if the concentration of legumin was high, but remained of the same viscosity when the concentration of legumin was low. It was concluded that in these cases the high viscosity of legumin is due not to unfolding of the compact coils of native legumin, but to the interaction of the particles with the molecules of the solvent and to subsequent structuration. Loosening and transformation in more elongated particles may be assumed in the cases with thiocyanate, salicylate, and the detergent.
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  • 75
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The variables of casting polystyrene films from methyl ethyl ketone and from benzene are investigated. It is shown that stringent drying is necessary to remove the last traces of solvent. The differences in dry film structure, second-order transition point, and temperature at which the dynamic modulus suddenly decreases are discussed.
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    Journal of Polymer Science 4 (1949), S. 13-36 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An apparatus has been constructed which enables one to follow continuously the formation of monomer during degradation in vacuum. Experimental results are presented on the degradation of fractionated and unfractionated polystyrene over a range of temperatures from 340-400°C. in vacuum. A mechanism has been proposed which accounts satisfactorily for the apparent zero-order reaction and for the dependence of the rate of degradation on chain length. This mechanism allows one to estimate relative number average molecular weights and the number of weak points per original chain. The influence of a platinum surface on degradation has been indicated. The degradation of poly-alpha-methylstyrene has been investigated over a range of temperatures from 281 to 363°C. in vacuum. The mechanism of the degradation of branched polymer chains has been discussed. The degradation of cross-linked polystyrene containing various amount of m-divinylbenzene has been studied at 364°C. in vacuum. The reaction shows long induction periods depending on the amount of m-divinylbenzene and on the presence of benzoyl peroxide during polymerization. The degradation of polyethylene shows this polymer to be more heat resistant than polystyrene. Various grades of different average molecular weight have been investigated over a range of temperatures from 375 to 436°C. in vacuum. The energy of activation has been found dependent on chain length. A mechanism has been suggested to account for the observed experimental results.
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  • 77
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Measurement of the infrared absorption spectrum of the lowmolecular liquid polymer formed at room temperature from gaseous isobutene using BF3 as a catalyst and D2O as a cocatalyst indicates that the dominant end groups in the final polymer are (CH3)3C and , and that the cocatalyst D2O undergoes partial conversation to H2O during reaction. These results substantiate the mechanism advanced by Polanyi and others, namely: (a) initiation through formation of the trimethyl carbonium ion by acceptance by isobutene of a proton (or deuteron) from the catalyst-cocatalyst complex, and (b) termination by explusion of a proton from a methyl group to the anionic complex fragment, with corresponding catalyst regeneration, i.e.:
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    Journal of Polymer Science 4 (1949), S. 63-74 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A relationship between tack temperature and molecular weight has been deduced and illustrated with polyvinyl acetate polymers. Provided the molecular weight is high enough to prevent cohesive failure, the adhesion of polyvinyl acetate to cellulose and aluminum is independent of molecular weight. The influence of humidity on adhesion of polymers to cellulose is shown. The influence of polymer composition on adhesion is illustrated with copolymers of vinyl acetate and methyl vinyl ketone and with styrene and methyl vinyl ketone. Above a mole fraction of ketone of 0.8, adhesion increases rapidly. The interdependence of tack temperature and composition on adhesion is exemplified with ethylene - vinyl chloride copolymers. A temperature dependence of adhesion is cited for copolymers containing maleic acid.
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    Journal of Polymer Science 4 (1949), S. 83-86 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A number of equations are suggested for estimating intrinsic viscosity from one measurement of relative viscosity at a convenient concentration. Experimental data illustrate the validity of the equations.
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    Journal of Polymer Science 4 (1949), S. 91-91 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science 4 (1949), S. 87-90 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Guaran triacetate, a linear molecule having one-unit branches, can be cast into clear, colorless films having a tensile strength of 7.5kg./mm.2 and an elongation at break of 4%. Thus, it appears that one-unit branches of the size of the glycosidic unit do not adversely affect the film-formingproperties of polysaccharide acetates. Plasticized films show more elasticity and greater elongation at break.
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    Journal of Polymer Science 4 (1949), S. 135-144 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The method for the evaluation of the percentage crystallinity in cellulose preparations from x-ray intensity measurements, previously described in detail (J. Appl. Phys., in press) is reviewed briefly and new material presented consisting of crystallinity percentages between 8% and 70%. Cotton, flax, and ramie possess equal crystallinity (70%) and so do the majority of rayons, independent of their degree of orientation and including cuprammonium and Lilienfeld rayons. Cellulose acetates saponified under varying conditions also yield almost the same value as rayon (40%). The New product Fiber G (du Pont) holds an exceptional position with 53% crystalline substance. In the series of native celluloses, wood pulp has about 65%, Valonia 65-70%, and bacterial cellulose about 40%. By dry grinding of rayon, a powder was obtained containing only slightly less than 10% crystalline substance, which on recrystallization in water, yields 2 product having the same crystallinity as rayon. The difference between the heats of wetting of the criginal and the recrystallized powder affords additional support of the results obtained.
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    Journal of Polymer Science 4 (1949), S. 145-151 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray measurements on 16 different specimens of regenerated cellulose reveals that there exists a pronounced negative correlation between the integrated intensity of the 101 interference and its halfwidth. The 101 plane is a preferred cleavage plane and represents the lamellar plane of the ribbon-shaped crystallites. Variations in the intensity of the other interferences are much less or nonexistent. These results show that the degree and the perfection of lateral order according to the 101 and 002 planes is little at variance, but that order according to the 101 plane is extremely variable in such a way that if the average thickness and (or) perfection of the lamellae increases, the total number of well-ordered 101 plane contacts diminishes. As a possible explanation of this phenomenon it is suggested that various degrees of recrystallization with reference to this particular plane (i.e., various degrees of lateral order) may be associated with the various rayon specimens. This, however, does not necessarily imply differences in the total amount of ordered substance. This explanation is corroborated by the fact that cellulose acetate fibers which were previously allowed to “recrystallize” by heating in methanol, after saponification yield a rayon with a particularly sharp, but also particularly weak, 101 interference, without exhibiting a higher total percentage of ordered substance than the saponification products of acetate treated in this manner.
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    Journal of Polymer Science 4 (1949), S. 747-748 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science 4 (1949), S. 751-754 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: During a definite polymerization time the rate of uncatalyzed polymerization of styrene may be decreased by the use of activated carbon. The intrinsic viscosities of the polymers formed may be either increased or decreased by the addition of active carbon, depending upon the activity of the carbon sample used.
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    Journal of Polymer Science 4 (1949), S. 755-757 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science 4 (1949), S. 759-761 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
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    Journal of Polymer Science 4 (1949), S. 763-765 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Polymer Science 4 (1949), S. 767-768 
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    Journal of Polymer Science 4 (1949), S. 770-770 
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    Journal of Polymer Science 4 (1949), S. 771-771 
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  • 93
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    Die Makromolekulare Chemie 3 (1949), S. 140-145 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
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    Die Makromolekulare Chemie 3 (1949), S. 146-163 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Die Polystyrole unterscheiden sich von anderen Vinylpolymeren dadurch, daß sie in guten Lösungsmitteln dem Staudingerschen Viskositätsgesetz gehorchen, wobei allerdings der Wert der Km -Konstante von den bei der Polymerisation vorliegenden Bedingungen abhängt. Die hierfür geltenden Beziehungen werden an Hand eines umfangreichen, aus zahlreichen Arbeiten entnommenen Materials geklärt.In schlechten Lösungsmitteln verhalten sich Polystyrole genau so wie andere Vinylpolymere (etwa zahlenmäßig übereinstimmend mit den Polyisobutylenen). Es gilt dann für sie die Gleichung von W. Kuhn.Zur Deutung der verschiedenen Km -Wurde bisher eine Verzweigung der Kettenmoleküle angenommen. Anknüpfend an Überlegungen von W. Kern und M. L. Huggins wird eine andere Deutung vorgeschlagen, die darauf beruht, daß jedes Monomere in einer 1- oder einer d-Form addiert werden kann. Bei tiefer Temperatur entstehen Kettenmoleküle mit alternierenden 1- und d-Bindungen, welche in guten Lösungsmitteln ziemlich steif und daher nur schwach geknäult sind. Bei höheren Temperaturen entstehen d-d- (bzw. 1-1-)Gruppierungen, die zu scharfen und starren Winkelungen der Kettenmoleküle Anlaß geben und dadurch die Km -Konstante herabsetzen. - Bei peroxydischer Polymerisation treten außerdem Verzweigungen auf.
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    Die Makromolekulare Chemie 3 (1949), S. 164-175 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Durch Aufstellung der Verteilungskurve wurde festgestellt, daß die Zellstoffnitrate aus zwei Komponenten zusammengesetzt sind, während das polymerhomologe Gemisch der Baumwollcellulosenitrate aus einer einheitlichen Cellulose resultiert. Da die Nitrate durch polymeranaloge Umsetzung erhalten wurden, sind die Verteilungsfunktionen auch für die Ausgangscellulosen gültig. Es ergibt sich, daß die für Baumwollcellulose gültige Km -Konstante nicht für Zellstoffe angewandt werden kann.
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    Die Makromolekulare Chemie 3 (1949), S. 223-246 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2-Chlorbutadien-1,3 (Chloropren) bildet schon bei niedrigen Temperaturen mit molekularem Sauerstoff ein Peroxyd. Die Bildungsgeschwindigkeit dieses Peroxyds ist so groß, daß es schwierig ist, peroxydfreies Chloropren herzustellen. Dies gelingt durch sorgfältige Destillation unter reinstem Stickstoff.Die Versuche zur Isolierung des Chloroprenperoxyds ergaben wegen seiner leichten Zersetzlichkeit keine befriedigenden Ergebnisse. Die quantitative Bestimmung des Peroxyds in Chloropren gelingt nach den üblichen Methoden nicht oder nur sehr schwierig. Chloroprenperoxyd oxydiert Antioxydantien, wie z. B. Phenyl-β-naphthylamin, zu gefärbten Produkten. Da Phenyl-β-naphthylamin die weitere Autoxydation des Chloroprens unterbindet, kann auf dieser Grundlage eine photometrische Bestimmung des Peroxyds durchgeführt werden.Die Geschwindigkeit der Sauerstoffaufnahme von Chloropren bei 0°C wurde volumetrisch gemessen. Die Sauerstoffaufnahme ist ein autokatalytischer, gleichförmig beschleunigter Vorgang. Er wird von Tetralinperoxyd stark beschleunigt, nicht aber von Benzoylperoxyde. Es wurden andere katalytisch wirkende Stoffe und der Einfluß des Lichtes untersucht.Da Chloroprenperoxyd die Polymerisation des Chloroprens auslöst und stark beschleunigt, ist es zweckmäßig, für die Stabilisierung dieser ungesättigten Verbindung solche Stoffe anzuwenden, die nicht nur die Polymerisation, sondern auch die Autoxydation hemmen. Die stabilisierende Wirkung der Antioxydantien wird bei Anwesenheit von Chloroprenperoxyd und Chlorwasserstoff nach einer Induktionsperiode durchbrochen. Dies kann dadurch erklärt werden, daß Phenyl-β-naphthylamin im Falle des Chloroprenperoxyds durch Oxydation, im Falle des Chlorwasserstoffs als Salz unwirksam gemacht wird.
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    Die Makromolekulare Chemie 3 (1949), S. 251-280 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Es wird der Einfluß von Seitenketten auf die Höhe der Viskositätszahl Zη von niedermolekularen Estern untersucht. Bei Dicetylmalonestern und Dicetylessigestern hat die Länge der Estergruppe keinen Einfluß auf die Höhe der Viskositätszahl. Bei substituierten Malonsäuredicetylestern resp. Disterylestern ändert sich dagegen die Viskositätszahl mit der Länge der in die CH2-Gruppe substituierten Alkylreste, und zwar ist sie bei kurzkettigen Substituenten kleiner, bei langgliedrigen größer als bei den unsubstituierten Verbindungen gleicher Kettenlänge. Das gleiche Verhalten zeigen β-alkylsubstituierte Stearinsäureester. Es wird weiter versucht, inwieweit das Einsteinsche Viskositätsgesetz in veränderter Fassung zur Klärung dieses Viskositätsverhaltens herangezogen werden kann.
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    Die Makromolekulare Chemie 3 (1949), S. 281-285 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Es wird ein einfaches Verfahren angegeben, den Transport von Wasser durch Textilfaserschichten zu messen, die einerseits in Wasser tauchen und andererseits an Luft mittlerer relativer Feuchtigkeit grenzen. Proteinfasern transportieren das Wasser langsam, Baumwolle rascher und Viskosekunstfasern sehr rasch.
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    Die Makromolekulare Chemie 4 (1949), S. 5-14 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Since the isolation of pectins by the usual technical processes is inevitably bound up with some splitting up the most preserving conditions were ascertained, by which it is possible, to extract sufficient pectin from the pulp of apples. By picking fruits of the most favourable time of fructescence, by eliminating all encymatic activity, by observing the lowest temperatures for extraction and choosing a suitable pH a pectin was obtained, that had undergone scarcely any splitting process. The percentage of methoxyl in that pectin was very nearly the same as that calculated for a completely esterifieated polygalakturonic acid. The molekular weight was determined by measuring the viscosity on a nitrate of that pectin. Here a nitration process was used, that was more preserving than that formerly applied. The values obtained were higher than those obtained so far. The „free pectin“ in apple - juice was found to have a lower molecular weight.
    Notes: Da nach den üblichen technischen Verfahren die Isolierung von Pektinen unvermeidlich mit einem gewissen Abbau verbunden ist, wurden die schonendsten Bedingungen festgestellt, unter denen es noch möglich ist, Pektin aus dem Fruchtfleisch von Äpfeln in ausreichender Menge zu gewinnen. Durch Wahl des günstigsten Reifezustandes, Ausschaltung einer Enzymtätigkeit, Einhaltung möglichst neidriger Extraktionstemperaturen und eines geeigneten pH konnte ein wenig abgebautes Pektin crhalten werden, dessen Methoxylgehalt dem für eine vollständig veresterte Polygalakturonsäure berechneten sehr nahe kommt. Die Molekulargröße wurde viskosimetrisch an einem aus diesem Material gewonnenen Pektinnitrat bestimmt, das nach einer schonenderen Nitrierungsmethode als der bisher üblichen hergestellt war. Die erhaltenen Werte liegen über den bisher beobachteten. Das im Apfelsaft vorhandene „freie Pektin“ wurde als niedriger molekular befunden.
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    Die Makromolekulare Chemie 4 (1949), S. 15-40 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Es wurde die Polymerisationsgeschwindigkeit des Vinylchlorids bei 50° unter Zusatz verschiedener Mengen Benzoylperoxyd als Katalysator untersucht, indem der Umsatz das Molekulargewicht und die Zeitdauer beginnender Trübung durch Ausfallen des Polymerisats bestimmt wurde.Der Umsatz steigt zunächst langsam, dann schneller mit der Zeit an; über 80 - 90% nimmt er nur noch sehr langsam zu, so daß die letzten 1 - 2% praktisch nicht mehr polymerisieren. Mit sinkender Katalysatorkonzentration wird die Reaktion langsamer, derart, daß sich die Umsatzzeitkurven durch Dehnung der Zeitachse proportional der Wurzel aus der ursprünglichen Katalysatorkonzentration zur Deckung bringen lassen. Bis zu 70 - 80% läßt sich der Umsatz durch die Gl. u = (eat  -  1)b gut darstellen, wobei b = 0,1 und a = 0,240 · √c20 zu setzen ist.  -  Gegen Ende der Reaktion ließ sich im restlichen Monomeren Salzsäure nachweisen.Das Molekulargewicht nimmt mit steigender Menge Benzoylperoxyd und Sauerstoff deutlich ab; bei mäßigen Peroxydkonzentrationen wird dieser Effekt in der Streuung der Versuchswerte nicht sichtbar.  -  Die Zeit bis zur beginnenden Trübung ändert sich umgekehrt proportional der Wurzel aus der Katalysatorkonzentration und ist ferner unter reinem Sauerstoff größer, unter Stickstoff kleiner als unter Luft.Der Katalysator verschwindet während der Polymerisation, und zwar in um so stärkerem Maße, je höher seine ursprüngliche Konzentration, und um so weniger, je größer die Menge an Sauerstoff ist.  -  Mit Kaliumpersulfat erfolgt die Polymerisation nur in der wäßrigen Phase.Mit den Beobachtungen im Einklang steht das folgende Reaktionsschema (B = Benzoylperoxyd, M = monomeres Vinylchlorid). Die Hemmung der Polymerisation durch eine Anzahl von dritten Stoffen wurde orientierend, etwas eingehender die durch Styrol untersucht. Schwache Reduktionsmittel, Vinylderivate und einige anorganische Stoffe hemmen die Polymerisation, während chemisch indifferente Stoff sie nicht beeinflussen. Die Hemmung beruht vermutlich auf vorzeitigem Kettenabbruch.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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