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  • 1980-1984  (6,093)
  • 1984  (3,071)
  • 1983  (3,022)
  • Polymer and Materials Science  (6,093)
  • Nuclear reactions
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  • 1980-1984  (6,093)
Year
  • 101
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2157-2172 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of organic solvents on the 31P-mr chemical shifts of various phosphate diesters have been investigated in water and mixed-organic solvent systems. The addition of organic solvents to cyclic phosphates and to diethyl phosphate causes large upfield shifts of the phosphorus resonance which are attributed to solvent-induced changes in the local hydration of the phosphodiester group. This is consistent with the fact that there is an inverse correlation between the hydrogen-bond-donating ability of the solvents and the magnitude of the shifts they induce. Other possible interpretations, such as solvent-induced ion pairing and solvent-induced conformational changes, appear to be eliminated. Fourier-transform ir study of the cyclic nucletides reveals that there are also large solvent-induced shifts in the frequency of the antisymmetric OPO stretching frequency, and a comparison of the two types of measurements indicates that there is a linear correlation between shifts observed in the ir and in the 31P-nmr spectra. With UpU, the solvent-induced 31P-nmr shifts are ∼3 times smaller than those observed with the cyclic phosphates and the solvent-induced shift of the OPO band is reduced (factor of ∼1.7) as compared with the cyclic phosphates. With the single-stranded polynuclotides, poly(C) and poly(U), the solvent-induced shifts in both the nmr and ir are quite small (∼0.1 ppm and ∼1 cm-1). The very small solvent effects observed with poly(U) and poly(C) are attributed to a combination of steric effects and a polyelectrolyte effect which maintains a high density of counterions with waters of hydration in the vicinity of the charged backbone and makes the phosphates much less susceptible to solvent-induced changes in hydration.
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  • 102
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2325-2334 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A systematic survey has been made, using molecular mechanics, of the conformation of the ring entity of the enkephalin analogs, [D-Cys2-L-Cys5]-enkephalinamide and [D-Cys2-D-Cys5]enkephalinamide. These molecules are considerably more flexible than the analog Tyr-cyclo(Nγ-D-A2bu-Gly-Phe-Leu-), but the favored conformations of all three are very similar. The results of these studies are compatible with a Gly3-Phe4 type II′ bend in the active conformation of enkephalin.
    Additional Material: 2 Ill.
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  • 103
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Energy pathways between the αR, β′, C7eq, and β-regions of the conformational energy surface of N-acetyl-N′-methylalanyl amide were obtained by SCF ab initio calculations on the 4-21G level, with gradient geometry optimization at each point. The calculations indicate that no barrier exists at this computational level between αR and β′. The variation of geometry (bond distances and bond angles) with conformation is analyzed in detail, and the most important geometrical parameters that should be treated as variables in both empirical energy calculations and in the fitting of polypeptide chains in proteins by x-ray methods are identified. In addition to the φ,ψ correlation discussed previously for the helical state, a correlation of these dihedral angles in the β-region is described.
    Additional Material: 6 Ill.
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  • 104
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Melting parameters of 2U:1A complexes formed by polyuridylic acid [poly(U)] and three adenine dinucleotides, diribonucleoside monophosphonate ApA and diastereoisomers of dideoxyribonucleoside methyl phosphonate [(dApA)1 and (dApA)2], in 1M NaCl and at a number of dinucleotide concentrations were obtained from differential scanning microcalorimetric data and interpreted in terms of the theory of helix-coil equilibrium in oligonucleotide-polynucleotide systems. The apparent binding constant, 1/cm, at 39°C and melting temperatures, Tm, at 1 × 10-3 M dinucleotide concentration indicate the following order of thermodynamic stability of the complexes: 2 poly(U) · (dApA)2 (2.27 × 103M-1, 44.2°C) 〉 2 poly(U) · (dApA)1 (9.9 × 102M1, 39.2°C) 〉 2 poly(U) · (ApA) (5.9 × 102M-1, 35.8°C). Corresponding calorimetric enthalpies of melting, ΔHm: 13.5, 12.7, and 12.8 kcal/mol (UUA base triplets) were found to be considerably lower than the van't Hoff enthalpies, ΔHapp: 29.4, 16.2, and 16.2 kcal/mol, respectively, evaluated from the dependence of the melting temperatures on dinucleotide concentration. Self-association of dinucleotides and their simultaneous binding as monomers, dimers, and higher-order associated species is suggested as the most probable cause of the differences between ΔHm and ΔHapp values. The differences in thermodynamic properties of the complexes formed by (dApA)1 and (dApA)2 diastereoisomers are discussed in connection with their known conformational properties. The higher and essentially enthalpic stability of the 2 poly(U) · (dApA)2 complex correlates with a lower degree of intramolecular stacking of the (dApA)2 isomer. The hydrophobically enhanced strong self-association of the latter greatly influences the thermodynamics of its complex formation with poly(U) and results in ΔHapp/ΔHm = 2.3.
    Additional Material: 7 Ill.
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  • 105
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    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2743-2759 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The static accessibility discrete charge algorithm for protein charge interactions is extended to the case of linear polyelectrolytes. In this model, the effective dielectric value between surface charge sites depends predominantly on the solvent ionic strength and the solvent accessibilities of the charge sites. This treatment accounts for the phenomena of specific ion binding in the context of a general electrostatic effect [Matthew and Richards (1982) Biochemistry 21, 4989]. Specific ion sites are determined by locating areas of high electrostatic potential at the solvent interface of the macromolecule. At a given ionic strength the calculated potential at a site is taken to describe a binding constant and therefore the ion site occupancy. For a 20-base-pair fragment of B-DNA, net charge of -40, 16 ion sites are indicated in the minor groove. The partial occupancy of each site increases from 0.2 to 0.5 as the ionic strength is increased from 0.01 to 0.50. Over the same range of ionic strength, the electrostatic free energy of this charge array is calculated to change from +0.6 to -0.05 kcal/bp. Parallel behavior is predicted for A- and Z-DNA charge geometries. The most stable configuration, based on electrostatic criteria, at high ionic strength (I = 0.1-0.5) is that of Z-DNA. In this range, the ratio of “bound” sodium to phosphate is predicted to be less than 0.4.
    Additional Material: 7 Ill.
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  • 106
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    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2781-2799 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energy computations were carried out on the packing of two identical collagenlike poly(tripeptide) triple helices in order to determine the energetics of favorable packing arrangements as a function of composition and chain length. The triple helices considered were [CH3CO-(Gly-Pro-Pro)nt-NHCH3]3 and [CH3CO-(Gly-Pro-Ala)nt-NHCH3]3, with nt = 3, 4, and 5. The packing arrangements were characterized in terms of their intermolecular energies and orientation angles Ω0 of the axes of the two triple helices. For short triple helices (nt = 3 or 4), many low-energy orientations, with a wide range of values of Ω0, can occur. When the triple helices are longer (nt = 5), the only low-energy packing arrangements of two poly(Gly-Pro-Pro) triple helices are those with a nearly parallel orientation of the two helix axes, with Ω0 ≈ -10°. This result accounts for the observed parallel (rather than antiparallel) arrangement of collagen molecules in microfibril assembly and stands in contrast to the preferred antiparallel arrangement of a pair of α-helices. Since the preference for a parallel arrangement of these collagenlike triple helices is less pronounced in the case of poly(Gly-Pro-Ala), it appears that this preference is a consequence of the frequent presence of imino acids in position Y of the Gly-X-Y repeating triplet. In poly(Gly-Pro-Ala), most of the low-energy packing arrangements are parallel, but a few arrangements with low energies and high values of |Ω0| occur. These packing arrangements have a high energy, however, when Pro is substituted for Ala, and thus they are not accessible for collagen with natural amino (imino) acid sequences. The computations reported here account for some of the characteristic features of collagen packing in terms of the local interaction energies of a pair of triple helices.
    Additional Material: 7 Ill.
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  • 107
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    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2891-2899 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman modes from amorphous α-helical poly(L-alanine) in the low-frequency region 〈 150 cm-1 have been observed and assignments and values compared with mode-analysis calculations. The temperature dependence of the complete Raman spectrum of α-poly(L-Ala) is also reported.
    Additional Material: 8 Ill.
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  • 108
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 601-605 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ends of rather short double-helical DNA segments (approximately two persistence lengths) can be enzymatically joined to form closed circles. Such covalent closure into circles is a measure of the likelihood of the two ends of the DNA coming into close contact. There is a length of DNA for which loop formation is most likely to occur. We have determined the chain-length dependence of loop formation for stiff chains using computer-generated chains of cylinders. The distribution from which the values for the angles between cylinders were chosen relates the chain parameters to a given chain persistence. Our results are compared with those of other theories, including a statistical wormlike chain model, and with the experimental measurements for ring closure of DNA restriction fragments.
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  • 109
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    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    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
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  • 110
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    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 629-645 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of salt on the intercalation of acridine dyes and DNA is rather well explained by the Gouy-Chapman double-layer theory as applied to a cylinder model of the DNA-dye complex. The free energy of transfer of a dye ion from the bulk solution to the complex is divided into several parts, one of which, ΔF0, accounts for the short-range, nonelectrostatic interactions. The assumption that ΔF0 should not depend on the amount of dye in the complex leads to an internal dielectric constant of the cylinder of about Di = 7. The scatter in ΔF0 values, as calculated from individual experimental points, is of order 0.5 kT per dye ion. This scatter is large enough to mask possible effects of heterogeneity in DNA sequences. The calculations are made for a long cylinder with radius 10 Å, with the DNA phosphate charges smeared uniformly at the surface, a uniform spacing of dye charges at the cylinder axis, and a length of b = 3.37 Å per base pair. Each intercalated dye ion also adds a length b to the total length of the cylinder. The salt-dependent part of the electric free energy of intercalation, ΔF1, is tabulated for complexes with r = 0-0.24 dye ions per DNA phosphate in 0.002-0.2M monovalent salt and dye solutions.
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  • 111
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    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 695-705 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We studied films of poly(L-tyrosine) with hydrogen phosphate (residue/phosphate, 1:1) by ir spectroscopy. The influences of the alkali cations (Li+, Na+, K+) and of the degree of hydration were clarified. If Li+ ions are present, the OH⃛-OP hydrogen bonds formed in the dried films between the tyrosine OH groups and hydrogen phosphate are asymmetrical. The formation of hydrogen phosphate-hydrogen phosphate hydrogen bonds is prevented by the presence of the Li+ ions. With an increase in the degree of hydration, the tyrosine-phosphate bonds are not broken but become slightly stronger. Completely different behaviour is found if K+ ions are present. In dry films, the OH⃛-OP ⇌ O-⃛HOP hydrogen bonds formed between tyrosine and hydrogen phosphate show large proton polarizability. The tyrosine proton has a noticeable residence time at the acceptor O atom of the phosphate. The difference in the behaviour of the system with K+ ions when compared to the system with Li+ ions can be explained, since the hydrogen acceptor O atom of phosphate ions is more negatively charged due to the weaker influence of the K+ ions. Furthermore, POH⃛-OP hydrogen bonds between hydrogen phosphate molecules are formed. With an increase in the degree of hydration, the tyrosine-hydrogen phosphate hydrogen bonds are broken, all tyrosine protons are found at the tyrosine residues, and the -PO3- groupings are in a symmetrical environment, indicating that the K+ ions are removed from these groupings. If the degree of hydration increases further, hydrogen-bonded systems such as hydrogen phosphate-water-hydrogen phosphate are formed that show large proton polarizability due to collective proton motion. When Na+ ions are present, the OH⃛-OP ⇌ O-⃛HOP hydrogen bonds formed in dry films still show proton polarizability, but the residence time of the tyrosine proton at the phosphate is very short.
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  • 112
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    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 735-745 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a general view of κ-carrageenan gelation and some new experimental results concerning their behavior in the presence of Na+, K+, or Rb+ counterions in semidilute concentration. The gelation mechanism is based on the aggregation of helical dimers.
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  • 113
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    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 56 (1984) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 114
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 272-278 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Information system for process development. An essential requirement for successful process development is the availability of relevant specialist information. Structuring the necessary activities by the techniques of systems engineering during the course of process development can provide detailed knowledge of the information required. However, comparison of available supply and demand shows that an essential part of the information, i.e. the solutions of unit operations and the accompanying equipment, have not hitherto been collected in systematic information systems. There fore principles are developed for the creation of information systems for process development and are demonstrated by the example of a „solution catalogue“ for filter equipments for the solid/fluid separation.
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  • 115
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New design and process engineering concepts for production of hydrogen by electrolysis. Electrolytic production of hydrogen has attracted particular interest in connection with expansion of nuclear generating capacity in France, Belgium, Canada, and Japan as a means of balancing load, and for developing countries with hitherto untapped hydroenergy resources it provides a means of supplying fertilizers with any need for oil imports. However, the present state of the art of water electrolysis leads to excessively high production costs owing to excessively high investment costs and to high an energy consumption, far above the thermodynamically calculated energy requirements: reduction of production costs will require satisfaction of opposing demands for raising the space-time yield of electrolyzers by increased current density while simultaneously lowering the energy consumption by reducing the cell potential. This contribution describes measures intended to save 20 to 30% in energy requirements; the production costs will fall by about 20 to 25%.
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  • 116
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Influence of wall friction on the design of silos - Aspects of process technology and statics. Mass flow and funnel flow are distinguished when considering the discharge of stored bulk solids. In order to cause mass flow to occur, i. e. the complete bunker filling is in motion, hopper walls need to be steep. Conditions close to the outlet are decisive, a large value of wall friction requiring steep hopper walls. For a safe design of bunker walls with respect to mechanical strength, DIN 1055, part 6 is commonly applied; it is currently being revised. From this regulation a strong influence of the angle of wall friction can be inferred, small values of the angle being associated with high horizontal pressures. In case the angle of wall friction depends on pressure and other parameters and safety factors are included there may be a considerable difference between the angle used by a process engineer and by a civil engineer.
    Additional Material: 9 Ill.
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  • 117
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 299-305 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Scope of glass as material of construction in plant engineering. In conjunction with PTFE as sealing material, borosilicate glass is nowadays recognized as a material for plant construction. A complete modular system of individual components with suitable connecting pieces is available. Moreover, a variety of equipment has been developed for accomplishing various processes while paying due attention to the special material properties of the material glass. In combination with other materials, primarily in the field of heat exchangers and evaporators, numerous processes are now conducted without any difficulty in glass plant. In this range of processes, a special place is assumed by those which urgently require glass for corrosion reasons, such as chlorination or bromination reactions or concentration of acids, because specialized know-how is sometimes required.
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  • 118
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 279-286 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biological purification of exhaust gases. The biological purification of exhaust typically employs microorganisms to transform undesired components, particularly those with pronounced odours into innocuous products. Since the activity of these organisms is localized in water, the odiferous substances must be transferred from the air to water. Oxygen must also be supplied to the water for product transformation. Large scale plant for biological purification of waste air from agricultural and industrial operations were introduced in Europe in the early 1960's. Since then this new technology has undergone remarkable developments. The principal plant types are biofilters, dripping units, and bioscrubbing units. In compost production and agriculture there is a current preference for biofilters and drip units, while biofilters and bioscrubbers are preferred in industry. Such plant already largely satisfy demands on purification performance and reliability. Further development in the direction of even higher performance and more compact plant is expected.
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  • 119
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 120
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Handling and removal of vapors generated on storage and loading of inflammable liquids. On storage and loading of liquid mineral oil products of high vapor pressure - e.g. gasoline and aromatic hydrocarbons - significant quantities of hydrocarbons will be lost. Mixtures with air can be inflammable. The limits of flammability of the three-component mixture of burning gas, oxidizer, and inert gas can be described in a diagram. The occurrence of inflammable mixtures in recovery and combustion plants can be reduced by appropriate measures. The hydrocarbon content in waste gases of recovery plants can be reduced to few grams per cubic meter. The limits for emissions defined in the „Technische Anleitung zur Reinhaltung der Luft“ (TA Luft) generally can only reached by thermal oxidation. Two plants are presented, in which vapors of mineral oil products are handled and combusted.
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  • 121
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 310-312 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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  • 122
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
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  • 123
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 317-317 
    ISSN: 0009-286X
    Keywords: Dispersionsmodell ; Doppelschneckenkneter ; Konzentrationsverteilung ; Stofftransportmodell ; Tracer-Versuche ; Verweilzeitverteilung ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 124
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 350-355 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Computer-aided retrieval of data collections in chemical engineering. Data collections are an important tool for more efficient and economical engineering in the various fields of chemical process technology. The computer-aided utilization of available data collections has major advantages compared with manual processing. Computer-aided utilization can be based on the identification retrieval or rank retrieval method. The advantage of the rank retrieval method is that it provides a spectrum of solutions sorted by the degree of coincidence with the ideal solution. Rank retrieval can be integrated into larger program packages within an integrated computer system which supports the design of chemical plants.
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  • 125
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Vibrational phenomena in chemical plant. This article draws on the practical experience of the author to provide a survey of vibrational problems in chemical plant and of their sources. Even though it is not always possible to eliminate all potential sources of vibration by appropriate calculation and design measures during the planning stage, they can usually be quickly identified subsequently by suitable measuring techniques and countermeasures adopted.
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  • 126
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 356-360 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Energy savings in industrial NH3 plant by heat recovery in the waste heat system. Minimization of energy consumption is nowadays a primary goal in the design of NH3 plant. In this context two aspects are particularly important: first, the process steps and their combination must be selected in such a way that the level of energy that has to be supplied to the plant is kept low from the very beginning; second, heat recovery must be optimized by the choice of process conditions and use of appropriate equipment. An industrial NH3 plant built according to these principles can operate at a consumption of as low as 29.5 GJ/t NH3, using proven processes and equipment. The first plant of this new generation with a capacity of 1120 t/d is currently under construction for Canadian Industries Ltd. (CIL) in Canada.
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  • 127
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 128
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 370-376 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Safe handling of pressurized hydrogen - storage and transport. For the necessary future transition to non-fossile energy sources hydrogen is considered to be the ideal energy vector and will therefore assume ever-increasing importance. However, safe handling of the gas will be a basic requirement. A particular difficulty with pressurized hydrogen is its relative incompatibility with many materials which are commonly used for pressure vessels, either for transportation or for storage. The paper summarizes the major factors instrumental in hydrogen embrittlement. In particular, it stresses the role played by service conditions and by the quality of the internal surface of the vessels when exposed to the gas. On the basis of these findings a number of recommendations are given with respect to vessel design and operating measures in order to secure safe working with high pressure hydrogen gas.
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  • 129
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 402-403 
    ISSN: 0009-286X
    Keywords: Blasensäulen ; Reaktionsapparate ; Abstromreaktoren ; Grenzfläche ; Mehrphasenströmung ; Betriebsparameter ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
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  • 130
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 408-409 
    ISSN: 0009-286X
    Keywords: Anlagenplanung ; Anlagenbau ; Datenverarbeitung ; Computer ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 131
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    Chemie Ingenieur Technik - CIT 56 (1984) 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 132
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    Chemie Ingenieur Technik - CIT 56 (1984), S. 427-431 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Measures for intensifying heat transfer. Various approaches to the intensification of heat transfer have occupied engineers for many years. Many proposals failed to be accepted while others have been adopted in practice and have led to considerable savings in energy and materials. This article considers a number of topical developments in the improvement of convective heat transfer, heat transfer on evaporation, and heat transfer on condensation. The authors cite primarily review articles from among the extensive body of literature pertaining to this field of study.
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  • 133
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 134
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 135
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    Die Makromolekulare Chemie 6 (1984), S. 239-243 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The abrupt decrease of electric resistance of thin polymer dielectric films and metal-polymer compositions has been observed in the course of their uniaxial compression. At pressures exceeding the critical one the conductivity of some metal-polymer compositions has been found to be as high as that for such metals as titanium. The dependences of specimen resistance on thickness, temperature and uniaxial pressure strongly support a new mechanism fo polymer dielectric conductivity based on the pressure induced injection of current carriers from a metal to the dielectric conduction band.
    Additional Material: 3 Ill.
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  • 136
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    Die Makromolekulare Chemie 185 (1984), S. 429-439 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The initiation of acrylamide polymerisation in aqueous media with a redox system of the type Fe3+/organic complex of Fe(III)/Na2S2O2 was studied. Several carboxylated amines containing the iminodiacetate group as a basic structural unit were used as complex forming reagents. A direct relation between complex stability and initiation efficiency was found. The polymerisation kinetics were studied with the most effective intiating system. Several kinetic parameters were determined and an essential relationship between polymerisation behaviour, polymer characteristices and component ratio of the initiation and polymerisation system was found. An attempt was made to explain these results.
    Additional Material: 3 Ill.
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  • 137
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    Die Makromolekulare Chemie 185 (1984), S. 459-465 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new HPLC method for cyclo-oligoamides 6 and 66 separation is proposed. Using an RP 8 column and an H2O/CF3CH2OH mixtures, all cyclic amides up to the decamer were separated and quantitative results were obtained using an internal standard.
    Additional Material: 3 Ill.
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  • 138
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    Die Makromolekulare Chemie 185 (1984), S. 1063-1068 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic viscoelasticity measurements at 90°C suggest an oxidation process for pristine polyacetylenes (PA's). For cis-rich PA, the oxidation can be divided into three regions: surface oxidation, bulk oxidation, and crosslinking. Crosslinking also occurs at the end of the surface oxidation period but does not occur in the bulk reaction period. For trans-rich PA, oxygen doping was complete after the first 15 min and occurred to a smaller extent than that of the cis-rich PA. The rate of reaction of trans PA chains with oxygen is slow in comparision to that of crosslinking by radical combination or addition reactions with the PA chains. In the case of trans PA the concentration of radical chains formed by reaction with oxygen retains a steady value after the initial period up to the end of oxidation.
    Additional Material: 5 Ill.
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  • 139
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    Die Makromolekulare Chemie 185 (1984), S. 1095-1104 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ethylene/propylene/5-ethylidene-2-norbornene terpolymers (1) are very sensitive to photooxidation. In the early stages, hydroperoxidation occurs specifically at the carbon atom in α-position to the ethylidene group. Isolated and hydrogen-bonded hydroperoxides can be detected by IR spectrophotometry at 3550 and 3380 cm-1, respectively. In post-thermolysis experiments at temperatures above 60°C the associated hydroperoxides were found to be less stable than the isolated hydroperoxides. Saturation of the ethylidene groups is concomitant with the decomposition of associated hydroperoxides, which are transformed thermally and photochemically into alcohols and cyclic saturated ketones. The lack of vinyl groups shows that hydroperoxidation proceeds only at the norbornene cycle.
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  • 140
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    Die Makromolekulare Chemie 185 (1984), S. 1133-1138 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relationships between the valence state of titanium in MgCl2-supported titanium catalysts and polymerization performances for ethylene and propylene were studied. When the titanium species of the supported titanium catalyst 1 was preliminarily reduced by treating it with AlEt3, the resulting catalyst system 2 had lost the activity for propylene polymerization completely. The catalyst activity for ethylene polymerization was found to be reduced to 20% of that of the original catalyst 1. In the AlEt3-pretreated catalyst 2 no Ti4+ is found and 80% of the total titanium is present as Ti2+. The catalyst system 2 plus AlEt3, however, does exhibit activity towards ethylene-propylene copolymerization, propylene insertion being possible if the end of the growing polymer chain is an ethylene unit. The titanium in the AlEt3-reduced catalyst 2 could be oxidized again by treatment with various agents. The oxidized catalysts 3, in conjunction with freshly added AlEt3 as cocatalyst, are active for propylene polymerization and show increased activity for ethylene polymerization in relation to the extent of oxidation.
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  • 141
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    Die Makromolekulare Chemie 185 (1984), S. 1177-1186 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The copolymerization parameters of N,N-dimethyl-2-aminoethyl methacrylate (DAMA) with methacrylic acid (MAA) were determined at 50°C in benzene, dimethylformamide, and pyridine solutions. The Alfrey-Price constants e and Q of the two monomers were determined by copolymerization of DAMA and MAA with styrene in the same solvents. Using these constants, the copolymerization diagrams of the pair DAMA-MAA were calculated and compared with the experimentally determined ones. The mutual interaction between the comonomers is discussed.
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  • 142
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    Die Makromolekulare Chemie 185 (1984), S. 1233-1234 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 143
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    Die Makromolekulare Chemie 185 (1984), S. 1265-1275 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We analysed by raster electron microscopy Luttinger-polyacetylene as a powder and as a film, both in pristine and (SbF6--electrochemically) doped form. The samples had been intensively washed with MeOH/HCl. One sample had, according to the results of transmission electron microscopy, fiber morphology. All samples show globules as primary structure arranged in clusters (in powder), mono-layers, or chains (in film) (which previously led to “fibril theory”). The primary spherical particles have diameters from 0,02-0,05 μm. The “fibril” sample has very small spherical primary particles, which may develop using low catalyst amounts. Our results support that the conductivity characteristics is governed by phenomena antiparallel to the chain direction (change-transfer-complexes).
    Additional Material: 11 Ill.
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  • 144
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Heterotactic poly(methyl methacrylate) (PMMA) is studied by light scattering and viscometry in the mixture acetonitrile + CCl4. Both liquids are poor solvents of PMMA, but their mixture is a very good solvent of this polymer. The total sorption potential of the coil is calculated from second virial coefficient and intrinsic viscosity results. Unperturbed dimensions, Mark-Houwink exponent, Schulz-Blaschke constant, and coil expansion factor are also determined. The enhanced total solvent sorption is larger in this mixture than in any other cosolvent system of PMMA thus far studied. This is due to the strong repulsive interactions between acetonitrile and CCl4. Such interactions also determine the inversion in preferential sorption that occurs close to equimolar composition. Acetonitrile can interact favourably with the ester group of PMMA and unfavourably with its methylene backbone. The role of such opposing interactions and of liquid order in acetonitrile are taken into account to discuss the results.
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  • 145
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    Die Makromolekulare Chemie 185 (1984), S. 839-846 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The addition of benzoic acid to the oxirane ring of epoxidized polymers of dienes is limited by side reactions which are promoted by increase of time, temperature, or epoxide concentration. Only high [Acid]/[Epoxide] ratios afford good yields of modification of the epoxidized polymers.
    Additional Material: 6 Ill.
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  • 146
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The enantioselective hydrolysis of dipeptide-type amino acid esters (Z-(L)-Ala-(L or D)-Ala-PNP (5a), Z-(L)-Ala-(L or D)-Leu-PNP (5b), and Z-(L)-Ala-(L or D)-Phe-PNP (5c)) by di- or tri-peptide nucleophiles (Z-(L)-Leu-(L)-His (2a), Z-(L)-Phe-(L)-His (2b), and Z-(L)-Leu-(L)-His (3)) in the bilayer vesicular aggregates of didodecyldimethylammonium bromide (6) resulted in the enantiomer rate ratio of LL/LD = 1, 1 to 18, the value of which was considerably higher than that (L/D = 1,0 to 4,6) in the hydrolysis of Z-(L or D)-Ala-PNP (4a), Z-(L or D)-Leu-PNP (4b), and Z-(L or D)-Phe-PNP (4c) by the identical vesicular system and that (L/D = 0,7 to 3,1) in the hydrolysis of the dipeptide substrates 5a - c by Z-(L)-His (1) and 6. The high enantioselectivity (LL/LD = 18) in the hydrolysis of 5c by the system of 2a and 6 was enhanced to be LL/LD = 36 by lowering the temperature from 25 to 10°C.
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  • 147
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    Die Makromolekulare Chemie 185 (1984), S. 957-967 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Six unfractionated samples of polyacrylamide were hydrolysed to varying extents. The partially hydrolysed polyacrylamides were investigated by viscosity, osmatic pressure and light scattering techniques in 0,12 M NaCl. The molecular weights of the hydrolysed polyacrylamides confirmed the absence of main chain degradation during hydrolysis. Intrinsic viscosities and dimensions increased with increasing extent of hydrolysis. On correlating the intrinisic viscosities with the extent of hydrolysis, a linear relationship between intrinsic viscosities and the square root of the extent of hydrolysis was obtained.
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  • 148
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    Die Makromolekulare Chemie 185 (1984), S. 983-989 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dimensions of partially hydrolysed polyacrylamides with varying molecular weights and extents of hydrolysis determined by light scattering were used to verify the relative applicability of the various macroion expansion theories. Expansions attributable solely to the presence of electrostatic charges were evaluated with references to the dimensions of the polyacrylamides used for hydrolysis. Total expansions and expansions due to long-range interactions were evaluated with reference to the estimated unperturbed dimensions of the strating polyacrylamides and the hydrolysed polyacrylamide samples, respectively. The expansion coefficients obtained from light scattering measurements were higher than those evaluated from intrinsic viscosities. The differences were maximum (30 - 100%) for the total expansion coefficients. Considering the variation of the Flory viscosity constant Φ with molecular weight and charge density, these differences were ascribed to the uncertainty in the applicability of the light scattering method for the determination of the dimensions of polyelectrolytes. However, the variation of the expansion coefficients with the extent of hydrolysis and molecular weight were similar to those of the expansion coefficients obtained from viscosity measurements. The total expansion coefficient was qualitatively in confirmity with the theory of Chien and Ishihara with reference to its dependence on charge density.
    Additional Material: 1 Ill.
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  • 149
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The particle size distribution is one of the most important characteristics of aqueous polymer dispersions (diameter range 20 〈 D 〈 2000 nm). In addtion, the knowledge of the average particle density ρPM, the density distribution, and the particle refractive index nPM gives information about the chemical composition of dispersions. We report of an ultracentrifuge method which allows to determine all these values simultaneously in one single run. For that purpose the dispersion is measured simultaneously in 3 media of different density, i.e., in H2O, H2O/D2O (1:1, by wt.), and D2O. We use a preparative ultracentrifuge with an analystical rotor with trubidity optics, but instead of an 1-cell-rotor an 8-cells-rotor and a multiplexer are used. In order to measure very small and very large particles simultaneously in one single run we do not work at the usual constant number of rotor revolutions, but at a rate of revolutions increasing from 0 to 40000 min-1. The ultracentrifuge is connected with a computer on-line. The calculations are based on Stokes' law and Mie's light scattering theory for homogeneous isotropic spherical particles.
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  • 150
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    Die Makromolekulare Chemie 185 (1984), S. 1827-1833 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Soluble catalysts of V(acac)3 and AIR2X (R = C2H5, n-C3H7, i-C4H9; X = Cl, Br) initiate a living polymerization of propene at -78°C to afford monodisperse polymers of syndiotactic structure. The stereochemistry of the living polymerization was investigated by examining the structures of monomdisperse polypropylenes and of propylene-ethylene block copolymers by means of 13C NMR spectroscopy. It was found that syndiotactic- and regio-specificities of the soluble vanadium-based catalysts are not influenced by the sequence length of the living polymer chain.
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  • 151
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    Die Makromolekulare Chemie 185 (1984), S. 1145-1154 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The possibilities of coupling size exclusion chromatography with light scattering (GPC-DDL) are studied. The continuous light scattering detector is a modified (laser He-Ne excitation) classical light scattering apparatus Fica 42000, equipped with a flow cell of low capacity (120μl). With this cell, a detection of the scattered light is obtained only at an angle of 90°. The light scattering detector is coupled with a GPC apparatus (packed with 10 μm gel particles). The precision, reproducibility and limitation to obtain molecular weight distribution curves of “standard” linear polystyrenes are studied.
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  • 152
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    Die Makromolekulare Chemie 185 (1984), S. 1187-1197 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Similarly to the three-block copolymer poly(styrene-b-butadiene-b-styrene), a radial block copolymer with four brances consisting of inner polybutadiene and outer polystyrene blocks forms, in a mixed solvent tetrahydrofuran/ethanol, spherical micelles with a polybutadiene core and polystyrene shell. The equilibrium between these micelles and the molecularly dissolved copolymer was studied as a function of the solvent composition by means of light scattering, sedimentation velocity, and GPC. The sedimentation diagrams were interpreted taking into account the Gilbert theory of mobile equilibrium in systems of associating macromolecules.
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  • 153
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    Die Makromolekulare Chemie 185 (1984), S. 1371-1381 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Simultaneous action of high pressure and shear deformation on various organic compounds is studied using an apparatus of Bridgeman anvil type. This apparatus allows to work in a temperature range from -196°C to 200°C at different shear forces. It is established that under these conditions the investigated materials are in the plastic flow state. Chemical transformations of more than 300 organic compounds of different chemical classes are observed. Reactions such as polymerization, polycondensation, polyaddition etc. are realized under plastic flow. In addition, copolymerization reactions with the formation of random copolymers occur for some substances. Kinetic peculiarities of the polymerization process under plastic flow are investigated on the example of acrylamide.
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  • 154
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    Die Makromolekulare Chemie 185 (1984), S. 1409-1417 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Complexation between tetrabutylammonium bromide, or oligomeric tetramethyl-2,6-ionene bromide (1), and high molecular weight poly(ethylene oxide) (PEO) was studied viscometrically, using the following media as solvents: water; 0,1 M aq. KCl; 2 M aq. KCl and 0,1 M aq. HCl. It was found that tetrabutylammonium bromide as well as the ionene 1 convert the initially linear ηred vs. cPOE relationships into bent and hunchbacked curves, thus suggesting the formation of water soluble complexes. In aqueous KCl and HCl solutions these complexes behave as typical polyelectrolytes. Contrary to cations of alkali metals, however, protons do not influence the linear ηred vs. cPOE relation, so that it is possible to determine intrinsic viscosities by use of 0,1 M aq. HCl as solvent. These viscosities are rising if the complexation between POE and ammonium salt is accomplished by the polyfunctional ionene. The increase of [η] depends on the unit mole ratio (u.m.r.) of the ionene to POE. With increasing unit mole ratio from 0 to 7 [η] increases from 9 up to 21 dl · g-1. In water the complexation between one unit mole of POE and two unit moles of ionene 1 causes an increase of the reduced viscosity ηred from 11,2 up to 80,2 dl · g-1.
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  • 155
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of tributylin hydride on different vanadium-based homogeneous catalytic systems for the ethylene/propylene/diene (EPD) terpolymerization was studied. Productivity improvements were always observed. Studied on the composition of the polymerization residues as well as on the interaction between single components of the catalytic system were also carried out. The results are interpreted on the basis of the enhanced oxidation of the vanadium(II) species by radical intermediates resulting from the reaction between tin hydrides and the chlorinated organic activator.
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  • 156
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly[(2-alkoxy (or 2,5-dialkoxy)-1,4-phenylenevinylene-1,4-phenylene)vinylene]s containing alkyl groups of different lengths (8a, b or 9a - c), were prepared by Wittig-reaction of terephthalaldehyde with “bis(Wittig-salt)s”. To establish the structure of the polymers, alkoxy(and dialkoxy)di-α-styrylbenzenes 10a, b and 11a - c were prepared as model compounds under similar conditions. Electrical conductivities, σ288K, of the polymers and their charge transfer (donor-acceptor) complexes with iodine were studied. The doped polymers show increased room temperature conductivities by several orders of magnitude.
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  • 157
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some new divinylidene compounds, 1,3-bis[4-(β-styryl)phenyl]propane (2b), 1,6-bis[4-(β-styryl)phenyl]hexane (2d), 2,6-bis(β-styryl)pyridine (1b), and 1,5-bis(β-styryl)naphthalene (1c), were prepared. Their reaction with electron transfer agents was investigated and compared with that of homologous divinylidene compounds. The cyclic oligomers formed after protonation were separated and characterized spectroscopically. In general, no preferential formation of isomers is observed. The cyclic dimer, however, is the main product of the electron transfer reaction of 1b and 1c.
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  • 158
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    Die Makromolekulare Chemie 185 (1984), S. 1937-1941 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal stability and degradation kinetics of methyl cellulose, polyacrylamide and methyl cellulose grafted with different amounts of polyacrylamide were investigated by thermogravimetry. Polyacrylamide was found to be more stable than methyl cellulose. The thermal stabilities of the graft copolymeres lie in between these two extremes. The order of reaction, n, and energy of activation, E, of the thermal degradation were determined for all polymer samples. It was found that E for the degradation of polyacrylamide (41,4 kcal/mol = 173,2 kJ/mol) is higher than that of methyl cellulose (31,3 kcal/mol = 131,0 kJ/mol) and that E for the graft copolymers lies in between those of the two homopolymers. The over-all reaction order of the degradation reactions was found to be unity for all polymer samples investigated.
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  • 159
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    Die Makromolekulare Chemie 185 (1984), S. 1979-1989 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of poly(ethylene oxide) with a poly(ether sulfone) were prepared by casting from a common solvent and were found to be miscible and show a single, composition dependent, glass transition temperature. Mixtures in both cyclohexanone and N,N-dimethylformamide phase, separated on heating and thus conditions need to be carefully chosen to obtain homogeneous blends. At higher PEO contents, PEO crystallised from the blends at lower temperatures. The melting point depression, as determined by trubidity measurements, was used to calculate an interaction parameter which was negative, as expected for miscible polymers. The blends also phase separated on heating, and the cloud point curve could be measured by turbidity measurements and confirmed by both visible and electron microscopy. The cloud point curve was very skew with a minimum at around 10 wt.-% PES content. This was not a strong function of the molecular weight and the skew nature was thus presumably due to differences in the state parameters of the pure components. The blends showed a very high mobility with sharp and reproducible could points which might make them ideal for future miscibility studies.
    Additional Material: 9 Ill.
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  • 160
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reactions of insertion of components serving as bridges between a pharmacologically active constituent and a water-soluble telomeric chain, were carried out. Model compounds containing hydroxyl, amine or carboxylic functions were studied. In each case a bifunctional compound could be found, which is capable of reacting with the model. The resulting products could be fixed on a telomer. The results with the model compounds were applied to the fixation of the carboxylic drug indometacin.
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  • 161
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly[γ-benzyl L-glutamate (BLG)-co-N5-(3-hydroxypropyl)-L-glutamine (HLG)] (3) and polyBLG/poly(ethylene glycol) (PBLG/PEG) block copolymers (6) were synthesized, and the adhesion behavior of rat lymphnode lymphocytes on these polymers was examined by the column method. An increase in the HLG content of polymer 3 caused a slight decrease in lymphocyte adhesivity. Lymphocyte subpopulation B cells were found to be more adhesive to polymers 3 than T cells, by a factor of 1,4 - 1,6. On the other hand, an increase in the PEG content of PBLG/PEG block copolymer caused a remarkable decrease inlymphocyte adhesivity and an increase in selectivity in the adhesivity between B cells and T cells up to a factor of 2,3.
    Additional Material: 3 Ill.
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  • 162
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    Die Makromolekulare Chemie 185 (1984), S. 1843-1854 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mass polymerised poly(vinyl chloride) (PVC), subjected to annealing treatment between 85-140°C under air, nitrogen, vacuum, and hydrogen chloride environment, was found to undergo very slight decomposition in which long polyenes (with more than ten conjugated carbon-carbon double bonds) were produced. Despite the presence of these polyenes the thermal stability of the resin at 190°C remained unaltered. Resin stability was also unaffected by the atmosphere in which the resin was annealed. By contrast, urea clathrate PVC, known to be highly crystalline, decomposed 300% faster than mass PVC and generated very long polyene sequences (n ≥ 42) at 190°C. The results are discussed in terms of two possible morphological populations of polymer.
    Additional Material: 5 Ill.
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  • 163
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    Die Makromolekulare Chemie 185 (1984), S. 1905-1913 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several mono- and diesters of four selected 2,2′-methylenediphenols with acrylic, methacrylic, and crotonic acid were synthesized for the first time. Special emphasis was paid to the preparation of diesters with two different acyl groups which could be obtained via the corresponding monoesters. The radical polymerization of these esters with AIBN (mainly in benzene) gave insoluble (crosslinked) products from dimethacrylates and soluble (linear) polymers from mixed diesters with methacrylic and crotonic acid, while the dicrotonates are not reactive.
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  • 164
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    Die Makromolekulare Chemie 185 (1984), S. 1921-1935 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal structure of three tetranuclear phenolic compounds - 6,6′-bis (2-hydroxy-5-methylbenzyl)-4,4′-dimethyl-2,2′-methylenediphenol (1), 6-(2-hydroxy-3,5-dimethylbenzyl)-6′-(2-hydroxy-5-methylbenzyl)-4,4′-dimethyl-2,2′-methylendiphenol (2), and 6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-6′-(2-hydroxy-5-methylbenzyl)-4,4′-dimethyl-2,2′-methylene-diphenol (3) -, was determined by single crystal X-ray analysis. Intramolecular hydrogen bonds between all hydroxyl groups of adjacent phenolic units are found for all molecules. They are directed to the opposite end of the molecule by the ortho-methyl or ortho-tert-butyl group in compounds 2 and 3, while no special orientation is found in 1. The conformation of the phenolic units is trans/trans (anti/anti) in 1 and cis/trans (syn/anti) in 2 and 3. Consequently, in the crystal lattice, 2 and 3 form cyclic dimers via intermolecular head-to-tail hydrogen bonds, while the molecules of 1 are arranged to chains of indefinite length by head-to-head and tail-to-tail hydrogen bonds.
    Additional Material: 7 Ill.
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  • 165
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    Die Makromolekulare Chemie 185 (1984), S. 2269-2281 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Examinations by GPC, HPLC and NMR of several commercial prepolymers containing epoxy groups show that they are based on bisphenol A (DGEBA) and brominated bisphenol A (DGEBtBr). In some cases, brominated monepoxides are also added to the mixture to diminish its viscosity. Consequently, the three-dimensional networks resulting from the polycondensation of brominated resins with diamines can be greatly affected by the presence of these monoepoxides that modify the epoxy/amine ratios.
    Additional Material: 13 Ill.
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  • 166
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Methyl methacrylate (MMA) was radically polymerized in the presence of highly syndiotactic deuterated or undeuterated poly(methyl methacrylate)s. In contrast to observations found in the literature no increase in isotacticity was observed. The stereoregularity of the polymers formed in the presence of an undeuterated PMMA as matrix was found by 1H NMR spectroscopy to be about the same as that in polymers prepared without any matrix, except the polymers formed in the early stage of polymerization which show a little lower syndiotacticity. Determinations of triad tacticities of polymers formed in the presence of deuterated PMMA, gave values of syndiotacticity a little higher than in the case of undeuterated matrixes. The polymer formed in the graft copolymerization of MMA onto pre-irradiated syndiotactic PMMA was fractionated by GPC. The high molecular weight fraction showed a lower syndiotacticity than that of lower molecular weight.
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  • 167
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    Die Makromolekulare Chemie 185 (1984), S. 2337-2346 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The anionic polymerization of exo-3,4,5-trithiatetracyclo[5.5.1.O2,6.O8,12]tridec-10-ene (1) in bulk and/or in aromatic solvents (benzene, toluene) was studied. The polymerization was initiated with sodium benzenethiolate (sodium cation complexed with dibenzo-18-crown-6). Polymers with high-molecular weights were obtained (Mn ≈ 105, osmometrically). The polymerization was found to be living and reversible; the equilibrium monomer concentration increases with the temperature. The ceilling temperature was estimated as 167°C. The thermodynamic data of the polymerization in toluene was determined and compared with those of the polymerization of exo-3,4,5-trithiatricyclo[5.2.O2,6]decane. The standard enthalpy ΔH0ss = -(6,6 ± 0,6)kJ · mol 1 and entropy ΔS0ss = -(29,3 ± 2,1)J · mol 1 · K 1 of the polymerization of 1 were evaluated from the temperature dependence of the equilibrium monomer concentration, determined dilatometrically.
    Additional Material: 5 Ill.
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  • 168
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    Die Makromolekulare Chemie 185 (1984), S. 2347-2359 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New macrocyclic oligoesters 3a - d, containing furan rings, were synthesized by condenzation of 5-hydroxymethyl-2-furancarboxylic acid (1) using 2-chloro-1-methylpyridinium iodide (2) as condensing agent. Water-insoluble products were separated by GPC and characterized by IR, NMR, MS, and elemental analysis. The product distribution was found to depend remarkably on the reaction conditions. When the mole ratio of 2 to 1 was 1,65 in pyridine was solvent, the cyclic trimer 3a and the tetramer 3b were obtained, both in more than 30% yield. In addition higher cyclic oligoesters (3c - d), linear oligoesters (5b - e), and the polyester (6) were formed. When a large amount of tributylamine was used as a scavenger of hydrogen halides in toluene as solvent, the polyester was the main product. Condensation in hexane in place of toluene, yielded the linear oligoesters as main products. A mechanism is proposed for the formation of the cyclic oligoesters.
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  • 169
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    Die Makromolekulare Chemie 185 (1984), S. 2451-2457 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relative reactivities of ethylene, 1-butene and 3-methyl-1-butene in the insertion reaction into the metal-methyl bond of the active site of the catalytic system δ-TiCl3/Al(13CH3)3/Zn(13CH3)2 are determined by 13C NMR end groups analysis. The relative reactivities of propene, 3-methyl-1-pentene and 3-ethyl-1-pentene are also calculated from previous data. Some correlations between relative reactivities and reaction mechanism are proposed.
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  • 170
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    Die Makromolekulare Chemie 6 (1984), S. 3-27 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A review is given in the field of liquid crystalline polymers having mesogenic groups in side branches and in the main chain. Conditions for liquid crystalline state formation are discussed in relation with chemical structure of monomeric units, molecular mess and type of mesogenic groups. Pathways to synthesize nematic, smectic, and cholesteric mesophases in polymers are discussed, peculiarities of structure and properties of polymeric mesophases and models of chain packing in them are analyzed. Electrooptical properties of such systems, when an electric and magnetic field is applied, are discussed-Frederick's effect, electrohydrodynclmic instability, “guest-host” effect, cooperative structural transi- tion induced by electric field, and some others. The possible directions of application of polymeric liquid crystals are considered.
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  • 171
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    Die Makromolekulare Chemie 6 (1984), S. 55-75 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyarylate-polyarylenesulfone oxide block copolymers were used as an example to consider several general problems of synthesizing polycondensation copolymers of the polyblock type and the dependence of their properties on the weight ratio of different blocks and their degree of polymerization. It was found that in glassy block copolymers, on the basis of homopolymers similar in structure, and in the whole complex of physico-chemical properties, microphase separation occurs when the degree of polymerization of one of the blocks becomes corresponding to that of the statistical segment, and when the content of this block reaches a proper value.
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  • 172
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    Die Makromolekulare Chemie 6 (1984), S. 141-161 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 6 Ill.
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  • 173
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    Die Makromolekulare Chemie 6 (1984), S. 211-226 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By partial sulfonation, desulfonation and ion exchange polytsyrene sulfonic acid resins were synthesized having the same capacity (1.3 milliequivalents/g). By the variation of the preparation methods, however, the distribution of the acid groups within the resins could be changed in a defined way so that different concentration profiles were obtained. It is shown that the properties and reaction behavior of the polymeric resins are determined to a large extent by the local concentration of the functional groups.
    Additional Material: 13 Ill.
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  • 174
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    Die Makromolekulare Chemie 6 (1984), S. 29-29 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 175
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    Die Makromolekulare Chemie 6 (1984), S. 41-46 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The orientational order in liquid crystalline side chain polymers was analysed by means of electric birefringence and small angle X-ray scattering studies. Strong pre-transitional effects were observed in the isotropic phase in the neighbourhood of the nematic phase transition.
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  • 176
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    Die Makromolekulare Chemie 6 (1984), S. 93-106 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A structon model of supercrystals for describing the dynamic properties and multiple phese transitions of superlattices, formed in systems of block copolymers with segregated domains, is applied and experimentally substantiated.
    Additional Material: 8 Ill.
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  • 177
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    Die Makromolekulare Chemie 185 (1984), S. 9-18 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Silicone macromers 5, having a methacryloyl group at one end, and controiled molecular weights, were prepared by anionic polymerization of hexamethylcyclotrisiloxane (2) and subsequent termination with chlorosilane compounds containing a polymerizable vinyl groups. Graft polymers with siloxane grafts were prepared by copolymerization of these macromers with methyl methacrylate (MMA) or styrene. The surface active properties of MMA-based graft polymers were investigated by studying the extent of surface modification of films of graft polymer-poly(methyl methacrylate) blends.
    Additional Material: 4 Ill.
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  • 178
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure of a number of polymers of the polyphenylene type, prepared by polycyclocondensation of aromatic diketones and their acetals was investigated by 13C NMR spectroscopy. The spectra provide a means to determine the content of 1,3,5-trisubstituted benzene rings and defective β-methylchalcone fragments, as well as the endgroups.
    Additional Material: 3 Ill.
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  • 179
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The anionic polymerization of β-propiolactone (βPL) in DMF initiated with CH3COO-K+ or CH3O-K+ has been found to proceed via the carboxylate ion as growing species. This is valid for all polymerization steps in the former system, starting from the first monomer addition, whereas in the latter CH3O-K+ was found to produce in the initiation reaction both alcoholate and carboxylate anions in almost equal properties. The alcoholate reproduces approximately half of itself in each subsequent step; thus, after a few addition steps all of the active species have become carboxylate ones. The anionic polymerization of ε-caprolactone (εCL), on the other hand, can only be induced by alcoholates and the growing species are alcoholate anions. Carboxylate anions, even with crowed cations, are inactive as initiators of εCL. These conclusions are based on NMR studies of the end-groups originating from the initiator and on UV-VIs studies of the reaction products of the active species with 2,4,6-trinitroanisole. The difference between the polymerizations of βPL and εCL are explained in terms of ring strain and conformation.
    Additional Material: 5 Ill.
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  • 180
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Provided a polymer is soluble, i. e., molecularly dispersed in another polymer irrespective of the molecular weight of the components, the solution is exothermic. By increasing the temperature two effects, both unfavourable to mixing become larger: (i) the excess entropy of mixing caused by contact interaction and (ii) the total effect from the difference of the free volumes of the pure components. So, an upper miscibility gap occurs. The thermodynamic properties of the mixture cannot be derived from the properties of the pure components. They can be described by the corresponding states theory of Prigogine, Flory, and Patterson with suitable values for the contact energy and contact entropy parameters X12 and Q12. The temperature of separation can be predicted from measurements on the mixture at low temperatures.
    Additional Material: 15 Ill.
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  • 181
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Tetrahydrofuran (THF) was polymerized by protic and non-protic cationic initiators in presence of acetic anhydride (Ac2O) in methylene dichloride. Due to a low transfer coefficient (CAc2o = 0,058) the molecular weight increases during the early part of the reaction. The consumption of Ac2O continues even when the THF concentration approaches zero, which results in a lowering of the number-average degree of polymerization Pn. Degradation of poly(THF) continues until the Ac2O is exhausted. The equilibrium concentration of THF can reach almost zero at small Pn. The equilibrium constants K2, K3, K4, etc., up to K23 for the successive monomer additions are obtained from gel permeation chromatography. With the exception of K2 the equilibrium constants Kn are independent of n.
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  • 182
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    Die Makromolekulare Chemie 8 (1984), S. 89-100 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is evidenced that charge-transfer interaction of electron-donor and acceptor groups incorporated in polymer chains improves substantially the rheological properties, mainly by extending the rubber plateau to higher temperatures and lower frequencies, respectively. The effect is attributed to thermoreversible network formation and can be used to increase the stability of incompatible polymer blends at least from the viscoelastic point of view.
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  • 183
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    Die Makromolekulare Chemie 8 (1984), S. 101-108 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sizes and shapes of the component phases of immiscible polymer blends are strongly influenced by the viscoelastic properties of each component. For mixtures of different poly(ethylene terephthalate)s and polyamide-6 it can be established that the morphology under shear is the result of the viscosity ratio, which determines the size of the droplet-phase, and of the difference in the component elasticities affecting the shape of the dispersed phase.
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  • 184
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    Die Makromolekulare Chemie 185 (1984), S. 37-49 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rate constants of the reaction of 1-azabicyclo[4.2.0]octane (1) with different alkyl esters or halides were measured using 1H NMR and UV spectroscopy as well as conductometric methods. The reactivities of the alkylating agents were found to decrease with increasing nucleophilicity of the derived anions (CF3SO⊖3 〉 I⊖ 〉 Br⊖ 〉 picryl⊖ 〉 Cl⊖). Reactivities of all ethyl derivatives, except ethyl chloride, are higher than the reactivity of the 1-alkyl-1-azoniabicyclo[4.2.0]octane cation (2), which means that for these compounds the rate constant of initiation is higher than that of propagation. The reactions proceed much slower in methanol than in nitrobenzene due to the strong donor-acceptor interactions between methanol and 1. Attempts to observe covalent active centers directly by NMR spectroscopy in the polymerization mixture or to detect them kinetically, were unsuccessfull. The reactivity of ethyl triflate, modelling the hypothetical active center, was found to be 2.104 times higher than the reactivity of ions 2. This is ascribed to the high strength of the bond in the cation 2, not sufficiently compensated by the strain of the four-membered ring.
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  • 185
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    Die Makromolekulare Chemie 185 (1984), S. 51-66 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cationic ring-opening polymerization of 1-azabicyclo[4.2.0]octane (1) was studied with initiators providing small and large anions, namely F⊖, Br⊖, I⊖, picryl(Pic⊖), CF3SO3⊖. In nitrobenzene as solvent the macroions and macroion-pairs, independently of the anion size, propagate with the same rate constant kp+ = kp± = 7,0 · 10-3 mol-1 · l · S-1 at 35°C ( Δ HP≠ = 55 ± 5kj· mol-1, Δ SP≠ = 105 ± 11 j · mol-1 · K-1). This result strongly indicates that it is not the large size of anoins which is exclusively responsible for the equality kP+ = kP±. The structure of the onium ions, their strong solvation, and the resulting weak interactions with anions are primarily responsible for the observed equalities. In methanol as solvent polymerization proceeds 30 times slowlier than in nitrobenzene and ion-pairs are more reactive by 40% than ions, in agreement with Enikolopyan's findings.
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  • 186
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    Die Makromolekulare Chemie 185 (1984), S. 157-165 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Alkaline hydrolyses of anionic phenyl esters such as 4-acetoxy-3-nitrobenzoic acid and 4-butyryloxy-3-nitrobenzoic acid were examined in the presence of cationic and polymeric liposomes, liposomes of low molecular weight compounds, and micelles. All the additives accelerate the reaction due to the hydrophobic interaction between substrates and additives and the electrostatic interaction both between substrates and additives and between OH- and additives. In the Arrhenius plots of the reactions catalyzed by the liposomes, discontinuous regions were observed due to the phase transition of liposomes from the gel state to the liquid crystal state. Activation parameters ΔH≠, ΔS≠ and ΔV≠ for these reaction systems were evaluated. Both ΔS≠ and ΔV≠ values increase upon the addition of cationic liposomes and micelles. These results were attributed to the desolvation of the activated complex by the strong electrostatic affinity to the cationic colloidal additives.
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  • 187
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A systematic investigation of transparent systems (“polymeric microemulsions”), obtained with amphiphilic block copolymers in the presence of water, toluene, and alcohol, was carried out. Their domain of existence in the pseudo-ternary phase diagram is limited compared to that observed for microemulsions with classical surfactants and located in the vicinity of the miscibility curve of the ternary solvents mixture. From dialysis equilibrium and viscosity measurements, it has been established that, whatever the respective lengths of the sequences are, these stable systems consist of a dispersed “phase”  -  containing the compolymer molecules  -  surrounded by an continuous “phase”. Both “phases” are composed of a mixture of the three considered solvents, the continuous phase being constituted by a ternary solvent mixture located on the mutual solubility curve. As a consequence, all water or oil is not trapped within the dispersed particles as in the case of classical micromulsions, but there is a preferential obsorption of the solvents by each type of blocks of the copolymer.
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  • 188
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    Die Makromolekulare Chemie 185 (1984), S. 249-253 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ring opening polymerization of oxetane and 3,3-dimethyloxetane was carried out in dichloromethane at 25°C with triethyloxonium hexafluoroantimonate as catalyst. After polymerization, the flow times were measured for active and terminated solutions in high vacuum. In the case of oxetane, the data support the presence of branched structures in the active solutions formed by an intermolecular chain transfer reaction to the polymer chains, to give non-strained oxonium-ions. This intermolecular side reaction was not detected in the case of 3,3-dimethyloxetane, if the presence of intramolecular chain transfer to a small extent is not excluded.
    Additional Material: 2 Ill.
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  • 189
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    Die Makromolekulare Chemie 185 (1984), S. 297-316 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The epoxy resins (TGMDA) obtained from 4,4′-methylenedianilic (2) and 1-chloro-2,3-epoxypropane (epichlorohydrin) were found to consist of oligomers with large distribution of molecular weights and functionalities. The structure of the main components separated by preparative gel permeation chromatography and by high pressure liquid chromatography (HPLC) was studied by 1H NMR. The best separation was obtained by HPLC on a preparected TGMDA with tert-butyl isocyanate at 60°C. For the impurities, as found with DGEBA prepolymers, we identified primary and secondary alcohol groups on chain ends but also secondary amino groups inside the oligomer chains.
    Additional Material: 13 Ill.
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  • 190
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reduction and hydrolysis of the ladder oligomers 1, 2, 3, 4, and 5 prepared from the acrylates of oligo (hydroxyphenylene-methylene)s was found to lead to a homologous series of oligo (allylalcohol)s (6a, 7a, 8a, 9a and10a) with good yields. These alcohols were characterized by analytical and spectroscopic methods. The reaction sequences, starting with the esterification of the oligo[(hydroxyphenylene) methylene]s 11a - 11e with acryloyl chloride followed by the formation of the ladder oligomers and ending with their reduction and hydrolysis into the oligo(allyl alcohol)s and the starting compounds 11a - 11e, represent a simple matrix reaction. A mixture of multiple acrylates was also subjected to the same reaction sequences, resulting in a multiple matrix reaction. A mixture of matrix compounds 11b - 11e with a known mole ratio was esterified with acryloyl chloride, then transformed into a mixture of ladder oligomers and subsequently reduced and hydrolyzed to afford a mixture of oligo(allyl alcohol)s with the same mole ratio of the starting matrices as shown by gas chromatographic analysis. This represents a paradigm for a replica oligomerisation.
    Additional Material: 5 Tab.
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  • 191
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    Die Makromolekulare Chemie 185 (1984), S. 697-707 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Furan-based diisocyanates and diamines were prepared unambiguously as potential monomers for polyurethane and polyamide production, starting from methyl furoate and furfurylamine, respectively. The syntheses were optimized and the product identity was confirmed by elemental analysis, IR and NMR spectroscopy, and also by preparation of derivatives which were similarly characterized.
    Additional Material: 1 Ill.
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  • 192
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    Die Makromolekulare Chemie 185 (1984), S. 757-764 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Interactions of counterions with segmented kappa- and iota-carrageenan sulfated polysaccharides were investigated by means of microcalorimetric and potentiometric measurements in dilute aqueous solution. The condensation of counterions onto the charged polymer chains leads, in general, to conformational transitions of the disorder-to-order type. A difference in the ability of different pairs of ionic species (monovalent/divalent counterions) to induce conformational transitions of carrageenate salts is demonstrated.
    Additional Material: 6 Ill.
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  • 193
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    Die Makromolekulare Chemie 185 (1984), S. 787-795 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Infrared spectroscopy was used to investigate the molecular orientation and the conformational change upon drawing for various ethylene/1-butene copolymers in a wide range of crystallinity (0 ≤ Xc ≤ 85% ). The degree of crystalline orientation at constant draw ratio decreases with increasing crystallinity. The orientation function for the amorphous CH2 sequence in the trans conformation, f(am), was calculated assuming additivity for the orientation functions of the trans bands. f(am) increases with drawing in a characteristical way for the different materials and reaches a value higher than that of the amorphous gauche bands. Furthermore, it was found that f(am) is strongly dependent on crystallinity. The relative concentration of the amorphous CH2 sequences in the trans conformation increases at the expense of that of the gauche sequences. The transformation from gauche to trans in the amorphous phase occurs simultaneously with the orientation of the amorphous CH2 sequences.
    Additional Material: 6 Ill.
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  • 194
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    Die Makromolekulare Chemie 185 (1984), S. 829-837 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A qualitative analysis of NMR relaxation data is reported, using motional models based on the consideration of conformational states arising from the architectural specificity of the different building units of a polysaccharide. The choice of a pertinent referential axis, such as either a local helical axis or a local inertial axis is discussed.
    Additional Material: 4 Ill.
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  • 195
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Various poly(trialkyl-3-(and 4-)vinylbenzylammonium chloride)s were prepared and their antibacterial activities were assessed by the conventional spread plate method and the viable counting method. They are in general more active against Gram-positive bacteria such as Bacillus subtilis and Staphylococcus aureus than against Gram-negative bacteria such as Escherichia coli, Aerobacter aerogenes and Pseudomonas aeruginosa. Compounds with the longest alkyl chain studied (dodecyl) were found to exhibit particularly high activity, and this was ascribed to the contribution of the increased hydrophobicity of the compounds to the activity. The most significant finding was that the polymers was discussed and interpreted in terms of their greater contribution to each elementary process in the cidal action: their favored adsorption onto the bacterial cell surface and the cytoplasmic membrane with subsequent disruption of its integrity.
    Additional Material: 2 Ill.
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  • 196
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular structures of (RS)-1,2-diphenylethyl methacrylate (DPEMA) and (RS)-α-tert-butylbenzyl methacrylate (t-BBMA) were determined by means of X-ray diffraction. Crystals of (RS)-DPEMA are monoclinic, space group C2/c, a = 33,341(3), b = 5,916(1), c = 15,911(2) Å, β = 106,42(1)°, and Z = 8. Crystals of (RS)-t-BBMA are also monoclinic, space group P21/c, a = 6,028(1), b = 31,009(3), c = 15,207(1) Å, β = 96,780(8)°, and Z = 8. Both structures were solved by the direct method and refined by the block-diagonal least-squares procedure: DPEMA, R = 0,113 for 1 100 observed reflections and t-BBMA, R = 0,081 for 2206 non-zero reflections, respectively. The molecule of DPEMA has an antiperiplanar conformation as to the C=C and C=O double bonds about the C(1)—C(2) bond, a synperiplanar conformation as to the C=O and C—O bond about the C(1)—O(1) bond, and an anticlinal conformation about the O(1)—C(5) bond. One of the two t-BBMA molecules in an asymmetric unit has an antiperiplanar conformation as to the C=C and C=O double bonds about the C(1)—C(2) bond, whereas the other antiperiplanar molecule may contain some synperiplanar conformation. Both molecules have a synperiplanar conformation as to the C=O and C—O bonds about the C(1)—O(1) bond and an anticlinal conformation about the O(1)—C(5).
    Additional Material: 6 Ill.
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  • 197
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    Die Makromolekulare Chemie 185 (1984), S. 991-1001 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal degradation of polystyrene (PS) was carried out in the absence of oxygen between 292 and 336°C. The formed volatile products were analysed qualitatively and quantitatively by means of gas charomatography. It was found that the composition of the volatile fraction is a function of conversion and independent of temperature for most of the products. A radical chain mechanism is proposed to explain these experimental results.
    Additional Material: 3 Ill.
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  • 198
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    Die Makromolekulare Chemie 185 (1984), S. 749-755 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The blue colored complex between poly(vinyl alcohol) (PVA) and iodine was prepared at 5°C by mixing an aqueous solution of PVA with an aqueous ethanolic solution of iodine containing boric acid. The absorption spectrum of the system shows bands at 226 nm (A), 290 nm (B), 355 nm (C), and 650 nm (D). Their relative absorbances change largely depending on temperature. When the system is gradually warmed, the chromophoric band D decays and the intensity of band A increases. By lowering the temperature again to 5°C the concentration of chromophore increases. It was found that the decay and the re-formation of the chromophore are reversible in the temperature range 5 to 15°C. Above 15°C, contrarily, hysteresis effects are encountered for the re-formation. Thus, when the chromophore is re-formed at 5°C, the spectra shows an isosbestic point at 420 nm, between bands C and D. The dependence on temperature of bands B and C is quite independent from each other, which strongly indicates that the latter band should be assigned to another iodide species than the I-3 ion (band B) and the I- ion (band A). Based on these experimental data a new mechanism is proposed involving the complex ion I-3 · I2 which is supposed to be a precursor of the chromophoric pentaiodide ion I5-.
    Additional Material: 3 Ill.
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  • 199
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 7-oxo-5-phenyl-5λ-5-phospha-1,4,6-trioxaspiro[4.4]nonane (3a) (C11H13O4P, monoclinic, P21/n, a = 14,751(2), b = 5,577(1), c = 14,490(3) Å, β = 106,91(2)°, V = 1140,5 Å3, Dx(Z = 4) = 1,398 g · cm-3, MW = 240,20, mp = 80°C) forms hygroscopic white needle-like crystals. The structure was solved by direct methods and the final R value is 0,068. The geometry around the phosphorus is trigonal bipyramidal with two five-membered rings in the apical-equatorial planes. The three P-O bond lengths are 1,615(5) (equatorial), 1,670(4) and, 1,808(4) Å (apical).
    Additional Material: 3 Ill.
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  • 200
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    Die Makromolekulare Chemie 185 (1984), S. 877-890 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(allylbenzene)s were synthetised by Ziegler-Natta catalysts: {VCl3 + Al[CH2CH(CH3)2]3} and {TiCl4 + Al[CH2CH(CH3)2]3}. Two different polymers were obtained. Examination of their microstructures by IR and 1H13C NMR spectroscopy suggests that one of the polymerization mechanisms proceeds via isomerization of allylbenzene.
    Additional Material: 6 Ill.
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