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  • Polymer and Materials Science  (8)
  • thermal conductivity  (3)
  • 1-substituted 1-oxo-1,2-dihydro-4H-3,1-benzoxaphosphorins  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Thermal conductivity of difluoromonochloromethane in the critical region (1991)
    Springer
    International journal of thermophysics 12 (1991), S. 53-65 
    Details
    ISSN: 1572-9567
    Schlagwort(e): critical phenomena ; difluoromonochloromethane ; refrigerants ; R22 ; thermal conductivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The thermal conductivity of difluoromonochloromethane (refrigerant R22) has been measured along six near-critical isotherms at reduced temperatures varying from τ=1.005 to τ=1.112 and at pressures ranging from 2.0 to 9.5 MPa. An anomalous enhancement of the thermal conductivity has been observed in the critical region. This anomalous behavior is consistent with theoretical predictions and equations for the thermal conductivity as a function of density and temperature are presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00506122
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  • 2
    Digitale Medien
    Digitale Medien
    The thermal conductivity of binary mixtures of liquid R22 with R142b and R152a at low temperatures (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 597-606 
    Details
    ISSN: 1572-9567
    Schlagwort(e): binary mixtures ; low temperatures refrigerants ; R22 ; R1426 ; R152a ; thermal conductivity ; transient method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The paper presents the thermal conductivity of mixtures of liquid refrigerants, The group of systems studied consists of two binary mixtures of R22/R142b and R22/R152a. The measurements have been carried out in the temperature range 160–300 K for pressures From 0.2 to 8.0 MPa in a transient coaxial-cylinder instrument. The uncertainty of the thermal conductivity data is estimated to be ±2%. The experimental method and apparatus were validated by using the measurements of refrigerant R22. The results presented have been used to develop a correlation for the description of the thermal conductivity of refrigerants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01441506
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  • 3
    Digitale Medien
    Digitale Medien
    Thermal conductivity of refrigerants R123, R134a, and R125 at low temperatures (1994)
    Springer
    International journal of thermophysics 15 (1994), S. 203-214 
    Details
    ISSN: 1572-9567
    Schlagwort(e): chloroffuorocarbons ; fluorocarbons ; isobaric heat capacity ; refrigerants ; R123 ; 11125 ; R134a ; saturated liquid ; thermal conductivity ; transient method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Using a transient coaxial cylinder technique, thermal conductivities were measured for liquid 1,1,1-trifluoro-2,2-dichloroethane (refrigerant R123), 1,1,1,2-tetrafluoroethane (refrigerant R134a). and pentalluoroethane (refrigerant R 125). The uncertainty of the experimental data is estimated to be within 2–3 %. Thermal conductivities of refrigerants were measured at temperatures ranging from −114 to 20°C under pressures up to IOMPa. The apparatus was calibrated with four kinds of liquids and gases. The features of the density dependence of thermal conductivity are indicated. Existing equations for calculating the coefficient are analyzed in cases where development has been sufficient to enable comparisons to be made with experiment. Saturated-liquid thermal conductivities for R134a and R123 are compared with corresponding experimental values.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01441582
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  • 4
    Digitale Medien
    Digitale Medien
    Synthesis and structure of 1-substituted 1-Oxo-1,2-dihydro-4H-3,1-benzoxaphosphorins (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 1704-1708 
    Details
    ISSN: 1573-9171
    Schlagwort(e): synthesis ; 1-substituted 1-oxo-1,2-dihydro-4H-3,1-benzoxaphosphorins ; structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract 1-X-1-Oxo-1,2-dihydro-4H-3,1-benzoxaphosphorins (X = CH2Cl, Ph, and OH) were obtained by reacting ortho-(butoxymethoxymethyl)phenylmagnesium bromide with derivatives of chloromethylphosphonic and chloromethylphosphinic acids, followed by intramolecular alkylation. X-Ray diffraction was used to study the molecular and crystalline structure of one of these compounds (with X = OH).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00863597
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  • 5
    Digitale Medien
    Digitale Medien
    Molekulare Konformation, hydrodynamische, dynamooptische und elektrooptische Eigenschaften von Polymeren mit Leiterstruktur in Lösungen (1972)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 160 (1972), S. 1-26 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The specific character of structure of ladder polymers that leads to sharp decreasing of flexibility of molecular chain requires the foundation of new approaches in investigating the structure and physical properties of these polymers.Experimental data on investigation of conformation, hydrodynamic, optical and electrical properties of some ladder polymers on the basis of polysiloxane chains in solution are listed and the analysis of these data using modern theories of persistent, worm-like molecular chains and chains with non-gaussian optical properties are carried out. On the basis of this analysis the quantitative conclusions about conformation, flexibility and possible defectness of double-chain structure of some investigated ladder polymers of various chemical composition are made.
    Notizen: Die Eingentümlichkeit des doppelkettigen Baus von Leiterpolymeren, die zu einer starken Verringerung der Biegsamkeit der Molekülkette führt, erfordert die Ausarbeitung neuer theoretischer und experimenteller Methoden bei der Aufklärung der Struktur und der physikalischen Eigenschaften dieser Polymeren.Es werden experimentelle Ergebnisse der Untersuchungen von Konformation, hydrodynamischen, optischen und elektrischen Eigenschaften in Lösung für eine Reihe von Leiterpolymeren aus Polysiloxanketten angeführt. Diese experimentellen Ergebnisse werden unter Hinzuziehung moderner Theorien (Theorie von Persistenz-Ketten, „wurmförmiger“ Ketten und Ketten mit nichtgaußschen optischen Eigenschaften) ausgewertet und quantitative Schlußfolgerungen über molekulare Konformation, Biegsamkeit und mögliche Defekte der doppelkettigen molekularen Struktur der untersuchten Leiterpolymeren unterschiedlicher chemischer Struktur gezogen.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1972.021600101
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  • 6
    Digitale Medien
    Digitale Medien
    Stereospecificity and optical properties of polymersPresented at the IUPAC International Symposium on Macromolecular Chemistry, Moscow, June 1960. (1961)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 54 (1961), S. 635-643 
    Details
    ISSN: 0022-3832
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Practically the only physical method of determining stereoregularity is x-ray analysis, permitting one to judge the presence of a crystalline structure in a given polymer. However, crystallinity is a phase property, only indirectly reflecting the molecular structure of a substance. It is well known that a stereospecific polymer may be both in the crystalline and in the amorphous states. It is therefore highly important to find a property of the polymer which would directly (and unilaterally) indicate stereoregularity in its structures. Attempts to use the geometrical properties of molecular chains for this purpose have up to the present been unsuccessful, the sizes of macromolecules in solution (as determined by viscometry or light scattering) being found to be independent of stereoregularity. In the present work another approach has been sought, the attempt being made to ascertain whether the optical anisotropy of a molecule would be a more sensitive index of the stereospecificity of the molecular chain. With this in mind the flow birefringence was investigated, of solutions of polystyrene (from Dzerzhinsk) and of polymethylmethacrylate (from the laboratory of A. A. Korotkov) with varying degrees of stereoregularity. Experimental investigation of both polymers showed a marked increase in the segmental anisotropy α1 - α2 of the macromolecules when passing from the atactic to the isotactic specimens. Thus for atactic polystyrene α1 - α2 = 140 × 1025 cm3. whereas for isotactic polymer, α1 - α2 = 200 × 10-25 cm3. In the case of polymethyl methacrylate the difference was still greater. The increase in α1 - α2 in the case of polystyrene may be explained by the increased hindrance to rotation of the phenyl side chains on transition from the atactic to the isotactic polymer. The interpretation in the case of polymethyl methacrylate is not so evident and requires further elucidation. At the same time the fact itself of the influence of the stereoregularity of a polymer chain on its optical properties lays open the possibility of utilizing the latter to characterize the former.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1961.1205416027
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  • 7
    Digitale Medien
    Digitale Medien
    Stereoregularity and optical anisotropy of polymers (1962)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 57 (1962), S. 727-741 
    Details
    ISSN: 0022-3832
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The flow birefringence and the photoelastic effect in films have been used to study the molecular optical anisotropy of stereoisomers of polystyrene (PS), poly(p-methyl styrene) (PMS), poly(methyl methacrylate) (PMMA), and poly-(n-butyl methacrylate) (PBMA). Considerable differences in the optical anisotropy are observed between the atactic and isotactic structures of the molecular chain. These differences change in value and sign for various polymers and in some cases cause a change of the sign of the birefringence. The observed effect is due to the difference between the character of the rotation of the side radicals of the macromolecule in the isotactic and atactic isomers. The molecular optical anisotropy is shown to be especially sensitive to side group rotation in those cases where the positive anisotropy of the principal molecular chain is to a considerable degree compensated by a negative anisotropy of similar absolute value in the side groups. In these cases the study of the molecular optical anisotropy may serve as a sensitive method for studying the stereoregularity. The strain birefringence observed in films of crystallizable polymers is a sum of the two effects: the orientation of chains in the amorphous phase and the orientation of the stereoblocks forming crystallites. These two processes can be differentiated owing to differences in their time dependences, and experimental study of these may serve as a sensitive method for revealing traces of a crystalline phase in a polymer.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1962.1205716558
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  • 8
    Digitale Medien
    Digitale Medien
    Dynamic flow birefringence, optical anisotropy, and shape of macromolecules in solutions (1957)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 23 (1957), S. 151-166 
    Details
    ISSN: 0022-3832
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The experimental study of the dynamic double refraction in polymer solutions in different solvents shows a parabolic dependence of the dynamooptical constant from the refractive index of the solvent. This character of the said dependence can be explained qualitatively in terms of the molecular coil asymmetry; it can be interpreted quantitatively on the basis of the equivalent molecular ellipsoids model. The investigation of the Maxwell effect in a series of polymer fractions with different MW gives the following law: If the refractive indexes, ns and nk of the solvent and polymer are equal, the ratio [n]/[η] is independent of the MW. Here [η] is the dynamooptical constant and [η] is the intrinsic viscosity. If the value of nk - ns is high enough, the ratio [n]/[η] increases as the MW becomes higher and sometimes changes the sign. This law is determined also by the form anisotropy of macromolecules. It agrees well with the theory of equivalent ellipsoids. This theory can be used for the quantitative interpretation of the experimental results. It gives the estimation of the value of the molecular coil asymmetry in agreement with Kuhn's theory. In some cases (e.g., polystyrene in dioxane) the experiment shows change of sign of double refraction as the flow velocity gradient increases. This effect can be explained also by the equivalent molecular ellipsoids theory. As the molecular chains are uncoiling in the field of flow velocity gradient, their intrinsic optical anisotropy increases more than the form anisotropy. The comparative study of photoelasticity in the films of some polymers and of dynamic double refraction in their solutions shows the direct dependence of both effects to be in accordance with Kuhn's statistical theory.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1957.1202310315
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  • 9
    Digitale Medien
    Digitale Medien
    A study of diffusion in polymer solutions by the use of the polarization interferometer (1958)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 30 (1958), S. 187-200 
    Details
    ISSN: 0022-3832
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The use of the polarization interferometer and the further perfection of the experimental technique makes possible the measurement of diffusion coefficients between solutions whose concentrations differ by less than 10-4 g./cm.3 These circumstances permit the direct measurement of the differential diffusion coefficient, D, corresponding to the given concentration c. The concentration dependence of the diffusion coefficient obtained for fractions of polystyrene in the region of not too small concentrations agrees well with the concentration dependence of the scattering of light in the same samples. In the region of low concentrations, the curve of the dependence D = D(c) has a horizontal section which cannot be described by the formulas usually used. In the region of concentrations, where the dependence D = D(c) may be considered as a rectilinear one, it is shown experimentally that the integral coefficient of diffusion between solutions whose concentrations differ by c1-c2 is equal to the mean of two differential diffusion coefficients, D1 and D2, where D1 = D(c1) and D2 = D(c2). In that region of concentrations, the integral diffusion curve shows a marked asymmetry, which agrees with the concentration dependence of the differential diffusion coefficient. The measurement of the diffusion coefficient D in dilute solutions of fractions of a series of polymers shows that the value of D is inversely proportional to the radii of the high polymer molecules calculated from viscosity and from light scattering data. The value of the empirical constant was determined, which permits the determination of the radius of the molecules from the measured values of the diffusion coefficient.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1958.1203012116
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  • 10
    Digitale Medien
    Digitale Medien
    The effects of shape in streaming birefringence of polymer solutions (1958)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 30 (1958), S. 297-314 
    Details
    ISSN: 0022-3832
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In this paper are presented new results obtained during further experimental and theoretical investigations of the form effect in the dynamic double refraction of polymers in solution. The use of the dumbbell theory of W. Kuhn for flexible chains in solution and of the optical modle of an equivalent ellipsoid for the macromolecule, permits the formulation of a theory of flow birefringence which takes account of the form effect for a wide range of shear rates. The conclusions of this theory are compared with new experimental data obtained in a study of polystyrene and p-tert-butylphenylmethacrylate in different solvents. In the range of low shear rates and concentrations, the theory is found to be in a good accord with experimental results. On the contrary, the study of the double refraction of several polystyrene fractions in dioxane in a wide range of shear rates and concentrations shows that macromolecules are less deformable in the flow than it follows from the dumbbell theory for ideally flexible chains. A new phenomenon was discovered experimentally - an anomalous dependence of the orientation angle on the shear rate of flow in the range of shear stresses at which the birefringence changes its sign because of compensation of the positive shape effect by the negative intrinsic anisotropy effect. Investigation of the concentration dependence of flow birefringence shows that this dependence is due to two causes - the hydrodynamic and optical interaction of the molecules. The optical interaction is characteristic only for those solutions in which the form effect takes place. A simple theory of concentration dependence of the form effect is proposed which is in good accordance with experimental data.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pol.1958.1203012124
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