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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 14 (1981), S. 1831-1833 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 788-795 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new mathematical model has been developed for the continuous esterification process of terephthalic acid (TPA) and ethlene glycol (EG) with consideration of oligomer characteristics. The liquid weight fraction in the reaction mixture, β, has been selected as a principal parameter in this model. The solubility of TPA in EG and bis β-hydroxyethyl terephthalate (BHET) has been measured in order to estimate more precisely the concentration of each component. Good agreement has been obtained by plotting the log of solubility data of TPA in EG and BHET against the reciprocal of the absolute temperature with correlation coefficients of 0.998 and 0.989, respectively. The validity of these data has been verified in comparison with other data.
    Additional Material: 3 Ill.
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  • 3
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It has been confirmed that the reaction model proposed previously, which can express simultaneously the oligomer properties and the distillate properties under low esterification pressure, is applicable to a continuous direct esterification process in a practical plant. The experimental data of the first esterification reactor (RA-1) was obtained under low reaction pressures (atomospheric or 1 kg/cm2G) with the pilot plant throughput based on poly(ethylene terephthalate) (PET) polymer production of about 50 kg/h. The Arrhenius' parameters, frequency factor, and apparent activation energy, were determined fitting the experimental data of the pilot plant by using the Simplex method as an optimization technique. The activation energy of diethylene glycol (DEG) formation, E7, is about twice as much as those of the esterifications, E1, E2, E3, and E4. The activation energies are E1, = 19640 cal/mol, E2 = 18140, E3 = 22310, E4 = 18380, E5 = 2810, E6 = 14960, and E7 = 42520 cal/mol. Good agreement was obtained between experimental data and calculated predictions for several oligomer and distillate properties. The vapor-liquid equilibrium can be expressed by Raoult's law with little problem of practical use.
    Additional Material: 11 Ill.
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  • 4
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 2455-2464 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of the dielectric relaxation of three poly(sulfonyl-1-butylethylene)s, (PSB), of different molecular weights were carried out in benzene solutions of polymer contents from 3,0 to 50,0 wt.-%. It was found that the distribution parameter of the dielectric relaxation time was constant above a critical polymer contents and the activation energy increased with polymer contents. The observed relaxation time was analyzed by Fröhlich's theory assuming limiting relaxation times. The lower limit in the relaxation time, τ1, was independent of polymer contents above the critical polymer contents, in contrast to the upper limit relaxation time, τ2, which depended on polymer contents. The polymer contents dependence of the critical frequency below and above the critical polymer contents was interpreted by the free volume effect. The unperturbed molecular dimension at the critical polymer contents was also discussed.
    Additional Material: 7 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 3533-3543 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational energies of the lower members of poly(oxymethylene), 2,4-dioxapentane and 2,4,6-trioxaheptane were estimated by the empirical force field method. The gauche states of the internal rotation around the skeletal C—O bonds were successfully predicted to be of lower energies in both molecules. In order to calculate the unperturbed dimension and dipole moment of poly(oxymethylene), rotational isomeric state approximations were made by using the results obtained from the force field calculations on 2,4,6-trioxaheptane. The first-order interaction energy was estimated to be a large negative value, and the second-order interaction energies for g±g± had non-zero values. Although these parameters were significantly different from those estimated earlier, they reproduced the observed results fairly well. Thus the “gauche effect” of poly(oxymethylene) was explained by taking account of the effects contributed by the lone pairs of electrons on the oxygen atoms. As adopted in this study, the procedure joining the empirical force field method to the statistical mechanical one was shown to be effective for the investigation of many sorts of configuration-dependent properties of chain molecules.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 1343-1351 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electric dipole moments (per repeating unit) of cellulose acetate and tricarbanilate, and amylose acetate and tricarbanilate were determined in 1,4-dioxane solution at 30°C. The parallel component of the moment to the chain contour was also estimated for samples of various molecular weights, and they were almost independent on molecular weight, indicating no excluded volume effect on the dipole moment. The persistence dipole moment, and monomer dipole component along the chain contour for cellulose derivatives were about 50% smaller than those for amylose derivatives. The relation between the dipole moment and the chain dimension is discussed for cellulose- and amylose derivatives.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 3109-3117 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The electric dipole moments per repeating unit of ethylcellulose (EC) of various molecular weights were determined by dielectric measurements at 1 kHz (μL) and at 1 MHz (apparent moment, μH) in 1,4-dioxane and benzene. The numerical values were μL = 5,23 D (= 17,45.10-30 C·m) and μH + 2,72 D (= 9,07.10-30 C·m) for 1,4-dioxane, and μL = 4,81 D (= 16,04.10-30 C·m) and μH = 2,42 D (= 8,07.10-30 C·m) for benzene, respectively. μL and μH were almost independent of the molecular weight in both solutions. The persistence dipole moment μq was estimated to be 13,6 D (= 45,36.10-30 C·m) in 1,4-dioxane, and 13,4 D (= 44,70.10-30 C·m) in benzene, respectively, and the flexibility of the EC chain was discussed.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 1219-1223 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric measurements were made in the frequency range from 30 Hz to 3 MHz for a series of the solutions of poly(2-methylpent-1-ene sulfone) (PMPS) having two different molecular weights in benzene at 30°C. The unperturbed chain molecular dimension was estimated from dielectric relaxation time at the critical polymer contents, Ccr. This value of the unperturbed dimension was much higher than that from the intrinsic viscosity measurement. The dielectric motion at Ccr involves simultaneous co-operative reorientations of about three spheres. The number of the spheres of reorientation may be related to the flexibility of the molecular chain of the polymer. The ratio of two effective volumes of the polymer obtained from the unperturbed chain molecular dimension and from the dielectric relaxation time, τm agreed with that of the two effective volumes obtained from the K value in Onogi's treatment and from the τm value.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1515-1523 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The conformational energies for the various rotational isomers of model compounds for poly(oxytrimethylene), POM3, and poly(oxytetramethylene), POM4, were calculated by means of the empirical force field method, and statistical mechanics calculations were made for the configuration-dependent properties of POM3 and POM4. Although the dipole moment ratios of these polymers directly calculated from the results of the force field calculations agreed well with the observed ones, the estimated characteristic ratios did not agree with the observed ones. When the two geometric parameters of POM3 were changed, excellent agreement between the experimental values and the estimated ones was obtained. In case of POM4, when only geometric parameters were changed, the agreement was less satisfactory. The value for the interaction energy Eσ, which is directly derived from the result of the force field calculation for the model compound of POM4, seems to be overestimated because of a fault minimum. The value for the interaction energy Eσ is estimated to be the same as for POM3. Moreover, when the four geometric parameters were changed, the estimated values agreed well with the experimental ones. The direct use of the results of the force field calculations is not always satisfactory, but the parameters obtained are a good initial set of parameters to reproduce the observed configuration-dependent properties.
    Additional Material: 3 Tab.
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