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  • 1
    Digitale Medien
    Digitale Medien
    Organotin polymers.I. Copolymerization on tributyltin methacrylate with (hydroxy) alkyl methacrylates (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 595-599 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Copolymers of tributyltin methacrylate (M1) with cyclohexyl methacrylate, ethoxyethyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate were synthesized in solution at 55°C utilizing azobisisobutyronitrile initiator. Copolymer compositions were determined by tin analysis; monomer reactivity ratios were calculated by Kelen-Tüdös method. Since the reactivity ratios indicate the distribution of different monomer units in the polymer chain, the measured values are compared and discussed. Preliminary results of the biotoxicity studies on some of the copolymers are also reported.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1988.080260222
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  • 2
    Digitale Medien
    Digitale Medien
    A molecular model for solid-state polymerization of nylon 6 (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 507-520 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A theoretical model is developed for the effect of segmental diffusion on reversible step growth polymerization. This model is an adaptation of the molecular model of Chiu et al. for characterizing the Trommsdorff effect in free-radical polymerization. The model is applied to the specific case of solid-state polymerization of spherical pellets of nylon 6. The results of the simulation are found to show qualitative trends as found by Gaymans et al. experimentally. The parameters of the model are curve fitted to their data using an optimal parameter estimation computer code. It is found that the optimal values of the parameters, which can be independently measured, are quite close to the values reported in the literature. The effect of varying the individual parameters on the progress of polymerization is also studied.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1992.070450315
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  • 3
    Digitale Medien
    Digitale Medien
    Effect of shear rate on solution polymerization of acrylonitrile (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1184-1189 
    Details
    ISSN: 0032-3888
    Schlagwort(e): Chemistry ; Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Application of shear is found to increase the rate of solution polymerization of acrylonitrile in N,N-dimethyl formamide (DMF) initiated by benzoyl peroxide by as much as 400 percent of the value in absence of shear. The solvent DMF acts as an inert and maintains a homogeneous reaction mass during the entire course of polymerization. To study the effect of shear systematically, a special dilatometer has been constructed such that a constant shear rate, \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \gamma \limits^. $\end{document} could be applied to the reaction mass. The rule of solution polymerization has been measured under the variation of \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \gamma \limits^. $\end{document} and monomer concentration in the system. The measurements of induction time on the addition of a strong inhibitor, hydroquinone, reveal that the increase in the rate of polymerization with shear rate can be largely attributed to the change in the initiator efficiency. As a further confirmation of the above hypothesis, the decomposition of benzoyl peroxide in nitrobenzene at 80°C was measured and was found to increase significantly on application of shear. This confirms the importance of mass-transfer resistance in removal of CO2, and the increase in the rate of polymerization of acrylonitrile occurs because the decomposition of benzoyloxy radicals is favored in the forward direction. Since the polymerization of acrylonitrile is preferentially initiated by phenyl radicals, the rate of polymerization is found to increase.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pen.760221803
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  • 4
    Digitale Medien
    Digitale Medien
    Modelling of reversible poly(ethylene terephthalate) reactors (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 4421-4438 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The second stage of batch poly(ethylene terephthalate) (PET) reactor with bis(2-hydroxyethyl) terephthalate (BHET) as the feed has been simulated. In this stage, the overall polymerization is not diffusion limited and is known to be a complex reaction. In this work it has been assumed to consist of polycondensation, reaction with monofunctional compounds (cetyl alcohol), redistribution, and cyclization reactions. The forward and reverse steps of each of these have been modelled in terms of the rate constants involving functional groups and the reacted bonds. The equations for the calculation of the molecular weight distribution (MWD) in batch reactors have been written and solved numerically. The MWD reported in this work is assumed to include the monofunctional products only, and, for the case where ethylene glycol is not removed from the reaction mass, it was found to be unaffected by the choice of the redistribution rate constant (kr). Since the removal of ethylene glycol is not mass transfer controlled, its concentration in the reaction mass is assumed be given by the vapor-liquid equilibrium existing at the pressure applied on the reactor. In this work, the level of ethylene glycol concentration, yg (≡[G]/[P1]0), has been taken as a parameter, and, on application of vacuum, the MWD results were found to vary with kr with the sensitivity increasing with yg. It was then shown that the importance of the redistribution reaction is enhanced when the cyclization reaction also occurs. The effect of vacuum on the performance of the reactor has been studied by varying yg. For yg less than 0.01, the change in the MWD of the polymer becomes very small. The effects of polymerization temperature and initial concentration of monofunctional compounds on MWD were found to be small.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1982.070271131
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  • 5
    Digitale Medien
    Digitale Medien
    Development and evaluation of a novel binder based on natural rubber and high-energy polyurethane/composite propellants (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 1095-1112 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Hydroxyl terminated natural rubber (HTNR) was prepared by the depolymerization of masticated natural rubber in the presence of H2O2 in toluene. Probable mechanisms leading to the formation of side reaction products are proposed based on the analytical data. A comparative study of some formulation variables was made for their effect in improving the flow characteristics and mechanical properties of an aluminized polyurethane (PU) propellant system based on HTNR. This PU system has also been compared for its theoretical performance characteristics with some other state-of-the-art systems.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1985.070300317
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  • 6
    Digitale Medien
    Digitale Medien
    Optimization of an industrial semibatch nylon 6 reactor (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 57 (1995), S. 209-218 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An industrial semibatch nylon 6 reactor has been optimized using a one-variable (at a time) search technique. The vapor release rate from the reactor and the final monomer conversion have been constrained to lie very close to the values currently present. The degree of polymerization of the product is , similarly, constrained to lie at a value of 152. The optimal pressure histories for two values of the jacket fluid temperature, Tj, have been evaluated using two objective functions, I1 and I3, namely, the total reaction time (I1 = tf) and the concentration of the cyclic dimer (I3 = [C2]f) in the product. It is observed that as Tj is increased from 270 to 280°C, I1 improves while I3 worsens simultaneously. This suggests that these two optimal points lie on the Pareto set for the two-objective function problem. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1995.070570209
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  • 7
    Digitale Medien
    Digitale Medien
    Structure and properties of polyblends of a thermotropic liquid crystalline polymer with an alloy of polyamide-6 and ABS (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 62 (1996), S. 1395-1405 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The relationship between the microstructure and corresponding mechanical properties developed during injection molding of blends containing a liquid crystalline polymer (LCP) as the minor component and an engineering polymer system has been studied. A wholly aromatic copolyester LCP (Vectra A950) was melt blended at different compositions with a thermoplastic matrix consisting of a commercial compatibilized blend of polyamide-6 and ABS (Triax 1180). These blends were prepared under two different sets of injection molding conditions. In the first case, a higher melt temperature, higher barrel temperature, lower injection pressure, lower mold temperature, and shorter residence time in the mold were used during injection molding, as compared with the second case. The mechanical properties of the blends were superior to those of the base polymer. In the second case, the resulting injection-molded specimens had a distinct skin-core morphology where elongated fibrils of LCP constituted the skin layer. The mechanical properties of the blends processed under the second set of processing conditions were superior to those of the first, though the trends in both cases were the same. To study the effects of process variables the 15% LCP blend and the second set of processing conditions were taken as the base. Samples were injection-molded by varying one parameter at a time. It was seen that the properties of the blend were increased by maintaining a lower barrel temperature, greater injection pressure, lower injection speed, higher mold temperature, and a greater residence time in the heated mold. Thus it was found that the processing conditions played a vital role in determining the mechanical properties and morphology of the polyblends. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Drying rates of polyamic acid solution film under (i) natural convection and (ii) induced draft drying conditions (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 4541-4552 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Drying rate studies were carried out with polyamic acid solution synthesized in the laboratory in dimethyl acetamide solvent, with a view to determine the process design parameters of a continous polyimide film casting machine. Studies reveal that drying under natural convection condition takes an unduly long time, whereas drying under induced draft/recirculation with partial recycle condition takes only ⅓ the time that of natural convection drying. Another important observation made was that under natural convection drying condition the initial adjustment period was too long and that the drying process was evenly spread over the initial adjustment, constant, and falling rates of the drying periods, whereas under induced draft condition drying mostly took place during the falling rate of drying period. The drying rate data obtained was used for generating the necessary process design, and operating parameters for a continuous polyimide film casting machine.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1986.070320419
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  • 9
    Digitale Medien
    Digitale Medien
    Chemistry of Substituted Sulphuric Acids. X. Acids and Bases in Methanesulphuric Acid Solvent System (1980)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 471 (1980), S. 203-207 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Chemie substituierter Schwefelsäuren. X. Lösungen von Säuren und Basen in MethansulfonsäurenMethansulfonsäure ist schwächer als Schwefelsäure. Eine Zahl von anorganischen protonischen Säuren wirken in Methansulfonsäure gelöst als Säuren, während starke Basen vollständig protoniert werden. Säure-Base-Titrationen in Methansulfonsäure zeigen bei starken Säuren, daß die elektrische Leitung über CH3SO3H2+ - und CH3SO3- - Ionen erfolgt. Leitfähigkeitsmessungen zeigen die Reihenfolge der Säurestärken, s. Abstract.
    Notizen: Methanesulphuric acid is weaker than sulphuric acid. A number of inorganic protonic acids act as acids in it while the strong bases are fully protonated. The acid-base titrations in it with strong acids indicate that the bulk of the current is carried by CH3SO3H2+ and CH3SO3- ions. The conductance measurements indicate that the order of the acid strength is: H[B(HSO4)4] 〉 HSO3F 〉 H2S2O7 〉 HAs(HSO4)4 〉 HSO3Cl 〉 H2SO4 〉 HX (X=Br 〉 Cl) 〉 H2SeO4.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19804710123
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  • 10
    Digitale Medien
    Digitale Medien
    On some Oxozirconium(IV) Compounds (1976)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 423 (1976), S. 91-96 
    Details
    ISSN: 0044-2313
    Schlagwort(e): Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Über einige Zirkonium (IV)-oxid-VerbindungenEinige neue Zirlconium(IV)-oxid-Komplexe, ZrO(An)2, ZrO(Gly)2, ZrO(HSal)2, ZrO(HPth)2, ZrO(Pic)2(HPic)2 und ZrO(Quin)2(HQuin)2 wurden dargestellt durch Reaktion von ZrO(CH3C00)2CH3COOH mit Anthranilsäure (HAn), Glycin (HGly), Salicylsäure (H2Sal), Phthalsäure (H2Pth), Picolinsänre (HPic) und 8-Oxychinolin (HQuin). Ihre wichtigsten IR-Banden und, soweit möglich, molaren Leitfähigkeiten und Molekulargewichte werden mitgeteilt.
    Notizen: Some new oxozirconium(IV) complexes: ZrO(An)2, ZrO(Gly)2, ZrO(HSal)2, ZrO(HPth)2, ZrO(Pic)2(HPic)2, and ZrO(Quin)2(H Quin)2 have been isolated from the reactions of ZrO(CH3COO)2CH3COOH with anthranilic acid (HAn), glycine (HGly), salicylic acid (H2Sal), phthalic acid (H2Pth), picolinic acid (HPic), and 8-quinolinol (HQuin) respectively. Their important infrared bands and wherever possible molar conductance and molecular weight have been reported.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/zaac.19764230113
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