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  • 1
    Electronic Resource
    Electronic Resource
    Poly(β-pinenes) carrying one, two, and three functional end groups. II. Syntheses and characterizationPart XX of New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers) (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 3229-3240 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conditions for the convenient synthesis of linear poly(β-pinenes) that carry one or two tert-chloro end groups (∼Clt) and three-arm star poly(β-pinenes) that carry three termini have been worked out. Specifically, the polymer with one ∼Clt end group was prepared by the H2O/BCl3 system, whereas those with two and three ∼Clt termini were prepared by the use of p-dicumyl chloride and sym-tricumyl chloride/BCl3 inifer combinations. The ∼Clt-terminated polymers were dehydro-chlorinated to yield the corresponding olefins. The molecular weights of the products were low enough to permit infrared (IR) and quantitative 1H-NMR investigations. Poly(β-pinene-b-tetrahydrofuran) diblock copolymers have been synthesized by inducing the polymerization of tetrahydrofuran (THF) by the Pβ—Clt/AgCF3SO3 initiating system.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170201118
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). VII. Synthesis and characterization of α,ω-di(hydroxy)polyisobutylene (1980)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 3177-3191 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new telechelic polyisobutylene diol, HO—CH2—PIB—CH2—OH, carrying two terminal primary hydroxyl end groups has been prepared from α,ω-di(isobutenyl)polyisobutylene, CH2=C(CH3)- CH2—PIB—CH2C(CH3)=CH2, by regioselective hydroboration followed by alkaline hydrogen peroxide oxidation. Infrared (IR) spectra, 1H-NMR analysis of the pure and silylated products, and ultraviolet (UV) spectra of phenylisocyanate-treated diols indicate quantitative yields and two —CH2OH termini per polyisobutylene chain. The viscosity of HO—CH2—PIB—CH2—OH is higher than that of the starting α,ω-diolefin. The telechelic diol prepolymer opens new avenues to the synthesis of many new materials, e.g., polyurethanes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1980.170181104
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  • 3
    Electronic Resource
    Electronic Resource
    Poly(β-pinenes) carrying one, two, or three functional end groups. I. The effect of reaction conditions on the polymerization of β-pinenePart XIX of New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers). (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 3219-3227 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: β-Pinene was polymerized with H2O/BCl3 (protic) and p-dicumyl chloride and sym-tricumyl chloride (nonprotic) inifer systems in CH2Cl2 or CH2Cl2/n-C6H14 solvents from -10 to -70°C. The effect of solvent polarity, temperature, and monomer and inifer concentration on conversions and molecular weights was investigated. Low conversions and molecular weights, M̄n = 1300-2500, obtained under these conditions suggest rapid termination.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170201117
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  • 4
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    An Application of the Difference Potentials Method to Solving External Problems in CFD (1997)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Numerical solution of infinite-domain boundary-value problems requires some special techniques that would make the problem available for treatment on the computer. Indeed, the problem must be discretized in a way that the computer operates with only finite amount of information. Therefore, the original infinite-domain formulation must be altered and/or augmented so that on one hand the solution is not changed (or changed slightly) and on the other hand the finite discrete formulation becomes available. One widely used approach to constructing such discretizations consists of truncating the unbounded original domain and then setting the artificial boundary conditions (ABC's) at the newly formed external boundary. The role of the ABC's is to close the truncated problem and at the same time to ensure that the solution found inside the finite computational domain would be maximally close to (in the ideal case, exactly the same as) the corresponding fragment of the original infinite-domain solution. Let us emphasize that the proper treatment of artificial boundaries may have a profound impact on the overall quality and performance of numerical algorithms. The latter statement is corroborated by the numerous computational experiments and especially concerns the area of CFD, in which external problems present a wide class of practically important formulations. In this paper, we review some work that has been done over the recent years on constructing highly accurate nonlocal ABC's for calculation of compressible external flows. The approach is based on implementation of the generalized potentials and pseudodifferential boundary projection operators analogous to those proposed first by Calderon. The difference potentials method (DPM) by Ryaben'kii is used for the effective computation of the generalized potentials and projections. The resulting ABC's clearly outperform the existing methods from the standpoints of accuracy and robustness, in many cases noticeably speed up the multigrid convergence, and at the same time are quite comparable to other methods from the standpoints of geometric universality and simplicity of implementation.
    Keywords: Aerodynamics
    Type: NASA-TM-110338 , NAS 1.15:110338
    Format: application/pdf
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