摘要:

AbstractTrimeric phosphonitrilic chloride, when purified by a sequence of operations involving recrystallization, refluxing at 130°C. over barium oxide in an atmosphere of dry nitrogen, passage of the vapor at 130°C. over phosphorus pentoxide, followed by repeated sublimation with degassing in a high‐vacuum, all‐glass apparatus, polymerizes only very slowly at 300°C., and polymerization is sharply accelerated on admission of dry oxygen. Crude trimer, which was purified by only a single vacuum sublimation, polymerized relatively rapidly at 270°C. The conversion–time curve for the highly purified trimer shows a continuously accelerating rate of polymerization up to high conversion at 320

ISSN:0449-2994    

DOI:10.1002/polc.5070160703

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractElectron spin resonance measurements on the systems TiCl4(Al(C2H5)Cl2)2, TiCl3‐CH3(Al(C2H5)Cl2)2, and TiCl4(Al(C2H5)2Cl)2have revealed the formation of a particle with an unpaired electron, S, the concentration of which could be continuously followed with time. The kinetics of the former two systems are estimated and a mechanism for the reduction of the Ti(IV) compounds is proposed. It is shown that the concentration of the unpaired electrons equals the concentration of trivalent titanium in solution. The rate of polymerization of ethylene with the catalyst TiCl4 (Al(C2H5)2Cl)2proves to be proportional to the concentrations of unpaired electrons. The structure of the particle carrying the unpaired electron is probably a complex consisting of TiCl3and the dimer aluminum alkyl

ISSN:0449-2994    

DOI:10.1002/polc.5070160704

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractA significant inner photoeffect in organic polymers with triple bonds R+CCR1CC+nR, and the metal polyacetylenides RCCM has been found and investigated by means of direct‐current photoconductivity and photoelectromotive force in intermittent light. The dependence of the photocurrent on the light intensity can be expressed by the equationiph≐ αLn, where 0.5

ISSN:0449-2994    

DOI:10.1002/polc.5070160705

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe kinetics of the polymerization of α‐methylstyrene by naphthylsodium at −78°C. in tetrahydrofuran has been studied for elucidating the mechanism of the polymerization. The experimental relationships obtained are accounted for by an assumption that the polymerization proceeds by the “coordination” mechanism and 4 elementary reactions take place: (1) generation of the active centers of polymerization; (2) chain propagation; (3) chain termination; (4) reaction of chain propagation upon the organometal compounds formed as a result of the termination reaction (upon the “living” polymers).This latter reaction proceeds without termination. In solving kinetic equations reduced time φ = ∫0τm·dτ is introduced heremis the monomer concentration and τ is the time. The apparent values of the constants of elementary reactions are determined from the dependence of the number‐average degree of polymerization\documentclass{article}\pagestyle{empty}\begin{document}$ \[\bar p\] $\end{document}on the initial catalyst concentrationn0and from the dependence of conversionXon reduced time φ. The coincidence of the expected relationshipX=F(τ,φ) with those experimentally found was traced with an electronic computer over all the range ofXvalues. Equations are derived for the dependence of the polymerization rate upon the initial concentration of the catalyst and for the molecular weight distribution of the polymer. Experimental points appear to agree with the calculated data. The curve of the molecular weight

ISSN:0449-2994    

DOI:10.1002/polc.5070160706

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractConformations of linear chain molecules of X(CH2O)nX type were studied by infrared spectra of polyoxymethylenes (POM) and oligomers of CH3O(CH2O)nCH3type (n= 3–8). The study was performed at broad ranges of temperature (−80°C.– +200°C.). Infrared spectra of liquid oligomers point at preference of the helical conformation for these compounds.Bands of unstable isomers were found which disappeared under “freezing up” conditions. The results are the following: (a) the helical conformation of the isolated polyacetalic backbone molecules are the most advantages; and (b) rotational isomerism in th

ISSN:0449-2994    

DOI:10.1002/polc.5070160707

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractNucleophilic additives and potassium and sodium chlorides, complexing with alkyl aluminum chlorides, are shown to result in an increase in the 1,2 structure of polybutadiene and a sharp decrease in molecular weight and polymerization rate. Trialkyl aluminum behaves in a similar way. There exists a correlation between these effects and the reducing power of the system. A mechanism of the influence of various compounds on the polymerization process is proposed. A mechanism of the formation of 1,4 and 1,2 polymer units is discussed with respect to the role of π‐allylic systems in diene polymerization and the nonequivalence of carbon atoms bonded to metal atoms in π‐crotylic sy

ISSN:0449-2994    

DOI:10.1002/polc.5070160708

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe antioxidative behavior of 2,2′‐bis(4‐methyl‐6‐tert‐butylphenols) in polypropylene were investigated with and without dilauryl‐thio‐dipropionate. The experimental methods used in this study were thermogravimetric analysis for determining sample weight loss and differential thermoanalysis for obtaining information on oxidative processes and induction periods. The best antioxidant found was the dithio group bridged compound. The methylene‐,n‐butylidene‐, cyclohexylidene‐, and thio‐bridged systems were less active antioxidants. All compounds showed synergism with DLTP. The effectiveness of the synergistic mixtures decrease with decreasing activity of the bisphenol compounds. The pure dithio‐bridged compound was a better antioxidant in polypropylene than is its “s

ISSN:0449-2994    

DOI:10.1002/polc.5070160709

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe polyesterification reaction in relation to proton catalysis was studied. The polycondensation reactions of maleic, fumaric, phthalic, succinic, adipic, and sebacic acids with various glycols were studied in the melt without catalysts. The results were classified into two groups. In the first group belong those reactions which proceed in the initial stage at a considerably greater rate than in the main stage, which kinetically is second order. The reactions of acids with greatly differing first and second dissociation constants, and with a high first dissociation constant, belong into this group. Acids with a relatively small difference between their first and second dissociation constants and a lower first dissociation constant belong in the second group. A reaction order of 2.5 was obtained for these acids. To provide evidence for a correlation between the auto‐catalytic effect and the dissociation constant, maleic and fumaric acids were esterified with methyl alcohol both with and without a foreign acid catalys

ISSN:0449-2994    

DOI:10.1002/polc.5070160710

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractIt has been demonstrated that electric regeneration of so‐called bipolar electrolyte exchange resins into the H+OH−form may take place between permselective ion‐exchange membranes provided that the resin was placed in an aqueous medium. The level of regeneration of cation and anion capacities depends on the ratio of the amount of cationic and anionic active groups\documentclass{article}\pagestyle{empty}\begin{document}$ \[\underline{\underline + } \] $\end{document}index in the resin. In resins of ±>1 type the cation exchange capacity in H+form—expressed in percentage of total cation exchange capacity—is constantly higher than the anion exchange capacity in OH−form, /expressed in the same way/ while in the case of\documentclass{article}\pagestyle{empty}\begin{document}$ \[\underline{\underline + }> 1\] $\end{document}<1 type resins the situation is inversed. An explanation has been given for the mechanism of this phenomenon. A method has been elaborated for the determination of H+and OH−capacitie

ISSN:0449-2994    

DOI:10.1002/polc.5070160711

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

ISSN:0449-2994    

DOI:10.1002/polc.5070160712

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY