摘要:

AbstractDouble oriented fiber spectra of syndiotactic polypropylene were obtained. It was possible to redetermine with greater accuracy the unit cell constants, which are:a= 14.50,b= 5.60,c= 7.40 A. Space group:C2221. It was proved that the chain hass(2/1)2 symmetry, corresponding to a succession of internal rotation angles A2B2A2B2. The agreement between experimental and calculated intensities on thehkllayers withl= 0, 1, 2, 3 up to the lowest observed Bragg distance (about 2 A.) is good for the packing model proposed. The structural results are briefly discussed.

ISSN:0449-2994    

DOI:10.1002/polc.5070160503

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

年代:1967

数据来源: WILEY

摘要:

AbstractSome data on the kinetic behavior of the catalytic system VCl4–Al(C2H5)2Cl, which is stereospecific (at low temperatures) for the polymerization of propylene to syndiotactic polymer, are reported here. The effect was studied of the reaction time and of the concentration of VCl4, of Al(C2H5)2Cl, and of the monomer on the polymerization rate, on the molecular weight, and on the index of syndiotacticity of the polymers obtained. The data reported are discussed on the basis of the hypotheses previously put forth about the nature of the catalytic complexes and the polymerization mechanis

ISSN:0449-2994    

DOI:10.1002/polc.5070160504

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

年代:1967

数据来源: WILEY

摘要:

AbstractData on the behavior of different heterogeneous catalyst systems in the polymerization ofα‐olefins to isotactic polymer are reported and compared. The effect of substituents on the kinetic behavior of the catalyst complexes, which in the different systems yield polymeric chains having comparable steric regularities, was investigated. Moreover, hypotheses are put forth on the factors influencing the stereospecificity of the catalyst systems studi

ISSN:0449-2994    

DOI:10.1002/polc.5070160505

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

年代:1967

数据来源: WILEY

摘要:

AbstractThetrans‐anti‐trans‐anti‐transisomer of perhydrotriphenylene C18H30forms crystalline inclusion compounds with linear macromolecules, such as polyethylene, 1,4‐polybutadiene, and poly(oxyethylene glycol). The main results concerning the constitution, determined by x‐ray diffraction and by differential thermal analysis, as well as the stability of these compounds, are reported here. Moreover, studies were made on the polymerization of various monomers included in PHTP byγ‐rays radiation. In several cases, an inclusion compound of the polymer in PHTP is obtained from such a reaction. A high degree of stereoregularity has been observed for some of the polymers obtained (e.g., polydiolefins); the first reported example of an isotactic polymer obtained byγ‐rays polymerization is due to the above method; it is the isotactictrans‐

ISSN:0449-2994    

DOI:10.1002/polc.5070160506

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

年代:1967

数据来源: WILEY

摘要:

AbstractButadiene has been polymerized byπ‐allyl‐Ni‐halides (I) to low molecular weight stereoregular polymers, with either benzene,n‐pentane, tetrahydrofuran, cyclohexanol, or ethyl alcohol used as solvents. Solid polymers and oily products were simultaneously obtained as polymerization products. In benzene as solvent,π‐allyl‐Ni‐I andπ‐allyl‐Ni‐Br gave predominantlytrans‐1,4 polymers, whileπ‐allyl‐Ni‐Cl gave polymers largely composed ofcis‐1,4 units. In the other solvents predominantlytrans‐1,4 polymers were obtained, irrespective of the nickel derivative used. By reactingπ‐allyl‐Ni‐Br, in benzene solution, with either AlBr3, Al2(O‐i‐C3H7)3Br3, BF3or TiCl2(O‐i‐C3H7)2, complexes were obtained (II) which polymerize butadiene to predominantlycis‐1,4 polymers. Evidence is reported that these complexes are of ionic type and contain the cationThe different stereospecificity observed in the polymerizations by I and II is interpreted on the basis of the different mode of coordination of but

ISSN:0449-2994    

DOI:10.1002/polc.5070160507

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

年代:1967

数据来源: WILEY

摘要:

AbstractHigh resolution 60 and 100 Mc. NMR spectra have been obtained for a series of deuterated polypropenes with compounds of the highest sterical purity used. The fundamental parameters of the spectra (chemical shifts and coupling constants) have been accurately determined and compared with previous results available in the literature. The results may be applied to quantitative estimates of the stereoregularity of polymers not deuterated by the NMR method.

ISSN:0449-2994    

DOI:10.1002/polc.5070160508

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

年代:1967

数据来源: WILEY

摘要:

Abstracttrans‐Polypentenamer, like natural rubber, crystallizes under stretching at room temperature. The x‐ray fiber spectra of crystallinetrans‐polypentenamer can be interpreted on the basis of an orthorhombic unit cell whose identity periods in A. units are:a= 7.28 ± 0.10;b= 4.97 ± 0.05;c= 11.90 ± 0.10 (chain axis);Z= 4(C5H8);dcalo= 1.049 g./cm.3. Probable space groupsC92v(Pna21) orD162h(Pnam). Atomic positions were deduced by trial and error. The (CHCHCH2CH2CH2) monomeric units repeat along a twofold helix. The molecular packing in the crystal state is essentially regulated by the H atoms of the CH2groups. The packing of thetrans‐polypentenamer molecules is very similar to the packing found for ort

ISSN:0449-2994    

DOI:10.1002/polc.5070160509

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

年代:1967

数据来源: WILEY

摘要:

AbstractOn the interaction of bis(aeetoacetyl)phenyl ether, 1,2‐bis(acetoacetyl)diphenyl ethane and sebacyl diacetone with beryllium acetylacetonate coordination polymers of high molecular weight have been synthesized. Kinetics of polycoordination of bis(acetoacetyl)phenyl ether with beryllium acetylacetonate in solution at 55–85°C. have been studied. The reaction is reversible and proceeds as a bimolecular process with activation energy in dimethylformamide at 25 kcal./mole. It was established that there are exchange reactions proceeding extraordinary easily (in solution already at room temperature) between units of coordination polymers. In concentrated solutions there occurs chiefly an intermolecular interaction between macromolecules of different length. In diluted solutions under influence of entropy factor principally intramolecular exchange reactions take place leading to degradation of the polymer with formation of macrocyclic products. Degradation of the coordination polymer of sebacyl diacetone with the beryllium resulted in the formation of a macrocyclic monomeric complex of sebacyl diacetone with beryllium with fair yield. The influence of solution concentration and temperature on the equilibrium linear polymer ⇌ macrocycles have been cons

ISSN:0449-2994    

DOI:10.1002/polc.5070160510

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

年代:1967

数据来源: WILEY

摘要:

AbstractThe decay of peroxy radicals was measured during the course of grafting styrene onto irradiated poly(tetrafluoroethylene) films. A linear decay was observed up to the time when the film was grafted through its whole thickness. The results of the electron spin resonance measurements could be correlated with the kinetic picture given earlier. In some cases, as a result of grafting, the appearance of fluorocarbon radicals was observed.

ISSN:0449-2994    

DOI:10.1002/polc.5070160511

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

年代:1967

数据来源: WILEY

摘要:

AbstractTheγ‐radiation‐initiated polymerization of NVSI in both the liquid and solid phases proceeds according to a radical mechanism. Polymerization rate and molecular weight of the product are higher in the liquid phase than in the solid phase. A number of features characteristic of monomers polymerizing according to accelerated kinetics can be demonstrated on the model of NVSI, which in many respects behaves similarly to acrylic amide. Kinetical data, the polymer formed and the accelerating effect of inert additives, the amorphous structure of the polymer formed, the high activation energy of polymerization, as well as the isotropic ESR spectrum of the assumed growing radical, are all findings which prove that in the course of growth the monomer molecule must leave the crystal lattice, that is, that the geometry of the crystal lattice does not favor polymeriza

ISSN:0449-2994    

DOI:10.1002/polc.5070160512

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

年代:1967

数据来源: WILEY