摘要:

AbstractPolymerization of 1‐oxa‐3‐thiacyclopentane with catalytic amounts of triethyloxonium tetrafluoroborate was studied. The initiation reaction was a fast and quantitative formation of ethylsulfonium salt of monomer. The propagation reaction was a slow and quite complex reaction with sulfonium transfer reactions. The reaction mechanism is disc

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801001

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractThermodynamics of the polymerization of 2‐oxo‐1,3,2λ5‐dioxaphosphorinane in bulk initiated by sodium metal is described. Enthalpy (ΔHp= 6,28 ± 0,84 kJ · mol−1) and entropy (ΔS p0= 19,25 ± 2,51 J · mol−1· K−1) of polymerization were evaluated from the temperature dependence of the equilibrium nomomer concentration determined directly by31P{1H} NMR. The results are compared with those obtained previously for the polymerization of other 2‐alkoxy‐2‐oxo

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801002

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractThe thermal degradation behavior of head‐to‐head (H‐H) and head‐to‐tail (H‐T) polystyrenes and poly(vinylcyclohexane)s has been investigated by direct pyrolysis in a mass spectrometer. Both H‐H and H‐T isomers show only small differences in their initial temperatures of decomposition but remarkably different degradation processes. Whereas H‐T polystyrene decomposes in accordance with earlier investigations mainly by a radicalic depolymerization into the monomer and yields only a small amount of dimer and trimer, the H‐H polystyrene shows no unzipping and only a statistic degradation into oligomeric styrenes. The formation of stilbene is a diagnostic reaction of H‐H polystyrene. The pyrolysis‐mass spectra of H‐H and H‐T poly(vinylcyclohexane)s are more similar than those of the polystyrenes but the favored thermal cleavage between the two tertiary carbon atoms or next to the tertiary carbon atoms of the polymer backbone chain leads to some characteristic fragments, e.g. 1,3‐dicyclohexylpropene from the H‐T and 1,2‐dicycl

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801003

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractMethacrylic acid esters having two different and same kinds of nucleic acid bases such as theophylline‐theophylline, theophylline‐thymine, theophylline‐uracil, and uracil‐uracil, were synthesized, and polymerized in DMF or DMSO at 70°C using 2,2′‐azoisobutyronitrile as an initiator. The polymers obtained were found to have molecular weights in the range of about 1800‐4000, according to vapor pressure osmometr y and gel filtration measurement. The white powdery polymers were soluble in DMSO, DMF, and trifluoroacetic acid, but insoluble in water, alcohols, and common or

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801004

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractHydrogenations of several hydroxy‐terminated low molecular weight polybutadienes (PB) or non functional PB and one polyisoprene by homogeneous catalysis were studied. Hydrogenation of 1,4‐polybutadienes gave solid crystalline polymers. In the case of hydrogenated 1,2‐polymers a decrease of the glass transition temperature was noted, the hydrogenation leading to amorphous polymers. The rheological behaviour of oligomers was found to be Newtonian at low shear rates (≤ 100 s−1). The viscosity atTg+100°C increased in every case with the hydrogenation rate. It was found that hydrogen bonding induced by hydroxyl groups has a great effect on the glass transition temperature but does not change the viscosity a

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801005

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

Abstract2‐(2,4‐Dioxo‐1,2,3,4‐tetrahydropyrimidin‐1‐yl)methylsuccinic acid (2a) and 2‐(6‐aminopurin‐9‐yl)methylsuccinic acid (2b) were synthesized through the addition reaction of uracil and adenine, respectively, to dimethyl methylenesuccinate, followed by hydrolysis of the resulting dimethyl esters. Dicarboxylic acid2awas further converted to the corresponding di‐p‐nitrophenyl ester3aand dicarboxylic acid2bwas converted to the di(cyanomethyl) ester3b. The active esters3aand3bwere polycondensed with diamines such as 1,2‐diaminoethane, 1,6‐diaminohexane, 4‐aminomethylbenzylamine, and piperazine in solution, giving polyamides containing uracil and adenine as the side group. The polyamides were found to have molecular weights in the range of about 1000–5000. The polyamides derived from 1,2‐diaminoethane and

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801006

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractPoly(urea‐urethane)s containing D‐glucosamine residues in the main chain were prepared by direct addition polymerization of D‐glucosamine and diisocyanates. The polymerization reaction proceeded smoothly inN,N‐dimethylacetamide or hexamethylphosphoric triamide under certain conditions without blocking the excess hydroxy groups. The resulting poly(urea‐urethane)s were all soluble in polar solvents and had inherent viscosities of up to 1,27 dl·g−1. These polymers had D‐glucosamine residues with three pendant hydroxy groups in each unit, and they exhibited good reactivity toward acetylation and also very high wa

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801007

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractComplexes of the tetrasodium salt of cobalt(II)‐tetrasulfophthalocyanine and poly(vinylamine) were applied as bifunctional catalysts for the autoxidation of thiols to disulfides. Optical and catalytic experiments gave supporting evidence to the hypothesis, that the isolation of cobalt centers and the catalytic activity can be promoted by increasing the relative amount of polymeric base. It appeared that the specific catalytic activity of the polymeric catalysts depends on the number average degree of polymerization (P̄n) of the applied polymer samples. In particular at relatively high cobalt content, samples with comparatively low P̄ngive more protection against aggregation of cobalt sites (i.e. inactivation) and, therefore, effect a higher specific catalytic activity. A statistical calculation, suitable to determine the distribution of cobalt sites over the polymeric coils, supports the interpretation of the experimental d

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801008

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractNascent polyethylene with high molecular mass (Mn≈ 105,Mw≈ 106) produced in hydrocarbon medium in presence of TiCl4/(C2H5)2AlCl/(C6H5)2Mg catalyst was studied by means of X‐ray diffraction, electron and light microscopy, and low‐angle light scattering. It consists of porous spherulite‐fibril aggregates indicating a not very high degree of crystallinity α(α≈). Data, concerning the dependence of spherulite dimensions, degree of crystallinity and other structure parameters of nascent polyethylene on polymerization time and temperature are discussed. Using the same structure‐analytical methods some samples of nascent polyethylene were studied after annealing them in nitrogen atmosphere at different temperatures between 110–250°C with successive cooling to room temperature. Furthermore both the endo‐ and exothermal transitions occurring in the nascent and annealed structures after heating to 250°C were studied by means of DTA and DSC. The experimental information leads to the conclusion that nascent polyethylene structures consist of crystalline folded chain lamellae with an increased amount of tie molecules between them as well as of ex

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801009

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY

摘要:

AbstractCopolymers of acrylonitrile (A) and styrene (S) were synthetized in eitherN,N‐dimethylformamide (DMF) or toluene by free radical polymerization. Their sequence distribution was studied by13C NMR at 25, 2 MHz. The observed sequence distributions follow first order Markov statistics and may be calculated using the set of reactivity ratiosrA= 0,13 andrs= 0,36 (DMF) or 0,40 (toluene) provided the copolymers remain soluble during polymerization. The reactivity ratios were calculated graphically from the experimental triad distributions observed by13C NMR using the method of Chiang et al. Deviations from first order Markov statistics were observed for heterogeneous polymerizations or for acrylonitrile rich initial monomer mixtures in DMF. No influence of steric hindrance on the cotacticity of the copolymer chain was noticed within the resolving power of our instrumen

ISSN:0025-116X    

DOI:10.1002/macp.1979.021801010

出版商:Hüthig&Wepf Verlag    

年代:1979

数据来源: WILEY