摘要:

The comprehensive polymerization mechanism of the nitrogen-containing cycles 1-azobicyclo (3,1,0)-hexane (ABH), conidine, quinuclidine, and triethylenediamine under the action of quaternary ammonium salts, ammonium salts, and BF3complex with conidine is studied. Polymerization is of the living polymers type, and the active centers of monomer polymerization are ions and ion pairs: the activity of the latter is comparable to and exceeds that of the free ions. The effects of the nature of the counterion, cation, and medium polarity on the reaction rate are investigated. The polymerization rate is found to depend on the nature of the counterion in the polymerization of ion pairs, but not to depend on the counterion in the polymerization of free ions. The reaction rate is proportional to the counterion size in the polymerization of ion pairs. In the case of conidine K+= 0.2, K±(Cl−) = 0.28, K±(Br−) = 0.36, K±(I−) = 0.51, and K±(ClO4−) = 0.62 (liter)/(mole)(min). The heats of nitrogen-cyclic polymerization are measured and correlated with the activation energy.

ISSN:0022-233X    

DOI:10.1080/00222337408065828

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Using elementary analysis, NMR on3 1P and1H nuclei, and electroconductivity methods, the acrylonitrile, methacrylonitrile, formaldehyde, and β-propiolactone anionic polymerization in the presence of triethylphosphine is shown to follow the macrozwitterion mechanism: quartary phosphonium being on one end of a polymer chain and the growing anion on the other. The number of covalent bonds through the whole polymer chain between charges forming the active center increases with the propagation reaction. The active centers stationary concentration in the system is low when connected with both the slow initiation reaction and with the fast active centers termination reaction. Thus the ion interaction of different growing polymer chains can be ignored. The active centers parts occurring in the form of ion pairs (the ends are near and form the “cyclic”) and of free ions (the ends are separated) are determined by the monomolecular equilibrium, and its constant depends upon the macro-zwitterion polymerization degree Kd(n)= Kd(I)n3/2. Such constant depends upon the chain length affords the macrozwitterion self-accelerated propagation with its length, as the free ion reactivity is more than that of ion pairs. The self-accelerated chain propagation effect shows up as an increase of polymerization initial rate order and polymer molecular weight in the monomer concentration. This effect can be avoided by the introduction of electrolyte into the system, which dissociates into ions and transforms all cyclic ion pairs into the linear form, the latter dissociating independently of chain length. The strict mathematical analysis of stationary and nonstationary polymerization kinetics made it possible to determine all the elementary constants separately: Ki= 5.6 × 10−4liters/ (mole) (min); K-= 2.5 × 104liter/ (mole) (min); K±= 2.0 liters/ (mole) (min); Kt= 0.84/min; Kt1= 4/min; Kd(I)= 10−4; K3= 0.07 × 10−4mole/liter.

ISSN:0022-233X    

DOI:10.1080/00222337408065829

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Recent oxidation studies on polysisoprene popcorn polymer have shown that the yields of volatile products are a function of the presence or absence of residual isoprene dimers on the polymer. In contrast to previously reported data, no carbon dioxide is detected when highly purified polymer is used. Also, the yields of water drop to approximately half the previously reported values. Quantitative data are presented for the production of water during the early stages of autoxidation. The reported data emphasize the possible errors that can occur when oxidation reaction mechanisms are based on the stoichiometry of volatile products produced from impure polymer samples.

ISSN:0022-233X    

DOI:10.1080/00222337408065830

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Some o,o′ -dihydroxydiphenyl methane type of synthetic compounds of uniform constitution and molecular weight have been prepared by stepwise synthesis. These synthetic novolaks, when mixed in various molecular proportions, resemble p-cresol formaldehyde condensation polymers. A study has been made on the titration curves of the mixtures of synthetic compounds in nonaqueous media. A large number of breaks and inflections have been observed in the titration curves, and they occur in simple multiples of the calculated amount of base required to neutralize OH groups in the various novolak molecules independently. These observations have been interpreted in terms of ion association, dielectric constant of the solvent, and intramolecular hydrogen novolak molecules.

ISSN:0022-233X    

DOI:10.1080/00222337408065831

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Radiation-induced grafting rates for pentafluorostyrene on nylon film were compared with those for pentafluorostyrene/polyethylene, styrene/nylon, and styrene/polyethylene. The effect of added methanol and/or acetone on grafting rate was determined for each system. Accelerating and retarding effects were interpreted in terms of how changes in the grafting solution affect termination rate and monomer concentration in the film. The effect of the grafting solution on termination rate appeared to depend upon the plasticizing efficiency of the grafting solution, as estimated from the difference in Hildebrand solubility parameters of the grafting solution and polymeric film. The grafting of minor amounts of pentafluorostyrene on nylon film greatly reduces its rate of water vapor absorption in a humid atmosphere, and considerably improves the clarity of the film.

ISSN:0022-233X    

DOI:10.1080/00222337408065832

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Magnesium chloride, calcium chloride, strontium chloride, and barium chloride were found to protect the shape of the external envelope of the protein molecule from radiation damage. The behavior of the viscosity change closely resembles that found with sodium glutamate and sodium benzoate, as shown by a similar dependence on concentration

ISSN:0022-233X    

DOI:10.1080/00222337408065833

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The copolymerization of butadiene and acrylonitrile in emulsion has been studied using gamma radiation for the initiation process. The polymerizations proceeded smoothly with good yields, G (monomer consumption) values ranging from 8,000 to 100,000. Some deviations from the standard Smith-Ewart Case II theory were observed, particularly with respect to the dependence of the rate on the soap concentration. A strong post-effect was observed showing a clear first-order radical termination process. The copolymer reactivity ratios were found to be normal.

ISSN:0022-233X    

DOI:10.1080/00222337408065834

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The polymerization of butadiene in emulsion initiated by6 0Co gamma radiation has been studied in some detail. Similar studies with styrene and styrene-butadiene comonomer mixtures were also conducted. The rates of polymerization were found to be much lower than anticipated from the reported kpvalues for butadiene and for the comonomer mixtures. Styrene, on the other hand, polymerizes at normal rates. A number of possible explanations for this behavior is discussed.

ISSN:0022-233X    

DOI:10.1080/00222337408065835

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Ehylene can be polymerized at low pressures in a radio-frequency glow discharge. The form of the resulting polymer may be a powder at low pressure (1 to 2 Torr) and low monomer feed rate (10 to 40 cc/min), a colorless film at low pressure and high feed rate (70 to 90 cc/min), or an oil at high pressure (4 to 5 Torr) and high feed rate. The powder and film forms of plasma-polymerized ethylene are insoluble in common organic solvents, indicating a highly cross-linked structure. The oily products, however, are soluble in acetone and xylene. Chemical evidence indicates that the oil is most likely composed of highly branched oligomers of ethylene. Mass spectrometric analysis of the gaseous effluents show that under film-forming conditions the only hydrocarbon species observable are those derived from ethylene. The powder- and oil-forming conditions, on the other hand, yielded oligomeric species. On the basis of this evidence, a mechanism for the plasma-polymerization of ethylene is proposed.

ISSN:0022-233X    

DOI:10.1080/00222337408065836

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The quaterpolymerization of methylcyclopentadienyl-5-endo-norborn-2-enyl-methane with ethylene, propylene, and either endo- or exo-dicyclopentadiene was studied by using the catalyst system VAcac3-Et2AlCl. The influence of catalyst and polyenes concentrations, catalyst modifiers, and other polymerization parameters on the general properties of quaterpolymers was investigated. The polymers obtained showed a random distribution of the comonomeric units and the ability to covulcanize with 1,4-cis-polyisoprene.

ISSN:0022-233X    

DOI:10.1080/00222337408065837

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor