摘要:

It is shown that lattice parameter changes that reflect the composition of the unpolymerized material occur during the solid-state polymerization of methacrylamide in solid solution with isobutyramide. In addition, phase changes also occur as is required by the phase diagram of the system. These results indicate that annealing and recrystallization must play an important role in this reaction and probably in other solid-state polymerizations. It is also likely that these effects are among the parameters that are important in determining the rate of solid-state polymerization.

ISSN:0022-233X    

DOI:10.1080/00222337008063147

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The reactivity of n-butyllithium-CH3OCH2CH2OLi in toluene (System A) in styrene-butadiene copolymerization reaction was found to be similar to that of the catalyst system n-butyllithium-poly(propylene oxide), which formed copolymers containing more styrene units than the feed monomer ratio at early stage of polymerization. Metalation reaction of toluene to produce benzyllithium was observed to take place in System A. Relative reactivity of each of chemical species present in System A was measured in the reactiom with butadiene, styrene, and 1,1-diphenylethylene, in connection with initiation and propagation reactions of copolymerization. From this study a living end anion possessing larger conjugated system was concluded to be more reactive toward monomers possessing larger conjugated system.

ISSN:0022-233X    

DOI:10.1080/00222337008063148

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

N-Alkylmethacrylaldimines were prepared directly from methacrolein and primary amines. Polymerization of some kinds of α,β-unsaturated aldimines were examined using various kinds of initiators. Methacryl- and acrylaldi-mines were polymerized by anionic catalysts. Polymerization of these imines proceeded exclusively through vinyl-opening. From the results of homo- and copolymerizations of cyclohexylmethacrylaldimine (HMI) and/or other conjugated vinyl monomers, anionic polymerizabilities of these monomers was found to decrease in the order:

ISSN:0022-233X    

DOI:10.1080/00222337008063149

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The concept of “flux” is proposed for quantitatively describing the manner in which the relative concentrations of three chain ends remain at a steady state in a terpolymerization. The flux is a measure of the net rate of transition from one chain end to another. If a terpolymerization remains at a steady state with respect to the relative concentrations of the three chain ends, then the flux must be either zero or some finite number which is independent of the choice of chain ends used to calculate it. It is a necessary and sufficient condition for Ham's concept of sequence reversibility to be true that the flux be zero. The flux calculated for many systems using reactivity ratio data is quite near zero. However, the calculations necessarily share the imprecision of reactivity ratio data. Ter-polymer sequence distribution data, if available, could be used in a proposed method of calculating flux.

ISSN:0022-233X    

DOI:10.1080/00222337008063150

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

This paper describes the kinetics of the ceric ion-initiated graft co-polymerization of vinyl acetate-acrylonitrile to poly(vinyl alcohol). The graft copolymerization rate Rpwas found to be first order with respect to the total concentration of the comonomer mixture [M], the concentration of vinyl alcohol repeating units [PVA], and the mole fraction of vinyl acetate in the comonomer feed mixture. Rpwas independent of cerous ion. The grafting rate was independent of ceric ion above a ceric concentration of 0.0020 M but first order in ceric ion below that concentration. Rp initially increased rapidly with [H+] to a maximum and then decreased and levelled off at hgher [H+]. The rate of ceric ion disappearance was first order in [PVA], independent of [MI, and increased with increasing [H+] with a leveling off at high [H+]. A reaction mechanism.

ISSN:0022-233X    

DOI:10.1080/00222337008063151

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Molecular weights and grafting frequencies of graft copolymers prepared with ferrous ammonium sulfate-hydrogen peroxide initiation showed a dependence on granule swelling similar to that found with ceric ammonium nitrate (increased swelling of starch granules decreased the number of grafted polyacrylonitrile chains and increased their average molecular weight). As with unswollen starch, the composition of the copolymer prepared from swollen starch was not influenced by granule size. Molecular weights of polyacrylonitrile branches grafted to swollen and unswollen starch were independent of reaction time; however, grafting frequencies with swollen and unswollen starch tended to converge toward a common value with increased reaction time and increased dilution. Data suggest that the influence of granule swelling on copolymer composition is due to a faster termination rate for growing polyacrylonitrile chains in unswollen starch.

ISSN:0022-233X    

DOI:10.1080/00222337008063152

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The EPR spectra of manganese(II) ions on sulfonated polystyrene cross-linked with either pure meta or pure para divinylbenzene show distinctions indicative of ionic environments of different symmetry.

ISSN:0022-233X    

DOI:10.1080/00222337008063153

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A comparison of BF3·Bu2O and Cl-N2PF6as catalysts for cationic homopolymerization and copolymerization of trioxane has been made by employing high resolution nuclear magnetic resonance techniques. While no substantial difference was detected for the homopolymerization, two important differences were observed for the copolymerization with ethylene oxide; viz., 1) with Cl-NPF6there is a lower build-up of formaldehyde concentration; 2) with Cl‒N2PF6, a lesser amount of cyclic compounds containing ethylene oxide units is formed (e.g., 1,3-dioxolane). Both observations suggest that depolymerization occurs to a lesser extent with the cl-N2PF6catalyst.

ISSN:0022-233X    

DOI:10.1080/00222337008063154

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The prototype dimeric chelating compounds 3,3′-methylenebis-[N(4-hydroxyphenyl) iminodiacetic acid] and 3,3′-methylenebis-[N(4-methoxyphenyl) iminodiacetic acid] were synthesized and characterized by composition analysis, infrared spectroscopy, and potentiometric titration data. Their chelating characteristics with Cu(II), Ni(II), Co(II), and Zn(l1) ions were established by composition analysis and comparative infrared spectroscopy.

ISSN:0022-233X    

DOI:10.1080/00222337008063155

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A series of benzimidazole and benzimide model compounds were oxidatively degraded at high temperatures (350-600°C). All of the compounds degraded to small fragments, i.e., carbon oxides, cyanogen (trace), and water, as well as condensable materials such as nitriles and anhydrides. The most outstanding feature of the degradation was the origin of these latter pyrolysis products; in each case they originated from the acid portion of the molecule. Nitrogen was noticeably absent in both the gas phase and the condensable degradation products except as nitrilo-moieties. Poly-2,2′(m-phenylene)53′-bibenzimidazole produced similar products. The proposed mechanism invokes a preferential attack by oxygen at the aminobenzenoid rings.

ISSN:0022-233X    

DOI:10.1080/00222337008063156

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor