摘要:

The processes of ZnCl2selective sorption by macromolecules of polymethyl methacrylate and polybutyl methacrylate in binary mixtures with ZnCl2have been studied using light scattering and equilibrium dialysis methods. It has been shown that to a certain concentration of ZnCl2, its average concentration in the volume of macro-molecular coils is equal to that of the complexing agent in the solution, i.e., the parameter of the selective sorption β = 0. However, for the system PBMA-BMA-ZnCl2with increasing [ZnCl2], a negative value of β is observed. After the “threshold” concentration of [ZnCl2]: methyl methacrylate = 0.08, butyl methacrylate = 0.15, an increase in the selective sorption of ZnCl2concentrations is found. The interaction of ZnCl2with macromolecules of polymethyl methacrylate and polybutyl methacrylate is accompanied by a change in the steric parameter and in the thermodynamic quality of the solvent. A probable mechanism of ZnCl2interaction with polymer coils is discussed.

ISSN:0022-233X    

DOI:10.1080/00222338408077231

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The copolymerization behavior of N-vinyl monomers was studied on the revised Q,e-scheme in order to investigate the monomer reactivity. Using methyl methacrylate as the comonomer instead of styrene, it was shown that the N-vinyl monomers cannot be classified as typical unconjugative monomers, but are quite different from popular conjugative monomers. They could be classified as the third monomers group on the revised Q,e-map. This result is predominantly caused by the different values of e-term depending on the comonomer, which is ascribed to the different e-terms of the polymer radical and the monomer.

ISSN:0022-233X    

DOI:10.1080/00222338408077232

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The use of gas chromatographic analysis of the actual monomer mixture at fixed time intervals to monitor the composition of copolymers in emulsion copolymerization has been described previously. The design has been now improved by the insertion of a dilution cell to avoid flocculation problems in the loop carrying the reaction medium from the reactor to the injection kit of the chromatograph. Then the copolymerization can be monitored up to completion. This system has been applied to the copolymerization of butadiene and acrylonitrile, and constant composition runs have been compared to the batch. Two main differences are observed. (1) Constant composition copolymers show a unique glass transition interval of limited width instead of two or at least one broad temperature interval for the copolymer produced in batch. (2) In the monitored copolymerizations, the production of insoluble gels is delayed and sometimes totally avoided. The production of the gels is related to the formation of 1,2-butadiene units which appear to be preferentially present in long sequences of butadiene units. The cross-linking process involves the consumption of the pendent vinyl groups by copolymerization with the monomers.

ISSN:0022-233X    

DOI:10.1080/00222338408077233

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Acrylamide has been polymerized electrochemically in aqueous medium in the presence of tartaric acid, and the effects of such reaction variables as monomer concentration, electrolyte concentration, and current on the rates of polymerization have been studied. The mechanisms of initiation and termination have been discussed in the light of the observed kinetic data. Initiation is believed to occur through the generation of radical ions during electrolysis, and electrolytic termination is found to be negligible during the polymerization process.

ISSN:0022-233X    

DOI:10.1080/00222338408077234

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Poly[2-methoxy-4,6-di (2,7-naphthyloxy)-s-triazine] was synthesized by interfacial polycondensation of 2-methoxy-4,6-dichloro-s-triazine with 2,7-dihydroxy-naphthalene. The polymer was characterized by IR and UV spectra, dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis. The polymer was fractionated by the fractional precipitation method and the fractions were characterized by viscometry and membrane osmometry. The polymer has a Tgof 175°C and is found to be stable up to 300°C in air. The polymer sample is found to degrade in air in two steps, and the energy of activation for the first step is around 25 kcal/mol.

ISSN:0022-233X    

DOI:10.1080/00222338408077235

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The graft copolymerization of methyl methacrylate (MMA) onto mulberry silk fibers was studied in aqueous solution using the acetylacetonate oxovanadium (IV) complex. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, the solvent composition of the reaction medium, the surfactants, and the inhibitors. The graft yield increases with increasing concentration of the initiator up to 8.75 × 10−5mol/L, of the monomer up to 0.5634 mol/L, and thereafter it decreases. Among the various vinyl monomers studied, MMA was found to be most suitable for grafting. Grafting increases with increasing concentration of HCIO4and with increasing temperature. Inhibitors like picryl chloride and hydroquinone significantly decrease the extent of grafting. Alcoholic solvents at a solvents/water ration of 10:90 seem to constitute the most favorable medium for grafting. A suitable reaction scheme has been proposed, and the activation energy calculated from the Arrhenius plots.

ISSN:0022-233X    

DOI:10.1080/00222338408077236

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Irradiation of benzophenone in the presence of a suitable hydrogen donor like alcohol leads to benzpinacol and the ketone as sole products. This reaction proceeds through ketyl radical intermediates. This photoredox system may be used for photopolymerization. Photopolymerization of acrylonitrile using isopropanol and benzophenone combination as initiator has been studied. The formation of the polymer is directly proportional to irradiation time, [acrylonitrile] and [isopropanol]. The rate of polymerization increases with an increase in concentration of benzophenone to an optimum and a further increase in benzophenone concentration decreases the polymerization rate. A suitable mechanism is suggested.

ISSN:0022-233X    

DOI:10.1080/00222338408077237

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

γ-Irradiation of copolymers of ethylene with propene, 1-butene, and 1-hexene, containing from 1 to 6 alkyl short chain branches per 1000 carbon atoms, at 25°C in vacuum, produced small amounts of n-alkanes with a maximum yield for the alkane corresponding to the alkyl branch of the α-olefin unit. A multilinear regression analysis showed a highly significant dependence of G(Cnalkane) on the frequency of alkyl branches containing n carbon atoms, determined by13C-NMR. The corrections to the G(Cnalkane) yields from other fragmentation processes were substantial but no dependence for G(Cnalkane) on fragmentation of chain ends or fragmentation of the chain following branch elimination could be deduced from the data. The scission efficiencies = G(alkane) divided by the branch frequency per 1000 carbon atoms ± 95% confidence limits were (0.7 ± 0.7) × 10−3, (2.7 ± 0.8) × 10−3, and (1.5 ± 0.3) × 10−3, for methyl, ethyl, and butyl branches, respectively. These factors can be used to determine the short-chain branch frequencies in similar polymers from n-alkane yields on γ-irradiation.

ISSN:0022-233X    

DOI:10.1080/00222338408077238

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A new empirical equation is presented which modifies the Krigbaum equation for calculating K values from measurements of intrinsic viscosity in good solvents. This is found to fit the molecular weight data better for the polymer systems investigated.

ISSN:0022-233X    

DOI:10.1080/00222338408077239

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Selective interpolymer complexation has been studied between methacrylic acid-methacrylamide copolymer and some complementary polymers such as poly(methacrylamide), poly(vinyl pyrrolidone), and poly(ethylene oxide). The relative order of complexation ability of the various nonionic polymers has been interpreted on the basis of the nature of interactions between different units of polymers. Configurational environment and neighboring group influences seem to affect interpolymer complex formation.

ISSN:0022-233X    

DOI:10.1080/00222338408077240

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor