摘要:

The molecular weight distribution (MWD) of crystallizable polyphenylacetylene prepared near room temperature in the presence of ferric acetylacetonate and triethylaluminum was determined through use of fractions characterized by vapor pressure osmometry and gel permeation chromatography (GPC). The number- and weight-average molecular weights (MnandMw) are both less than the molecular weight corresponding to the maximum of the weight distribution function, which lacks a high molecular weight tail.MwandMnis less than is consistent with models allowing for chain termination characteristic of vinyl polymers. GPC elution volumes are much less than those characteristic of polystyrene of similar molecular weight, and the Mark-Houwink exponent is high (2.4 forMv4800 to 6800). These data indicate more rodlike behavior than for polystyrene of equivalent molecular weight. The MWD and other data suggest intramolecular chain termination, possibly associated with the molecule's tendency to form paramagnetic defect states.

ISSN:0022-233X    

DOI:10.1080/00222337508065859

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Silicon-containing condensation polymers were prepared starting from difunctional silicon-containing carboxylic acids or diols derived from long-chain fatty acids. Polyesters were synthesized by reaction of diacids containing siloxane linkages with diols, and diols containing siloxane linkages with various diacids. 1,3-Bis (10-carboxydecyl)tetramethyldisiloxane was condensed with various diamines to yield polyamides. 1,3-Bis(11-hydroxyundecyl)tetramethyldisiloxane and 1,3-bis [9(10)-hydroxyoctadecyl]tetramethyldisiloxane were condensed with diisocyanates to yield polyurethanes. Polycarbonates were synthesized by reacting the diols containing siloxane linkages with ethyl chloroformate. Some polybenzimidazols were synthesized by heating the diesters of the silicon-containing carboxylic acids with 3,3′ -diaminobenzidine. Some of the polyurethanes and polybenzimidazoles were thermally stable up to 300°C as indicated by TGA.

ISSN:0022-233X    

DOI:10.1080/00222337508065860

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

During the statistical analysis of copolymers obtained by the heteropolycondensation method, simulating the difference in the reactivity of the original comonomers by varying the preset reactive conditions, it is shown that the microstructure of the condensation copolymer chains should not depend on the relative reactivity of the comonomers. It is also shown that the microstructure of the chains can be influenced by choosing the copolycondensation conditions in such a way that the process would proceed from a insufficient quantity of the intermonomer in the reactive zone.

ISSN:0022-233X    

DOI:10.1080/00222337508065861

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Some examples demonstrate the feasibility of interpreting the results of polycondensation from stoichiometry. Utilizing only the consequences of stoichiometric principles, it is possible to draw conclusions of the basic principles of forming polymers in the polycondensation process and to substantiate the physical meaning of a number of averaged values used during calculations. The results confirm the relationships found earlier by means of other methods and make it possible to draw significant conclusions with respect to the character of the process and the peculiarities of the products obtained.

ISSN:0022-233X    

DOI:10.1080/00222337508065862

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Syntheses of metal-containing unsaturated polyesters based on divalent metal salts (I) of mono (hydroxyethyl)phthalate were investigated by the polycondensation reactions of I-glycols with maleic anhydride (MA)-phthalic anhydride (PA). Among various combinations of components, the systems of MA-PA-diethylene glycol (DEG)-Mg salt, and MA-PA-ethylene glycol (EG)-propylene glycol (PG)-Mg salt gave polyesters soluble in styrene. Viscosities of styrene solutions of the polyesters obtained showed a tendency to increase with increase in metal content in the polyester. The styrene solutions could be cured. The cured polyester resins were evaluated for physical properties. Generally, the polyesters of MA-PA-EG-PG-Mg salt have good physical properties. Further, resistance to chemical attack and boiling water, and thermal behavior are also discussed.

ISSN:0022-233X    

DOI:10.1080/00222337508065863

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The thermal stability of poly(vinyl chloride) prepared by radiation polymerization has been examined by thermogravimetric analysis, hydrogen chloride evolution, and visible spectra measurements in films and solutions. Radiation polymerized PVC, prepared with relatively high radiation doses, is much less stable than a commercial suspension polymerization PVC. On the other hand, the stabilities of radiation polymerized PVC, prepared with relatively high radiation doses, is much less stable than a commercial suspension polymerization PVC. On the other hand, the stabilities of radiation polymerized samples, which had received less than 0.45 Mrad, are comparable with commercial PVC. It is suggested that the allylic chlorine atoms produced in the radlysis of the polymer, concurrent with its formation, are chiefly responsible for the instability of the high doses samples.

ISSN:0022-233X    

DOI:10.1080/00222337508065864

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The shape parameter obtained from the geometric model of Ishihara and Hayashida for ovaloid polymers, together with the scaled-particle theory, are applied to a mixture of methane and ethylene. The results are in good agreement with the experimental values, indicating the validity of the model and suggesting application to other polymer properties.

ISSN:0022-233X    

DOI:10.1080/00222337508065865

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Two tricopolypetides with varying amounts of glycyl, ϵ-carbobenzoxy-L-lysyl, and γ-benzyl-L-glutamyl residues were synthesized and characterized by determining their intrinsic viscosity, refractive index increment, molecular weight, and second virial coefficient in the random coil solvent dichloraoacetic acid. The characteristic ratio (C∞) of the two polypetides was determined using the Brant-Flory equation. C∞ decreased from 8.1 to 4.8 on changing the content of glycine from 27.3 to 46.0 mole %. These values of C∞ are markedly higher than those expected from a consideration of the effect of glycine on random coil dimensions of copolypeptides.

ISSN:0022-233X    

DOI:10.1080/00222337508065866

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Organic solvents penetrating into a spherical cross-linked polystyrene bead advance over a sharp front and cause the bead to swell. The changing location of the advancing front and the increasing radius of the swelling bead were measured by microscopic techniques. The rate of solvent uptake by the copolymer beads was shown to be of the Fickian type. A mathematical model of the Fickian diffusion process, showing both the advancing front and the expanding sphere, was developed. Effective diffusivity coefficients for methylene chloride, trichloroethylene, tetrahydrofuran, and benzene were obtained by least-squares fitting of the calculated and the measured times necessary for complete swelling.

ISSN:0022-233X    

DOI:10.1080/00222337508065867

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Equations are presented weighing the contribution of triad sequences to copolymer Tgs. Improved correlation is shown for acrylonitrile-methyl methacrylate copolymer and suggested for certain other systems.

ISSN:0022-233X    

DOI:10.1080/00222337508065868

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor