摘要:

AbstractThe dielectric properties of methyl methacrylate–styrene copolymers in benzene solution have been measured, and in a theoretical treatment it has been attempted to evaluate the effective dipole moment of the methyl methacrylate group in relation to the distribution of polar group sequences in the copolymer molecule. If it is assumed that the polar groups in a polar (A)–nonpolar (B) copolymer molecule can be classified into three types such that the nearest neighbors along the chain are (I) two polar groups A, (II) a polar group A and a nonpolar group B, and (III) two nonpolar groups B (the molecular polarizations of which are denoted byPAA,PAB, andPBB, respectively), then the average molecular polarization of polar group A in the copolymer molecule,Pav, can be written in the form\documentclass{article}\pagestyle{empty}\begin{document}$$ P_{{\rm av}} = P_{{\rm AA}} \overline {f_{{\rm AA}^{\rm 2} } } + 2P_{{\rm AB}} (\overline {f_{{\rm AA}} } - \overline {f_{{\rm AA}^{\rm 2} } } ) + P_{{\rm BB}} (1 - 2\overline {f_{{\rm AA}} } + \overline {f_{{\rm AA}^{\rm 2} } } ) $$\end{document}HerefAAandfAA2are the probabilities of an AA sequence and a double AA sequence arising in the copolymer molecule, respectively. The values offAAandfAA2can be calculated from the reactivity ratios of the two monomers and the composition of the initial monomer mixture. The measurements were made on six samples of different compositions. It has been shown that the experimental values ofPavagreed satisfactorily with the values calculated from the above equation, over the whole range of copolymer composition. This seems to indicate that only the nearest neighbors in the polymer chain affect the effective dipole moment of the polar group in the copolymer molec

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616318

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractBoth the glass transition temperature and the melting point of poly(vinyl chloride have been found to increase as the temperature at which the ample is polymerized is decreased). The glass transition temperature changes from about 70°C. for polymer prepared at 125°C. to about 100°C. for polymer prepared at −80°C. It is believed the increase in percentage of syndiotactic structure which results from decreasing the polymerization temperature is responsible for the change in glass transition temperature. The effect of polymerization temperature on melting point is even more striking. The melting point changes from approximately 160 to above 300°C. on lowering the polymerization temperature from 125 to −80°C. X‐ray diffraction studies show that polymers prepared at low temperature form crystals which have a substantial increase in perfection along the chain axis. It seems probable that this increase in crystalline perfection along the chain axis is responsible for the very marked increase in me

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616319

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractThe relation between the intrinsic viscosity [η] and the number‐average degree of polymerizationP̄nis a function of the molecular weight distribution of the polymer. In a polymer in which the termination of polymer radicals occurs partly by combination of two growing chains, this molecular weight distribution depends on number and extent of additional reactions such as chain transfer; i.e., it is variable. ThereforeP̄nof such polymers cannot be obtained from intrinsic viscosity measurements by means of an equation of the type [η] =KP̄na.A new method is proposed which allows the evaluation ofP̄nin these cases, without necessity of osmotic (or related) measurements or fractionation. The viscosity‐average degree of polymerizationP̄η, which can be obtained exactly by experiment, is related to the number average byP̄η=P̄n(1 +F). HereFis given as a function of experimental data:P̄ηand the overall rate of polymerization. This function is represented in a graph which enables the exact determination ofP̄nwithout knowledge of number and extent of additional reactions.TheP̄nvalues calculated according to the proposed method are compared with measured values (osmosis, endgroup analysis) for several polystyrene samples. The agreement is

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616320

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractThe alcoholysis of polyvinyl acetate in ethyl alcohol solution catalyzed by sulfuric acid is accompanied by a side reaction leading to formation of a certain amount of polyvinyl sulfate. Aqueous solutions of the polyvinyl monosulfates possess a comparatively high emulsifying capacity, which increases with increase in the bound sulfur content, comprising 0.06–0.08% for 1–5% sulfuric acid in the reaction medium. Attempts to incorporate the sulfate group to a great degree with the objective of obtaining sulfated polymers of specific properties (efficient emulsifiers, stabilizers, ion exchangers etc.) did not yield satisfactory results when methods described in the literature were employed. Direct sulfation of polyvinyl acetate with subsequent conversion to polyvinyl alcohol or the sulfation of polyvinyl alcohol, to obtain a derivative with a large ester content, is impossible, owing to stereochemical hindrance. Because of this we investigated the possibility of sulfating the polymer during the process of alcoholysis of polyvinyl acetate in ethyl alcohol. It was found that under the reaction conditions for various amounts of acetate residual groups polyvinyl alcohol may be obtained with a varying content of acid or neutral esters. Under the chosen conditions a hitherto undescribed acid sulfuric acid ester of polyvinyl alcohol with 10–15% bound sulfur content was obtained. In contrast to the original polyvinyl alcohol soluble in water this sulfur‐containing product dissolved in ethyl alcohol, water or aqueous alcohol. Neutral sulfates of polyvinyl alcohol are soluble only in ethanol but not in water. The acid sulfates possess high emulsifying and stabilizing properties. If the reaction is carried out in methanol, esterification of the acid sulfuric acid ester of polyvinyl alcohol takes place as a side reaction. The resultant products are devoid of emulsifying pro

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616321

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractThe effects of various gases on irradiated acrylamide and methacrylamide were studied by ESR. The results are not the same with irradiated monomers and irradiated polymers. Nitrogen oxide and hydrogen sulfide are known as radical scavenger, but they act as radical transformers for these samples. In source and postirradiation reaction of polyacrylamide or polymethacrylamide with hydrogen sulfide give rise to broad spectra having agfactor of 2.0267 and the new radicals produced here are concluded to be of the RS.type.

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616322

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractThe dielectric dispersion of bovine hemoglobin, ovoalbumin, and bovine ferrimyoglobin was investigated in a glycerin‐water mixture. It was found that the dispersions, of these protein solutions were largely modified by the increase of the viscosity of the solvent and a linear relationship was obtained between the relaxation times and the viscosity of the solvent postulated by the Stokes law. On the contrary, the dispersion of catalase solution was not affected by the addition of the glycerin, which indicated that the dielectric polarization of this protein was due to the different polarization mechanism and the polarization by surface ion conduction was suggeste

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616323

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractTitanium tetrafluoride has been successfully employed in combination with triisobutyl aluminum (TBA) as a Ziegler type of catalyst to polymerize butadiene. The resulting polymer has a highercistotransratio and a higher degree of crosslinking than one prepared with the titanium tetrachloride–TBA catalyst. It is of interest that vinyl chloride, a monomer containing a donor atom, was polymerized with the TiF4–TBA catalyst. Titanium tetrafluoride is not a very effective catalyst for the Friedel‐Crafts type of reac

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616324

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractViscosity measurements were made on the plastic polyvinylidene fluoride at 240°C. The flow properties continually change with time, the viscosity increasing steadily at constant stress and temperature. This is probably due to slight simultaneous evolution of HF gas and crosslinking of the polymer chains

ISSN:0022-3832    

DOI:10.1002/pol.1962.1205616325

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY