摘要:

AbstractIt is shown how chemical and colloidal heterogeneity can result in multiple dispersion regions of the mechanical or electrical loss factor as a function of temperature. Heterogeneity can be produced in several ways: (a) mechanical blending (mixing) of certain polymers, (b) non‐uniform copolymerization, (c) block or graft polymerization, (d) external plasticization, and (e) certain types of molecular weight distribution. Specific examples are given to demonstrate the effec

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157901

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractPolyhydrocarbons were prepared by the dehydrogenation of 1,4‐dimethyl substituted aromatic hydrocarbons and other related starting materials by several methods. A study was made of the intermediates formed and of their chemical reaction

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157902

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractHydrocarbon polymers prepared by the hot tube pyrolytic dehydrogenation of 1,4‐dimethyl substituted aromatic hydrocarbons have been studied and characterized as to chemical and physical properties. Tough, chemically resistant products were obtained, but fabrication of these polyhydrocarbons was difficult due to the relative intractability of the polymers obtaine

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157903

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractIn the first part of the paper various orientation phenomena of the drawing‐relaxation behavior are interpreted in terms of the changes occurring within the submicroscopic helices which form the spherulites. Not only drawing and relaxation but also the redrawing of the relaxed samples were followed, and it was shown that the observed anomalous orientation effects cannot be described in terms of tilts of planes with simple indices. However, by considering also the possible shapes of the submicroscopic units these orientation effects can be visualized. In the second part a new general type of orientation, the “row orientation” is introduced. This arises when crystallization takes place while the melt is flowing. Flow produces lines of high nucleus density, leading to growth of the crystallites in all directions perpendicular to the direction of drawing. This results in elongated aggregates of helices, and the alignment of these complex units produces a unique type of orientation which has been established from various a

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157904

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractInfrared absorption spectra were used to study the structural changes resulting from oxidation in a number of unvulcanized, purified polymers under a variety of experimental conditions. The results showed that as oxidation progressed, the structural changes which were detected were qualitatively the same for all of the polymers under all of these experimental conditions. Correlation of volumetric measurements with spectral data indicated that considerably more oxygen was absorbed by the polymer samples before structural changes could be detected than the minimum amount required for the initial detection of the hydroxyl and carbonyl structures. From the interpretation of information from the absorption spectrum, it is believed that the structural evidence is in substantial agreement with current theories on autoxidation. Although the initial hydroperoxide formation is not observed in the spectrum, it is quite probable that this reaction takes place with almost immediate decomposition which results in a net hydroperoxide concentration so low as to make infrared methods insensitive for its detection. Correlation of physical properties with structural studies indicate that little change in these properties take place until the hydroxyl and carbonyl structures become evident in the infrared spectrum.

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157905

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractEquilibrium swelling and salt accumulation were investigated for highly swollen polymethacrylic acid gels in aqueous salt solutions of 0.8 × 10−2to 0.5MLiCl, NaCl, and KCl, at varying degrees of ionization of the polymer. The same equilibrium results were obtained with all three cations, thus showing that in the range investigated, specific interactions between the cations and the polyacid network may be disregarded. It was shown that the Donnan distribution, uncorrected for activity factors, cannot be applied to highly charged, highly swollen gels, even as a rough approximation. A general theory was developed which satisfactorily describes these equilibrium results in the entire ionization range of the gel in salt solutions up to 0.5M. This theory was based on Flory's equation for the contractile free energy of the network, and on the equation of Katchalskyet al. for the electrostatic free energy of polyelectrolyte solutions. It was found that the activity factor of the salt in the gel‐phase is chiefly determined by the electrostatic factor, and closely approximates the activity factor in polyelectrolyte solut

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157906

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractAn intrinsic viscosity‐molecular weight study has been made of several polybutadienes and synthetic polyisoprenes. The Fox‐Flory treatment of such data was applied in each case. This serves for the determination of a constant characteristic only of the polymer and related to the unperturbed end‐to‐end distance of the polymer chain. A comparison of the dependence of this constant on polymer structure with that predicted theoretically shows good agreement. A further comparison of the values of this constant for the synthetics with those for natural polyisoprenes leads to the conclusion that the diene polymers, natural and synthetic, do not differ markedly in hindrances to free r

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157907

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe swelling of a crosslinked polydimethylsiloxane in a number of swelling agents has been measured. Values of the solvent‐polymer interaction parameter, χ1, have been computed and have been compared with the solubility parameters of the swelling agents and with other data from the literature. The magnitude of the solubility parameter of the polymer depends markedly on the swelling agents and method used for its estimation. The values reported here range from 7.7 to 5.

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157908

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe formation of crosslinks in silicone rubber by benzoyl peroxide was studied by tension and swelling techniques as a function of curing conditions and filler content. The ability of benzoyl peroxide to form crosslinks was found to decrease markedly as the peroxide concentration was increased. The peroxide seems to form crosslinks in an amount independent of the concentration of the silica filler. High crosslink concentrations were found to be necessary to fully utilize the polymer‐filler attachments. Values for the bulk and solution densities of silicone gum and the specific volume of the filler in silicones were determined. The melting point of benzoyl peroxide immersed in silicone gum is reported. The aging of silicone gum at 150°C. in air was found to neither increase nor decrease the number of crosslin

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157909

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe cell model forr‐mers andr‐mer solutions developed by Prigogine, Trappeniers, and Mathot is applied to pure diphenyl, diphenylmethane, dibenzyl, and tolan (diphenylacetylene) and to their solutions in benzene. This model introduces new contributions for the excess functions arising from volume changes and modification of the curvature of intermolecular potential with change in composition. The excess functions are written in an explicit form and contain only molecular quantities without any arbitrary parameter. The agreement for the different excess functions (excess free energy, entropy, and excess volume) is satisfactory. The existence of a negative excess specific heat can also be understood on the basis of the cell model and is related to the negative excess vol

ISSN:0022-3832    

DOI:10.1002/pol.1955.120157910

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY