摘要:

Abstractcis‐transisomerizations have been effected in natural rubber, gutta‐percha, squalene,cis‐ andtrans‐3‐methylpent‐2‐ene, andcis‐polybutadiene by treatment with thiol acids, sulfur dioxide, and allied reagents. Natural rubber, and gutta‐percha, andcis‐ andtrans‐3‐methylpent‐2‐ene have been converted into equilibrium mixtures of similar isomeric composition (57%transat 140°C.). A sensitive infrared method of analysis has been developed for estimatingcisandtransd

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013601

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractA detailed description is given of the preparation of an anionic polysoap, poly[styrenecopotassium styrylundecanoate], or poly‐K‐SSU, by the following route. Polystyrene is alkylated with methyl undercylenate in the presence of aluminum chloride; the polyester is then saponsified. Only about 50% of the phenyl groups are alkylated; thus, the structure may be written:Products of molecular weight from 60,000 to 1,760,000 have been prepared. Another anionic polysoap has been made by alkylation with methyl oleate; here, only about 35–39% of the phenyl groups are alkylated, apparently due to steric hindrance. Nonionic polysoaps have been prepared by ester interchange of the unsaponfied methyl esters with methoxy polyethylene glycol. A sulfate ester polysoaps has also been prepared. The properties of poly‐K‐SSU have been studied in some detail. The solubilizing power, and the viscosity of the aqueous solutions, are comparable to ordinary soaps; but the surface tension of the aqueous solution is very close to that of pure water. The nonionic polysoaps are also good solubilizing agents, e.g., for cholesterol; possible medical applications are c

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013602

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractA study was made of the polymerization of siloxances with transient basic catalysts. These catalysts are active as polymerization catalysts for siloxanes and will decompose rapidly to inactive products at elevated temperatures with the formation of stable polymers. Several quaternary ammonium bases were studied as polymerization catalysts. It was found that bases such as tetramethylammonium hydroxide and benzyltrimethylammonium hydroxide were efficient catalysts. Similar bases having β‐hydrogen atoms decomposed too rapidly via an elimination reaction and were not good catalysts. The polymerizations of organosiloxanes with quanternary phosphonium hydroxides were also studied. The phosphonium bases decomposed thermally in a different manner than the ammonium bases to give phosphine oxides and hydrocarbones. The most efficient transient catalysts were found to be phosphonium silanolates. Tetrabutylphosphonium silanolate was conveniently prepared in an anhydrous form and it proved to be extremely efficient for the preparation of homopolymers and copolymers of organosiloxan

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013603

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractThe thermodynamic theory of nonelectrolyte solutions proposed by Maron has been applied to the experimental data of Gee and Treloar on solutions of rubber in benzene at 25°C. The theory was found to be capable of representing these thermodynamic data very satisfactorily on the basis of a constant interaction parameter μ, and on the basis of the dependence of the heat of mixing on the derivative of μ with respect to temperature rather than μ itself. Further, by assuming the heat of mixing to be temperature independent, an expression was set up for μ as a function of the volume fraction,v2, and the temperature. This equation reproduces\documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\Delta F} _1 $\end{document}values measured at 100°C. with an accuracy of better than 4%, and shows that at temperatures above and below 25°C. μ is concentration‐ as well as temperature

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013604

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractDispersions of metallic lithium, sodium, and potassium and some of their organoderivatives were used to initiate the polymerization of isoprene in several solvents. The propagating species in all cases were ion pairs of the type . The structure of the resultant polyisoprene depends on the character of the propagating pair. This in turn depends mainly on the counterion M+ and the solvent type. One quality of this ion pair which is of utmost importance is its ionic character (or degree of charge separation). In solvents such as diethyl ether and tetrahydrofuran, where we might expect large charge separation in the ion pair, all initiatiors produce similar, though not necessarily identical, polymer structures comprising 1,2 ‐3,4‐, andtrans‐1,4‐adducts. With potassium‐dependent initiators, very nearly the same polymer structure is obtained in hydrocarbons as in the more basic ethers, attesting to the highly ionic character of the potassium‐carbon bond; this might perhaps be considered as the “limiting anionic behavior”. Sodium has smaller inherent ionic‐character and is more sensitive to changes in solvent basicity, but still it parallels the behavior of potassium. With lithium, the most covalent of the alkali metals, a dramatic change in behavior occurs when polymerization is conducted in hydrocarbon media; a 93%cis‐1,4‐,7% 3, 4‐polyisoprene structure is obtained. This may be merely a limiting structural from at the low end of the scale of ionic character of the propagating ion‐pair. The steric factors arising from complexes formed between the propagating ion‐pair. The steric factors arising from complexes may also have an important influence on the polymer structures product in the various solvents. A continuous seriese of polyisoprene structures intermediate between those formed in hydrocarbons with Li and the limiting “anionic structure” can be obtained by use of such solvents as phenyl ether or anisole, or by judicious choice of appropriate hydrocarbon–solvent ratios wit

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013605

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractThe aim of this work was to demonstrate the clear‐cut correlation between the results of light‐scattering and osmotic measurements, primarily in the case of polyelectrolytes. The correlation is expressed to terms of formulas whose forms are adapted to the specific nature of each of the several possible kinds of comparison. Experimental results of both methods are given for water solutions of ionized PMA, PAA, and BSA. A special technique for the optical clarification was found to be indispensable for obtaining reasonably reliable light scattering results. The osmotic measurements were carried out in a special concentration osmometer. The osmotic coefficients ϕ, calculated from the results of both methods, are compared and found to be in reasonable accord. This justifies, in our belief, the use of light scattering as a method for measuring the activities of ionized polyelectrolytes. The method of treating the results is shown to be advantageious also in the case of nonelectrol

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013606

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractThe osmotic coefficients were determined for aqueous solutions of a polyethylene glycol sample (Carbowax 6000) by means of light scattering. An equation is given for a simple computation of this coefficient. Light scattering was determined in the concentration range 0.5–20%. Above 3%, the scattered intensities do not increase with concentration. The computed osmotic coefficients are unusually high. High osmotic pressures can thus be obtained with concentrated solutions of PEG‐6

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013607

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractA “concentration osmometer” which is easy to operate and very simply constructed is described. The principle of the measurement is based on the comparison of the unknown solution to a standard (in this case, a solution of polyethylene glycol Carbowax 6000 in water) which has a known calibrated value of the activity of water. During the measurement, the concentration of the two solutions changes as a result of free flow of water across the dividing semipermeable membrane, while the pressure in both solutions remains equal. By measurement of the amount and the direction of flow, the concentration of the standard which would be in equilibrium with the unknown solution can be interpolated. Examples are given of experiments performed with solutions of ionized PMA. The apparatus described has been employed in a concentration range of activities 10−1to

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013608

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractAccording to a recent theory of the glassy state, chain stiffness is the main determinant of the glass transition. In this paper the theory is applied to the problem of predicting the glass temperatures of copolymers of varying composition and therefore varying chain stiffness. It is found that a simplified treatment leads to an equation which is identical in form to the Gordon–Taylor equation but whose coefficients have a different physical significance. Evaluation of these coefficients requires knowledge of only the structures of the homopolymers. This simplified treatment can be applied to various types of copolymer systems but amounts to more of an approximation in the case of random copolymers of the addition (vinyl) type than in the case of random copolymers of the condensation type. The glass temperatures of the condensation copolymer system polyethylene adipate/terephthalate are predicted within experimental error. The average per cent deviation between theory and experiment for 10 well‐characterized vinyl type copolymer systems is found to be 6.4%. In order to illustrate the applicability of the equation to systems not normally considered as copolymeric, the glass temperatures of the polymer system poly‐n‐alkyl methyl methacrylate (varyingn) are cor

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013609

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractThe parallel plate compression rheometer is a typical measuring apparatus for the plastic flow of high polymers. In this rheometer, compressive creep curves of test specimens were studied at low rates of shear at constant temperature. Assuming Newtonian flow in the test specimen between the parallel plates, the coefficient of apparent viscosity was calculated from the lapsed viscous‐flow portion of these creep curves. The test specimen was a disk type with an initial‐diameter‐to‐initial‐height ratio of more than 30. Under low rates of shear, structural viscosity has little effect on the experimental results with cellulose acetate derivative plastics. At high rates of shear in the extrusion rheometer, however, the coefficient of apparent viscosity increases with a decrease of extrusion pressure. The experimental results in the parallel plate compression rheometer corresponds to those of zero extrusion pressure in the extrusion rheometer by the extrapolation method. The intrinsic flow energy,Uint., as a comparative value of the flow behavior of various kinds of linear polymers, is measured directly by the parallel plate compression

ISSN:0022-3832    

DOI:10.1002/pol.1959.1204013610

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY