摘要:

AbstractThe kinetics of the reaction between natural rubber hydrocarbon and sulfur monochloride is investigated in dilute hydrocarbon solution by the dilatometric technique. Control experiments with trilaurin and triolein show that the reaction requires unsaturated linkages in the compound to be cold‐vulcanized. The extent and rate of the nonaccelerated reaction with rubber is shown to depend strongly on the nature of the solvent. Moreover, the nonaccelerated reaction is autocatalytic in nature, and exhibits kinetics that are first order with respect to sulfur monochloride. The accelerating effects, on the reaction, of Butyl 8, mercaptobenzothiazole, dibutylammonium dibutyl‐dithiocarbamate (DBA), and methanol are investigated and it is shown that, in the presence of sufficient Butyl 8 or DBA, the autocatalytic nature of the reaction is changed to one that is kinetically of pure first order. The accelerated (Butyl 8) reaction is found to be first order with respect to sulfur monochloride. The accelerated reaction is further shown to be first order with respect to DBA and second order with respect to methanol. A free radical mechanism is proposed for the nonaccelerated reaction, involving attack by the intermediate$ \mathop {\rm S}\limits^ * {\rm \bond S \bond Cl} $at the double bonds of the rubber molecule. It is suggested that accelerators function by reacting with sulfur monochloride to produce the active intermediate$ \mathop {\rm S}\limits^ * {\rm \bond S \bond Cl

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147501

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThere are investigated the relations between the liquid compositions in the two phases formed when a polymer equilibrates in a mixed solvent. By imposing the simplifyng constraint that all of the polymer be located in one of the two phases, an expression for the equilibrium composition ratio,R= (φ1/φ2)/(v1/v2), is obtained through use of the customary expressions for the free energy of polymer solutions:\documentclass{article}\pagestyle{empty}\begin{document}$ \ln R = 2_{\chi 12^\varepsilon} + [\chi 12(v_2 - v_1) + l_{\chi 23} - \chi 13]\varphi _3 - (1 - l)\ln (1 - \varphi _3 - \varepsilon /v_2) $\end{document}Here subscripts 1, 2, and 3 refer to the two liquids and the polymer, respectively, χ is a free energy parameter,lis the ratioV1/V2of the molar volumes of the two liquids, φ andvrepresent the volume fraction in the ternary and binary phases, respectively, and ϵ is an auxiliary variable relating φ andvfor the two liquid components. Certain consequences of the equilibrium composition relationship are examined, and there are suggested possible applications to diffusion, light scattering, and solubility. The results of analysis of the two phases formed when crosslinked natural rubber equilibrates with the mixed solvent pairs: benzene–nitromethane andm‐xylene–nitromethane confirm the form of the equilibrium composition relationship, and the values for the free energy parameters required to represent the data for these ternary systems appear to be

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147502

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147503

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractRelaxation distribution functions for concentrated solutions of six polyisobutylene samples, using three different solvents, have been derived from measurements by the methods of the single transducer, wave propagation, and stress relaxation following cessation of steady‐state flow. The ranges of molecular weight, concentration, and temperature were about 0.3 to 2.5 × 106, 5 to 40%, and −5 to 40°C., respectively. When plotted with reduced variables with a reference state of unit density and viscosity at a standard temperature, data at different temperatures superpose; data at different concentrations superpose except for the two samples of highest molecular weight, where there are perceptible deviations. The reduced distribution functions for all the samples lie close together at long times where there is a drop associated with the finite lengths of the molecules. The theory of Rouse for viscoelastic properties of dilute solutions, when modified for concentrated solutions by assuming that all segmental mobilities are equally affected by interlacing of neighboring molecules, agrees with the reduced mechanical properties at long times fairly well. However, it does not predict the plateau region characteristic of distribution functions of polymers of high molecular weight. The existence of this plateau in concentrated solutions and undiluted polymers represents an abnormal prolongation of the longest relaxation times in these systems, which is attributed to molecular coupling by entanglement as discussed by Bueche with respect to steady flow visc

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147504

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractTurbidities and Rayleigh ratios have been measured at 25°C. and at wave lengths of 4358 and 5461 A. for benzene, carbon tetrachloride, toluene, and methyl ethyl ketone. The results obtained are in agreement with the theoretical Einstein equation for the scattering of light by pure liquids, the data yielding for Avogadro's number a value of 5.98 × 1023± 4.7%, as against the accepted value of 6.02 × 1023. Further, the Rayleigh ratios are in accord with the published measurements of Doty, Zimm, Brice, and their co‐workers, but not with the older literature or the values of Stamm and B

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147505

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe dielectric increment of a specimen of carboxymethylcellulose in aqueous solution has been studied as a function ofpH. For the free acid a low increment was obtained which increased with increasing ionization (sodium salt). With excess sodium or hydrogen ions the increment decreased. Similarly there was a marked increase of the increment per gram per liter for the sodium salt with increasing dilution. The dielectic increments obtained for various salts of carboxymethylcellulose followed the order: Li+>Na+>NH4+>K+in agreement with the ion exchange affinities found previously for these ions (reversed order). The data have been interpreted along the lines of current theories for polyelectrolytes, by taking into consideration the net charge of the polyion, and the polyion‐counterion association under varying condition

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147506

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractChanges in the infrared spectra due to the introduction of 1 to 4 chlorine atoms per isoprene unit in the natural rubber molecule have been studied. Four prototypes are discussed in greater detail: hydrochlorides, rubber dichlorides, chlorinated hydrochlorides, and products obtained by the direct chlorination of rubber and of cyclized rubber. Within certain limits it is possible to follow double bond shifts which occur during the process of hydrochlorination or of chlorination. Chlorinated rubber differs from other chlorinated polymers with a similar composition by a large reduction of the intensity of the CH3frequency. Absorptions due to the presence of chlorine atoms are observed in the 13–18 μ region, but these bands show little individual differences. Small quantities of oxygen in the form of CO or OH groups are readily detect

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147507

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractBased on a general equation correlating DP and rate for catalyzed polymerization in the presence of solvents, an experimental method has been devised for determining all three transfer coefficients,viz.monomer transfer (CM), solvent transfer (CS), and catalyst transfer (CI), in a simple and straightforward way. Three types of methods are possible for solvent transfer determination: (1) by determining the slope of\documentclass{article}\pagestyle{empty}\begin{document}$ \left[{\frac{1}{{\bar P}} - \frac{1}{{A^2 M^2}}R_P} \right]{\rm versus}\frac{S}{M} $\end{document}at constant1(catalyst):M(monomer) ratio; (2) by determining the intercept of\documentclass{article}\pagestyle{empty}\begin{document}$ \left[{\frac{1}{{\bar P}} - \frac{1}{{A^2 M^2}}R_P} \right]{\rm versus}\frac{l}{M} $\end{document}at constantS/M; and (3) by direct use of the general equation, especially using a catalyst whoseCIis known to be zero. It has been further shown that the existing method (slope of 1/PversusS/M) in uncatalyzed polymerization would give correct results for all solvents only over the range in which the rate of uncatalyzed polymerization is proportional to the square of monomer concentration. It has also been pointed out that, in systems in which the more usual rate equation,RP=KP(ki/kt)1/2I1/2M3/2is valid, the slope of 1/PversusS/M(at constantI/M) would give correctCSvalues for catalyzed polymerization also.

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147508

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147509

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147510

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY