ISSN:0022-3832    

DOI:10.1002/pol.1954.120136801

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractA pyrolytic dehydrogenation technique originally proposed by Szwarc has been employed for the preparation of polyhydrocarbons fromp‐xylylene, pseudocumene, and durene. With particular emphasis on poly‐p‐xylylene, the structure and physical properties of the polymers were investigated. Poly‐p‐xylylene may be obtained in two modifications: a transparent form and opaque form. The transparent form of poly‐p‐xylylene exhibits uniaxial, negative birefringence. The opaque form on purification by chloroform extraction melts at 412°C. Heat treatment of either modification appears to result in an irreversible, polymorphic transition. Poly‐p‐xylylene may be stretched at temeratures above 150°C. to reveal a well‐defined x‐ray fiber diagram, having an identity period of one. Sulfonation of poly‐p‐xylylene yields a product having one sulfonic acid group per benzene ring. The product swells anisotropically but does not dissolve in water. This observation, as well as the observation that the rate of dissolution of poly‐p‐xylylene in high boiling solvents is dependent upon the presence of oxygen, suggest that the polymer is crosslinked to a small but finite extent. The polymer derived from pseudocumene is also crosslinked but contains up toca.21% of a chloroform‐extractable component. The number‐average molecular weight of the chl

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136802

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe phases which are formed at,e.g., 22°C., when a solution containing,e.g., 1.1% polystyrene and 1.7% ethyl cellulose is made in benzene, are characterized by having a low interfacial tension (⋍10−3erg/cm.2), which permits droplets of the one phase in the other to be easily deformed and disrupted in a field of flow. The size and shape of the droplets thus formed were determined by an optical method depending upon the statistical addition of the deflections suffered by a beam of light in its passage through the medium. It is found that at intermediate velocity gradients very small and extremely elongated droplets are stable and that, at a given temperature, the phase separation can be reversed by raising the velocity gradient above a definite value. A full discussion of the observations is given and it is shown in particular that the appearance of extremely elongated drops at certain velocity gradients is due to a stationary state equilibrium between processes causing the drops to break up and others causing them to recombine again. The superposition of break‐up and recombination is thus responsible for the existence in practice of inherently unstable drop

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136803

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

Abstract(1) The electrostatic internal energy of a solution of rodlike, ionized polymolecules is calculated by an integration which makes use of the molecular potentials evaluated previously. (2) The electrostatic free energy is calculated by a charging process for which the reference state is a discharged solution of the same concentration as that of the charged solution. (3) A series of graphs is presented for the numerical evaluation of the internal and free energies of salt‐free polyelectrolyte solutions as a function of concentration, degree of ionization, and temperature. (4) The osmotic pressure of stretched polyelectrolytes is calculated from the free energy expression. The calculated osmotic coefficients are practically independent of molecular weight and polyelectrolyte concentration, and are determined by the degree of ionization. A comparison with the measurements of Kern on salt‐free polyacrylic acid at higher degrees of ionization (for which the macromolecules are stretched) gives a very satisfactory agreement. (5) An expression for the light scattering by polyelectrolyte solutions is derived from the equation for osmotic pressure and discussed brie

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136804

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractSix amphoteric copolymers of different composition of 2‐vinylpyridine and methacrylic acid were investigated. The specific viscosities of the copolymer solutions exhibit a pronounced minimum at the isoelectric point and the spectrometric titration of the pyridinium groups shows a pronounced jump in pH at the isoelectric degree of ionization. A theory of the polyampholyte behavior, based on the shape changes of the macromolecules and the field energy of the ionized groups, is developed and compares satisfactorily with the experimental results. The theory permitsinter aliathe evaluation of the intrinsic dissociation constants of the monomeric units and the determination of the isoelectric points from copolymer compositio

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136805

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe electrolytic dissociation of several polymeric acids and bases in aqueous solutions has been investigated. The potentiometric behavior is well described by the following equations, For polyacids:\documentclass{article}\pagestyle{empty}\begin{document}$$ p{\rm H} = pK_0 - \log \frac{{1 - \alpha }}{\alpha } + 0.4343\frac{{\varepsilon \psi _0 }}{{kT}} $$\end{document}and for polybases:\documentclass{article}\pagestyle{empty}\begin{document}$$ p{\rm H} = pK_0 - \log \frac{\beta }{{1 - \beta }} - 0.4343\frac{{\varepsilon \psi _0 }}{{kT}} $$\end{document}pK0is the intrinsic dissociation constant of the monomeric unit, α and β are the degrees of ionization of the polyacid and the polybase respectively, ψ0is the electrostatic surface potential of the polyion. It is shown that ψ0is equal to (1/ϵ) (δFe/δv) for polyacids and (1/ϵ) (δFe/δζ) for polybases whereFeis the electrostatic energy of the polyion andvor ζ the number of negative or positive ionized groups respectively. Equations for the calcualtion of ψ0in the cases of randamly kinked and stretched polyelectrolytes are given and discussed. As the potential ψ0can be obtained independently from electrophoretic measurements, the above equations correlate potentiometry and electrophoresis. The potentials of polymethacrylate ions were calculated from theory and obtained from electrophoretic and potentiometric measurements. The potentials obtained by the three methods agree within 3% thus justifying the use of the combined potentiometric and electrophoretic measurements for the evaluation ofpK0. Application of this method to the potentiometric analysis of pectic acids gave good agreement with experiment and lead topK0= 3.40. Combined potentiometric‐electrophoretic analysis for polyaspartic acid gavepK0= 3.53 and for poly

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136806

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe viscosity of a partially (60.8%) quaternized polyvinylpyridine withn‐butyl bromide has been investigated in dilute‐water and sodium chloride solutions, in a rotation (Couette) viscometer, at low gradients of flow. It was possible to extrapolate the ηsp/cagainst concentration plot in water by working at very low concentrations of the polymer. At about 5 × 10−5g./ml. the curve reaches a maximum and decreases sharply upon dilution to about one‐sixth the value at the maximum. The shape and size of the equivalent ellipsoid corresponding to the 60.8% polyvinylpyridinium bromide (DP = 7660) ions was estimated from the limiting viscosity number ([η] = 9500 ml./g.) and birefringence (extinction angle) data. The length of the stretched molecule was estimated to be 7420 A., corresponding to

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136807

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractA new theory of strong polyelectrolyte solutions based upon the Poisson‐Boltzmann equation is presented. Assuming that the ratio of the effective charge of the macro ion to its original charge is very small, the Poisson‐Boltzmann equation is solved without adopting the Debye‐Hückel approximation. As a result of the calculation, the effective charge of the actual coiled macro ion with the strongly dissociative groups was found small enough to justify this assumption for the solutions of varying concentration over wide range. Moreover, the free energy, and consequently the chemical potential of the components, of the polyelectrolyte solution with or without simple salt are calculated. The idea of “ion fixation” is theoretically introduced as convenient for representing the state of the polyelectrolyte solution. The theoretical results obtained above are quantitatively compared with experimental data with very good

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136808

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe persulfate‐initiated polymerization of allyl acetate has been studied at 70°C. in the absence and in the presence of sodium lauryl sulfate. In the absence of the detergent a polymer of molecular weight about 800 is formed from initially homogeneous reaction mixtures at an initial rate approximately proportional to concentration of persulfate and approximately independent of concentration of monomer. The ratio of the initial rates of disappearance of allyl acetate and persulfate is about 14, corresponding to the ratio calculated from the molecular weight. With a separate phase of monomer the molecular weight is about 1000. The addition of the detergent does not increase the rate of initiation or affect the molecular weight of the polymer formed in innitially homogeneous media, although the rate of polymerization is increased somewhat. With a separate phase of monomer the polymer formed in the presence of detergent has a molecular weight of about 13

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136809

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1954.120136810

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY