摘要:

AbstractThe influence of water vapor on the rate of diffusion of organic molecules has been studied at 40°C. by the sorption method for the systems water‐acetone‐polyvinyl acetate, water‐carbon tetrachloride‐polyvinyl acetate, water‐acetone‐cellulose acetate (37.9% acetyl) and water‐benzene‐polystyrene. For the first three systems the rate of diffusion of the organic vapor is markedly faster for the mixture of water and organic vapor than for the pure organic vapor. With polyvinyl acetate, the rate of diffusion of 80 mm. of acetone is increased about 25‐fold if 36 mm. of water vapor is mixed with the acetone. Diffusion of the larger carbon tetrachloride molecule is accelerated by water even more than is acetone. Water vapor at a pressure of 36 mm. causes about a 30‐fold increase in the rate of diffusion of 80 mm. of acetone into cellulose acetate even though the diffusion of acetone itself into cellulose acetate is anomalous. With polystyrene the presence of water vapor causes no acceleration of the diffusion of benzene which is the expected result since, in contrast to the other two polymers, polystyrene sorbs only very small amounts of water. It is concluded that the marked effect of water vapor on the diffusion of organic vapors into polyvinyl acetate and cellulose acetate involves (a) a rapid diffusion of water into the polymer and (b) more rapid diffusion of the organic vapor into the “water plasticized” polymer t

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147601

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe following systems were observed in the Tiselius moving boundary apparatus: (1) poly‐4‐vinyl‐N‐n‐butylpyridinium bromide (PBr) with added potassium bromide/potassium bromide in osmotic equilibrium with the PBr‐KBr solution; (2) KBr/PBr, both solutions adjusted initially to the same conductance; (3) LiBr/PBr and (4) PBr‐(c1)/PBr(c2). Series 1 showed that the mobility of the polycation decreased with increasing KBr concentration. The schlieren patterns were strikingly asymmetric. Series 2 showed that the mobility of the polycation does not depend very much on molecular weight. Series 3 showed strong interaction between polyelectrolyte and simple electrolyte. Series 4 indicates that the mobility of the polycation depends on concentration much more than in the case of simple electrolytes. Both in Series 3 and 4, more moving boundaries appeared than are theoretically called for by the number of ionic sp

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147602

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractMeasurements are reported for the reversible changes in force with temperature at constant length of wet and dry viscose rayon and wet ramie. It was found that the force was a reversible function of the temperature although the components of its thermodynamic equivalent, the product of modulus and coefficient, are very time dependent. The entropies of stretching obtained as the negative slopes of the force‐temperature curves are interpreted in terms of the mechanisms of reversible stretching. Completely dry rayon is glasslike and shows no slippage of chains but only deformation of valence bonds and angles on reversible stretching. Wet rayons exhibit a rubberlike slippage of chains above 50°C. but below this temperature chain movement is restricted. This inhibition of the chains produces at low temperatures a yield point in the wet stress‐strain curves and poor work recovery. Sodium hydroxide, although speeding up stress relaxation, has no effect on the reversible stretching of the amorphous wet cellulose. In room air, the entropy of stretching is opposite to that of completly dry rayon even up to 92°C. Wet ramie appears to be in the glassy state like the completely dry

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147603

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe stress–strain behavior of reinforced rubber is discussed in respect of the softening with applied stress and accompanying dissipation of energy. The concept of linkage strength factorsXfor attachments between rubber molecules and filler particles is shown to have wide application and usefulness, and to be related to the energy dissipated in breaking the linkages. The strength factors are a function of the prestress when the linkages break, and also the corresponding extension ratio and residual stiffness; and for a variety of fillers and considerable range of values they can be roughly converted to energies of breakage in calories per unit change in modulus by multiplying by η = 0.013. The range of strengths of these secondary linkages due to fillers may be expressed in terms ofXby one distribution parameterKcommon to widely different rubber compounds. Energy data suggest that they are formed by physical attachments involving a number of chemical groups in the long chain polymer molecules. Presumably the strength distribution is mainly due to differences in the number of groups involved. The particle diameter of the filler has little or no importance in determining the energy dissipated in breaking secondary linkages, or their number as judged by stiffening action; yet it is a major factor in reinforcement as judged by tensile strength, tearing, and abrasion. Considerations of secondary linkages in conjunction with particle diameter show no prospect of explaining the differences in reinforcing action between types and grades of filler. An appreciation of the presence of some of strong‐type (primary) linkages due to carbon black is apparently necessary to understand the wide differences between fillers in the energy dissipated on breaking secondary linkages by a fixed prest

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147604

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractEvidence is discussed for and against the existence of a common meeting point when linear plots of ηsp/CagainstCfor polystyrene in a number of solvents are extrapolated to negative concentrations. There is rather more evidence in favor than against, and most of the contrary evidence falls into a category for which exceptional behavior might be anticipated. The ordinate of the common meeting point, unlike the limiting viscosity number, is independent of solvent and is conveniently called the true limiting viscosity number [η]T. [η]Thas been identified with the intrinsic configurational character of a polymer chain. The common point of intersection has the coordinates [η]TandC2, whereCxis a negative concentration. The product of [η]TandCxhas been found to be constant over a considerable molecular weight range. This leads to an expression for [η]/[η]Tin terms of Huggins'k′. [η]/[η]Trepresents the ratio of the hydrodynamically equivalent volume of a polymer in an actual solvent to the equivalent volume of the chain in its natural state of extension. [η]Tis considered in relation to [η]θ (Flory‐Fox) and [η]P(Bawan). The effect of polymer heterogene

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147605

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractA thermostat for light scattering studies is described in which the glass cell containing the solution under investigation is immersed in water maintained at constant temperature. The construction is such that the phototube used for detection of scattered light is at room temperature whatever the temperature of the sample. The liquid bath about the sample cell minimizes both troublesome reflections of the incident light and errors arising from refraction effects.

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147606

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractThe relative reactivities of polymer radicals in vinyl polymerization have been correlated semiquantitatively according to the Alfrey‐PriceQ′ andescheme. Polystyrene radicals are arbitrarily assigned aQ′rvalue of unity. The relative reactivities of other polymer radicals are then characterized by theQ′ andevalues of the parent monomers. This is shown by data concerned with copolymerization, homopolymerization, and chain transfer. It is proposed that the dispersion forces of London are the predominant influence in chain transfer reactions of polymer radicals with s

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147607

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

摘要:

AbstractIn continuation of a previous investigation on the small‐angle scattering of rayons in the dry and water‐swollen condition, a number of samples are investigated in lithium hydroxide solutions of increasing concentration up to 5N, in which considerably higher degrees of swelling can be reached. In samples showing an intensity maximum in the water‐swollen condition, the locus of this maximum shifts to smaller angles upon further swelling in LiOH solutions, to disappear in 5Nsolutions. Samples exhibiting neither a maximum nor an inflection point in no case yield straight Guinier plots even at the highest degree of swelling att

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147608

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147609

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1954.120147610

出版商:Interscience Publishers, Inc.    

年代:1954

数据来源: WILEY