Studies in the Thermodynamics of Polymer-Liquid Systems. I. Natural Rubber and Polar Liquids

Abstract There is a great lack of reliable thermodynamic data on concentrated polymer solutions. This group of papers contributes further measurements, especially on systems consisting of a polar liquid and nonpolar polymer, and presents a review of the current situation. This first part records observations on the swelling of natural rubber in several polar liquids, using two different techniques. One of these is the conventional study of vapor pressures; the other is a novel procedure involving measurements of swelling and tension in stretched crosslinked samples. The results are compared with the Flory-Huggins equation, and show that as swelling proceeds and approaches saturation, there is a marked fall in the interaction parameter χ`. At the same time the entropy of dilution falls progressively further below the curves predicted by current theories.

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Polymer swelling, 13: Correlation of flory–huggins interaction parameter, χ, with molecular structure in polystyrene–liquid systems

Journal of Applied Polymer Science ◽

10.1002/app.1992.070450409 ◽

1992 ◽

Vol 45 (4) ◽

pp. 619-631 ◽

Cited By ~ 12

Author(s):

L. A. Errede

Keyword(s):

Molecular Structure ◽

Interaction Parameter ◽

Polymer Swelling ◽

Liquid Systems ◽

Interaction Parameter Χ

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Studies in the Thermodynamics of Polymer-Liquid Systems. II. A Reassessment of Published Data

Rubber Chemistry and Technology ◽

10.5254/1.3535651 ◽

1965 ◽

Vol 38 (2) ◽

pp. 325-333

Author(s):

C. Booth ◽

G. Gee ◽

M. N. Jones ◽

W. D. Taylor

Keyword(s):

Polymer Solutions ◽

Solid Polymer ◽

Published Data ◽

Polar Liquids ◽

Polymer Liquid ◽

Entropy Of Mixing ◽

Polar Polymers ◽

Liquid Systems ◽

Single Method ◽

Degree Of Order

Abstract Part II contains a complete reassessment of all published data on polymer solutions, using a single method of analysis. Non-polar liquids in non-polar polymers show an entropy of mixing higher than predicted by current theories. The discrepancy is attributed to a degree of order in the solid polymer. Polar liquids in non-polar polymers follow the pattern described in Part I: this behavior is attributed to non-random mixing at concentrations approaching saturation.

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Accounting for Cooperativity in the Thermotropic Volume Phase Transition of Smart Microgels

Gels ◽

10.3390/gels7020042 ◽

2021 ◽

Vol 7 (2) ◽

pp. 42

Author(s):

Simon Friesen ◽

Yvonne Hannappel ◽

Sergej Kakorin ◽

Thomas Hellweg

Keyword(s):

Phase Transition ◽

Interaction Parameter ◽

Quantitative Description ◽

Water Molecules ◽

Volume Phase Transition ◽

Network Chain ◽

Solvent Interaction ◽

Volume Phase ◽

The Cross ◽

Interaction Parameter Χ

A full quantitative description of the swelling of smart microgels is still problematic in many cases. The original approach of Flory and Huggins for the monomer–solvent interaction parameter χ cannot be applied to some microgels. The reason for this obviously is that the cross-linking enhances the cooperativity of the volume phase transitions, since all meshes of the network are mechanically coupled. This was ignored in previous approaches, arguing with distinct transition temperatures for different meshes to describe the continuous character of the transition of microgels. Here, we adjust the swelling curves of a series of smart microgels using the Flory–Rehner description, where the polymer–solvent interaction parameter χ is modeled by a Hill-like equation for a cooperative thermotropic transition. This leads to a very good description of all measured microgel swelling curves and yields the physically meaningful Hill parameter ν. A linear decrease of ν is found with increasing concentration of the cross-linker N,N′-methylenebisacrylamide in the microgel particles p(NIPAM), p(NNPAM), and p(NIPMAM). The linearity suggests that the Hill parameter ν corresponds to the number of water molecules per network chain that cooperatively leave the chain at the volume phase transition. Driven by entropy, ν water molecules of the solvate become cooperatively “free” and leave the polymer network.

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Mastication of Rubber. II. Interpolymerization of Natural Rubber and Neoprene on Cold Milling

Rubber Chemistry and Technology ◽

10.5254/1.3542540 ◽

1956 ◽

Vol 29 (2) ◽

pp. 427-437

Author(s):

D. J. Angier ◽

W. F. Watson

Keyword(s):

Free Radicals ◽

Natural Rubber ◽

Small Molecules ◽

The Other ◽

Polymer Molecules ◽

Commercially Important ◽

The Individual ◽

Cold Mill ◽

General Method ◽

Butadiene Styrene

Abstract The softening of elastomers on cold milling results from scission of the polymer molecules by the applied shearing forces. The ruptured chains are free radicals, which can undergo mutual combination, interaction with oxygen and various additives, and branching (grafting) on to other polymer molecules. A general method of producing graft and block interpolymers between elstomers is therefore indicated, namely, to cold-mill the polymers together in the absence of small molecules which can terminate the polymeric radicals in order that the radicals may cross-terminate or graft onto the polymer molecules of the other type. A survey of several pairs of the commercially important elastomers, natural rubber, butadiene-styrene, Neoprene, and butadiene-acrylonitrile, has shown that cold milling does effect interlinking. Detailed results for the rubber-Neoprene system are reported in this communication. Experimental verification of polymer interlinking was obtained from the solubility properties of the milled elastomers. Cold milling of Neoprene under nitrogen produces gel, whereas of natural rubber does not, but the milling of mixtures gives gels containing natural rubber. Also, the solubilities and precipitation of the milled mixtures cannot be accounted for by these properties of the individual polymers. Finally, Neoprene-natural rubber mixtures, after and not before cold-milling, can be cross-linked by magnesium oxide, with rubber bound into the vulcanizate.

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Molecular Interpretations of Chemo-Mechanical Responses in Polymer-Liquid Systems

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x9300400204 ◽

1993 ◽

Vol 4 (2) ◽

pp. 161-168 ◽

Cited By ~ 1

Author(s):

L.A. Errede ◽

Yoshihito Osada ◽

George V.D. Tiers

Keyword(s):

Polymer Liquid ◽

Mechanical Responses ◽

Liquid Systems

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HYSTERESIS IN SILICA GEL SORPTION SYSTEMS

Canadian Journal of Research ◽

10.1139/cjr34-059 ◽

1934 ◽

Vol 10 (6) ◽

pp. 713-729 ◽

Cited By ~ 6

Author(s):

L. M. Pidgeon

Keyword(s):

Hysteresis Loop ◽

Silica Gel ◽

Sulphur Dioxide ◽

Water System ◽

The Other ◽

Vapor Pressures ◽

Large Pressure ◽

Pressure Changes ◽

Permanent Gases ◽

Sorption Systems

The hysteresis which normally appears in the isotherms of the silica gel-water system has been attributed by Patrick to the presence of permanent gases in the system. Only one case has been found in which a reversible isotherm has been recorded in the silica gel-water system. For alcohol and benzene only one case of hysteresis has been reported. These results seem to be independent of the presence or absence of air or other gases.The sorption of water, benzene and ethyl alcohol has been examined using the sorption balance. A hysteresis loop appears for water only. This hysteresis may not be eliminated by special methods of evacuation and must be considered as a real effect. The isotherms of alcohol and benzene, on the other hand, are completely reversible. It has been shown that the dimensions of the hysteresis occurring in the water system may be affected by the manner of addition of vapor to the apparatus. Only when the vapor pressures remain reasonably constant during sorption are the dimensions of the effect evident. If very large pressure changes take place the hysteresis may disappear.A comparison of the isotherms for water showing hysteresis, and those of the sulphur dioxide system (upon which the original suggestion as to the cause of hysteresis was based) show that there is not necessarily any relation between the two.

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The Separation and Characterization of Graft Copolymers from Natural Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3542343 ◽

1958 ◽

Vol 31 (4) ◽

pp. 819-828 ◽

Cited By ~ 1

Author(s):

F. M. Merret

Keyword(s):

Natural Rubber ◽

Intrinsic Viscosity ◽

Benzene Solution ◽

Graft Copolymers ◽

General Pattern ◽

The Other ◽

Vinyl Monomers ◽

Major Increase ◽

Made In

Abstract The solubility of graft copolymers prepared from rubber and vinyl monomers follows a general pattern whereby one of the constituents can be insolubilized while the other remains soluble, the compound forming a stable sol which is largely unaffected by heat or ionic materials at suitable ratios of solvent to precipitant. The onset and flocculation of the sol are such that the graft copolymer can be completely separated from either free constituent homopolymer. This insolubilization of the rubber trunk chain by addition of methanol to a benzene solution of the coploymer has been followed by the changes in the intrinsic viscosity and turbidity, which show that the collapse of the rubber chain continues to a point beyond where the molecularly equivalent free rubber would be precipitated. This period also marks the major increase in turbidity. Osmotic data show that μ-values for the grafted copolymers of rubber are the same as for rubber itself, thus supporting similar assumptions made in the application of the theory of the equilibirium swelling of crosslinked rubber.

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