摘要:

AbstractThe quantitative calculation of vapor‐liquid equilibria in mixtures consisting in part of chain molecules requires a partition function valid at both low and high densities. A preliminary partition function for this purpose is described. It is based on the hole theory of liquids and incorporates the concepts of Prigogine and Hijmans for chain molecules. The new partition function is used to represent the vapor‐liquid coexistence curves of long‐chain n‐

ISSN:0449-2994    

DOI:10.1002/polc.5070390103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThermodynamic properties of pure nonpolar liquids, including long‐chain hydrocarbons are obtained accurately by derivation from an analytical partition function and the corresponding‐states principle. The characteristic parameters are interpreted in terms of group contributions in order to relate them to the structure of the molecule and further to provide a useful basis for a predictive theory of the properties of mixtures. The model for interactions between molecules takes into account the influence of molecular shape on the number of nearest neighbors and the limited number of interacting groups in a binary intermolecular contact. One obtains energy and size characteristic group interaction parameters related to those derived from London's formula and a unique function of the number of carbon atoms to characterize the shape of the molecules. Using these results obtained from pure liquids, one can predict at the same time excess enthalpies and Gibbs free energies of mixtu

ISSN:0449-2994    

DOI:10.1002/polc.5070390104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractA theory is proposed for the entropy of mixing of polymer and solvent. The theory is an extension of Hildebrand's derivation of the Flory‐Huggins combinatorial entropy of mixing by use of free‐volume concepts. The noncombinatorial (or equation of state) entropy of mixing originates, according to the proposed theory in the different free volume fractions which characterize ordinary simple solvents and high polymers. Two parameters are introduced: a parameter ρ, which is the ratio of the free volume fractions in the polymer and in the solvent, and a parameter c, which describes the external degrees of freedom of the polymer segments and is equivalent to Prigogine's parameter c. The noncombinatorial entropy of mixing, as derived from the present theory is equivalent (but not identical) to that derived from the newer theory of Flory et al. Concomitantly, the agreement with experiment of the calculated interaction parameter × for the athermal system polyisobutylene‐cyclohexane is about the same as that obtained from the theory of Flor

ISSN:0449-2994    

DOI:10.1002/polc.5070390105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThe Flory‐Huggins form of the free enthalpy (Gibbs free energy) of mixing expression for solutions of linear homopolymers, generalized to make the interaction parameter × a function of concentration (as well as temperature) has been extended further to cover in general copolymeric and branched systems. From the resulting expression it is still possible to obtain the chemical potential, spinodal, and consolute state relationships in closed form. One simple case to which this treatment can be applied is that of the linear homopolymer system in which the interaction parameter is regarded as a function of molecular weight.A particular form for the molecular weight dependent interaction function is considered. After reducing the number of parameters by applying some thermodynamic restrictions, the remaining constants are evaluated with the aid of critical point data. The resultant interaction function is compared with other available experimental data. The process of reducing the number of floating parameters by means of restrictions of a thermodynamic nature is of general significan

ISSN:0449-2994    

DOI:10.1002/polc.5070390106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractA limiting critical point of a binary solution of a homodisperse polymer of molecular weight M, is any point in a (concentration, Φ, temperature, T)‐plane which is a critical point for a limit M → ∞. At any such point four conditions subsist for a function Φ defined in terms of the free enthalpy of mixing for (polymer) solutions. Because this definition is quite general, the conditions are universal and are not limited by any interpretation of Φ in terms of a particular model. Thus they are to be regarded as thermodynamic constraints on any model which may be applied to polymer solutions over conditions which extend to a critical region. If the limiting critical concentration, ΦL, is zero, then the limiting critical temperature, TL, is identical to the theta temperature, Tθ. If ΦLis not zero, Tθcan be obtained from Φ and is less than TLin a Flory (upper critical) system, or greater than TLin a Rowlinson (lower critical) system. It is concluded that theta temperatures have been seriously misestimated by classical extrapolati

ISSN:0449-2994    

DOI:10.1002/polc.5070390107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThermodynamic functions for mixing of a solvent with a crosslinked (branched) polymer are derived by considering the primary chains as copolymers of crosslinked and uncrosslinked units. Primary chains and solvent molecules are placed on a lattice with coordination number z. The crosslinked units bear one crosslinkable (C) and z‐3 (inner units) or z‐2 (end units) uncrosslinkable (U) contact surfaces. The free enthalpy of mixing is obtained by the quasichemical equilibrium approach and Tompa's modification for polymer molecules with different contact points. The condition of quantitative pairing (of purely entropic nature) of C contact surfaces is then introduced leaving only U contact surfaces available for the quasichemical equilibrium. In the polydisperse case, primary chains with a constant number of crosslinked and uncrosslinked units are taken as components. If mixing causes the dimensions of elastically active network chains (EANC) to be different from their reference (rest) dimensions, an elastic contribution proportional to the number of EANCs is added to the free enthalpy change. Comparing the result with the swelling equation of Flory relating the chemical potential of the solvent to the lattice site fraction of the polymer after swelling (θP) and at crosslinking (θP) and the fraction of EANCs per polymer unit (ve) ΔμS/RT = In (1 ‐ θP) + θP+ XθP2+ve(θP1/3θP02/3‐ αθP) (with α ± 1/2), it is shown that the interaction parameter × is a function of the coordination number, degree of crosslinking, molecular weight of primary chains (and concentration); the depedence vanishes if z goes to infinity. The coefficient α depends on the network structure and is equal to 1/2 only for an ideal network obtained by crosslinking of an

ISSN:0449-2994    

DOI:10.1002/polc.5070390108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThe product of chlorination of poly(vinyl chloride), perchlorovinyl (PerCV), dissolves in most organic solvents, a fact explained by the weakening of intermolecular interaction by irregular disposition of chlorine atoms along the chain. For evaluation of the changes in these forces, solubility parameters were determined by the method of turbidimetry and viscosimetry proposed by Suh, Clark, and Mangarai.For turbidimetry 15 solvents of differing chemical nature and 2 nonsolvents were used: hexane (low solubility parameter) and methanol (high solubility parameter). Values of the intrinsic viscosity and Huggins constants were obtained from viscometric data. Consideration of the results in terms of the Flory‐Huggins theory gave a value of 9.30(cal/cm3)1/2for the solubility parameter of PerC

ISSN:0449-2994    

DOI:10.1002/polc.5070390109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractCondensation polymers of phenolphthalein with sebacic acid (PA‐1) and of phenolphthalein with isophthalic acid (PA‐2) covering a wide molecular weight range were prepared and fractionated. Studies of solution viscosity were carried out on the fractions dissolved in tetrahydrofuran and in tetrachloroethane. Mark‐Houwink plots for PA‐1 are markedly nonlinear, and the effect is interpreted in terms of coil permeability. It is concluded that permeability effects are negligible in PA‐2. The molecular weight dependence of the second virial coefficient (determined by the Archibald method) in tetrahydrofuran is abnormal for both polymers. The characteristic unperturbed dimension for PA‐1 calculated by the Flory‐Williams method agrees with deductions fr

ISSN:0449-2994    

DOI:10.1002/polc.5070390110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractWe performed light scattering measurements on some polymers (polystyrene, polystyrene/poly(methyl methacrylate) graft copolymer, cellulose derivatives) to contribute to the clarification of the structure of solutions in the region of moderate concentrations. In particular, we investigated the influence of molecular weight, chain structure, and conditions of preparation of the solutions. Since a theory is lacking for the quantitative evaluation of scattering curves in this concentration range, we treated the results by the theories of dilute solutions and tried to draw conclusions about the structure of solutions at higher concentrations. Our results suggest network formation at high concentrations.

ISSN:0449-2994    

DOI:10.1002/polc.5070390111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractBy use of the perturbation theory, the number of contacts between blocks in a molecule of an A–B block polymer is expressed as a function of an excluded volume parameter in the from of a power series. The first two coefficients of this series are evaluated as functions of the relative length of one of the blocks. Introducing an approximate assumption according to Casassa and Markovitz, a closed‐form expression is obtained; its limiting value and first derivative as the excluded volume effect vanishes are in agreement with those given by the exact power series. Similarly to the preceding results obtained with the Flory‐Krigbaum segment cloud model, it turns out that on a change of thermodynamic conditions the number of interblock contacts is lowered only gradually; however the extent of this block segregation is higher than that according to the Flory‐Krigbau

ISSN:0449-2994    

DOI:10.1002/polc.5070390112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY