Poisson_ratio-PAAm_gels_Macromolecules_Geissler_(1980)_ma60077a047

Poisson_ratio-PAAm_gels_Macromolecules_Geissler_(1980)_ma60077a047

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1276 Macromolecules 1980, 13, 1276-1280 for which Tg data is well fit by the form of eq 15. For PPO blended with PS oligomers, the pure-component glass- transition temperatures differ by >200 K, and the value K1 = 2.50 reproduces blend transition temperatures to within 5 K.I* Equations 16 and 17 give, respectively, K1 = 2.79 and = 1.60. Thus, although strictly the differ- ence between pure-component glass-transition tempera- tures might seem rather large for the single-term expan- sions necessary for eq 16 and 17, the former is the more acceptable for compatible blends of PPO and PS (for which AC,,/AC,, C 1) and, indeed, is fairly accurate. Final Remarks A phenomenological theory for the compositional vari- ation of glass-transition temperatures in one-phase mix- tures based on a model of these as regular solutions has now been shown to account with some success for the phenomenon in binary mixtures of high polymers and, also, to give an acceptable description of the variation of glass-transition temperatures with molecular mass for homopolymers. Further, as described in the present con- tribution, these two formal treatments can be combined to predict glass-transition temperatures in compatible blends of arbitrary composition and pure-component de- gree of polymerization from component chain end and high-polymer glass-transition temperatures and their re- ciprocal heat-capacity increments, equivalent to the gen- eration of a %n-dimensional surface. Acknowledgment. This research was supported by the National Science Foundation Division of Materials Re- search under Grant DMR79-151715, Polymers Program. References and Notes (I) Gordon, M.; Taylor, J. S. J. Appl. Chem. 1952,2, 493. (2) Wood, L. A. Polym. Sci. 1958, 28, 319. (3) Kelley, F. N.; Bueche, F. J. Polym. Sci. 1961, 50, 549. (4) Fox, T. G. Bull. Am. Phys. SOC. 1956, I, 123. (5) Mandelkern, L.; Martin, G. M.; Quinn, F. A. J. Res. Natl. Bur. Stand. (U.S.) 1957, 58, 137. (6) Gibbs, J. H.; DiMarzio, E. A. Chem. Phys. 1958, 28, 807. (7) Pochan, M.; Beatty, C. L.; Pochan, D. F. Polymer 1979,20, 879. (8) Kovacs, A. J. Adu. Polym. Sci. 1963, 3, 394. (9) Couchman. P. R.; Karasz, F. E. Macromolecules 1978.11.117. Couchman; P. R.’Macro&olecules 1978,II, 1156; Phys. Lett. 1979, 70A, 155. Couchman. P. R. J. ADDL Phvs. 1979.50. 6043. Couchman; P. R. J. 6ter. SEi. 1980,’15,’1680. Kanig, G. Kolloid 2. 2. Polym. 190, 1. Fox, T. G.; Flory, P. J. J. Polym. Sci. 1954,4, 315. Boyer, R. F. J. Macromol. Sci., Phys. 1973, 7, 487. See, for example: Naito, G.; Johnson, G. E.; Allara, D. L.; Kwei, T. K. Macromolecules 1978, 11, 1260. MacKnight, W. J.; Karasz, F. E.; Fried, J. R. In “Polymer Blends”; Newman, S., Paul, D. R., Eds.; Academic Press: New York, 1978; Vol. 11, Chapter 5. Kwei, T. K.; Frisch, H. L. Macromolecules 1267. Fried, J. R.; Karasz, F. E.; MacKnight, W. J. Macromolecules 21, 150. Ueberreiter, K.; Otto-Laupenmuhlen, E. 2. Naturforsch., A 1953,8, 664. The Poisson Ratio in Polymer Gels E. Geissler* Laboratoire de Spectroscopie Optique, UniuersitB de Sauoie, 7301 1 Chambery Cedex, France A. M. Hecht Laboratoire de SpectromBtrie Physique,+ UniversitB Scientifique et MBdicale de Grenoble, 38041 Grenoble Cedex, France. Received February 6, 1980 ABSTRACT: A comparison is made between the longitudinal elastic modulus and the shear modulus in polyacrylamide gels. The former is measured by inelastic light scattering as well as by osmotic deswelling; the latter is measured by observation of the frequency of standing waves excited in the samples. The ratio
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This note was uploaded on 07/20/2011 for the course EMA 6165 taught by Professor Brennan during the Spring '08 term at University of Florida.

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Poisson_ratio-PAAm_gels_Macromolecules_Geissler_(1980)_ma60077a047

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