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Relaxations in Copolymers of Tetrafluoroethylene and Hexafluoropropylene
1.R. K. Eby and K. M. Sinnott, J. Appl. Phys. 32, 1765 (1961).
2.R. K. Eby (to be published).
3.J. D. Eshelby, J. Appl. Phys. 25, 255 (1954).
4.R. W. Balluffi and R. O. Simmons, J. Appl. Phys. 31, 2284 (1960).
5.N. G. McCrum, Makromol. Chemie 34, 50 (1959).
6.A. K. Schultz, J. chim. phys. 53, 933 (1956).
7.D. E. Kline, J. A. Sauer, and A. E. Woodward, J. Polymer Sci. 22, 455 (1956).
8.H. W. Starkweather, unpublished data (see Table II of text).
9.H. J. McSkimin, J. Acoust. Soc. Am. 23, 429 (1951).
10.In reference 5, the name glass II is applied to the γ relaxation and glass I is applied to the α relaxation. However, developments in polymer morphology suggest that the name “glass” is inappropriate. Therefore, the simpler Greek‐letter terminology is followed here.
11.The data are not shown since they offer only these results.
12.S. P. Kabin, Soviet Phys.‐Tech. Phys. 1, 2542 (1956).
13.The ultrasonic and low‐frequency data5 were obtained on samples with different amounts of HFP. Therefore, in order to make comparisons of data for polymers of the same composition, it was sometimes necessary to obtain the relaxation temperature from either the high‐ or low‐frequency data by interpolation.
14.The equation, was used. In this equation: f is the frequency of measurement, T is the absolute temperature, is the activation enthalpy, and is the activation entropy. It is recognized that there is some uncertainty about the form and magnitude of the term in the square brackets. However, the proposed variations are not large enough to affect greatly the magnitude of and
15.A. W. Lawson, J. Chem. Phys. 32, 131 (1960).
16.R. K. Eby, Bull. Am. Phys. Soc. 6, 143 (1961); and (to be published).
17.A. H. Willbourn, Trans. Faraday Soc. 54, 717 (1961).
18.W. Kauzmann, Revs. Modern Phys. 14, 12 (1942).
19.The value for the homopolymer is taken from reference 1. Values for the copolymers are unpublished data of N. G. McCrum.
20.The concept of the defects resulted from a study of the relation between the crystalline transition temperatures (“19 °C” “30 °C,” and melting) and the lamellar thickness. The results of electron microscopy and small‐angle x‐ray diffraction indicate that the perfluoromethyl groups are within the lamellae. Both the energy of the defects, and the lamellar thickness determine the transition temperature.2
21.For example, under similar crystallization conditions, the lamellar thickness decreases and therefore the concentration of molecular folds increases with increasing HFP content.2
22.R. W. Kedzie, Bull. Am. Phys. Soc. 7, 240 (1962).
23.D. H. Reneker, J. Polymer Sci. 59, S39 (1962).
24.G. P. Mikhailov, S. P. Kabin, and A. L. Smolianski, J. Tech. Phys. (U.S.S.R.) 25, 2179 (1955).
25.F. Krum and F. Müller, Kolloid‐Z. 164, 81 (1959).
26.F. Müller (personal communication).
27.We are indebted to C. E. Day for making these measurements.
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