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Viscous Liquids and the Glass Transition. II. Secondary Relaxations in Glasses of Rigid Molecules
1.A. E. Woodward and J. A. Sauer, in Physics and Chemistry of the Organic Solid State (Interscience, New York, 1965), Vol. II, p. 638.
2.N. G. McCrum, B. E. Read, and G. Williams, Anelastic and Dielectric Effects in Polymeric Solids (Wiley, New York, 1967).
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11.G. P. Johari and C. P. Smyth, J. Am. Chem. Soc. 91, 5168 (1969).
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18.and F. Krúm and F. H. Müller [Kolloid Z. 164, 8 (1959)] have found a low temperature loss peak in Teflon at 1 kHz at presumably resulting from the presence of polar impurities attached to the polymer chain.
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22.Our measured value of the calorimetric for the molecularmixture glasses is insensitive to the cooling rates when compared to other amorphous substances, e.g., organic polymers or silicate glasses. This is not surprising because the amount of change in temperature required to cause a tenfold increase in relaxation time for liquids having a low is very small. A simple calculation for the decrease in temperature needed to cause a tenfold increase in the volume, shear, or dielectric relaxation time near assuming an activation energy of 100 kcal/mol (which is not unrealistic) gives 6° for a substance of and 0.7° for that having Thus a tenfold increase in the cooling rate will increase our measured value of by 0.7° in most of our glasses and by 6° in polystyrene.
23.After these experiments were done, a very careful analysis of the effect of cracks and consequent air gaps in a dielectric sample on the dielectric loss spectrum and dielectric relaxation time was published by O. Wörz and R. H. Cole [J. Chem. Phys. 51, 1546 (1969)]. They found that the dielectric absorption spectrum and dielectric relaxation time for ice I remains unaffected by the appearance of cracks in the sample, despite the fact that the apparent dielectric constant of ice I in a cracked sample was significantly smaller.
24.Johari and Smyth in Ref. 11 have mistakenly reported the loss spectrum in chlorobenzene‐decalin solution as a symmetric distribution of relaxation times. Our results, however, confirm the broadening of the spectrum with decreasing temperature reported by them.
25.W. Kauzmann, Rev. Mod. Phys. 14, 12 (1942).
26.It appears that broadening of the distribution in dielectric absorption with decreasing temperature in the form seen here is typical of glass‐forming liquids, molecular or polymeric, near D. J. Denney and J. W. Ring’s results on long chain alkyl halide solutions in 2‐methylpentane [J. Chem. Phys. 44, 4621 (1966)]
26.at low temperatures also show this behavior. S. Havereliak and S. Negami [J. Polymer Sci. C14, 99 (1966)] have examined the Cole‐Cole plots of a large number of polymers above and have found this behavior. They have also suggested a generalized form of analytical equation which, with appropriate choice of parameters, can produce a semicircle, an arc, a skewed arc, or any other shape in between. We do not see any advantage to our understanding from attempting to fit data to their equation.
27.A. E. Owen, in Progress in Ceramic Science, edited by J. E. Burke (Macmillan, New York, 1963), Vol. III, p. 77.
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29.D. C. Douglass (private communication).
30.W. Frank and H. A. Stuart [Kolloid Z. 225, 1 (1968)] have found that isothermal annealing below increases the shear modulus and decreases the mechanical loss factor in several polymers. We are not aware of any studies of the effect of annealing on the dielectric properties of polymers.
31.G. P. Mikhailov, in Physics of Non‐Crystalline Solids, edited by J. A. Prins (North Holland, Amsterdam, 1965), pp. 270–282.
32.For a detailed description of the causes of this effect, see, L. K. H. van Beek, in Progress in Dielectrics, edited by J. B. Birks (Chemical Rubber, Cleveland, Ohio, 1967), pp. 69–114.
33.See entry under “Ockham” in Webster’s Third New International Dictionary, edited by P. B. Gove (Merriam, Springfield, Mass., 1961), p. 1561.
34.Reference 2. pp. 20–25.
35.W. Kauzmann, Chem. Revs. 43, 219 (1948).
36.J. H. Gibbs, in Modern Aspects of the Vitreous State, edited by J. D. MacKenzie (Butterworths, London, 1960), Vol. 1, pp. 152–187.
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