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19
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1542770393
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have found a low temperature loss peak in Teflon at 1 kHz at [formula omitted] presumably resulting from the presence of polar impurities attached to the polymer chain.
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(1959)
Kolloid Z.
, vol.164
, pp. 8
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Krúm, F.1
Müller, F.H.2
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23
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84951212769
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Our measured value of the calorimetric [formula omitted] 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 [formula omitted] 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 [formula omitted] assuming an activation energy of 100 kcal/mol (which is not unrealistic) gives 6° for a substance of [formula omitted] and 0.7° for that having [formula omitted] Thus a tenfold increase in the cooling rate will increase our measured value of [formula omitted] by 0.7° in most of our glasses and by 6° in polystyrene.
-
-
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24
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0000642623
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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
-
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.
-
(1969)
J. Chem. Phys.
, vol.51
, pp. 1546
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-
Wörz, O.1
Cole, R.H.2
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25
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84951213872
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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.
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-
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28
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0001785405
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at low temperatures also show this behavior.
-
have examined the Cole-Cole plots of a large number of polymers above [formula omitted] 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.
-
(1966)
J. Polymer Sci.
, vol.C14
, pp. 99
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Havereliak, S.1
Negami, S.2
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32
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0042616219
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have found that isothermal annealing below [formula omitted] 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.
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(1968)
Kolloid Z.
, vol.225
, pp. 1
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Frank, W.1
Stuart, H.A.2
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34
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84951213870
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For a detailed description of the causes of this effect, see, L. K. H. van Beek
-
edited by J. B. Birks (Chemical Rubber, Cleveland, Ohio)
-
(1967)
Progress in Dielectrics
, pp. 69-114
-
-
-
36
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84951213878
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Reference 2. pp. 20–25.
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