ISSN:
1436-2449
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Summary The dielectrical behaviour (in the frequency range f=20 Hz — 200 kHz) of two networks — polyacrylamide (PAAm) network and a network obtained by the copolymerization of acrylamide with 3 mol.% sodium methacrylate (MNa) in a mixed solvent deionized water — acetone (acetone concentration a=0–80 vol.%) at T=298 K and pH ∼ 7 was investigated. High values of complex permitivity ɛx(=ɛ′+iɛ″) were found for both networks. For the PAAm network the dependence of both components of ɛx on a is continuous. On the other hand, for the ionized network the jumpwise decrease in swelling at the phase transition is accompanied by a jumpwise increase in the values of both components of ɛx at all frequencies; the critical concentration of acetone a at the collapse is frequency independent. The high values of components of ɛx and their dependences on a observed with both networks can be explained qualitatively by the polarization of the space charge in the measured samples. While with the PAAm network the charge is given by the dissociation of water, in the case of the P(AAm-MNa) network ions arising by the dissociation of MNa also contribute to this charge. The collapse in the ionized network is accompanied by a jumpwise increase in the effective charge concentration in the gel. The fact that the extent of the jumpwise change of components of ɛx in the collapse is frequency dependent suggests that the dependence of ɛx on a is also affected by the mobility of charge carriers.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00255826
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