TSDC studies of the effects of plasticizer and water on the sub-T_grelaxations of an epoxy resin system

Polymer dynamics in rubbery epoxy networks/polyhedral oligomeric silsesquioxanes nanocomposites

“…The large magnitude of the peak indicates that its origin cannot be dipolar. In agreement with results obtained with other epoxy networks, 41 the peak is attributed to interfacial Maxwell-Wagner-Sillars (MWS) relaxation. Such a peak is characteristic for heterogeneous samples and arises from the accumulation of charges at interfaces separating regions of different electrical conductivity.…”

“…It is very likely that DGEBA itself makes a contribution to the dielectric response in the region of the secondary relaxations, which may be ignored, however, at a first stage against that of Jeffamine, as indicated by comparison with the results of dielectric measurements in epoxy resins based on DGEBA cured with low molar mass cross-linkers. 41,51,52 Please note that the two relaxations have practically the same time scale in Jeffamine and in the networks, this result providing support for the local character of the two relaxations against a relaxation of Goldstein-Johari type. 51 In agreement with previous work, the c relaxation is assigned to local motions of (CH 2 ) n sequences and the b relaxation to motion of polar ether groups with attached water molecules, as confirmed also by measurements on cross-linked polyurethanes based on polymer polyols synthesized from poly(oxypropylene glycol), at various levels of humidity/water content.…”

Dielectric studies of chain dynamics in homogeneous semi-interpenetrating polymer networks

“…19 The disagreement between TSDC and DMA results with respect to number, location (timescale), and origin in terms of molecular motion should not be surprising, as mechanical and dielectric spectroscopies may be sensitive to different molecular motions. 36 It is perhaps more interesting to critically compare the TSDC data obtained here on PCN with TSDC data obtained on similar epoxy resin systems, 37 as indicated in ref. 24.…”

“…A TSDC peak in an epoxy resin system based on diglycidyl ether of bisphenol-A at about 150 K has been attributed to the motion of methyleneethylene or diethylene ether linkages, whereas a second peak at 240 -280 K has been attributed to motions of phenyl rings and space charge contributions. 37 This interpretation is adopted here for the TSDC data obtained with the PCN network.…”

Dielectric properties of cured epoxy resin+poly(ethylene oxide) blends

“…In this report dielectric probes [15][16][17] are used to study the influence of the molecular structure, components polarity and their interactions, on the apparent relaxation response of the initial phases and the crosslinked structure, with the aim to acquire information on their compatibility. Hitherto, dielectric methods have been implemented to monitor phase separation, gelation and vitrification processes during curing [18] and study local-chain or segmental relaxation modes in ERs [1,2,19,20].…”