Molecular Mobility in Polycyanurate/Clay Nanocomposites Studied by Dielectric Techniques

Abstract

Nanocomposites, having neat polycyanurate networks (PCN) and modified by polytetramethylene glycol polycyanurate networks (PCN/PTMG) as matrices and montmorillonite (MMT) as filler, were prepared using thermal polymerization, and studied with respect to polymerization kinetics, morphology and in particular, molecular mobility. In order to investigate the influence of the clay modifier and the way of preparation two types of commercial MMT were used, while the mixing was obtained mechanically and by using ultrasound. IR-spectroscopy, Wide Angle X- ray Scattering (WAXS) and dielectric techniques including Dielectric Relaxation Spectroscopy (DRS) and Thermally Stimulated Depolarization Current (TSDC) techniques were used to provide information on polymerization kinetics, morphology and molecular mobility, respectively.

Dielectric relaxation in polymer–clay nanocomposites

“…Comparative TSDC thermograms on neat PU and the various NCs show that for the secondary g and b relaxations practically neither the peak position (115 and 160 K, respectively) nor the magnitude of the peak change with composition. thus, both timescale and relaxation strength of the local relaxations remain unchanged in the NCs under investigation, in agreement with results obtained with other NCs (Maroulas et al, 2009).…”

“…Polymerization kinetics was followed by using ir spectroscopy. Details of preparation have been given elsewhere (Bershtein et al, 2008;Maroulas et al, 2009). the materials prepared were investigated with respect to morphology by wide angle X-ray spectroscopy (WAXS) and TEM, whereas DSC was employed to study thermal transitions.…”

Polymer dynamics in epoxy/alumina nanocomposites studied by various techniques

“…Moreover, comparative isothermal ε′( f ) plots at low temperatures (in the glassy state), not shown here, reveal that for the samples with a fixed filler fraction of 3 mass % ε′ increase in the order DER, D40, OS2, OS1, whereas E ′ ( T ) in Figure 3 decreases in exactly the same order. Different results have been obtained in other polymer Ncs, such as epoxy/clay Ncs, 43 polycyanurate/clay Ncs, 44 and polyimide/silica Ncs, 45 where rigid nanofillers interact with the matrix, in some cases being covalently attached to the chains, and impose constraints to the motion of the polymeric chains, resulting in a reduction of ε′ in the glassy state. Please note that this represents a common route for preparing materials with low values of ε′ (low‐k materials) for microelectronics applications.…”

“…Analysis showed that the three relaxations are symmetric (β = 1), as often observed for secondary relaxations. 28, 44 In what follows, we focus mainly on the time scale of the relaxations, the most significant information extracted from the analysis. This was further analyzed in terms of the Arrhenius diagram by plotting the logarithm of the frequency of maximum dielectric loss, $f_{\max } = {\raise0.7ex\hbox{$1$} \!\mathord{\left/{\vphantom {1 {2\pi \tau }}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${2\pi \tau }$}}$ , obtained at each temperature from the HN analysis, against reciprocal temperature (Fig.…”

Thermostable cyanate ester resins and POSS-containing nanocomposites: influence of matrix chemical structure on their properties

“…However, to our knowledge the specific papers on comparison of properties of various CER are not published. Because of the discrepancy between the analytical techniques and, for the same technique, between the sample preparations, comparison between two values of, for example, T g or T d or mechanical strength from distinct publications is tricky, if not impossible.The nanocomposites of PCN with montmorillonite, [8][9][10][11][12][13] carbon nanotubes, [14,15] nanostructured aluminum borate, [16] ZnO, [17] ZrW 2 O 8 , [18] nanosilica, [19] and polyhedral oligomeric silsesquioxanes (POSS) [20][21][22][23][24][25][26][27][28][29][30][31][32] have been developed and characterized. In the majority of these works, the authors have studied usually only one type of CER as well.…”