Dielectric Relaxation Dynamics of Clay‐Containing Low‐Density polyethylene Blends and Nanocomposites

Abstract

Series of clay-containing nanocomposites have been prepared and investigated using frequency-domain dielectric spectroscopy at different temperatures. Different matrix materials have been used: neat low-density polyethylene (LDPE) with and without compatibilizer and co-continuous blends of LDPE with two grades of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) copolymers. Two major relaxation modes were detected in the dielectric losses of all the nanocomposites and associated with Maxwell-Wagner-Sillars interfacial polarization and dipolar relaxation, respectively. Characteristic relaxation rates, activation energies, dielectric strength, and shape parameters of these relaxation mechanismes were calculated and discussed for the LDPE/clay nanocomposites. The addition of compatibilizer was found to slightly increase the dielectric loss of the nanocomposites while slowing the dynamics due to an improved dispersion. When combined with a high loading of nanofiller (15%), the compatibilizer addition led to lowfrequency dispersion. A new relaxation process was then observed for the nanocomposites with the blend matrix. Several speculations were made as to the origin of this phenomenon, all of which were related to the SEBS phase. POLYM. ENG. SCI., 60:968-978, 2020.

Investigation and characterization of dielectric, thermal, and chemical properties of recycled high‐density polyethylene blended with virgin polyethylene

“…This is due to the changes in density predicted by the Clausius–Mossotti equation 37 . The dielectric constant was also relatively frequency‐independent because of the non‐polar nature of polyethylene which is consistent with previous reports for PE 38 . Figure 8B shows the isothermal curve of PCRF as a function of frequency for temperatures ranging from 25°C to 85°C.…”

“…37 The dielectric constant was also relatively frequency-independent because of the non-polar nature of polyethylene which is consistent with previous reports for PE. 38 Figure 8B shows the isothermal curve of PCRF as a function of frequency for temperatures ranging from 25 C to 85 C. At high frequencies, the curves were similar to the virgin HDPE, but at low frequencies, significant discrepancy was found due to the contribution of charge carrier fluctuation to the overall polarization. Indeed, the real and imaginary parts of the permittivity were affected by phenomena such as Maxwell-Wagner polarization, electrode polarization, and low-frequency dispersion, unlike pure dc conductivity, which only affects the imaginary part, as reported in previous literature.…”

Use of Dynamic Mechanical Analysis (DMA) for Characterizing Interfacial Interactions in Filled Polymers

“…Nuclear magnetic resonance (NMR) spectroscopy has been used to study the effect of different fillers on the chain dynamics of polymers, especially the elastomers used in the rubber industry [19][20][21][22][23][24][25][26]. Raman spectroscopy [27][28][29][30] and the dielectric relaxation spectrum [31][32][33][34][35][36][37] have also been used to characterize the interaction between different fillers and polymeric matrices. Different research groups have used atomic force microscopy (AFM) to study the interfacial interactions of filled polymeric systems [38][39][40], whereas some researchers [18,[41][42][43][44][45] have used AFM for the quantitative characterization of the polymer-filler interface (e.g., for measuring the thickness of the interfacial layer between the polymer and the filler particles) and the microscopic mechanical properties of the nanocomposites.…”

Melt‐reprocessable linear low‐density polyethylene/cyclic olefin copolymer blends with low dielectric constant and low thermal expansion

“…Low‐density PE has good melt processability and relatively low melting points, as well as its low cost 6,7 . In addition to low cost and low permittivity and tan δ values, low‐density PE offers low temperature flexibility coupled with chemical and moisture resistance, making it an attractive candidate for insulation applications, especially in early cable constructions 8–13 . Nevertheless, the main disadvantages of low‐density PE include high CTE, that is, poor dimensional stability, and relatively high dielectric constants for communication cable applications.…”

“…flexibility coupled with chemical and moisture resistance, making it an attractive candidate for insulation applications, especially in early cable constructions. [8][9][10][11][12][13] Nevertheless, the main disadvantages of low-density PE include high CTE, that is, poor dimensional stability, and relatively high dielectric constants for communication cable applications. Low-density PE was later replaced by cross-linked PE due to its improved properties.…”