Molecular dynamics of poly(ε‐caprolactone)/beidellite organoclay bionanocomposites obtained by in‐situ polymerization highlighted by dielectric relaxation spectroscopy

Abstract

Nanocomposites of poly(ε‐caprolactone) (PCL) reinforced by an organomodified beidellite (BDT) with 3% of cetyltrimethylammonium bromide (CTAB) (labeled PCL/3CTA‐BDT) were prepared by varying the content of filler (1, 2, 3, and 5 wt%). Their molecular dynamics were investigated by broadband dielectric spectroscopy at temperatures ranging from 0 to 40°C and a frequency window from 10−1 to 106 Hz. Three relaxation processes were detected for unfilled PCL: electrode polarization (EP), the Maxwell–Wagner–Sillars (MWS) polarization, and the α‐relaxation. The incorporation of the filler induced the emergence of a fourth process at high frequency of dipolar origin labeled as interfacial polarization (IP). Fitting the data with the Havriliak–Negami model as well as a study of the relaxation time variation with temperature demonstrated the noncooperative nature of the IP process. Activation energy and dielectric strength values demonstrated that the PCL/3CTA‐BDT with 3 wt% of filler showed a higher quality of dispersion and better interfacial features compared to those with other filler contents (2 and 5 wt%). This work highlights the challenges of dielectric green nanocomposites used for capacitors (storage energy) and cable/wire insulation.Highlights The various samples were analyzed using broadband dielectric spectroscopy. Relaxation processes in pure matrix: EP, MWS, and α‐relaxation. Incorporation of the filler induced the emergence of interfacial polarization (IP). Noncooperative behavior of the IP process. 3 wt% loading showed a higher quality of dispersion and interfacial features.