Abstract
In this study, we used electrical impedance spectroscopy (EIS) to analyze dispersion and distribution states of CNT conductive nanoparticles in poly(butylene adipate-co-terephthalate) PBAT. We also used field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and rheology along with EIS, to investigate how CNT surface chemistry affects dispersion and electrical response in PBAT/CNT nanocomposites. PBAT nanocomposites containing 1.5 vol% of pristine CNTs, hydroxylated CNTs (CNT-OH), or carboxylated CNTs (CNT-COOH) were prepared by melt mixing. FE-SEM and Raman analyses showed considerably better dispersion for the PBAT/CNT-COOH sample. Rheological measurements further supported this observation; the rheological Cole–Cole plots of the PBAT/CNT-COOH composite exhibited a pronounced tail at low frequencies, indicative of strong CNT–polymer interactions and the formation of a bound polymer layer. The EIS results revealed a cutoff frequency of 70 Hz for PBAT/CNT-COOH, compared to 403 Hz for the other samples which implies that CNT interparticle distance is larger in the former. Fitting the Nyquist data with a modified Randles circuit yielded a parallel resistance of 694 Ω for PBAT/CNT-COOH, whereas the other two composites exhibited a considerably lower resistance of approximately 70 Ω. We attribute these electrical and rheological signatures to stronger interactions between COOH groups of CNT and ester groups of PBAT, which promote the adsorption of a bound polymer layer around the nanotubes. This interfacial layer effectively increases the average interparticle distance and polymer interlayer thickness, leading to higher electrical resistance and reduced capacitance. These findings of EIS are applied to the behavior of the whole bulk of the nanocomposite while other methods such as SEM only characterize tiny limited areas of the samples. The dispersion state, interparticle distance, bond polymer layer on CNTs and several electrical properties are detectable by EIS which all are the bulk characteristics of conductive polymer nanocomposites.
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
