Enhancing the electrical conductivity of PA6/PPO/CNT/CCB nanocomposites via control of PA6 transcrystalline layer formation, morphology, and selective localization of nanofillers. (April 2023)

• Record Type: Journal Article
• Authors: Farhadpour, Mohammad; Pircheraghi, Gholamreza; Marouf, Bahereh T.; Bagheri, Reza
• Is Part Of: Polymer testing. Volume 121(2023)
• Publication Date: 2023-04
• Subjects: Nanocomposites -- Electrical conductivity -- Carbon nanotubes -- Selective localization -- Transcrystalline layer -- Co-continuous morphology; Polymers -- Testing -- Periodicals; Polymères -- Tests -- Périodiques; 620.1920287
• DOI: 10.1016/j.polymertesting.2023.107978
• Languages: English
• ISSNs: 0142-9418

Abstract

Abstract: Electrically conductive polyamide-6 (PA6)/poly(phenylene oxide) (PPO) nanocomposites containing conductive nanofillers such as carbon nanotubes (CNTs) and conductive carbon black (CCB) have attracted considerable interest from both academia and industry. Despite their importance in applications such as electrostatic painting, only a few studies have been reported. In the current study, the effects of the morphological structure and selective localization of CNTs/CCB (into the PA6 or at the interface of the PA6/PPO) on the electrical conductivity of the nanocomposites have been investigated. The PA6/PPO ratio and mixing sequence are the two parameters that control the morphology and the selective localization. FESEM, TEM, and solution experiment observations showed selective localization of CNTs/CCBs in PA6 during melt blending. It was found that at a low PPO weight percentage, when the morphology of the blend is dispersed droplets, two-step mixing is more favorable due to the selective localization of CNTs/CCB in the PA6 matrix and double percolation effect. However, at a higher PPO percentage (between 40 and 55 wt%), when the morphology of the blend starts to change to a co-continuous structure, one-step mixing is more favorable due to the localization of some nanofillers at the interface of the PA6/PPO. Moreover, the effect of increasing the PPO percentage on the transcrystalline layer of PA6 on the surface of CNTs was examined using DSC and electrical conductivity measurements. It was observed that a significantly higher electrical conductivity could be obtained due to the reduction of the insulative transcrystalline layer when the PPO content increases. Thus, increasing the PPO weight percentage can increase the electrical conductivity in two ways: (i) creating the more preferable morphology, and (ii) reducing the PA6 transcrystalline layer. Highlights: CNT/CCB are selectively localized in PA6 in PA6/PPO nanocomposites based on FESEM, TEM and solvent extraction analysis. Mixing sequence can enhance the electrical conductivity depending on the nanocomposites morphology. Using a second bulky polymer such as PPO can reduce PA6 transcrystalline layer. Electrical conductivity increases by the PA6 transcrystalline layer reduction.