Low percolation threshold polyvinylidene fluoride/multi-walled carbon nanotube composites: A perspective of electrical conductivity, crystalline, rheological and mechanical properties

Recently, conductive polymer-based composites (CPC) have gained considerable interest for their outstanding processing, mechanical, electrical properties, and resistance tunability. Multi-walled carbon nanotube (MWCNT) was introduced into polyvinylidene fluoride (PVDF) as the conductive filler via means of melt blending in this work. Effects of MWCNT on crystalline structure, thermodynamic behavior, electrical conductivity, processing and mechanical properties of PVDF/MWCNT were under investigation. By measuring the volume resistivity of PVDF/MWCNT, it was observed to have declined from 1.54 × 10¹² to 3.71 × 10¹ Ω∙m with the MWCNT content changed from 0.7 to 1 vol%, which plummeted by 11 orders of magnitude. Therefore, it can be inferred that the percolation threshold of MWCNT lies within the range of 0.7–1 vol%. Additionally, the percolation threshold is obtained as 0.81 vol% by fitting using the percolation theory equation. Around the percolation threshold, PVDF/MWCNT composites exhibit negligible alterations in their rheological properties when contrasted with pure PVDF, yet their mechanical properties are improved. Furthermore, MWCNT does not substantially impact the crystalline structure and thermodynamic behavior of PVDF/MWCNT. Highlights: The percolation threshold of MWCNT in PVDF is 0.81 vol%. The volume resistivity of the 1 vol% MWCNT sample was only 3.71 Ω∙m. 1 vol% MWCNT exhibit favorable rheological and mechanical properties.