Liquid-sensing behaviors of carbon black/polyamide 6/high-density polyethylene composite containing ultrafine conductive electrospun fibrous network

Liquid-sensing behaviors of carbon black (CB)/polyamide 6 (PA6)/high-density polyethylene (HDPE) composite containing conductive electrospun fibrous network were investigated by detecting electrical resistance variations toward different solvents. The material exhibited a good sensing selectivity, which could be predicted by Flory-Huggins interaction parameter χ ₁₂. In immersion-drying runs (IDRs), the composite showed a large liquid-sensing responsivity but poor reproducibility toward “good solvent” xylene. After long-term immersion treatment in xylene, the metastable conductive pathways became stabilized, and a better reproducibility was finally achieved. Absorption/desorption equilibrium state of the composite in “moderate” or “poor” solvents was reached more easily than that in good solvent. Additionally, more rapid response, higher sensing responsivity, and better reproducibility of the composite in “moderate solvent” cyclohexane were observed at a higher environment temperature. These results indicated that liquid-sensing behaviors of conductive polymer composites could be tailored by tuning the microstructure or utilizing the pretreatment.