The interrelation between morphology, resistivity, and flow properties of carbon black-containing HIPS/EVA blends

Abstract

Immiscible polymer blends based on high-impact polystyrene/ethylene vinyl acetate (HIPS/EVA) are interesting host multiphase systems for the incorporation of low concentrations of carbon black (CB). The conductive filler CB tends to accumulate preferentially within the EVA phase, forming segregated structures, and thus conductivity of the blends is only obtained when double percolation is realized. Material properties such as surface tension and crystallinity of the CB-containing polymer are found to influence filler distribution, accordingly affecting the electrical conductivity. A rheological-electrical method is presented, whereupon extrudates of CB-containing binary immiscible polymer blends are produced by a capillary rheometer, and the effect of shear level on the extrudates' structure and resultant resistivity is determined. A descriptive model was derived, illustrating the effect of shear on double percolation at various blend compositions. The flow behavior of the CB-containing compounds was studied in regard to the filler packing factor, m , and related to the electrical properties of the extrudates. Blend composition, CB content, and shear level were considered as significant parameters, determining the structure and the resultant electrical properties.

Surface Modification and Vapor-Induced Response of Poly(Vinylidene Fluoride)/Carbon Black Composite Conductive Thin Films

“…The experimental results indicate that the percolation threshold lies in about 3% and the percolation region is from 3 to 5%. In evidence, the percolation value of the PVDF=PVDF-g-CB conductive film in this study is much lower than that of many other polymer composites [32,33] .…”

Effects Of Heat-Treatment On The Gas Response Of PVDF/CB Conductive Composite Sensing Films

“…The percolation threshold of the material lay in about 3 wt % and the percolation region was among 3~5 wt %, much lower than that of many other polymer composites (see Fig. 3) [18,19]. Figure 4 suggested that after heat-treatments the initial resistance values reduced gradually with the prolonged annealing time at 40°C.…”

Electroactive Thermoplastics

“…In this study polymer melt viscosity was adjusted by temperature and shear rate. [30] Independent of the particular effect under consideration, the critical question for each composite is whether the morphology is governed by thermodynamics or kinetics. Soares et al report that the conductivity of styrene±butadiene and PS systems is significantly impacted by molding time, temperature, and pressure.…”