A study on electrical and thermal conductivities of ethylene–octene copolymer/expandable graphite composites

Abstract

A series of ethylene–octene copolymer (EOC) composites have been prepared by melt‐mixing with different weight ratios of expandable graphite filler (0–50% by weight). Electrical conductivity [both alternating current (AC) and direct current (DC)] and thermal conductivity studies were carried out. Effect of filler loading and frequency on electrical conductivity was studied. DC conductivity has increased from 1.51 × 10−13 S cm−1 to 1.17 × 10−1 S cm−1. Percolation threshold by DC and also AC methods was observed at about 16 vol% of the filler. Real part of permittivity was found to be decreasing with increase in frequency while conductivity was increasing. Thermal conductivity was also found to be increasing gradually from 0.196 to 0.676 Wm−1 K−1 which is about 245% increase. Graphite not only increases the electrical and thermal conductivities but at and above 40 wt%, also acts as a halogen‐free, environmental friendly flame retardant. Shore‐A hardness of EOC/graphite composites shows that even with high graphite loading, the hardness is increased from about 50–68 only so that the rubbery nature of the composite is not affected very much. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Synergistic effects of ammonium polyphosphate and red phosphorus with expandable graphite on flammability and thermal properties of HDPE/EVA blends

“…At the loading level of below 13.3 phr APP, the stringent rating UL-94 V-0 is achieved for samples (3)-(6); however, the amount of APP increases further; the composites do not reach the classification. When APP is replaced by RPM in the same loading level, the stringent rating UL-94 V-0 is achieved for all of samples (8)- (12). The results further suggest that a favorable synergistic effect exists between (APP + RPM) and EG on enhancing the flame-retardant properties of HDPE/EVA blends.…”

Thermoelectric Properties of Carbon Nanotube and Nanofiber Based Ethylene‐Octene Copolymer Composites for Thermoelectric Devices

“…The apparent thermal conductivity of the composites, hereafter called simply thermal conductivity, was measured using experimental setup shown schematically in Figure 1 according to the method described in [20,21]. At the beginning of the measurement, the central brass cylinder (CBC) was annealed to a temperature 45 ∘ C using a hollow cylinder connected to a water thermostat.…”

“…To describe the temperature time dependence of the central brass cylinder (Figure 1), the following heat balance equation is used [21]:…”

The Thermal Stability and Flammability of Expandable Graphite-Filled Polypropylene/Thermoplastic Polyurethane Blends

“…For example, polyethylene terephthalate-EG-clay nanocomposites with good flame-retardant performances were prepared by melt blending. [22] Svoboda and his coworkers [23] have investigated the effect of different weight ratios of EG on the thermal conductivity and flame retardancy of ethylene-octene copolymer composites. The results demonstrated that EG is an efficient additive which acts as a blowing agent as well as a carbonization agent.…”