THERMAL-CONDUCTIVITIES OF BLENDS OF POLYETHYLENE SEBS BLOCK COPOLYMER AND POLYSTYRENE SEBS BLOCK COPOLYMER

Thermal conductivities of two series of blends of polystyrene and styrene-ethylene/butyrene-styrene block copolymer (PS/SEBS), and polyethylene and styrene-ethylene/butylene-styrene block copolymer (PE/SEBS) were measured. Here the PS part and hydrogenated polybutadiene (EB; ethylene-butene-1 copolymer) part of SEBS were confirmed to be miscible in PS and PE homopolymers, respectively, by the differential scanning calorimetry. The thermal conductivity of PS/SEBS increased, while that of PE/SEBS blends decreased monotonically, with increasing SEBS content. No significant changes in the range where microphases usually occur were noted. The thermal conductivities of PS/SEBS and PE/SEBS were explained by modifications of our equation for composites. Thermal conductivity of EB in SEBS was estimated from that of PS/SEBS blend as 4.9 X 10(-4) cal/s cm-degrees-C. Further, the thermal conductivity of PE/SEBS could be predicted by substituting the obtained value of EB into the modified equation. Therefore, the modified equations were confirmed to be applicable to thermal conductivities of PS/SEBS and PE SEBS blends.