Melt rheology of compatibilized polystyrene/low density polyethylene blends

Investigations have been made on the melt rheological behaviors of compatib ilized blends composed of polystyrene, low density polyethylene and hydroge nated (styrene-butadiene-styrene) triblock copolymer used as a compatibiliz er. The experiments were carried out on a capillary rheometer. The effects of shear stress, temperature and blending ratio on the activation energy fo r viscous how and melt viscosity of the blends are described. The study sho ws that the viscosity of the blends exhibits a maximum or minimum value at a certain blending ratio. The activation energy for viscous flow decreases with increasing LDPE content. Furthermore, the concept of equal-viscosity t emperature is presented and its role in the processing of the blend is disc ussed. In addition, the morphology of the extrudate sample of the blends wa s observed by scanning electron microscopy and the correlation between the morphology and the rheological properties is explored. (C) 1999 Society of Chemical Industry.