Ternary blends of high-density polyethylene-polystyrene-poly(ethylene/butylene-b-styrene) copolymers: Properties and orientation behavior in plane-strain compression

Ternary blends of high-density polyethylene (HDPE) with atactic polystyrene (PS) and styrene- ethylene/butylene-styrene block copolymer (SEBS) were de formed by plane-strain compression in a channel die. The samples were defor med up to the true strain of 1.8 (compression ratio of 6) at 100 degrees C. Thermal and mechanical properties of the deformed blends were studied in a ddition to the study of the deformation process. The basic mechanism of pla stic deformation is crystallographic slip, the same as that active in defor mation of plain HDPE and binary blends of HDPE and PS. This slip is supplem ented by the plastic deformation of an amorphous component. In blends of hi gh SEES content, the role of deformation of an amorphous component by shear and flow increases markedly due to reduced overall crystallinity of these blends. In such blends an amorphous component includes a semicontinuous emb edding of crystallites, and therefore, the deformation process is dominated by deformation mechanisms active in a more compliant amorphous phase. Cons equently, with increasing the content of SEES in the blend, the texture of the oriented blends changes from a single-component (100)[001] texture to a texture with a strong fiber component in addition to a (100)[001] componen t. In blends with high content of SEES, the crystalline lamellae of polyeth ylene do not undergo fragmentation up to the compression ratio of 6, while in blends with low and moderate content of SEES, such lamellar fragmentatio n was detected. (C) 2000 John Wiley & Sons, Inc.