Solid state extrusion of thermoplastic elastomers, 2. Structure and properties of solid state extruded block copolyesters

Block copoly(ether ester)s based on poly(butylene terephthalate) containing different amounts of poly(oxytetramethylene) were oriented by solid state extrusion. The degree of die swell decreases with increasing crystallinity of the extrudates. The morphological properties of the extrudates depend on the extrusion conditions. The long period is only determined by the undercooling. The dependence of the mechanical and dynamical‐mechanical properties of the extrudates on the extrusion condition was investigated. The chemical composition influences the mechanical behaviour strongly. It was concluded that this is due to the different concentration of the taut tie molecules.