Preparation of s-SEBS foamed elastomers via direct twin-screw extrusion and their properties
摘要
Star-shaped polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (s-SEBS) foamed elastomers are prepared via direct twin-screw extrusion using polymer microcapsules encapsulating liquefied hydrocarbons (PMC) as a foaming agent. The melt strength and relaxation behavior of s-SEBS are sufficient to promote PMC foaming, while maintaining its structural integrity without breaking under shear. The SEM images confirmed that the foam cells and the matrix existed in an isolated and independent state. These foamed elastomers retain the intrinsic properties of thermoplastic elastomers. Although the brittle detachment of the foam cell from the matrix occurs, s-SEBS foamed elastomer 150/2 exhibits optimal tensile properties, in which the tensile strength of 3.03 MPa, the Young ‘s modulus of 0.89 MPa, and elongation at break of 1875.69%. During reciprocating stretch, s-SEBS foamed elastomers exhibit good elastic recovery capability while maintaining the structural integrity of the foam cells. The hysteresis loss is primarily attributed to the plastic deformation of S domains, rearrangement of the entanglement network, relocation of the foam cells primarily, and orientation / disorientation of chains. Higher naphthenic oil content endows higher tensile resilience to s-SEBS foamed elastomers. The preparation of s-SEBS foamed elastomers by a twin-screw extruder provides an efficient and economical method from an industrial and technical point of view. The evaluation of s-SEBS foamed elastomers in this paper will provide a practical solution for industrial-scale prefabricated plastic tracks.