Improvement of Mechanical and Thermal Properties of Elastomeric Polystyrene-block-poly (ethylene-co-but-1-ene)-block-polystyrene Triblock Copolymer upon Ordering of Spherical Microdomains on BCC Superlattice

Abstract

We report the improvement of mechanical and thermal properties of an elastomeric polystyrene-block-poly (ethylene-co-but-1-ene)-block-polystyrene triblock copolymer upon ordering of spherical microdomains on the body-centered cubic (bcc) superlattice. The sample has a minor polystyrene (PS) composition (the volume of PS, φPS =0.084), and therefore forms glassy spherical microdomains being embedded in rubbery poly (ethylene-co-but-1-ene) matrix. The microdomain structures were analyzed by small-angle X-ray scattering technique and transmission electron microscopy. The mechanical properties were examined by dynamic viscoelastic measurements and tensile stress-strain tests. Upon annealing at 130°C for 10h, regularity of the bcc superlattice was improved as compared to a sample annealing at 150°C for 10h. Accordingly, the tensile modulus increased significantly, which can be ascribed to ordering of the glassy PS spheres on the bcc superlattice. Moreover, the thermal resistance was also improved. Namely, a decrease in the tensile modulus above Tg of PS was less remarkable in the film annealed at 130°C for 10h than at 150°C for 10h.