Processing temperature dependent mechanical response of a thermoplastic elastomer with low hard segment

The mechanical responses including monotonic and cyclic tensile responses have been investigated on a microphase-separated poly (styrene-isoprene-styrene) triblock copolymer (SIS). The specimens were injection-molded by using different melt temperatures to acquire different microphase structures. As a result of temperature-dependent segregation driving force, the specimens with reduced microphase separation can be obtained by increasing processing melt temperature from 180 °C to 240 °C. On the basis of stress-strain behavior, Young's modulus was found to increase with increasing PS domain continuity in the order of disorder state to disordered spheres to body-cubic-centered (BCC) spheres to oriented cylinders morphology. Meanwhile, cyclic hysteresis decreases with reduced microphase separation and with decreasing the applied predetermined maximum tensile strain. In addition, the Mooney-Rivlin phenomenological approach was used to evaluate and explore the relationship between the polymer topological networks and the rubber elasticity of thermoplastic elastomers.

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