Preparation and study of mechanical and thermal properties of silicone rubber/poly(styrene–ethylene butylene–styrene) triblock copolymer blends.

Herein, a compound has been developed via melt blending and curing of poly(styrene–ethylene butylene–styrene) triblock copolymer (SEBS) with silicone rubber (SR). The cure characteristics, mechanical, thermal, and dynamic mechanical properties of the SR/SEBS blends of different mass ratios (100/0, 90/10, 75/25, 50/50, 25/75, and 0/100) are investigated. The cure characteristics reveal that the crosslinking and cure rate of SEBS are lower than SR. The cure rate of SEBS is 0.35 dN.m/min, while it is 15.35 dN.m/min for SR. Also, in the blends, as the content of SR increased, the crosslinking and cure rate of the blends show an upward trend. The results of mechanical properties indicate that the presence of SEBS with a formed (simultaneously physical and chemical) double network can strengthen the mechanical properties of SR, as the tensile strength and elongation at break of the blends improve by increasing the content of SEBS. It is found that adding 25% of SEBS to SR enhances the tensile strength and elongation at break of the SR blend from 5.66 to 7.56 MPa and from 116 to 185%, respectively. Thermogravimetry demonstrates the better thermal stability of SR than SEBS and the blends. The obtained primary thermal parameters reveal that the thermal stability of the SEBS phase in the blends improves with growing the SR content. Dynamic mechanical thermal analysis exhibits two loss tangent peaks for SEBS at 119.61 and − 45.36 °C, which are related to the glass transition temperatures of polystyrene (as a physical crosslinker phase) and ethylene–butylene blocks, respectively. Also, two peaks are observed for SR at − 37.16 and − 134.16 °C. Differential scanning calorimetry confirms that the two temperatures are related to the melting and glass transition temperatures of SR, respectively. [ABSTRACT FROM AUTHOR]