Relationship Between Mechanical Properties and Dynamic Thermomechanical Properties and Structure of Oil-Filled SEEPS/SEBS

A variety of representative SEEPS and SEBS were analyzed for structure and molecular weight. SEEPS Kuraray-4055 and SEBS YH-502T, which have different chemical structures but the same styrene content and similar molecular weight, were selected. The microstructures of oil-extended SEEPS and SEBS systems were characterized by small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). It shows that the phase size (49.1 nm) and phase spacing (47.9 nm) of the SEEPS system are larger than the phase size (38.3 nm) and phase spacing (38.1 nm) of the SEBS system, the SEEPS system has a more complete microphase separation. Combined with the 1H-NMR results, it is found that due to the hydrogenated isoprene segment units in the SEEPS soft segments, which makes the segments more flexible than SEBS. According to the results of the Instron universal material testing machine and DMA, the mechanical properties and storage modulus of the SEEPS system, with a higher degree of microphase separation, are greater than the SEBS system. The results show that the molecular structure of SEEPS/SEBS is the main factor affecting the microstructure, mechanical properties, and dynamic thermomechanical properties of the oil-extended system. The results provide a theoretical basis for the popularization and application of the new SEEPS, and propose new ideas and ways for the preparation of advanced elastomer materials. © 2021, Editorial Board of Polymer Materials Science & Engineering. All right reserved.