Viscoelastic relaxation of styrene–butadiene–styrene block copolymers with different topological structures

摘要: The viscoelastic relaxation of linear styrene–butadiene–styrene triblock copolymer (l-SBS) and star (s-SBS) with four arms were investigated differential scanning calorimetry dynamic rheological measurements. Three characteristic responses l-SBS s-SBS in the plot loss tangent (tan δ) temperature at different frequencies (ω's), which corresponded to polybutadiene (PB) block (peak I), glass transition polystyrene (PS) phase II), mutual diffusion between PB blocks PS III), respectively, observed experimental range. Although ω was 0.1 rad/s, a noticeable peak III gained for both s-SBS. storage modulus (G′) showed two distinct types behavior, depending on temperature. At (T) T2, G′ decayed much more rapidly. However, displayed very weak dependency T T2. Only near T2 did decay little sharply. These indicated, contrast l-SBS, that still exhibited elasticity even > because its crosslinking point (the structure). In lower range, stronger than despite same styrene content high tan δ value considered be related internal friction among or whole chain, not blocks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci,