The aromatic hydrocarbon resins with various hydrogenation degrees part 2. The adhesion and viscoelastic properties of the mixtures of resins and block copolymers

The adhesion and viscoelastic properties, and the order-to-disorder transition temperature (T_ODT) were investigated for the mixture of polydiene-based block copolymers/hydrogenated aromatic resins (HRs) with various degrees of hydrogenation (DHs). The block copolymers employed were commercially available ones: (1) polystyrene-block-polybutadiene-block-polystyrene (SBS) copolymer (Kraton D1102; Shell Development Co.); and (2) polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer (Vector 4211; Dexco Co.). HRs with various DHs were synthesized via the hydrogenation of an aromatic C-9 hydrocarbon resin by monitoring the amounts of hydrogen added and the reaction times. We found that viscoelastic properties, such as plateau modulus and glass transition, depend predominantly on the miscibility between polystyrene (PS) block and HRs as well as that between polybutadiene (PB) (or polyisoprene (PI)) block and HRs, which in turn are strongly affected by the DH in an HR. At lower values of DH, HRs are associated with PS end block; thus tack properties become negligible, although the plateau modulus increases greatly. The tack properties depended remarkably on the miscibility between HRs and elastomeric mid-block in the block copolymers. With increasing DH, tack properties of the mixture of Kraton D1102/HRs increased up to DH = 0.7, reached a maximum at DH = 0.7 and finally decreased. However, tack properties of the mixture of Vector 4211/HRs increased steadily up to DH = 0.951 which is the largest value in this study. This is because the miscibility between PI block and HR increases steadily with increasing DH, which is explained by the difference in the solubility parameter. When the weight fraction of HRs is less than 0.5, the T_ODTs of the mixture having either Kraton D1102 or Vector 4211 and HR always decreased with the increasing amount of HR due to the lower molecular weight of HR. Interestingly, the T_ODTs of both the mixture systems was the smallest at DH to approximately 0.3 when the weight fractions of HR in the mixture were 0.1 and 0.3.