The aromatic hydrocarbon resins with various hydrogenation degrees Part 1.The phase behavior and miscibility with polybutadiene and with polystyrene

The miscibility of hydrogenated aromatic hydrocarbon resin (HR) with polybu tadiene (PB) and polystyrene (PS) was investigated using turbidity measurem ent. Hereafter, the aromatic hydrocarbon resin having nine carbon atoms per monomer is referred to as C-9 resin. We found that C-9 resin, which has on ly a limited (or partial) miscibility with PB, became completely miscible w ith PB as the degree of hydrogenation (DH) in HR was increased to the optim um value of DH. The hydrogenation reaction of C-9 resin, which was conducte d in the presence of a palladium (Pd) catalyst supported by activated carbo n, converted aromatic rings in the resin to alicyclic rings. We controlled DH of C-9 resin by monitoring the amount of hydrogen used and the duration of reaction. The DH in HR was determined by elemental analysis and density measurement, and the chemical structures of HRs were determined by Fourier transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance sp ectroscopy, and ultraviolet/visible Light spectroscopy. On the basis of the results of the upper critical solution temperatures of the blend systems i nvestigated, it was found that a favorable interaction between PS and HRs d ecreased steadily with increasing DH and that there exists an optimum value of DH (approximately 0.7) in HR that gives the most favorable interaction with PB, The significance of the enhanced miscibility between PB and HRs, c ompared to the miscibility between PB and C-9 resin, was demonstrated by me asuring the tack property of pressure-sensitive adhesives (PSAs), which wer e prepared from a polystyrene-block-polybutadiene-block-polystyrene (SBS tr iblock) copolymer and HRs, and from an SBS triblock copolymer and neat C-9 resin. We found that the probe tack of SBS triblock copolymer/HRs mixtures goes through a maximum (1100 g/cm(2)) for HR having DH = 0.7, at which HR h as the most favorable interaction with PB as determined from turbidity meas urement, whereas the probe tack of SBS triblock copolymer/C-9 resin mixture is negligibly small. These results were qualitatively interpreted by the s olubility parameter approach using group contribution method. (C) 2000 Else vier Science Ltd. All rights reserved.