Effect of Ultrasonic Treatment on Properties and Structure of SBR/BR Blends and Filled Compounds

The ultrasonic treatment of SBR/BR 50/50 blend in single screw extruder was carried out at amplitudes up to 10 micron. The untreated and treated SBR/BR blends were mixed with CB and silica to prepare 50/50/60 compounds. It was found that ultrasonic power consumption increased with increase of ultrasonic amplitude and die pressure dropped. Molecular weight of blends treated at 3.5 micron increased and high molecular weight tail was observed at 5, 7.5 and 10 micron. Solvent extraction showed formation of gel in blends treated at 7.5 and 10 micron and no observable gel in blends untreated and treated at 3.5 and 5 micron. SBR/BR blend treated at 5 micron and compound with silica reduced loss tangent at -30^oC, 0^oC and 60^oC, indicating a lower snow, wet traction and rolling resistance. Reduced loss tangent after ultrasonic treatment was a result of reduced filler flocculation. The tensile strength and elongation at break of all treated SBR/BR and SBR/BR/CB vulcanizates treated at 3.5 and 5 micron increased. Modulus (M100) of vulcanizates prepared from SBR/BR/Silica treated at 5 micron was also increased.