Media type: E-Article Title: Kinetics of crazing in polybutadiene/polystyrene blends Contributor: Spiegelberg, Stephen H.; Argon, Ali S.; Cohen, Robert E. imprint: Wiley, 1994 Published in: Journal of Applied Polymer Science Language: English DOI: 10.1002/app.1994.070530912 ISSN: 0021-8995; 1097-4628 Keywords: Materials Chemistry ; Polymers and Plastics ; Surfaces, Coatings and Films ; General Chemistry Origination: Footnote: Description: <jats:title>Abstract</jats:title><jats:p>The crazing behavior of blends of polystyrene (PS) and a low molecular weight polybutadiene (PB) was examined as part of a continuing study of toughening mechanisms in thermoplastic polymers. These PS/PB blends attain high levels of toughness from the stress‐activated plasticizing action of the polybutadiene (PB), a mechanism that is active only in the region of a growing craze. The plasticization is therefore localized and leads to enhanced toughness without loss in stiffness. The net result of this plasticization is a reduction in craze flow stress accompanied by an increase in craze velocity, which, in turn, allows the specimen to reach substantial strains‐to‐fracture in uniaxial deformation under an imposed strain rate. The ability of the PB to plasticize a growing craze is expected to be a function of the mobility of the PB. To investigate the role of diluent mobility, tensile tests and craze velocity measurements were conducted at −20°C and compared with previously published results collected at 23°C. Although the blends displayed high levels of toughness at 23°C, the blends tested at −20°C showed brittle behavior. Craze velocities measured at −20°C were 2 orders of magnitude lower than the results at 23°C. Addition of 3 wt % PB at −20°C led to craze velocities only as large as those found in pure PS at 23°C. Comparison of the craze velocities with an asymptotic theoretical model describing the dependence of the craze velocity on the PB content showed good agreement with the results at −20°C and only fair agreement with the room‐temperature results. © 1994 John Wiley & Sons, Inc.</jats:p>