Rubber toughening of polystyrene–acrylonitrile copolymers

Abstract

The efficiency of rubber toughening of PSAN depends on the size of the rubber particles, their agglomeration, the deformation rate, the temperature, and the orientation of the polymer molecules. Large particles are more effective than small particles. By a suitable choice of processing, however, small particles can agglomerate, forming large soft units and improving in this way impact toughness. At high deformation rates crazing or/and stretching of the matrix wall between the rubber particles must be activated for ductility, otherwise the material is brittle. The temperature at impact must be above the glass transition temperature of the rubbery phase for toughening. Increasing the orientation of the material decreases the tendency for craze formation with the consequence of embrittlement, if stretching is not activated.

Commercial Polymer Blends

“…The toughening mechanism is believed to involve the internal cavitation and debonding of the rubber, which induces localized shear yielding of the polyamide matrix as the primary energy dissipation processes (Borggreve and Gaymans 1989;Ramsteiner and Heckmann 1985;Borggreve et al 1988) occurring during the impact deformation. Rubber particle size, distribution, and interparticle distance (Wu 1988) are some of the key parameters that have been correlated to the impact Fig.…”

A Mathematical Model of the Bulk Copolymerization of Styrene and Acrylonitrile in the Presence of Polystyrene‐block‐Polybutadiene

“…The mechanical properties of both materials are mainly determined by the size, morphology, and volume fraction of the rubber particles. [3][4][5][6][7][8][9][10][11][12][13][14] Typically, HIPS is produced by polymerizing S in the presence of polybutadiene (PB), and a styrenebutadiene graft copolymer is generated from the very beginning of the reaction. Generating graft copolymer compatibilizes the phases, stabilizes the particles, and promotes the formation of particle occlusions.…”

Effect of compatibilizer on micromehanical deformations and morphology of dispersion in PP/PDMS blend

“…These micromechanical deformations include crazing, shear yielding, voiding (internal cavitations of elastomer domains or debonding at the elastomer matrix interface), and dilatational shear yielding. The characteristics of these different micromechanical processes are described by Bucknall et al1, 2 and Zebarjad et al3 The role of voiding as a toughening mechanism in elastomer‐modified polymer matrix has been illustrated by many authors 4–8. Voiding relieves the buildup of local hydrostatic tension around the rubber particles and the triaxial stress condition thus generated in the matrix is transformed to plane stress conditions, which give rise to shear yielding of the matrix.…”