INFRARED IMAGING OF STRESS-CRAZING IN RUBBER-MODIFIED POLYSTYRENE

The plastic yield and fracture of rubber-modified polystyrene specimen s under tensile load have been investigated at room temperature. The e xperimental procedure consisted of rapidly alternating measurements of transmitted and emitted infrared (IR) radiation from samples under te nsile stress. The load-displacement data were simultaneously recorded. Both single-edge-notched and dog-bone-shaped test coupons were studie d. In each tensile test run, we observed a significant decrease of mat erial transparency in the IR which occurred near the low yield point. A further increase in material deformation was accompanied by a substa ntial temperature increase. After material failure, the surface morpho logy of the test specimens in the vicinity of the crack was examined u sing atomic force microscopy (AFM). Our results are explained in the c ontext of existing models of material crazing.