Mechanics of Failure of Plastics by Thermal Imaging Examination of a Polypropylene + Ethylene Propylene Diene (EPDM) Blend*

Nandika Anne D'Souza and Witold Brostow
Laboratory of Polymers and Composites
Department of Materials Science
University of North Texas
Denton, TX 76203-5308

A. C. Ramamurthy
Automotive Components Group
Ford Motor Co.
24300 Glendale Avenue
Detroit, MI 48239

Yingxia Wang, Robert L. Thomas, and Lawrence D. Favro
Department of Physics and Institute for Manufacturing Research
Wayne State University
Detroit, MI 48202


Thermal wave imaging combined with Stress Pattern Analysis by measurement of Thermal Emission (SPATE) is used to study the failure behavior of a polypropylene (PP) + ethylene propylene diene (EPDM) blend. Images corresponding to a propagating crack in a single edge-notched specimen at three rates of testing: 4 mm/min, 8 mm/min and 20 mm/min. Conversion to stress values is made through use of a thermoelastic function. It is found that in the 4 mm/min test the crack tip radii blunts rather than propagates with little initiation. Large scale necking precedes fracture. At 8 mm/min, some blunting occurs followed by rapid crack propagation. At 20 mm/min, rapid crack propagation occurs. The images are digitized to obtain the values of the temperatures at every point in the sample. Data corresponding to the plane of the propagating crack over the span of the test are presented.

*Polymer Eng. & Sci. 1996, 36, 194.

Maintained by Dr. Antje Stein de Vilchez.