Abstract: A bipolar battery substrate includes overlying layers of binder material containing particulate conductive material. In the most preferred form, one layer includes carbon as the conductive material, while the conductive material for the other layer comprises a conductive form of a transition metal oxide. Electrode structures are also disclosed.

Abstract: A method and apparatus for determining the environmental stress crack resistance of plastic articles, such as polyethylene terephthalate containers, are provided. In accordance with the method of the invention, the internal chamber of a hollow plastic article is pressurized, the exterior of the base is then exposed to an environmental stress cracking agent, and it is then determined if crazing and/or changes in the base clearance of the plastic article have occurred. Subsequent increases in pressure and subsequent exposures and determinations yield information on the environmental stress cracking characteristics of the container.