The use of miniature disc bend tests with plastic materials

The use of miniaturised disc bend tests, a method that is commonly used wit h metallic materials, is assessed for use with polymeric materials. The tes t method uses the indention force/displacement characteristics for a hemisp herical-ended punch forced onto a small disc of the test material. Characte risation tests were performed using acetal, PMMA and polypropylene, under a range of different test rates and temperatures. These were compared with c onventional tensile tests under the same conditions. Although no quantitati ve comparison beween the two methods has been formulated good qualitative a greement was found for all materials, including a wider comparison with nin e materials. The advantages of the disc bend test are that smaller amounts of material are needed, the sample preparation is easier, the test is often easier to perform, it shows ductile-brittle transitions more sharply and i s a very convenient method of performing environmental stress cracking test s. (C) 1998 Elsevier Science Ltd. All rights reserved.