Precision in polymer testing: An important world-wide issue

Abstract

There is no question about the importance of testing in the modern technologically oriented world. We strongly rely on it. However, the quality of testing, especially on a laboratory-to-laboratory basis, is often marginal or poor. This poor test quality, or lack of agreement in test results, often upsets the commercial, scientific and regulatory efforts of society. Test method precision is a ‘figure of merit’ for various tests and the issue of obtaining valid precision parameters and clearly expressing the precision results is currently being addressed by standardization organizations such as ASTM and ISO. This paper gives an overview of the action on precision assessment currently being conducted in ASTM Committee D11 and ISO/TC-45, both of these being devoted to Rubber and Rubber Product testing. Definitions for precision, i.e. repeatability and reproducibility, are given in addition to details on the organization of interlaboratory programs needed to acquire the basic precision data. A precision example using the Mooney viscosity test is presented as well as a discussion of the uses of precision parameters and the problems currently being encountered in this work.