Critical Reflections on Physical and Technological Test Methods in the Rubber Industry

Abstract

Abstract Surveying the development of test methods for vulcanizates since World War II and the currently used tests, we can distinguish three groups: (1) Tensile strength as well as tests for hardness and rebound, (2) Viscoelastic tests, (3) Endurance and aging tests. Along with the first group, during the war simplified tests appeared for flow and aging. Admittedly, tensile strength will continue to be employed in the future as the basic property for characterizing a vulcanizate and, still more, of a reinforcing system, even though vulcanizates of the equal tensile strength often differ in durability. For comprehensive description of vulcanizates, viscoelastic tests are advantageous and are finding ever wider use. Hardness and rebound resilience are related to viscoelastic properties and can serve as preliminary tests. Today there are numerous testing instruments, although these are mostly constructed and described by a single author. With respect to test conditions, they are very different. With increasing service requirements the necessity of endurance tests is becoming more and more recognized. These tests describe internal and external crack formation, with degradation from simultaneous heat generation. Aging from long usage, as shown by changes in properties, belongs in this group. All methods roust have a proven correlation with present product performance and, above all, be improved.