OVERVIEW

Most of this book is concerned with tests on vulcanised (or thermoplastic) rubber, which is the state in which the consumer receives the product. The consumer is generally only interested in the properties of the finished product, whereas the supplier is also concerned about the properties of the raw and compounded rubber. His interest is in the control of his rubbers and rubber compounds as regards their processing qualities and the likehhood of them producing satisfactory mouldings, extrusions etc. Consequently, processibility tests are of immediate concern in the rubber factory and great emphasis has been placed on the development of methods and apparatus which provide reliable, and also very rapid, quality control data. The behaviour of rubbers during processing is complicated and has proved difficult to predict in many cases. Materials frequently managed to exhibit a processing quirk which did not show up in the laboratory tests. Hence, the aim has been to develop tests which more realistically predict processing behaviour.

Processibility is a particularly vague and ill-defined term but is taken to mean all aspects of material behaviour that contribute to the production of a satisfactory compound and forming it into a satisfactory product. The principal properties requiring measurement are viscoelastic flow behaviour and curing characteristics. Cure rate or, more generally, curing characteristics is a reasonably precise concept but viscoelastic flow behaviour is used here as a convenient term to cover plasticity, viscosity and other parameters which collectively are in fact processibility . Plasticity measurements were the first processibility...