Development of the Moving Die Rheometer and the Rubber Process Analyzer

The introduction of the Oscillating Disc Rheometer (ODR) curemeter by the Monsanto Instruments & Equipment (I&E) Group in the 1960s revolutionized the compounding of rubber and the quality control testing done on mixed rubber.  The Monsanto I&E Group knew that as long as there were significant limitations in the ODR, there was always an opportunity for a new improved device to be invented somewhere.  In the late 1970s, the Monsanto I&E Group launched an effort to do just that.  The project was intended to take one year but it actually took a number of years because many alternate designs forced materials to operate beyond their operating limits.  The project was not considered a success until the results were repeatable and had reasonable variation from instrument to instrument.  Eventually, all of the efforts lead to the introduction of the Moving Die Rheometer or MDR in the late 1980s.  This curemeter design naturally lead to the introduction of a more complex instrument called the Rubber Process Analyzer or RPA 2000. 

This paper discusses the development and introduction of both the MDR and the RPA.  These instruments significantly changed the data used by the rubber industry to fully characterize raw elastomers and mixed stocks.  In addition, these instruments also made significant improvements in testing productivity.