Bisphenol-onium systems

The bisphenol-onium systems achieved considerable market penetration during the mid-1970s. The normal approach was for the rubber to be supplied with the curative system already incorporated into the polymer and such compounds have been widely used for O-rings and other applications requiring low compression set at elevated temperatures. The development of these systems has been the subject of a review by Hill (1975). 

Extruded Articles. In an extruded article, the most important parameters are scorch safety and flow characteristics (49). The bisphenol/onium cure system provides the best scorch resistance. Gum viscosities and process aids affect flow characteristics. Typical formulations for extrusion-grade fluorocarbon elastomers are given in Table 8. 

The data in Table 6 clearly show the effect of cure system on scorch stability and processing, as determined by standard testing techniques (MS at 121°C). The most workable formulations are compoimded with raw gums containing the bisphenol/onium cure systems. These cure systems offer maximum processibility safety. 

The manufacture of the majority of fluorocarbon elastomer gums includes the addition of an incorporated cure system comprising an organic onium cure accelerator, such as triphenylbenzylphosphonium chloride [1100-88-5] and a bisphenol cross-linking agent, such as... 

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