Binder plays important roles in friction materials such as binding all the ingredients firmly so that they can contribute to the overall performance of a friction material (FM) for which they were added, apart from offering mechanical integrity and contributing to the tribological performance. Currently the binders for almost all the FMs are from the class of phenolic resins (unmodified or modified versions). These thermosetting polymers cure on heating and hence form three-dimensional network. Although it has a combination of excellent properties required for FMs, it also has serious shortcomings such as limited shelf life, emission of noxious volatiles during curing, shrinkage in the product etc. Hence search for an alternate binder is continuously going on. The present paper explores the possibility of two thermoplastic specialty polymers having high temperature stability viz. Polyetheretherketone (PEEK) and Polyaryletherketone (PAEK) as an alternative for phenolics. The three FMs with identical formulations except resins were developed and evaluated on Chase dynamometer and FAST machine. It was concluded that PAEK proved significantly superior to phenolics in all the properties. PEEK, however, proved to be inferior in some properties.
Simon Goehring, Institute of Lightweight Engineering and Polymer Technology (ILK), Technische Universität Dresden, Germany; Niels Modler, Albert Langkamp, Umesh Marathe, Vishal Mahale, Jayashree Bijwe, Industrial Tribology Machine Dynamics and Maintenance Engineering Centre, Indian Institute of Technology Delhi, India