ULTRASONIC DEVULCANIZATION OF RUBBER VULCANIZATES .1. PROCESS MODEL

Tire and rubber waste recycling is an important issue facing the rubbe r industry. In addressing this issue, the present article describes th e first attempt to formulate a model and to simulate a novel continuou s ultrasonic devulcanization process. The proposed model is based upon a mechanism of rubber network breakup caused by cavitation, which is created by high-intensity ultrasonic waves in the presence of pressure and heat. Dynamics of bubble behavior is described by the Notlingk-Ne ppiras equation with incorporation of an additional term based upon el astic strain-energy potential. Acoustic pressure arising in the ultras onic field is related to void formation. Their concentration is calcul ated based upon nucleation and growth of gas bubbles in crosslinked el astomers under negative driving pressure. The breakup of a three-dimen sional network in crosslinked rubbers is combined with flow modeling. The viscosity function required for this modeling is based upon a powe r-law model which includes temperature, shear rate, and gel fraction d ependence. (C) 1996 John Wiley & Sons, Inc.