PERCOLATION SIMULATION OF THE NETWORK DEGRADATION DURING ULTRASONIC DEVULCANIZATION

The percolation model of network degradation during rubber devulcaniza tion is presented. The model is based on a random crosslink scission a nd molecular chain breakup. The obtained results indicate that the pri mary model parameter characterizing the network degradation is the rat io of the probabilities of backbone breakup to crosslink scission. The predicted dependences of the gel fraction of devulcanized rubber on c rosslink density are in excellent agreement with experimental data for styrene-butadiene rubber and ground rubber tire. The estimated critic al exponents indicate that the process of devulcanization for the vulc anizate without filler appears to belong to the universality class of standard 3D bond percolation while devulcanization for the vulcanizate with filler appears to belong to its own new universality class. (C) 1996 John Wiley & Sons, Inc.