Ultrasonic degradation of sol rubber in solution

Abstract

AbstractSol rubber dissolved in three solvents—cyclohexane, petroleum ether (40‐60°C. fraction), and toluene—was degraded by ultrasonic waves, the degradation kinetics being followed by measuring spectrophotometrically the consumption of the free radical scavenger α,α′‐diphenyl‐β‐picryl hydrazyl. The kinetic data have been examined by the rate equations developed from two different approaches: one by Jellinek and the other by Ovenall. It has been observed that the number of bonds broken as a function of time can be fitted equally well by both equations in the initial stage, but as the time of degradation increases, especially when the number‐average degree of polymerization attains a value less than 3Pe/2, the rate can be described better by Jellinek's equation than that of Ovenall. The rate constants K and the final degree of polymerization for rubber are found to depend on the nature of the solvent.