EFFECTS OF MECHANICAL-STRESS ON THE REACTIVITY OF POLYMERS - ACTIVATION OF ACID-HYDROLYSIS OF DEXTRAN BY ULTRASOUND

The influence of ultrasonic irradiation on the kinetics and mechanism of acid hydrolysis of dextran is studied. The increase in the rate constants of the combined hydrolytic and ultrasonic degradation was investigated as a function of the molecular weight of dextran. For molecular weights higher than the limiting value for ultrasonic degradation the rate constants are proportional to the molecular weight raised to the power of 4/3; for molecular weights below the limiting value the rate constants are proportional to the molecular weight raised to the power of 5/6. The effects are discussed in connection with stretching forces which act on the polymer molecules as a result of ultrasonic cavitation. © 1979 Springer-Verlag.