抄録
The ultrasonic degradation of polymers has been studied by many investigators. There is general agreement that cavitation ia an indispensable factor in ultrasonic degradation, although there are a large number of factors that influence both the rate and the limiting molecular weight achieved on sonication.. Parameters characterizing the ultrasound are the frequency and intensity. However, it is still difficult to explain their frequency dependence of the ultrasonic degradation. Here, we report a reinvestigation of ultrasonic degradation of water-soluble polymer, polyethylene oxide (PEO), by using several frequencies at controlled intensities. Molecular weight of starting PEO was 100,000. Frequencies used were 25.8; 298.0, 480.0, and 926.5 kHz. Intensities inside the reaction solution were measured by calorimetry. The degradation process was monitored by gel permeation chromatography. Initial rate of ultrasonic degradation were observed at the order of 480.0 > 926.5 > 298.0 > 25.8 kHz at a constant intensity, 6.3±0.7W. Effect of concentration of PEO solution, 0.05, 0.1, 0.5 1.0%, also was investigated.
