ULTRASONIC VULCANIZATION OF NATURAL RUBBER
Conventionally rubbers are vulcanized in the presence of sulphur or peroxide at high temperature and pressure. This process has several significant shortcomings. In the present paper, natural rubber is vulcanized with the application of ultrasonic energy. The products of ultrasonic process exhibit the same properties as those that are vulcanized by using conventional process. However,the ultrasonic vulcanization process demonstrates many advantages over the traditional vulcanization methods such as high production rate, energy saving, uniform cure, etc. Energy generated due to phase difference between strain and stress,and sonochemical reaction within the compound are considered responsible for the vulcanization of rubber. The dynamic properties of unvulcanized natural rubber under ultrasonic frequency are obtained by means of the method of reduced variables of Ferry and Fitzgerald.Temperature rise curves at the beginning stage of the vulcanization are calculated from such properties.The calculated curves agree with the experimental results.