3. Dry of natural rubber latex
Latex from Hevea trees is usually coagulated by acid to prepare the sheets for the production process. In this acid coagulation process, the negative charge of the phospholipid–protein complex on the surface of colloidal NR particles was neutralized by the positive charge of the acid hydrogen ions. The commercial acids used for this purpose are formic and acetic acids. Since these acids are petrochemicals, an alternative, more sustainable materials are on high demand with rising petrol prices (Baimark Y. and Noi N.,2009)
4. Ultrasonic technique
Sound frequency above 18 kHz is considered to be ultrasound (US) and a huge amount of research has gone into the application of ultrasound at both high and low power. The use of the latter is mainly confined to medical ultrasonography whilst the former has a myriad of uses including ultrasonic welding, degassing of solutions, defect detection and sonochemistry. When US is applied to an aqueous solution or suspension an increase in mixing, shearing and mass transfer is observed. Under certain conditions cavitation is produced which manifests itself in the production of tiny bubbles which implode to produce so called “hotspots” which tend to generate highly reactive hydroxyl radicals and unusual chemical transformations( Santos.,2007)
Ultrasound is technique for many applications, for example reaction initiation, enhancing reaction rates and improving the selectivity of chemical reactions. This property may be explained by the fact that ultrasound can be used to produce free radicals (such as hydrogen and hydroxide from water)