A rapid and accurate method for determining the dry rubber content and total solid content of NR latex

Abstract

The dry rubber content of field latex is determined roughly by means of the hydrometer known as the ‘Metrolac’, which is an instantaneous method. However, accurate determination of the percentage dry rubber content (%DRC) and the percentage total solid content (%TS) of natural rubber latex is important for the export certification of shipments of latex in the producing countries. Accurate determination of %DRC and % TS are also important for many other purposes such as research experiments in the field of chemical modification of rubber. At present, determinations of %DRC and %TS are carried out by the BS methods which involve heating the latex or coagulum samples for over 6 h in a conventional oven. Hence these methods are not suitable for a factory producing large quantities of centrifuged latex for production control purposes or for export. This paper reports convenient methods of determining %DRC and %TS of latex in 10 min and 25 min, respectively, with the same accuracy as the BS or ISO methods.