Measuring Dry Rubber Content in Field Latex using Optical Fiber Sensor

Abstract

Quality of the natural rubber latex collected from a para rubber tree is normally expressed in terms of dry rubber content (DRC), which is defined as the weight percentage of solid rubber content obtained from a weighed quantity of latex.  The most commonly used methods for in-field measurement of the DRC are the microwave drying.  It is rapid and easy DRC determination technique, although with much less accuracy than the standard drying method.  Therefore, a novel, rapid and effective method to measure DRC in latex based on turbidity analysis using optical fiber sensor was created in this work.  A red light photodiode with a wavelength of 660 nm used as a light source was connected to one end of plastic-clad-plastic optical fiber.  The other end of optical fiber, at which the fiber cladding surface was removed by approximately 1 cm, was immersed into middle-level latex sample volume that was contained in the solution chamber.  When a laser beam transmitted through latex solution, the rubber particles scattered light to the another optical fiber connected to light detector.  The intensity of detected light was linearly proportional to the DRC.  The error percentage of measured DRC was less than 3.4%.  This developed portable device can be used to measure the DRC presented in latex for practical field use at latex collection points with high accuracy.