Design and development of a system based on transient hot wire technique to determine dry rubber content in natural rubber latex

This paper introduces an innovative methodology for evaluating the dry rubber content (DRC) of natural rubber latex (NRL) through the utilisation of transient hot wire (THW) technique. To accomplish this objective, an instrumentation system has been devised and implemented, which operates based on this underlying principle. The proposed approach capitalizes on the significant disparity in thermal conductivity between rubber particles (0.13 W/m-K) and water (0.58 W/m-K). A series of NRL samples obtained from the field were assessed using the developed instrument and their corresponding DRC values determined using conventional weighing-drying technique. The outcomes reveal a strong correlation between measured temperature increments for each sample within a predefined time frame and their respective DRC values. Furthermore, the proposed method offers the advantage of a significantly reduced measurement time, requiring only approximately 10 min to determine the DRC, in contrast to the existing weighing-drying technique, which necessitates around 18 h. Both techniques yield a measurement accuracy of ± 2%.