A Portable System for Rapid Measurement of Dry Rubber Content With Contaminant Detection Feature

This paper presents a system which is able to determine dry rubber content (DRC) as well as detect contaminants in latex. The system was designed and implemented with a six-port reflectometer. An open-ended coaxial sensor was designed as a measurement probe. The constant amplitude sinusoidal wave at 1 GHz transmits from the probe tip, incidents on the test sample and reflects back to the probe. A standing electromagnetic wave is formed and converted to the electrical signal by the probe. This electric signal is digitized and fed to the algorithms programmed in the microcontroller. These algorithms were developed for classifying the latex sample and determining its DRC. The system accuracy was tested with several pure and contaminated latex samples. The contaminated samples were prepared by mixing pure latex with 10 and 15% (by volume) of cassava flour solution. One hundred and ten samples, 50 pure, 40 contaminated of 10%, and 20 contaminated of 15%, were tested. The overall detection accuracy was 91.8% across the DRC range from 24 to 55%. For DRC determination, the system was tested with 30 latex samples at 27 °C. This was compared with the standard oven method (ISO 126:1972 DRC, BS 1672:part 1:1950 and ASM D 1076–80) where the mean absolute error of DRC achieved was 0.74%.