Rapid Evaluation of the Properties of Natural Rubber Latex and Its Products Using Near-Infrared Spectroscopy

The parameters including physico-chemical properties such as dry rubber content (DRC), total solids content (TSC), volatile fatty acid (VFA) number, alkalinity (ammonia content) and potassium hydroxide (KOH) number and physical properties such as viscosity and cross-link density are important to the trading and processing of natural rubber latex and its products. Traditionally these properties of field and concentrated latices and their products including thin and thick films are evaluated with chemicals and time-consuming methods and with the need of technical experts. The near-infrared (NIR) spectroscopy is a nondestructive, rapid, accurate and environment-friendly technique. It needs no chemical. This chapter describes the application of NIR spectroscopy on evaluation of the properties of natural rubber latex and its products. latex The PLSR models were developed using original and pretreated absorbance spectra. The model developed from smoothing and range normalization pretreated spectra in the wavelength range of 700–950 nm the best prediction accuracy for DRC, and the models using raw spectra in the same wavelength range gave the best results for TSC. The slope, offset, r 2 , SEP and bias were 1.0154, − 0.6286, 0.992, 1.1092 and 0.0321%, respectively, for the DRC prediction and 1.0084, − 0.2332, 0.991, 1.3611 and 0.1456%, respectively, for the TSC prediction. The best models were validated using new unknown sample sets of 50 and 35 samples for DRC and TSC, respectively. The models provided an r 2 , SEP, RPD and bias of 0.988 and 0.974, of 1.4296 and 2.1255, of 10.0 and 6.2 and of − 0.6191 and 0.5476% for DRC and TSC, respectively. This work showed that the SW-NIR spectroscopy in the evaluation TSC for quality assurance process control latex the factory