Thesis Nondestructive Evaluation of Viscosity of Field Latex and Concentrated Latex for Factory Laboratory by Near Infrared Spectroscopic Technique Student Miss. Rawiphan Chowbankrang Student ID 51061204 Degree Master of Engineering Program Agricultural Engineering Year 2010 Thesis Advisor Assoc. Prof. Dr. Panmanas Sirisomboon

ABSTRACT

The objective of this research was to study the possibility of nondestructive evaluation of field latex and concentrated latex viscosity for factory laboratory by near infrared spectroscopic technique at wavelength between 1100 - 2500 nanometers by an FT-NIR Spectrometer using spectra from field latex and/or concentrated latex. The concentrated latex by medium level of ammonia was obtained from rubber factory with 7 different levels initial viscosity and 8 quantity levels of dry rubber content (%DRC) and total solid content (%TSC). The DRC and TSC were prepared from latex produced from Para rubber tree (RRIM 600 variety) for study the flowing behavior and for analyse the spectrum characteristic. In additional, the determination of field latex and/or concentrated latex viscosity were predicted by comparing of the values from reference laboratory by applying the Partial Least Squares (PLS) method. The result of the flowing behavior of concentrated latex, shows that, concentrated latex behave like Non-Newtonian Fluid which the viscosity changing rely on the share rate. The best calibration models, which related the absorbance variables to the viscosity of the latex, was the model developed from the raw spectra of the combined data of field and concentrated latex where the viscosity was measured by Rotational Viscometer LVDV-E (Brook field, USA). It correlation coefficient (r) was 0.974, Standard error of prediction (SEP) = 8.6 cP and Bias = -0.4 cP. The best model, which the viscosity was measured by Rotational Viscometer LVT (Brook field, USA), was developed from the spectra pretreated by Standard Normal Variant (SNV) method. It showed r of 0.972, SEP of 9.3 cP and Bias of 0.3 cP. From the graphs of regression coefficient and x-loading weight, the wavelengths which affected model were 1705 (CH3), 1715 (CH3), 2280 (CH3), 2290 (amino acid) and 2310 (CH2) nanometers. 1