Updated Model for Fast Dry Rubber Content Determination in Natural Rubber Latex Using Shortwave Near Infrared Spectroscopy

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Lim Chin Hock
Panmanas Sirisomboon*

Abstract

The analysis of dry rubber content (DRC) of Para rubber latex including field latex and concentrated latex, using near-infrared spectroscopy was carried out by a ultra violet/visible/near-infrared (UV/VIS/NIR) Spectrometer in transmittance mode over the wavelength range of 350–1100 nm. The original model provided the best accuracy of prediction was developed using the partial least square regression (PLSR) from the spectra which were pretreated by the smoothing and range normalization in the wavelength range of 700-950 nm. The slope, offset, correlation coefficient (r), standard error of prediction (SEP) and bias were 1.0154, -0.6286, 0.9960, 1.190% and0.0322%, respectively. The updated model was done by adding the 180 samples merged into the 280 original samples. The slope, offset, correlation coefficient (r), standard error of prediction (SEP) and bias were 1.0126, -0.3729, 0.9931, 1.2654% and 0.1103%, respectively. Therefore, it is needed to make more robust updated model by NIRS technique for determining the DRC of Para rubber latex, for both field latex and concentrated latex.


Keywords: Natural Rubber Latex, Dry Rubber Content, Shortwave, Near Infrared Spectroscopy


*Corresponding author: Email: kspanman@kmitl.ac.th

Article Details

Section
Short Communications

References

[1] Blackley, D.C. Polymer Latices, Vol. 1, 2nd Edition, Chapman & Hall, London, 1997.
[2] ISO 126:2005 Natural rubber latex concentrate – Determination of dry rubber content.
[3] ISO 506:1992 Rubber latex, natural concentrate – Determination of volatile fatty acid number.
[4] Takeno, S., Bamba, T., Nakazawa, Y., Fukusaki, E., Okazawa, A. and Kobayashi, A. A High-Throughput and Solvent-free Method for Measurement of Natural Polyisoprene Content in Leaves by Fourier Transform Near Infrared Spectroscopy Journal of Bioscience and Bioengineering, 106(6), 537-540 (2008).
[5] Marinho, J.R.D. and Monteiro, E.E.C. Analysis of natural cis-and trans-polyisoprene mixtures by nearinfraredspectrophotometry. Polyme Testing, 19 (6), 667-672 (2000).
[6] Sirisomboon, P., Kaewkuptong, A. and Williams, P. “Feasibility study on the evaluation of the dry rubber content of field and concentrated latex of Para rubber by diffuse reflectance near infrared spectroscopy”, J. Near Infrared Spectroscopy. 21, 81–88 (2013).
[7] Sirisomboon,P., Deeprommit M., Suchaiboonsiri W. and Lertsri W. Shortwave near infrared spectroscopy for determination of dry rubber content and total solids content of Para rubber latex. J. Near Infrared Spectroscopy, 21(4), 269–279 (2013).
[8] Williams, P. Near-infrared Technology – Getting the best out of light. A short course in the practical implementation of near-infrared spectroscopy for the user. 5.4. ed. PDK Grain, Nanaimo, Canada, (2010).