Quick determination of dry rubber content in natural rubber latex by low-resolution pulsed NMR technique
1993
Gambhir, P.N. | Joshi, D.K. | Tiwari, P.N. (Indian Agricultural Research Institute, New Delhi (India)) | Mani, J.
Proton Nuclear Magnetic Resonance technique using a spin-echo sequence has been used for quick determination of dry rubber content (DRC) of natural rubber latex. The measurement is based on the fact that the relaxation rates of solid and aqueous phases of the latex are markedly different. The combined signal of the two phases is obtained by sampling the free induction decay (FID) following a 90 pulse (immediately after the dead time of the receiver) in a spin-echo sequence. The echo signal representing the aqueous phase is measured when the solid phase signal has decayed the negligible value. Using these two signal values and correction factor to account for the difference in hydrogen content in the solid and liquid phases, DRC of twenty amminiated latex samples were determined. The DRC values obtained by this method are in good agreement with those obtained by the standard laboratory method (R2=0.991, P=0.001). The study shows the feasibility of a quick and precise NMR method of DRC determination without requiring any preparation or weighing of sample or a calibration curve
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