DETERMINATION OF THE REFRACTIVE INDEX INCREMENT OF NATURAL AND SYNTHETIC POLY(CIS-1,4-ISOPRENE) SOLUTIONS AND ITS EFFECT ON STRUCTURAL PARAMETERS

作者：Kim Chandy^*; Deratani Andre; Bonfils Frederic

来源：Journal of Liquid Chromatography & Related Technologies, 2010, 33(1): 37-45.

DOI：10.1080/10826070903427072

• natural rubber
• polyisoprene
• refractive index increment
• size-exclusion chromatography with multi-angle light scattering

The refractive index increment (dn/dc) of a solution is a constant that indicates the variation of the refractive index with the solute concentration. It is used in the multi-angle light scattering technique to determine the concentration and the weight-average molar mass of polymers. It depends on many parameters, including the structure of the polymer, the solvent, the wavelength of the light and the temperature of the solution. To obtain accurate results, it is necessary to determine the dn/dc at the same condition as for the multi-angle light scattering measurement. In this work, the dn/dc at 633nm of standard synthetic monodispere poly(cis-1,4-isoprene) (PI) and natural rubber (NR) solutions in THF were determined at 25 and 40 degrees C using an Optilab DSP refractometer. The mean value of the dn/dc obtained for NR and PI was 0.13mL/g. No significant difference between different types of samples and temperatures (25 degrees C and 40 degrees C) were observed. The nanoaggregates in NR solution that were not retained after filtration through 1m filter had no effect on the dn/dc. The intercept value of the conformation plot increased in line with the dn/dc, but the Flory exponent remained unchanged.

• 出版日期2010