CHARACTERIZATION OF POLY(LACTIC ACID) BY SIZE EXCLUSION CHROMATOGRAPHY, DIFFERENTIAL REFRACTOMETRY, LIGHT SCATTERING AND THERMAL ANALYSIS *

A number of experimental techniques are employed to characterize physical and thermal properties of poly(lactic acid), PLA. To characterize PLA in terms of molecular mass and molecular mass distribution, size exclusion chromatography was used. The value of the specific refractive index increment was measured by differential refractometry. The thermal properties of semicrystalline PLA were measured by standard and temperature-modulated differential scanning calorimetry. The thermal stability of PLA was monitored by measuring the changes of mass using thermogravimetric analysis. The mechanical properties of amorphous PLA were measured by dynamic mechanical analysis and the results were discussed and compared with DSC in the glass transition region.