Effect of enantiomeric monomeric unit ratio on thermal and mechanical properties of poly(lactide).

The monomer of poly(lactide), i.e. lactic acid is an optically active compound and thus renders optical activity in the polymer itself. In the present studies highly crystalline and low crystalline grades of poly(lactide) were used to prepare blends with different d- and l-ratios to explore the relation between d- and l-content and various properties of poly(lactide). Optical rotation was measured by Polarimetry to analyse d-content in the blends which was found to vary from 0.05 to 4.14 %. Polarized light microscopy revealed that both the growth rate and final average size of the spherulites increased with the decrease of d-content. The crystallinity was measured by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) methods. It was noticed that a small change in d-content produced remarkable changes in crystallinity and other properties of the blends. The mechanical properties were slightly modified with the decrease in d-content. [ABSTRACT FROM AUTHOR]