Characterization of Cold Drawn Poly L Lactic Acid by Raman Spectroscopy and Raman Hyperspectral Imaging

Artificial modulation of bone growth and repair processes is an important area of current research. Studies have established that the micro mechanical and bulk physical properties of a polymer implant influence its performance behavior and degradation patterns in the body. One important parameter for the class of polymers known as polylactides is the degree of crystalline character. Hence, studying the bulk and micro crystalline composition of an important polymer implant, Poly-L-Lactic acid is the objective of this study. Poly-L-Lactic acid has elastic properties that can be tailored to resemble natural bone and its reaction to mechanical stress. Varying degrees of crystallinity have been induced in the polymer by stretching it to different draw ratios. Differential scanning calorimetry has been used to establish the bulk crystalline character of PLLA and to study and characterize functional group orientation changes induced at different draw ratios. The data from these investigations has been integrated to explain how the functional groups and their orientations with respect to draw axis and polarization axis impart unique characteristics to the Raman spectra of samples drawn to different draw ratio