The chain scission radiation chemical yield G(S) of irradiated PLLA films has been calculated directly from the ketone absorption band of its FT-IR spectra recorded at different absorbed dose. The maximum value G(S) = 2.85 ± 0.1 scission/100 eV was determined at 100 kGy, in excellent agreement with previously reported G(S) but determined from CO2 and CO gas analysis. Furthermore, from the FT-IR spectra, the rate constant of PLLA radiolityc degradation was determined in the range of 4.2–4.5 × 10–3 h‑1 at a dose rate of 3 kGy/h. The optical rotatory dispersion analysis of the irradiated PLLA films has shown that the complete radioracemization is reached at 100 kGy. The irradiated PLLA films were also analyzed by thermal analysis (both DSC and TGA) and spectrophotometrically.