Figure 4.

Spectrum related to degradation points 0 to 4 of PLGA plates for the period of 0, 15, 30, 60, and 120 days, respectively. Ester groups = red: 1760–1745 cm⁻¹ and 1300–1150 cm⁻¹; alkanes groups = blue: 3000–2800 cm⁻¹ and 1450–1370 cm⁻¹; oligomer groups = yellow: 1600–1500 cm⁻¹.