FTIR analysis of hydrolysis in aliphatic polyesters

Infrared (IR) spectroscopy was adopted to study the hydrolytic degradation of films of aliphatic polyesters in alkaline environment. A measurable increase with the time of immersion of the absorbance of the peak centered at about 1570 cm⁻¹ was observed. Analysis of the IR spectra showed that the integrated peak area in that region can be used to quantify changes in the concentration of degradation products and thus to provide indications regarding the kinetic constant of the hydrolysis reaction. It was found that the hydrolysis of ester bonds proceeds linearly with time, and this result suggests that the controlling mechanism is the chemical reaction rather than water diffusion. The results also show that degradation rate increases with increasing polydispersity.