The Effect of Gamma Irradiation in a Wide Dose Range on the Functional Composition of Lightly Crosslinked Polyacrylic Acid (Carbomer 940)

The effect of γ-irradiation in the dose range from 5 to 1700 kGy on the structural changes of the lightly crosslinked polyacrylic acid Carbomer 940 has been studied using IR spectroscopy to analyze the features of radiation-chemical transformations in the polymer matrix. It has been established that irradiation causes a stepwise change in the functional composition of the polymer, including redistribution of hydrogen bonds and rupture of crosslinks followed by modification of functional groups at high doses. At doses up to 400 kGy, a reformation of intermole cular interactions without degradation of the polymer backbone is observed. In the 400–800 kGy range, irreversible oxidative degradation occurs, forming anhydride structures. High doses lead to polymer carbonization. Characteristic spectral indicators of each step of radiation-induced transformations have been identified, including the appearance of new absorption bands and changes in the intensity of the existing ones. Importantly, the integrity of the polymer backbone is maintained even at maximum radiation doses, despite significant changes in its functional composition.