Radiation Effects on Biodegradable Polymer Systems

Biodegradable polymers such as polylactic acid, polycaprolactone and poly(lactic-co-glycolic acid) are increasingly employed in medical devices, packaging and environmental applications owing to their renewable origins and favourable degradation profiles. Exposure to ionising radiation (gamma rays, electron beams) or non-ionising radiation (ultraviolet light) can induce chemical and physical changes, notably chain scission, crosslinking and alterations in crystallinity. These modifications manifest as shifts in molecular weight distribution, mechanical strength, thermal transitions and surface energy. In the context of sterilisation, radiation offers a non-thermal route to microbial inactivation but may compromise polymer integrity and shelf life. Conversely, controlled radiation processing enables tailored crosslinking to enhance thermal stability or mechanical performance. Understanding the interplay between radiation parameters and polymer architecture is vital to balance sterilisation efficacy, material performance and biodegradation kinetics in both biomedical and industrial environments.

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Research from all publishers

Recent investigations into the long-term effects of sterilisation on polylactic acid reveal a two-phase degradation under accelerated ageing conditions. Ethylene oxide sterilisation produces minimal alterations in mechanical and thermal properties, whereas gamma irradiation accelerates chain scission in amorphous regions, increases crystallinity and compromises tensile strength and elongation over a two-year period.

Complementary studies on poly-L-lactic acid (PLLA) compare ethylene oxide and gamma irradiation sterilisation, demonstrating that exposure near the glass transition temperature increases crystallinity and reduces molecular weight. Ethylene oxide yields milder effects on wettability and toughness, identifying it as the preferred method for maintaining surface energy and biocompatibility in medical implants.

Work on PLA–chitosan nanocomposites subjected to γ-irradiation (5–40 kGy) shows dose-dependent oxidative degradation and chain scission, with composite samples exhibiting enhanced resistance due to chitosan’s radical-scavenging properties. Irradiation in solution accelerates degradation relative to solid films, reducing tensile strength, glass transition and melting temperatures, while higher chitosan loadings mitigate these effects and preserve thermal stability.

Radiation Effects on Biodegradable Polymer Systems publication trend

The graph below shows the total number of articles in radiation effects on biodegradable polymer systems across all publications each year (not limited to Nature Index journals).

Technical terms

Chain scission: A process in which radiation breaks polymer backbone bonds, reducing molecular weight and altering mechanical properties.

Crosslinking: Formation of covalent bonds between polymer chains induced by radiation, enhancing rigidity and thermal resistance.

Crystallinity: The degree of ordered molecular arrangement in a polymer, affecting stiffness, transparency and degradation rate.

Irradiation dose: The amount of radiation energy absorbed per unit mass, usually measured in kilograys (kGy), governing the extent of polymer modification.

Molecular weight: The average mass of polymer chains, dictating viscosity, strength and biodegradation behaviour.

References

1. Influence of ethylene oxide and gamma irradiation sterilization processes on the degradation behaviour of poly(lactic acid) (PLA) in the course of artificially accelerated aging. Polymer Testing (2024).
2. Influence of Ethylene Oxide and Gamma Irradiation Sterilization Processes on the Properties of Poly-L-Lactic-Acid (PLLA) Materials. Polymers (2023).
3. Physico-chemical Characteristics of Biodegradable Poly(lactic acid) and Poly(lactic acid)/Chitosan Nano-Composites Under the Influence of Gamma Irradiation. Journal of Polymers and the Environment (2023).