To promote the application of bio-based materials in the field of medical technology, it is essential to conduct additional research, focusing on their long-term performance after sterilization. For this purpose, the study examines the aging behaviour of three poly(lactic-acid) (PLA) materials, sterilized with either ethylene oxide or gamma irradiation, over a two years aging period, in accordance with ASTM F1980-21. During these investigations, a direct correlation between moisture absorption and degradation progression was observed. Crystallinity increased, due to chain scission mainly in amorphous regions, resulting in a reduction in melting peak temperature. Tensile strength and elongation at break, decreased with aging, accompanied by embrittlement. Color analysis revealed that Luminy® L130 brightened during aging, while NP HT 202 and NP HT 203 shifted towards green and yellow tones, attributed to the release of softeners from the materials. Regardless of the initial condition, the degradation process followed a two-stage linear process with an acceleration in the second phase, possibly due to the formation of catalytic end groups. The impact of sterilization is predominantly observed concerning the initial condition of the materials before aging and therefore affects the shelf life rather than the course of aging.

中文翻译：

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环氧乙烷和伽马辐照灭菌工艺对聚乳酸（PLA）人工加速老化过程中降解行为的影响

为了促进生物基材料在医疗技术领域的应用，有必要进行额外的研究，重点关注其灭菌后的长期性能。为此，该研究根据 ASTM F1980-21 的规定，检查了三种聚乳酸 (PLA) 材料在两年老化期内的老化行为，这些材料经过环氧乙烷或伽马射线照射灭菌。在这些研究过程中，观察到吸湿性和降解进程之间的直接相关性。由于断链主要发生在非晶区，结晶度增加，导致熔融峰值温度降低。拉伸强度和断裂伸长率随老化而下降，并伴有脆化。颜色分析显示，Luminy® L130 在老化过程中变亮，而 NP HT 202 和 NP HT 203 则转向绿色和黄色色调，这归因于材料中软化剂的释放。无论初始条件如何，降解过程都遵循两阶段线性过程，在第二阶段加速，这可能是由于催化端基的形成。灭菌的影响主要是针对老化前材料的初始条件观察到的，因此影响保质期而不是老化过程。