Shape memory polymers (SMPs) are a class of smart materials that are used in diverse applications and exhibit unique shape-changing abilities in response to external stimuli. Incorporating nanoparticles such as multi-walled carbon nanotubes (MWCNTs) into SMPs can further enhance their performance. However, Gamma (γ) irradiation effect on these nanocomposites remains relatively unexplored. In the current work, nanocomposite specimens were subjected to varying γ-irradiation doses of 100, 200, and 300 kGy. A comprehensive analysis was conducted to evaluate the changes in mechanical, thermal, micrographic, and shape memory behavior of the nanocomposites before and after irradiation. The results revealed a significant improvement in mechanical and thermal properties, with a 41 % increase in tensile strength, a 38 % increase in flexural strength, and a 11 % in glass transition temperature (Tg) observed at the 200 kGy γ-irradiation dose. The influence of γ-irradiation on MWCNTs and their interaction with SMP was also examined. Furthermore, the shape recovery responses of strip and waveform specimens in extension and compression were investigated. It was observed that all the investigated parameters of the SMP nanocomposites showed a decline beyond an optimum irradiation dosage.

中文翻译：

---

4D 打印聚氨酯/MWCNT 纳米复合材料在γ辐照下的形状恢复行为和力学性能


形状记忆聚合物 （SMP） 是一类用于各种应用的智能材料，在响应外部刺激时表现出独特的形状变化能力。将多壁碳纳米管 （MWCNT） 等纳米颗粒掺入 SMP 中可以进一步提高其性能。然而，γ （γ） 辐照对这些纳米复合材料的影响仍相对未得到探索。在目前的工作中，纳米复合材料样品经受了 100、200 和 300 kGy 的不同γ照射剂量。进行了综合分析，以评估纳米复合材料在辐照前后的机械、热、显微和形状记忆行为的变化。结果显示，机械和热性能显著改善，在 200 kGy γ照射剂量下，拉伸强度增加了 41%，弯曲强度增加了 38%，玻璃化转变温度 （T _g ） 增加了 11%。还检查了γ照射对 MWCNT 的影响及其与 SMP 的相互作用。此外，还研究了带状和波形试样在拉伸和压缩过程中的形状恢复响应。据观察，SMP 纳米复合材料的所有研究参数都显示出超过最佳照射剂量的下降。