AI 中文总结
本文针对增材制造聚合物加速老化温度极限不明的问题，以FDM制备的ABS为研究对象，明确水环境下加速老化的50℃温度阈值，提出了确定此类阈值的方法。
AI 中文摘要
加速老化被广泛用于在实验室时间尺度内研究材料的长期行为，尤其是针对长期暴露于溶剂环境的材料，这对增材制造（AM）聚合物尤为重要——这类材料在海军及商业水下应用中的使用日益增多，需要可靠的方法评估其在服役条件下的耐久性。常见的加速老化方法是将温度升高至低于玻璃化转变温度或熔融温度以加速降解，但增材制造聚合物加速老化的温度极限仍知之甚少，因为超过阈值的温度可能会激活服役条件下不存在的变形与降解机制。为填补这一空白，本文研究了熔融沉积建模（FDM）制备的丙烯腈-丁二烯-苯乙烯（ABS）在盐水和去离子（DI）水中的表现，以建立水环境下加速老化的温度阈值，并提出确定此类阈值的方法。研究采用了可控几何形状和不同打印方向，以明确探究潜在机制。结果显示，暴露于高于阈值温度的样品会因工艺诱导内应力的松弛，沿打印方向出现明显收缩和翘曲，据此确定ABS的加速老化温度阈值为50℃，超过该阈值会激活服役条件下不存在的额外机制；此外，产生的几何变形在厚结构中被掩盖，但在薄结构中极为明显；同时，溶剂离子含量对吸水率影响显著，盐水在1天内达到饱和，而去离子水即使经过30天也未达到饱和，且吸水量更大。
英文摘要
Accelerated aging is widely used to study the long-term behavior of materials within laboratory time scales, particularly for materials exposed to solvent environments over extended periods. This is especially important for additively manufactured (AM) polymers, whose increasing use in naval and commercial undersea applications requires reliable methodologies for assessing durability under in-service conditions. A common approach relies on elevating the temperature below the glass transition or melting temperature to accelerate degradation. However, the temperature limits for accelerated aging of AM polymers remain poorly understood, particularly because temperatures beyond a threshold may activate deformation and degradation mechanisms that are absent under service conditions. To address this gap, this paper investigates fused deposition modeling (FDM) Acrylonitrile Butadiene Styrene (ABS) exposed to saltwater and deionized (DI) water to establish a temperature threshold for accelerated aging in aqueous environments and propose a methodology for determining such thresholds. Controlled geometries and varying print directions were employed to explicitly probe the underlying mechanisms. We show that samples exposed to temperatures above the threshold exhibit pronounced shrinkage and warping along the printing direction due to the relaxation of process-induced internal stresses. These observations establish an accelerated-aging temperature threshold of 50$^\circ$C for ABS, beyond which additional mechanisms absent under service conditions become active. Additionally, the resulting geometric distortions are masked in thick geometries but become highly pronounced in thin structures. Moreover, solvent ionic content strongly influences water uptake, with saltwater reaching saturation in 1 day, whereas DI water did not reach saturation even after 30 days and exhibited greater mass uptake.
