Low Y J, Kittur M I, Andriyana A, Ang B C, Zainal Abidin N I
Center of Advanced Materials, Faculty of Engineering, Universiti Malaya, 50603, Kuala Lumpur, Malaysia; Department of Mechanical Engineering, Faculty of Engineering, Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
Center of Advanced Materials, Faculty of Engineering, Universiti Malaya, 50603, Kuala Lumpur, Malaysia; Department of Mechanical Engineering, Faculty of Engineering, Universiti Malaya, 50603, Kuala Lumpur, Malaysia.
J Mech Behav Biomed Mater. 2023 Apr;140:105723. doi: 10.1016/j.jmbbm.2023.105723. Epub 2023 Feb 10.
Poly(glycolide-co-caprolactone) (PGCL) has become a novice to the bioresorbable suture owing to the synergistic properties taken from the homo-polyglycolide (PGA) and polycaprolactone (PCL) such as excellent bioresorption and flexibility. In addition to under conventional monotonic loading, the understanding of mechanical responses of PGCL copolymers under complex loading conditions such as cyclic and stress relaxation is crucial for its application as a surgical suture. Consequently, the present work focuses on evaluating the mechanical responses of PGCL sutures under monotonic, cyclic, and stress relaxation loading conditions. Under monotonic loading, the stress-strain behavior of the PGCL suture was found to be non-linear with noticeable strain-rate dependence. Under cyclic loading, inelastic responses including stress-softening, hysteresis and permanent set were observed. During cyclic loading, both stress-softening and hysteresis were found to increase with the maximum strain. In multi-step stress relaxation, the PGCL sutures were observed to exhibit a strong viscoelastic response. In an attempt to describe the relationship between the stress-relaxation and strain-induced crystallization (SIC) occurring during the loading and relaxation processes, a schematic illustration of the conformational change of polymer chains in PGCL sutures was proposed in this work. Results showed that SIC was dependent on the strain level as well as the loading and relaxation durations. The inelastic phenomena observed in PGCL sutures can be thus correlated to the combined effect of stress relaxation and SIC.
聚乙交酯-己内酯共聚物（PGCL）由于兼具均聚物聚乙交酯（PGA）和聚己内酯（PCL）的协同特性，如优异的生物可吸收性和柔韧性，已成为生物可吸收缝线领域的新成员。除了传统单调加载情况外，了解PGCL共聚物在复杂加载条件（如循环加载和应力松弛）下的力学响应对于其作为手术缝线的应用至关重要。因此，本工作重点评估PGCL缝线在单调、循环和应力松弛加载条件下的力学响应。在单调加载下，发现PGCL缝线的应力-应变行为是非线性的，且具有明显的应变率依赖性。在循环加载下，观察到包括应力软化、滞后和永久变形在内的非弹性响应。在循环加载过程中，发现应力软化和滞后都随着最大应变的增加而增大。在多步应力松弛过程中，观察到PGCL缝线表现出强烈的粘弹性响应。为了描述加载和松弛过程中发生的应力松弛与应变诱导结晶（SIC）之间的关系，本工作提出了PGCL缝线中聚合物链构象变化的示意图。结果表明，SIC取决于应变水平以及加载和松弛持续时间。因此，PGCL缝线中观察到的非弹性现象可与应力松弛和SIC的综合作用相关联。
