Poly(lactic-co-glycolic acid) (PLGA) is one of the most prominent bioresorbable materials, currently used in several medical applications (screws, craniofacial plates etc.). Looking to extend the knowledge about the thermomechanical behavior of bioresorbable medical materials, this research presents a series of experiments and results based on nonhomogeneous compression tests for the polymer PLGA 85/15. Instead of focusing on tensile and bending conditions for compression-molded products, such as usually presented in the literature, attention is given to compression tests and samples machined from injection-molded parts. Additionally, PLGA strain rate sensitivity, which is an issue less discussed in the literature, is analyzed. In the current study, this material is tested by observing the main features related to resorbable medical materials. The effects of a material heat treatment that are associated with PLGA shape-memory properties are investigated. Differential scanning calorimetry (DSC) was also employed in the thermal characterization. A finite element analysis of the compression testing provides a complementary overview of the mechanical behavior of PLGA 85/15. Results indicate that PLGA has a linear rate-insensitive response for small strains but presents a strong rate dependence for strains beyond the material yielding. PLGA shows a remarkable post-yielding strain-softening behavior, with a steep descent slope. Samples present significant mechanical changes after heat treatment at temperatures above \(T_{g}\), with reduction of 35% in the material elastic modulus and 30% in the upper-yielding stress and no significant changes for further heat-treatment procedures. DSC analysis confirmed the existence of significant residual stress in PLGA specimens. Mechanical deformation and manly heat treatment seem to reduce this residual stress caused by molecular orientation and rapid solidification. Finally, finite element simulations show that the limit of the homogeneity hypothesis is associated with the yield strain, after which highly non-uniform stresses develop.

聚乳酸-乙醇酸共聚物（PLGA）是最杰出的生物可吸收材料之一，目前用于多种医疗应用（螺钉，颅面板等）。为了扩展对生物可吸收医用材料热力学行为的了解，本研究提出了一系列基于PLGA 85/15聚合物非均匀压缩试验的实验和结果。不再关注通常在文献中介绍的压缩成型产品的拉伸和弯曲条件，而是关注压缩测试和由注塑成型零件加工而成的样品。此外，分析了PLGA应变速率敏感性，这是文献中很少讨论的问题。在当前的研究中，通过观察与可吸收医学材料有关的主要特征来测试这种材料。研究了与PLGA形状记忆特性相关的材料热处理的影响。差示扫描量热法（DSC）也用于热表征。压缩测试的有限元分析提供了PLGA 85/15力学性能的补充概述。结果表明，PLGA对小菌株具有线性的速率不敏感响应，但对超出材料产量的菌株具有很强的速率依赖性。PLGA表现出显着的屈服后应变软化行为，并具有陡峭的下降斜率。样品在高于150°C的温度下进行热处理后呈现出明显的机械变化 差示扫描量热法（DSC）也用于热表征。压缩测试的有限元分析提供了PLGA 85/15力学性能的补充概述。结果表明，PLGA对小菌株具有线性的速率不敏感响应，但对超出材料产量的菌株具有很强的速率依赖性。PLGA表现出显着的屈服后应变软化行为，并具有陡峭的下降斜率。样品在高于150°C的温度下进行热处理后呈现出明显的机械变化 差示扫描量热法（DSC）也用于热表征。压缩测试的有限元分析提供了PLGA 85/15力学性能的补充概述。结果表明，PLGA对小菌株具有线性的速率不敏感响应，但对超出材料产量的菌株具有很强的速率依赖性。PLGA表现出显着的屈服后应变软化行为，且具有陡峭的下降斜率。样品在高于150°C的温度下进行热处理后呈现出明显的机械变化 结果表明，PLGA对小菌株具有线性的速率不敏感响应，但对超出材料产量的菌株具有很强的速率依赖性。PLGA表现出显着的屈服后应变软化行为，且具有陡峭的下降斜率。样品在高于150°C的温度下进行热处理后呈现出明显的机械变化 结果表明，PLGA对小菌株具有线性的速率不敏感响应，但对超出材料产量的菌株具有很强的速率依赖性。PLGA表现出显着的屈服后应变软化行为，并具有陡峭的下降斜率。样品在高于150°C的温度下进行热处理后呈现出明显的机械变化\（T_ {g} \），材料的弹性模量降低了35％，上屈服应力降低了30％，并且在后续热处理程序中没有明显变化。DSC分析证实PLGA标本中存在明显的残余应力。机械变形和男子气概的热处理似乎减少了由分子取向和快速凝固引起的残余应力。最后，有限元模拟表明，同质性假设的极限与屈服应变相关，此后会出现高度不均匀的应力。