Significant amount of research, both experimental and numerical, has been conducted to study the mechanical behaviour of biodegradable polymer PL(L)A due to its wide range of applications. However, mechanical brittleness or poor elongation of PL(L)A has limited its applications considerably, particularly in the biomedical field. This study aims to study the potential in improving the ductility of PLA by blending with PBS in varied weight ratios. The preparation of PLA and PBS blends, with various weight ratios, was achieved by melting and mixing technique at high temperature using HAAKE™ Rheomix OS Mixer. Differential Scanning Calorimetry (DSC) was applied to investigate the melting behaviour, crystallization and miscibility of the blends. Small dog-bone specimens, produced by compression moulding, were used to test mechanical properties under uniaxial tension. Moreover, an advanced viscoplastic model with nonlinear hardening variables was applied to simulate rate-dependent plastic deformation of PLA/PBS blends, with model parameters calibrated simultaneously against the tensile test data. Optical Microscopy showed that PBS composition aid with the crystallization of PLA. The elongation of PLA/PBS blends increased with the increase of PBS content, but with a compromise of tensile modulus and strength. An increase of strain rate led to enhanced stress response, demonstrating the time-dependent deformation nature of the material. Model simulations of time-dependent plastic deformation for PLA/PBS blends compared well with experimental results. The crystallinity of PLA/PBS blends increased with the addition of PBS content. The brittleness of pure PLA can be improved by blending with ductile PBS using mechanical mixing technique, but with a loss of stiffness and strength. The tensile tests at different strain rates confirmed the time-dependent plastic deformation nature of the blends, i.e., viscoplasticity, which can be simulated by the Chaboche viscoplastic model with nonlinear hardening variables.

中文翻译：

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聚乳酸和丁二酸丁二酯共混物力学性能的测试，表征和建模

由于可生物降解的聚合物PL（L）A的广泛应用，已进行了大量的实验和数值研究。但是，PL（L）A的机械脆性或伸长率差限制了其应用，特别是在生物医学领域。这项研究旨在研究通过与各种重量比的PBS混合来提高PLA延展性的潜力。通过使用HAAKE™Rheomix OS混合器在高温下熔融和混合技术，可以制备各种重量比的PLA和PBS共混物。差示扫描量热法（DSC）用于研究共混物的熔融行为，结晶和混溶性。小型狗骨标本，通过压缩成型制成，用来测试单轴张力下的机械性能。此外，将具有非线性硬化变量的高级粘塑性模型应用于模拟PLA / PBS共混物的速率依赖性塑性变形，同时针对拉伸试验数据对模型参数进行了校准。光学显微镜显示，PBS组合物有助于PLA的结晶。PLA / PBS共混物的伸长率随着PBS含量的增加而增加，但拉伸模量和强度却有所降低。应变速率的增加导致应力响应增强，证明了材料随时间变化的变形特性。PLA / PBS共混物随时间变化的塑性变形的模型模拟与实验结果进行了比较。PLA / PBS共混物的结晶度随PBS含量的增加而增加。通过使用机械混合技术与延性PBS混合可以提高纯PLA的脆性，但会失去刚度和强度。在不同应变率下的拉伸试验证实了掺混物随时间变化的塑性变形性质，即粘塑性，可以通过带有非线性硬化变量的Chaboche粘塑性模型来模拟。