The effect of crystallinity on the deformation mechanism and bulk mechanical properties of PLLA
The effect of crystallinity on the deformation mechanism and bulk mechanical properties of PLLA
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DOI：
10.1016/j.biomaterials.2005.03.002
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发表时间：
2005-10-01
期刊：
影响因子：
14
通讯作者：
Cameron, RE
中科院分区：
文献类型：
--
作者：
Renouf-Glauser, AC;Rose, J;Cameron, RE
聚（l -丙交酯）是一种被广泛研究的生物材料，目前被批准用于一系列医疗器械，然而，到目前为止，大多数体外研究都集中在降解和/或变形过程中的体积特性，或降解过程中卸载材料的微观结构。本研究旨在通过同时进行小角度x射线散射和长达8个月的不同降解阶段的拉伸测试技术，将这些方法结合起来，对具有一系列诱导微观结构的材料进行拉伸测试。结果表明：非晶态材料在干燥、潮湿和退化状态下均发生裂纹变形，而在水化作用下，裂纹的形成机制发生了显著变化。尽管存在这种差异，但总体力学性能变化不大。晶体材料通过晶体介导的变形变形，由空化和纤化剪切共同作用，但令人惊讶的是，在不同温度下退火引起的球晶结构内长度尺度的差异对变形机制的影响很小，尽管在体性能上存在差异。此外，水化作用对晶体材料几乎没有影响，尽管在较高退火温度下产生的样品在8个月以上的降解会导致机械性能的损失。综上所述，结晶度的引入对PLLA的体积性能和微观性能都有巨大的影响，但晶体材料的球晶结构对体积性能的影响明显大于变形的微观机制。(c) 2005 Elsevier Ltd版权所有。
Poly (L-lactide) is a widely studied biomaterial, currently approved for use in a range of medical devices, however, most in vitro studies have so far focussed upon either the bulk properties during degradation and/or deformation, or on the microstructure of the unloaded material during degradation. This study aimed to combine these approaches through the technique of simultaneous small-angle X-ray scattering and tensile testing at various stages of degradation up to 8 months, on material with a range of induced microstructures. Results showed that the amorphous material deformed by crazing in the dry, wet and degraded states, however, the mechanism by which the craze developed changed significantly on hydration. Despite this difference, there was little change in the bulk mechanical properties. Crystalline materials deformed through crystal-mediated deformation, with contributions from both cavitation and fibrillated shear, but surprisingly, differences in the length scales within the spherulitic structure caused by annealing at different temperatures had very little effect on the mechanism of deformation, though differences were seen in the bulk properties. Furthermore, hydration had little effect on the crystalline materials, though degradation over 8 months resulted in loss of mechanical properties for samples produced at higher annealing temperatures. In conclusion, the introduction of crystallinity had a huge effect on both bulk and microscopic properties of PLLA, but the spherulitic structure of the crystalline material affected the bulk properties significantly more than it did the micromechanism of deformation. (c) 2005 Elsevier Ltd. All rights reserved.