School of Mechanical and Aerospace Engineering, Queen's University, BT9 5AH Belfast, UK.
School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9, Ireland; Centre for Medical Engineering Research, School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9, Ireland; School of Pharmacy, Queen's University, Belfast, BT9 7BL, UK; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin 2, Ireland.
J Mech Behav Biomed Mater. 2018 Oct;86:113-121. doi: 10.1016/j.jmbbm.2018.06.017. Epub 2018 Jun 15.
The development of coronary stents from poly(L-lactic acid) requires knowledge of its mechanical properties and the effects of manufacturing processes on those properties. The effects of the biaxial stretching procedure on the mechanical and microstructural properties of poly(L-lactic acid) are hereby investigated. The mechanical properties were evaluated before and after biaxial stretching, with a Design of Experiments methodology employed to identify processing parameters that had the most significant effect on the elastic modulus and yield strength of the biaxially stretched sheets. Microstructural characterisation was performed using differential scanning calorimetry to evaluate crystallinity and thermal transitions of the biaxially stretched sheets. The results show that the mechanical properties of the stretched sheets are highly dependent on the extent of stretch ratio applied during processing; however, neither the elastic modulus nor yield strength are directly attributable to crystallinity, but are affected by the degree of amorphous orientation. The results of this study have the potential to be applied in the design of high stiffness, thin-strut polymeric expandable scaffolds for the application of coronary stents.
聚（L-乳酸）冠状动脉支架的开发需要了解其机械性能以及制造工艺对这些性能的影响。本文研究了双轴拉伸工艺对聚（L-乳酸）机械和微观结构性能的影响。采用实验设计方法评估了双轴拉伸前后的力学性能，以确定对双轴拉伸片弹性模量和屈服强度影响最大的加工参数。使用差示扫描量热法进行微观结构表征，以评估双轴拉伸片的结晶度和热转变。结果表明，拉伸片的力学性能高度依赖于加工过程中应用的拉伸比程度；然而，弹性模量和屈服强度都与结晶度没有直接关系，而是受到无定形取向程度的影响。本研究的结果有可能应用于设计用于冠状动脉支架的高刚度、细支柱聚合物可扩张支架。
