Biodegradation of polyurethane under fatigue loading.
Biodegradation of polyurethane under fatigue loading.
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疲劳载荷下聚氨酯的生物降解。
DOI：
10.1002/jbm.a.10565
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Hiltner,Anne
中科院分区：
文献类型：
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作者：
Wiggins,MichaelJ;Anderson,JamesM;Hiltner,Anne
采用膜样膨胀法研究了聚醚氨酯脲（PEUU）在动态载荷（疲劳）条件下的生物降解。有限元模型被用来描述的应变状态，其范围从单轴的膜的边缘平衡的双轴拉伸应变在中心。在测试过程中，膜暴露于H2 O2/CoCl 2溶液，其模拟PEUU的体内氧化生物降解。通过红外分析确定化学降解的程度。通过光学显微镜和扫描电子显微镜对膜表面的物理损伤进行了表征。动态加载并不影响降解速率相对于无应力和恒定应力（蠕变）控制在经历主要单轴疲劳的膜的区域，但是，降解加速在经历平衡双轴或几乎平衡双轴疲劳的区域。得出的结论是，动态加载和双向拉伸应变的组合加速了该系统的氧化降解。化学降解产生了一个脆弱的表面层，其特征是许多凹坑和凹痕。仅在疲劳试验中才出现表面开裂形式的物理损伤。在无应力或蠕变试验中未观察到开裂。裂纹起始于由化学降解产生的凹坑处，并在由应变状态确定的方向上扩展。© 2003 Wiley Periodicals，Inc. J Biomed Mater Res 65A：524-535，2003
A method utilizing expansion of a diaphragm‐type film specimen was developed to studyin vitrobiodegradation of poly(etherurethane urea) (PEUU) under conditions of dynamic loading (fatigue). A finite element model was used to describe the strain state, which ranged from uniaxial at the edges of the film to balanced biaxial tensile strain at the center. During testing, the film was exposed to a H2O2/CoCl2solution, which simulatedin vivooxidative biodegradation of PEUU. The extent of chemical degradation was determined by infrared analysis. Physical damage of the film surface was characterized by optical microscopy and scanning electron microscopy. Dynamic loading did not affect the rate of degradation relative to unstressed and constant stress (creep) controls in regions of the film that experienced primarily uniaxial fatigue; however, degradation was accelerated in regions that experienced balanced biaxial or almost balanced biaxial fatigue. It was concluded that the combination of dynamic loading and biaxial tensile strain accelerated oxidative degradation in this system. Chemical degradation produced a brittle surface layer that was marked by numerous pits and dimples. Physical damage of the surface in the form of cracking occurred only in fatigue experiments. Cracking was not observed in unstressed or creep tests. Cracks initiated at the dimples produced by chemical degradation, and propagated in a direction that was determined by the strain state. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 524–535, 2003