疲劳

Abstract(#br)Segmented polyurethane multiblock polymers containing polydimethylsiloxane and polyether soft segments form tough and easily processed thermoplastic elastomers (PDMS-urethanes). Two commercially available examples, PurSil 35 (denoted as P35) and Elast-Eon E2A (denoted as E2A), were evaluated for abrasion and fatigue resistance after immersion in 85 °C buffered water for up to 80 weeks.

Abstract(#br)The use of soft, synthetic materials for the replacement of soft, load-bearing tissues has been largely unsuccessful due to a lack of materials with sufficient fatigue and wear properties, as well as a lack of fundamental understanding on the relationship between material structure and behavior under cyclic loads.

摘要 将钛酸钡( BT )纤维和BT粉末分别与聚二甲基硅氧烷( PDMS )基体相和叉指电极( IDE )结合，制备了一种柔性压电纳米发电机( FPENG )。采用静电纺丝法制备BT纤维。采用X射线衍射( XRD )技术对样品进行物相分析。采用Rietveld细化方法，可以确定BT纤维的四方结构。扫描电镜结果表明，BT纤维表面不光滑，说明聚合物和有机前驱体已被去除。采用50 % BT纤维制备的FPENG，其开路电压约为12 V，短路电流约为1μA，且FPENG内部分散相的影响对其输出性能的提高起到了一定的作用。该FPENG装置在退化前可运行5k次。通过连续加压至40k次，输出电压趋于零值。研究发现，机械疲劳效应与IDEs与PDMS界面在压制过程中产生的损伤有关。研究结果可为进一步设计FPENG器件的材料和器件结构，获得高性能和稳定性提供指导。

In this study, for the matrix / fiber interface strength is investigated in the fatigue experiment for the glass-fiber reinforcing polycarbonate (GFPC). Here the effect of modified PC resin is discussed when Epoxy (EP) or Polydimethylsiloxane (PDMS) are blended into PC. The microscopic damage process and fracture surface is examined through the optical microscope and the scanning electron microscope. The EP and PDMS are found to improve the matrix / fiber interface strength since they may control crack propagation along the fiber.

一种可替代的颅内动脉瘤栓塞剂正在以水凝胶的形式出现，因为它可以在液相中注入并原位固化。与弹簧圈栓塞等固体植入物相比，水凝胶具有填充动脉瘤囊的能力。最近，在体外实现光聚合聚乙二醇二甲基丙烯酸酯( PEGDMA )水凝胶的可行性已被证明用于动脉瘤的应用。尽管如此，这类水凝胶的物理和力学性能还需要进一步的表征来评估其长期的完整性和稳定性，以避免植入物压实和动脉瘤随时间而复发。为此，调节水凝胶的分子量和聚合物含量，使其与动脉瘤组织的弹性模量和顺应性相匹配，同时使溶胀体积和压力最小化。将水凝胶前驱体注射并光聚合于体外动脉瘤模型中，通过在3D打印水溶性牺牲模周围浇注聚二甲基硅氧烷( PDMS )设计。然后在生理脉动流作用下对水凝胶进行疲劳试验，诱导周向和剪切应力的组合。该水凝胶经550万次循环后，种植体未见明显失重，聚合水凝胶也未向母动脉突起或迁移。与未加载水凝胶的2μm最大值相比，加载后观察到2 ~ 10μm深度的轻微表面冲蚀缺陷。这些结果表明，我们微调的光聚合水凝胶有望承受体内植入研究的生理条件。