Fundamental Study for the Prediction of Fatigue Lives of Elastomeric Polymers Used in Artificial Heart Pump

对于心血管应用程序，一系列的分段聚合物多聚烯的机械性质与不同分子权重的软分段组件（<M_W>=850， 1350，和2000）是由张力和硬度测试进行的。软片段由聚对苯二甲酸乙二醇酯和4，4'-二苯甲基二氰酸酯（MDI）组成;硬片段含有丙二胺和MDI。在这种增加<M_W>的情况下，弹性模量和张力强度减弱，但最后的延长增加。设计的TM 5多密度（<M_W>=2000）展示了最低的弹性模块和相当高的强度和导电性。这一材料被认为是合适的，以满足需要高灵活性和坚韧性的前列腺成分。TM 3多元性（<M_W>=1350）指示的最适合的血液相容性和表面特征，可能是用于血液接触表面的。用于罐头和水泵房等结构组件，TM 1（<M_W>=850）被认为是 ... More 由于其高强度和低导电性，对测试温度（24 ° C、37 ° C和50 ° C）和循环速率（0.8 Hz、2 Hz和5 Hz）的影响是研究TM 5聚合物和生物体（伦理）的目标，以获得用于加速寿命测试方法的发展和建立标准的影响。随着环境温度的增加、动态压力的放松和动态弹性模块中的退化变得更大。如果循环率较高，机械性能中的变化较少，则与相同的重复数进行比较。在37 ° C上对saline解决方案进行了初步的耐久性测试，表明TM 5多甲苯结局200万个循环在50%平均应变、15%应变幅度和5 Hz循环速率条件下的变形周期。“平均压力的减少是被观察到的一个时期。”这种压力放松现象可能是一个严重的问题，因为这种材料的长期应用是血液泵。Less（低）

For cardiovascular applications, mechanical properties of a series of segmented polyether polyurethanes with soft segment component of different molecular weights ( <M_W> =850, 1350, and 2000) were studied by tensile and fatigue tests. The soft segment is composed of polytetramethylene glycol and 4,4'-diphenylmethane diiso-cyanate (MDI); the hard segment contains propylene diamine and MDI. With the increase in <M_W> , the elastic modulus and tensile strength decreased, but the ultimate elongation increased. The designated TM5 polyurethane ( <M_W> =2000) showed the lowest elastic modulus and fairly high strength and ductility. This material was considered to be suitable for prosthetic components which need high flexibility and toughness. TM3 polyurethane ( <M_W> =1350) indicated favorable blood compatibility and surface characteristics, which might be useful for the blood-contacting surfaces. For structural components like cannulae and pump housings, TM1 ( <M_W> =850) was considered to … More be most suited because of its high strength and low ductility.Effects of test temperature (24゜C, 37゜C, and 50゜C) and cyclic rate (0.8Hz, 2Hz, and 5Hz) on the fatigue properties were studied on TM5 polyurethane and Biomer (Ethicon) aiming to obtain basic data for the development of an accelerated endurance test method and the establishment of a criterion for the fatigue-life prediction. With the increase in the ambient temperature, the dynamic stress relaxation and the decrease in the dynamic elastic modulus became larger. The higher the cyclic rate was, the less the change in the mechanical properties was, if compared at the same repetition number. Preliminary durability tests in the saline solution kept at 37゜C indicated that TM5 polyurethane endures 200 million cycles of deformation under conditions of 50% mean strain, 15% strain amplitude, and 5Hz cyclic rate. The reduction of the mean stress was observed throughout the period. This stress relaxation phenomenon might be a serious problem for the long-term application of this kind of material for blood pumps. Less