Schwerin Matthew R, Walsh Donna L, Coleman Richardson D, Kisielewski Richard W, Kotz Richard M, Routson Licia B, David Lytle C
Office of Science and Technology (HFZ-150), Center for Devices and Radiological Health, Food and Drug Administration, 9200 Corporate Boulevard, Rockville, Maryland 20852, USA.
J Biomed Mater Res. 2002;63(6):739-45. doi: 10.1002/jbm.10467.
Barrier integrity of unaged and oven-aged (at 70 degrees C) natural rubber latex examination gloves was assessed with a biaxial flex-fatigue method where failure was detected electronically, and by live viral penetration testing performed according to a modified version of ASTM F1671-97a. When no change in barrier properties was detected during flex testing, no virus passage was found after viral challenge. Conversely, when a change in the barrier properties was indicated by the electrical signal, virus passage was found in 74% of the specimens. Flex-fatigue results indicated that unaged test specimens from powdered (PD) and powder-free (PF) nonchlorinated gloves had significantly longer fatigue lives than powder-free chlorinated (CL) gloves from the same manufacturer. Biaxial flexing of oven-aged glove specimens showed a marginal increase in fatigue life for the PF gloves, but no increase for the PD gloves. The fatigue life of the CL gloves was observed to increase significantly after oven aging. However, this appears to be due to a design feature of the test apparatus, wherein peak volume displacement of the worked specimen is held constant. An aging-induced change in the viscoelastic properties of the CL gloves-permanent deformation of the specimens early in the fatigue test-relieves the stress magnitude applied as the test progresses. Thus, permanent deformation acts as a confounding factor in measuring durability of latex gloves by fixed displacement flex-fatigue.
采用双轴弯曲疲劳法评估未老化和经烘箱老化（70摄氏度）的天然橡胶乳胶检查手套的屏障完整性，其中通过电子方式检测失效情况，并按照ASTM F1671-97a的修改版进行活病毒渗透测试。在弯曲测试中未检测到屏障性能变化时，病毒攻击后未发现病毒通过。相反，当电信号表明屏障性能发生变化时，74%的标本中发现了病毒通过。弯曲疲劳结果表明，来自粉末状（PD）和无粉（PF）非氯化手套的未老化测试标本的疲劳寿命明显长于同一制造商的无粉氯化（CL）手套。烘箱老化手套标本的双轴弯曲显示PF手套的疲劳寿命略有增加，但PD手套没有增加。观察到CL手套在烘箱老化后的疲劳寿命显著增加。然而，这似乎是由于测试设备的设计特点，即工作标本的峰值体积位移保持恒定。CL手套粘弹性性能的老化诱导变化——在疲劳测试早期标本的永久变形——减轻了随着测试进行施加的应力大小。因此，永久变形在通过固定位移弯曲疲劳测量乳胶手套耐久性时是一个混杂因素。
