Sarkar Das Srilekha, Coburn James C, Tack Charles, Schwerin Matthew R, Richardson D Coleman
Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD 20993.
Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD 20993.
Contraception. 2014 Jul;90(1):86-93. doi: 10.1016/j.contraception.2014.01.020. Epub 2014 Feb 4.
Male condoms act as mechanical barriers to prevent passage of body fluids. For effective use of condoms the mechanical seal is also expected to remain intact under reasonable use conditions, including with personal lubricants. Absorption of low molecular weight lubricant components into the material of male condoms may initiate material changes leading to swelling and stress relaxation of the polymer network chains that could affect performance of the sealing function of the device. Swelling indicates both a rubber-solvent interaction and stress relaxation, the latter of which may indicate and/or result in a reduced seal pressure in the current context.
Swelling and stress relaxation of natural rubber latex condoms were assessed in a laboratory model in the presence of silicone-, glycol-, and water-based lubricants.
Within 15 minutes, significant swelling (≥6 %) and stress reduction (≥12 %) of condoms were observed with 2 out of 4 silicone-based lubricants tested, but neither was observed with glycol- or water-based lubricants tested. Under a given strain, reduction in stress was prominent during the swelling processes, but not after the process was complete.
Lubricant induced swelling and stress relaxation may loosen the circumferential stress responsible for the mechanical seal. Swelling and stress relaxation behavior of latex condoms in the presence of personal lubricants may be useful tests to identify lubricant-rooted changes in condom-materials.
For non-lubricated latex condoms, material characteristics--which are relevant to failure--may change in the presence of a few silicone-based personal lubricants. These changes may in turn induce a loss of condom seal during use, specifically at low strain conditions.
男用避孕套作为防止体液通过的机械屏障。为了有效使用避孕套，机械密封在合理使用条件下（包括使用个人润滑剂时）也应保持完好。低分子量润滑剂成分被男用避孕套材料吸收可能引发材料变化，导致聚合物网络链膨胀和应力松弛，进而影响该装置密封功能的性能。膨胀既表明橡胶与溶剂的相互作用，也表明应力松弛，在当前情况下，后者可能表明和/或导致密封压力降低。
在实验室模型中，评估天然橡胶乳胶避孕套在硅酮基、二醇基和水基润滑剂存在下的膨胀和应力松弛情况。
在15分钟内，测试的4种硅酮基润滑剂中有2种使避孕套出现显著膨胀（≥6%）和应力降低（≥12%），但测试的二醇基或水基润滑剂均未出现这种情况。在给定应变下，膨胀过程中应力降低显著，但过程完成后则不明显。
润滑剂引起的膨胀和应力松弛可能会使负责机械密封的圆周应力松弛。乳胶避孕套在个人润滑剂存在下的膨胀和应力松弛行为可能是识别由润滑剂引起的避孕套材料变化的有用测试。
对于未润滑的乳胶避孕套，与失效相关的材料特性在存在一些硅酮基个人润滑剂时可能会发生变化。这些变化可能进而导致使用过程中避孕套密封失效，特别是在低应变条件下。
