Exposure of natural rubber to personal lubricants – swelling and stress relaxation as potential indicators of reduced seal integrity of non-lubricated male condoms

Abstract

BackgroundMale 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. MethodsSwelling and stress relaxation of natural rubber latex condoms were assessed in a laboratory model in the presence of silicone-, glycol-, and water-based lubricants. ResultsWithin 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. ConclusionsLubricant 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. ImplicationFor 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.