Glass wool-H2O2/CoCl2 test system for in vitro evaluation of biodegradative stress cracking in polyurethane elastomers.

Environmental stress cracking (ESC) in polyetherurethanes has been demonstrated in animal models. However, duplication of this phenomenon in vitro has been a challenge. The glass wool-H2O2/CoCl2 test system was designed to provide oxidation components found in vivo, i.e., hydroxyl radical (HO.), molecular oxygen (O2), and superoxide (O2-.) required for auto-oxidation of polyetherurethanes. The in vitro test is not only reliable in duplicating the characteristics of in vivo stress cracking in polyetherurethanes at 37 degrees C, but also accelerates ESC as much as seven times. The test results on several types of polyurethanes showed that Tecothane 80A was as vulnerable to biodegradative stress cracking in vitro as Pellethane 2363-80A, while the new generation of polyurethanes, Corethane, demonstrated great resistance against stress cracking.