Investigating Speed and Temperature Effects on Puncture of Elastomers

Abstract Background The failure of elastomers has begun to be understood through the lens of an intrinsic material lifetime rather than critical energy criteria. Objective This study gathers and describes phenomenology concerning the effects of speed and temperature on elastomeric puncture in terms of this recently proposed theoretical framework of elastomeric failure. Methods Continuous indentation experiments until puncture were performed over a range of indentation speeds and temperatures. Delayed puncture tests were conducted for the first time to experimentally measure the incubation time required for rupture under constant load. Results Continuous indentation reveals that, like tensile extension, elastomers exhibit higher strength on shorter timescales and under lower temperatures, i.e., the resistant normal force and displacement until puncture increase with indentation speed and decreasing temperature. Furthermore, the measured incubation time $${t}_{del-punct}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>t</mml:mi> <mml:mrow> <mml:mi>d</mml:mi> <mml:mi>e</mml:mi> <mml:mi>l</mml:mi> <mml:mo>-</mml:mo> <mml:mi>p</mml:mi> <mml:mi>u</mml:mi> <mml:mi>n</mml:mi> <mml:mi>c</mml:mi> <mml:mi>t</mml:mi> </mml:mrow> </mml:msub> </mml:math> uncovers the elastomeric lifetime as an internal clock, which controls when puncture occurs. Conclusions (a) Stronger resistance to puncture at lower temperatures and higher indentation speed has been demonstrated and explained in terms of network rupture through chain scission, (b) for any pair of speed and temperature, another pair exists that produces puncture at the same strength and degree of indentation, implying the existence of a distinct time–temperature equivalence where the internal clock is network lifetime not polymer relaxation time.