Mechanical Ageing Protocol Selection Affects Macroscopic Performance and Molecular Level Properties of Ethylene Vinyl Acetate (EVA) Running Shoe Midsole Foam

• DOI: 10.1016/j.proeng.2014.06.082
• Publication Date: 2014-06-19T17:08:27Z
• Authors: Nadine Lippa; Elise Hall; Scott Piland; Trent Gould; James Rawlins
• Keywords: Degradation; Ethylene-vinyl acetate; Sine wave

Existing attempts to evaluate footwear via cyclic compression fail sufficiently represent biofidelic force-time curves or provide the underlying mechanism of EVA foam fatigue. A uniaxial waveform was compared a sine wave same frequency examine differences in (1) net displacement, (2) absorbed energy, and (3) peak force from ASTM F1614. non-destructive molecular-level technique (ATR-FTIR) recorded hydroxyl, ester, unsaturated moieties due degradation. It concluded that waveforms may better simulate human running, material degradation is discernible, inferences regarding polymeric macroscopic performance require further investigation.