Unraveling the high strain-rate dynamic stiffening in select model polyurethanes − the role of intermolecular hydrogen bonding

Molecular dependencies of dynamic stiffening and strengthening through high strain rate microparticle impact of polyurethane and polyurea elastomers

“…The laser-induced particle impact test (LIPIT) is an in-house designed tabletop method for micro-impact experiments. 23 The LIPIT is capable of inducing impacts with strain rates on the order of 10 6 -10 8 s -1 and has been used for testing high strain rate impact responses in gels 24 , segmented elastomers [19][20][21]25 , and other various materials [26][27][28] . Using this platform, Hsieh et al found that intersegmental mixing between the soft and hard phases strongly affected the high strain rate impact response of poly(urethane urea) and polyurea elastomers 21 .…”

“…Using this platform, Hsieh et al found that intersegmental mixing between the soft and hard phases strongly affected the high strain rate impact response of poly(urethane urea) and polyurea elastomers 21 . Wu et al recently used solid-state nuclear magnetic resonance spectroscopy (ssNMR) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) data along with LIPIT experiments to provide a comprehensive discussion on the importance of an intersegmental hydrogen bonding network for dynamic stiffening in twocomponent polyurethanes without segregated hard domains 25 .…”

“…As impact velocity and strain rate approaches zero, we expect CoR to trend towards the ideally elastic limit of 1 in all materials. Figure 3 shows the CoR curves for MDI-BDO-650 and other polyurethanes 25 . Clearly at the lowest performed impacts around 50 m/s, the responses are distinctly inelastic.…”

“…MDI-650 and MDI-BDO-1000 exhibit similar curves, though MDI-650 has a higher threshold velocity. Data for MDI-650, HDI-650, and MDI-BDO-1000 are reproduced from Wu et al 25 with permission from Elsevier. presumably undergo room temperature glass transition at a sufficiently high strain rate, MDI-BDO-650 is the most likely to do so at the strain rates achievable with the LIPIT.…”

“…For all fractions and constants, see Table S1 (see supplementary material). Data for MDI-650 and HDI-650 are reproduced from Wu et al 25 with permission from Elsevier.…”