Stabilisation of hydrogen bonding in polypropylene glycol at EHL contact region

In the present work. the stabilisation of hydrogen bonding of polypropylene glycol at elastohydrodynamic lubrication (EHL) contact was investigated by In situ observation with a micro-Fourier transform infrared spectrometer. and the effect of hydrostatic pressure on infrared (IR) spectra was confirmed using a diamond anvil cell Polypropylene glycols with different molecular weights were used as sample oils. Polypropylene glycol molecules interact with themselves by hydrogen bonding with their hydroxyl groups Stability of the hydrogen bonding is observed by IR peak shift of the O-H stretching mode (3400-3700 cm(-1)) In the case of the dynamic condition under EHL. the C-H stretching mode shifted to a higher wavenumber. whereas the O-H stretching mode shifted to a lower wavenumber at the Hertzian contact region This result means that the hydrogen bonding of polypropylene glycol was stabilised under high pressure, and the stabilisation of hydrogen bonding by pressure was dependent on the molecular weight of polypropylene glycol. Copyright (C) 2010 John Wiley & Sons, Ltd.