Time-resolved SAXS investigation on structural evolution of plant fibrillar-network during dehydration

Dehydration induced shrinkage of fibrillar network is ubiquitous in nature. In this work time-resolved smallangle X-ray scattering has been employed to probe such structural shrinkage of plant fibrillar network. We have taken husk of Green Cardamom as a model fibre. It is demonstrated that evolution of shrinkage of inter-fibrillary voids depends strongly on the nature of hydration medium. For neutral and acidic media, shrinkage follows a logistic shrinkage model with time but shrinkage in case of alkaline medium remains insignificant. For neutral and acidic media, the Porod level, an indicator of contrast weighted volume fraction, reaches a maximum and then decreases with passage of time. However, a contrasting behaviour is observed for alkaline medium where the same does not manifest any maximum even after three hours. Electron microscopy and infrared spectroscopy reveal significant alteration of fibrils under hydration in strong alkaline medium. This could hinder the shrinkage process and did not allow retrieving the virgin structural configuration after drying in contrast to the cases for acidic and neutral media.