USE OF THE ENVIRONMENTAL SCANNING ELECTRON-MICROSCOPE FOR THE OBSERVATION OF THE SWELLING BEHAVIOR OF CELLULOSIC FIBERS

We have developed a method for observing transverse swelling of cellul osic fibres in the environmental scanning electron microscope (ESEM). The presence of liquid water in the ESEM specimen chamber allows the o bservation of in situ hydration without the need for coating, freezing , or drying of the sample. For reproducibility of the hydration and de hydration process, specialised mounting techniques are required and co ntrol of the conditions for condensation and evaporation of liquid wat er is necessary. The sensitivity of these cellulosic materials to the electron beam was investigated, showing that some damage mechanisms ar e enhanced by the continual presence of water vapour in the chamber. A discussion is presented of the effect of various experimental paramet ers on the extent and time of onset of the damage, and we outline step s to maximise the amount of useful experimental time for these fibres.