Question

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SEM images: (a) purified cellulose microfibers, (b) oven-dried cellulose nanofibers hydrogel (c) freeze dried cellulose nanofiber hydrogel

Discuss the effect of drying (air and freeze drying) on morphology of cellulose nanofiber hydrogels based on scanning electron microscopy (SEM) images.

Based on the above picture to analyze

Answer 1

Scanning electron microscopy provides information about the surface morphology of the material.  

Oven drying: In case of air drying there is considerable loss of water and the surface of the nanofibrils dries up shrinks. The undulations on the surface show that due to loss of water the fibres get unevenly spread.

Freeze drying: In case of freeze dying there is excessive loss of water which is very rapid (sublimation), which results in the stucture break down and formation of porous morphology. Numerous pores are formed with non-uniform diameter. It appears to be more disrupted stucture having amorphous form.