Celgard sample

Celgard Sample 

Celgard is an interesting material that is used as a porous battery separator membrane and as a filtration membrane in medical applications. It is made by stretching isotactic polypropylene. The topography has sections with drawn fibrils (which form the pores) and also sections with undrawn crystalline lamella. The fibrils form something like a 1D grating and are challenging to track. Because the fibrils are freely suspended, tapping too hard will displace them. Lighter tapping gives rise to a slower cantilever response, so for this sample having a fast cantilever as well as a fast Z actuator is important.