Shrinkage

Commonly seen in hydrophobic membrane after prolonged usage

Increase in hydrophilicity decreases shrinkage ratio

High shrinkage ratio decrease pore size

Membrane thickness

Flux decreases with increasing thickness

increase of transmembrane resistance

Thick membrane increases mechanical strength (tensile strength and bursting pressure)

Porosity

Volume of pores divided by total volume of porous membrane

Initially Porosity increases with increasing glycerol concentration, until a certain point it decreases

due to cast solution viscocity, affects solvent diffusion rate.

Contact angle

Measure the wettability of a surface or material

Hydrophobic have higher contact angle than hydrophilic

Membrane with higher concentration of glycerol have lower contact angle

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021965/

http://scholarly-journals.com/sjer/archive/2012/August/

df/Shobana%20et%20al.pdf

Precaution

Do not dispose glycerol into the sink as glycerol is flammable and have high viscosity and some will remain in the sink. All apparatus in contact with glycerol should be washed thoroughly.

Rubber gloves should be worn when handling pvdf membrane to avoid contamination.

Surgical blade should be handled with care as pvdf membrane is slippery to avoid injury.

Care should be taken not to shake the table which holds the contact angle goniometer to avoid the water droplet from falling before it reaches a specific volume.