Polyacrylamide and its derivatives for oil recovery

Pore Occlusion Performance
 
The nuclear-pore membrane, model pore occlusion testing apparatus was 
originally described by Zhao et al.
22,31
The apparatus schematic is provided as Figure 1.
Samples of swollen microgel dispersions were prepared by adding dry particles into DI 
water at a concentration of 0.5 wt.-%. Particle dispersion samples were placed into an 
oven at 80 º
C, for two weeks to allow microgels to absorb water and swell to equilibrium 
size. The original dispersions were then diluted by DI water to different concentrations: 
50, 100 and 250 ppm, respectively. Dispersions of these concentrations were injected to 
the injection membrane reservoir through the nuclear pore membrane sample holder.
Volume of the filtrate as a function of filtration time was recorded during the injection 
process. The membranes employed spanned a series of pore sizes (0.45 µm, 0.8 µm, 1.2 

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µm, 5 µm, and 10 µm). A low differential pressure (10 psi) and a higher differential 
pressure (100 psi) were chosen for the pore occlusion simulation testing. 
Figure 1. 
Schematic diagram of the pore occlusion filtration test apparatus.
 
Scanning Electron Microscopy (SEM) Study 
 
SEM was performed using a Hitachi S-4700 field emission microscope. Powder 
of crosslinked polymer microspheres and blank membranes were used directly. SEM 
samples were mounted to a stainless steel stub using conductive tape and sputter coated 
with Au/Pd. Images were obtained with ESI software and analyzed by Image J (NIH) 
software to determine size distribution. Membranes were visualized for particle residues 
after the pore occlusion filtration test upon drying the membrane at ambient temperature.
SEM imaging was conducted using a field emission source at a 5 kV accelerating voltage 
and 11 pA current at a working distance of 3~6 mm with an Everhart-Thornley detector. 

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