The bead porosity was assessed using mercury
porosimetry (AutoPore IV 9500 V1.03,
Micromeritics, GA, USA) (n=2). The pressure
was varied from 0 to 50 psi. A 10 s equilibration
time was set for each intermediate data point. At
each equilibrium point, mercury intrusion data
were recorded and plotted against pressure. Standard
values for the contact and surface tension of
mercury were used.