Cellulose concentration in NaOH–urea–water had a small effect
on volume and weight (Fig. 2C, upper). Beads were coagulated into
2 M acid at 25 ◦C, which caused rapid formation of the skin layer.
Since the dimensions did not change much, also changes in weight
and size distribution parameters were small (Table 3). Peak values did not change and width of the distribution was narrow for
all cellulose concentrations, 6% being slightly wider than others.
Cellulose concentration had very little effect on circularity (Fig. 2C,
lower). A small decrease was seen in circularity when concentration
was 6%. This is due to higher viscosity and tail formation when the
droplet leaves the tip. However, porosity decreased with increasing
cellulose concentration (Fig. 2C, lower). Since the constant volume
was filled with more cellulose, apparent density of cellulose was
founded to be higher. With low cellulose concentration same volume is filled with more voids. When cellulose concentration was
further decreased to 3%, beads did not hold together anymore. On
the other hand, cellulose solutions with concentrations above 6%
were too viscous to extrude through the tip of the pipette without
forming a continuous flow.