This work evaluated the production of j-carrageenan and
j-carrageenan – Na-CN microgels by extrusion, using potassium
chloride for gelation. The results showed that an increase in air
flow rate and decrease in feed flow rate and apparent viscosity promoted
the formation of the smallest microgels, which was verified
by the increase of some dimensionless numbers (Rekl and Wel).
However, the aspect ratio of the particles was mainly influenced
by the apparent viscosity and surface tension of the solutions,
which was confirmed by the evaluation of Ohnesorge number
(Oh). The biopolymer composition also influenced the microgel
morphology, the mixed microgels (j-carrageenan/Na-CN) being
larger than the pure ones (j-carrageenan), probably due to incompatibility
between the protein and polysaccharide. The microgels
were very unstable when dispersed in water, but they maintained
their shape when diluted in solutions with a high salt content (10%
KCl). The wide range in size (d32 between 84 m and 235 m) and
shape (AR between 1.33 and 1.9) of the microgels led to different
rheological behavior of their suspensions, from shear thinning to
shear thickening with the presence (or not) of yield stress, depending
on the volume fraction of the particles.
This work evaluated the production of j-carrageenan andj-carrageenan – Na-CN microgels by extrusion, using potassiumchloride for gelation. The results showed that an increase in airflow rate and decrease in feed flow rate and apparent viscosity promotedthe formation of the smallest microgels, which was verifiedby the increase of some dimensionless numbers (Rekl and Wel).However, the aspect ratio of the particles was mainly influencedby the apparent viscosity and surface tension of the solutions,which was confirmed by the evaluation of Ohnesorge number(Oh). The biopolymer composition also influenced the microgelmorphology, the mixed microgels (j-carrageenan/Na-CN) beinglarger than the pure ones (j-carrageenan), probably due to incompatibilitybetween the protein and polysaccharide. The microgelswere very unstable when dispersed in water, but they maintainedtheir shape when diluted in solutions with a high salt content (10%KCl). The wide range in size (d32 between 84 m and 235 m) andshape (AR between 1.33 and 1.9) of the microgels led to differentrheological behavior of their suspensions, from shear thinning toshear thickening with the presence (or not) of yield stress, dependingon the volume fraction of the particles.
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