  Processing of concentrated lignocellulosic biomass suspensions typically
involves the conversion of the cellulose into sugars and sugars into ethanol.
Biomass is usually pre-processed (i.e. via comminution, steam explosion, etc.)
to form fine cellulosic fibers to be dispersed into an aqueous phase for
further treatment. The resulting cellulose suspensions need to be pressurized
and pumped into and out of various processing vessels without allowing the
development of flow instabilities that are typically associated with the
demixing, i.e., the segregation of the cellulosic biomass from the aqueous
phase. Here, it is demonstrated that the use of a gelation agent, hydroxypropyl
guar gum (HPG) at the relatively low concentration of 0.5 wt% significantly
affects the development of viscoelastic material functions of cellulosic
suspensions, and improves the dispersive mixing of the cellulose fibers within
the aqueous phase. This results in the reduction of the flow instabilities and
associated demixing effects that are ubiquitously observed during the
pressurization of cellulosic suspensions in Poiseuille and compressive squeeze
flows.
