Rheological Properties of Dense Particle Suspensions of Starches: Shear Thickening, Shear Jamming, and Shock Absorption Properties

Concentrated suspensions of Brownian and non-Brownian particles display distinctive rheological behavior highly dependent on shear rate and shear stress. Cornstarch suspensions, composed of starch particles from corn plants, served as a model for concentrated non-Brownian suspensions, demonstrating discontinuous shear thickening (DST) and dynamic shear jamming (SJ). However, starch particles from other plant sources have not yet been investigated, despite their different sizes and shapes. This study is focused on the evaluation of the effects of the structural parameters of starch particles by preparing concentrated suspensions of starch particles from 13 different plants at particle fractions of 25-50% and their rheological behavior through steady shear, pull-out, and ball-drop tests. Starch particles can be roughly classified as polygonal and ellipsoidal. The DST and SJ behavior typically reported for concentrated cornstarch suspensions were confirmed for other starch particles in both particle groups. The ball-drop test demonstrated excellent shock absorption properties for 11 concentrated suspensions of starch particles, except for sago palms. In the case of concentrated suspensions of starch particles, the particle fraction and shear applied were the dominant factors that significantly affected the rheological behavior, whereas the particle shape was not a primary contributor. The findings of this study drive further investigation on the effect of liquid and particle surface properties in concentrated particle suspensions on DST and SJ behaviors.