Particle Aspect-Ratio Dependence of Shear Jamming in Dense Suspensions

Dense suspension of particles in a Newtonian liquid can exhibit non-Newtonian behaviors such as shear thinning, shear thickening and shear jamming. Although recent studies show that friction between the particles and the particle surface chemistry plays an important role, little is known about how particle shape a↵ects shear jamming characteristics. To address this, we here report on experiments where we synthesize silica particles, designing the particle surface chemistry such that the particles exhibit strong shear jamming over experimentally relevant packing fractions. Our synthetic approach enables us to synthesize particles with aspect ratios ranging from 1 (spheres) to 15 (slender rods). This allows us isolate the e↵ect of particle anisotropy on suspension thickening and jamming. The results uncover new physics about the rheological behavior of anisotropic particles, and shed new light on how to rationally design shear jamming characteristics for protective material applications.