Powder Technology, Vol.371, 96-105, 2020
Cohesivity assessment of semi-crystalline and crystalline powders using a Warren Springs cohesion tester
The direct measurement of cohesion under high strain and the quantitative effects of solid matrix structure on particle morphology and bulk rheology have not been explored thoroughly in literature. A Warren Springs geometry installed on an air bearing rotational rheometer capable of capturing the amount of shear stress required for powder failure at a wide range of initial consolidation states was implemented in the study to measure the cohesion trend of over-consolidated powder materials. Wheat, potato, corn starches and microcrystalline cellulose (MCC PH101) powders were analyzed. MCC PH101 powder exhibited the highest weighted cohesion strength among the powders at all consolidation stresses because of the high particle aspect ratio given the inherited crystallinity of its compositional matrix. MCC sample also had greater variation between incipient and steady state portions of the torque profile attributable to its characteristic particle stiffness, which, consequently, yielded in distinct particle deformation behavior. (C) 2020 Elsevier B.V. All rights reserved.