Mechanical behavior of powder constituents and their mixtures - An experimental study

A powder mixture's mechanical properties play a vital role with respect to the handling, processing, and product quality. In industries, powders are generally processed in mixed form rather than powder as individual constituents. Powder mixture's constituents have different characteristics. The present study was conducted to determine the fundamental mechanical properties namely bulk modulus, shear modulus, compression index, and spring-back index of components and their mixture; in addition, to measuring and quantifying the effect of constituents on the mixture. Towards this end, corn starch, Avicel (microcrystalline cellulose) and their mixture formulated in equal weight proportion were used. Two types of triaxial tests, namely, conventional triaxial compression (CTC) and hydrostatic triaxial compression (HTC), were conducted at different pressures using a medium pressure flexible boundary cubical triaxial tester (CTT). Overall, the bulk modulus, compression index and spring-back index values increased with increase in pressure. The bulk modulus of mixture was higher than that of corn starch and Avicel which demonstrated that the presence of corn starch influenced the bulk modulus property of Avicel. The compression index for the mixture was more than that of corn starch but less than Avicel which means addition of corn starch reduced Avicel's compressibility. Similar trend was observed for spring-back index. At 2.0 MPa confining pressure, as expected, the shear modulus at stress difference of 500 kPa was higher than that at 1000 kPa stress difference. The shear modulus for Avicel was highest followed by Avicel-corn starch mixture, and corn starch.