Jones (1960) expressed the density-pressure data of compacted powder in the form of equation 1.

ln(p) = mln(P) + b (1)

where, p is bulk density of compact powder mixture, kg/m3, P is applied compressive pressure, MPa; m and b are model constants.

The constants b and m are determined from the intercept and slope, respectively, of the extrapolated linear region of the plot of ln(p) vs ln(P). The constant m has been shown to be
equal to the reciprocal of the mean yield pressure required to induce plastic deformation (York and Pilpel, 1973). A large m value (low yield pressure) indicates the onset of plastic deformation at relatively low pressure, thus, the material is more compressible.