The relationship between viscosity, elasticity and plastic strength of a soft material as illustrated by some mechanical properties of flour dough IV— The separate contributions of gluten and starch

In the earlier papers of this series (Schofield and Scott Blair 1932, 1933 a, 1933 b) the endeavour has been to give a quantitative description of the behaviour of flour dough under stress. Use was made of the equation de/dt=(1/n·dS/dt-dx/dt)+1/ƞ·S, which is the expression originally put forward by Maxwell with the addition of — dx/dt to take account of elastic after-effect. In this equation de/dt represents the rate of elongation of a cylinder of dough, and S the shearing stress which is one-third the longitudinal stress per unit area. The equation serves to define n, the modulus of rigidity, and ƞ the viscosity, and enables these to be evaluated from experimental observations of e and S.