Temperature coefficient of viscosity introduction

Viscosity is more correctly termed shear viscosity and is closely analogous to the shear modulus [ 1 ]. Where a velocity features in the shear viscosity expressions, a displacement is found for shear modulus. To compare these terms, consider two cases  

It is worth considering the units of viscosity. In SI units, P is pressure in Pa and dv/dy is m and therefore the unit of ti is Pas. For many years in the glass industry, the cgs (centimetre, gramme, second) was used giving ti the units of (dyn s)/cm, known as Poise . This is still encountered in much literature and can easily be converted as 1 Poise = 0.1 Pa s. 

Compare this to Equation (10.3). For an incompressible elastic solid E = 3G, where E is Young s modulus. From this, many equations for deformation can be applied to viscous flow. 

Technique T range/Pa s Specimen geometry TMA cel 1 geometry Reference 

Beam bending 10 to 10 Rectangular beam about 10 X 0.8 X 2.5 mm Specimen supported across top of a notched holder made from silica glass tubing about 8 mm internal diameter and 10 mm deep. Short, 1 -mm-diameter silica glass rod (ground flat) as knife edge between silica probe and the beam [31] 

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