Modulus of elasticity, also know as "young's modulus," is a metric that represents a material's resistance to being deformed elastically. Throughout the site we use the terms "high modulus" and "low modulus" frequently to describe a cured polymer adhesive product. This post is dedicated to spelling out exactly what each of these terms mean.
For those of you just looking for the quick answer, here it is. Modulus of elasticity represents a material's resistance to being deformed, so low values mean low resistance and high values mean high resistance. In other words:
Low Modulus = Flexible
High Modulus = Stiff
It's as simple as that.
But How Is The Elastic Modulus Of A Material Specifically Defined?
For those of you looking for a little bit deeper of an explaination, we're going to have to work through some definitions.
Strain is the amount a material is deformed (stretched) relative to its original dimensions
Stress is the amount of force applied to the material and can be thought of as the material's resistance to strain (stretching).
A Stress-Strain Curve is a graphical representation of the relationship between stress and strain for a particular material. Stress is plotted as a function of strain (strain along x-axis, stress along y-axis). The curve is basically how much the material will resist various amounts of stretching. If the curve has a high slope then it takes a lot of force to stretch the material a small amount (stiff). If the curve is has a low slope then it it takes very little force to stretch the material very far (flexible).
The Elastic Deformation Region of a stress-strain curve is the region in which the material exhibits elastic behavior (if allowed the material will elastically return to its original dimensions).
The Elastic Modulus of a material is the slope of the stress-strain curve in the elastic deformation region.
When we put all these definititons together this of course fits with our understanding above: the elastic modulus of a material represents a material's resistance to being deformed elastically.