I need ways to test/get data about homemade plastics. What can I do with Flexural Strength and Flexural Modulus...

I’m going to be making “bioplastics” and am trying to test which starches would create the strongest, most flexible plastic. (Another Idependent Variable of this experiment is the amount of glycerin involved, but that’s another story.)

I’m having trouble learning HOW I can measure strength and flexibility, then I stumbled across these terms:

Yield strength: is defined as the stress at which a material begins to deform plastically. (Elastic Limit)
ex. when a piece of plastic cracks under weight

Flexural strength: an object’s ability to bend without obtaining any major deformities. A standard experiment called the three-point test can calculate an object’s flexural strength
(http://www.wisegeek.com/what-is-flexural-strength.htm)

Flexural modulus: a measure of how a material will deform and strain when weight or force is applied. It describes the ability of a material, with a specific cross-section, to resist bending when placed under stress.
(http://www.wisegeek.com/what-is-the-flexural-modulus.htm)

I’m not sure how to apply this stuff though, I’m assuming the “strength” of the different plastics= flexural strength, but I don’t know how the flexural modulus differs from flexural strength…