Epoxy Resin is a totally reactive resin supplied as a liquid or solid, used across castings, coatings, tooling, potting, adhesives, and reinforced applications. This page covers its classification and a documented finding on how hardener ratio shapes its cured mechanical performance.
What is it?
Epoxy Resin is classified under ASTM D1763 as a totally reactive resin, supplied without hardeners, in six types grouped by chemical nature. It requires a separate hardener to cure into its final form.
Why should I use it?
- A single specification covers six chemically distinct resin types — see “What is it?” above.
- Its cured mechanical properties are directly tied to hardener ratio — see Limitations for the trade-off this creates.
How it’s used
In Plastics & Polymers, Epoxy Resin is used across the full range of applications covered by ASTM D1763.
Limitations — when it isn’t the right choice
- There is no single hardener ratio that optimizes every mechanical property at once. A 2021 peer-reviewed study on a base epoxy diane resin (ED-20) cured with an L-20 hardener at varying mass-fraction ratios found that a 1:0.9 (hardener:resin) ratio produced the highest hardness, tensile strength, compressive strength, and bending strength — but impact toughness peaked at a different ratio, 1:0.8. Getting the hardener ratio wrong for the intended application is a real, measured trade-off. This was documented for one specific resin-hardener system; the exact optimal ratios should not be assumed identical across every commercial epoxy resin and hardener combination.