DGEBA-PACM Epoxy Thermoset

This tutorial covers a step-growth cure between a diepoxide (DGEBA) and a diamine (PACM): primary amines open epoxide rings to form secondary amines, which can then react with a second epoxide to form tertiary amines. Compared to example 2, the new wrinkles are:

• Two sequential cure reactions. The product of the first reaction (a secondary amine) is itself a reactant in the second reaction (forming a tertiary amine). htpolynet chain-expands these into a full set of templates that cover both bond environments.

• Symmetry-equivalent atoms. DGEBA has two chemically equivalent reactive carbons (and two equivalent oxiranes); PACM has two equivalent reactive nitrogens. The symmetry_equivalent_atoms block tells htpolynet to expand the user-supplied reactions into the full set of symmetry-equivalent products.

• A cap reaction that re-forms a ring. Any leftover unreacted oxirane gets its hydroxyl-to-carbon bond re-formed as an epoxide three-ring at the end of the build.

Contents:

• Introduction
• Monomers
  • DGEBA
  • PACM
• Reactions
  • Capping
• The Configuration File
  • constituents
  • Reaction expansion via symmetry_equivalent_atoms
  • Diastereomer expansion via stereocenters
• Running the Build
  • Setup
  • Densification + precure
  • CURE iterations
  • Capping and postcure
• Results
  • Before and after
  • Profile
• Post-build simulations and analyses