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Epoxies

Epoxies. A. Brent Strong. Epoxies. Second most widely used family of thermosets (after polyesters) Large portion of uses are non-reinforced (adhesives, paints, etc.) Circuit boards are the largest reinforced application (low conductivity, low volatiles)

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Epoxies

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  1. Epoxies A. Brent Strong

  2. Epoxies • Second most widely used family of thermosets (after polyesters) • Large portion of uses are non-reinforced (adhesives, paints, etc.) • Circuit boards are the largest reinforced application (low conductivity, low volatiles) • Advanced composites use epoxies because of • Thermal stability • Adhesion • Mechanical properties

  3. Epoxy Structure Epoxy ring Epoxy ring ( C C )n C C O O Polymer portion Number of repeat units

  4. Epoxy − specific molecules c c n a) Diglycidyl Ether of Bisphenol A (DGEBPA) ( )n b) Tetraglycidylmethylenedianiline (TGMDA) c) Epoxidized phenolic resin (Epoxy Novalac)

  5. Properties − chain length (n)

  6. Epoxy − specialty molecules Toughened Epoxy Resin High Temperature Epoxy Resins

  7. Epoxies − HDT and structure

  8. Curing Epoxies • Epoxies use hardeners instead of initiators for curing • Hardeners can be almost any molecule that will react with (open) the epoxy ring

  9. Epoxy Crosslink Mechanism C C H Epoxy H Cured Polymer Hardener The other end can also react.

  10. Curing Epoxy ring Epoxy ring ( C C )n C C O O H H N N H H Hardener molecules have two reactive ends, so they can each react with two epoxy molecules. N N H H H H

  11. Effects of various hardeners

  12. Epoxy and Polyester Comparison

  13. Polyester and Epoxy − Properties

  14. Epoxy

  15. Thank you Brent Strong

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