Introduction: Recovery of Epoxy Thermoplastic and Carbon Fiber From Epoxy Composite Made With Recyclamine®
Recyclamine® is epoxy hardener developed by Connora Technologies (Hayward, CA) for recyclable epoxy thermoset technology. Recyclamine® epoxy thermoset materials can be easily recycled unlike any other epoxy thermosets, that are essentially non-recyclable or very difficult to recycle. This instructable explains how to recover epoxy thermoplastic and carbon fiber (CF) from CF epoxy composites scrap. The instructions can be used for any other Recyclamine® epoxy thermoset scrap materials as: glass fiber composites made with Recyclamine®, post-manufacturing scraps of Recyclamine® thermoset epoxy materials from production of sporting goods, etc. Both: epoxy thermoplastic and all other materials used (carbon fiber, glass fiber, wood, rubber) can be recovered from all post-manufacturing scrap materials.
Materials needed for the Recyclamine® epoxy recycling:
- CF composite scrap (for example plate 2in x 2in)
- 0.5L of 25% aqueous acetic acid
- 0.5L of 5% aqueous sodium hydroxide
- 1L beaker, big watch glass to cover beaker, magnetic stirring plate with heating, magnetic stirring bar, pH paper, gloves,
Step 1: Composite Recycling
~0.5L of approx. 25% acetic acid aqueous solution is poured into a 1L glass beaker and placed on the hot plate. CF composite is placed in the solution until fully submerged and heated gently. The beaker may be covered with any type of cover to reduce evaporation (e.g. watch glass, glass plate, etc). No stirring is needed. After 1-2 hours all epoxy is completely dissolved and CF 'free flowing'. CF is removed and let to dry.
Step 2: Epoxy Thermoplastic Solution
Obtained from previous step is a solution of epoxy thermoplastic in aqueous acetic acid. The solution should be let to cool down and can be stored tightly closed for re-used for future Recyclamine® epoxy thermoset scrap materials recycling. The epoxy thermoplastic recycling solution can be reused as long as its pH is acidic.
Step 3: Epoxy Thermoplastic Recovery From Recycling Solution
Epoxy thermoplastic solution is slightly acidic and needs to be neutralized with dilute sodium hydroxide (5% in water) to recover epoxy thermoplastic. 100mL of sodium hydroxide 5% solution in water is poured into a 1L beaker on a stirring plate and stirring is started with a (preferably) big magnetic stirring bar. Thermoplastic solution is poured slowly with stirring into the beaker. Suspension of thermoplastic is formed immediately and the mixture simultaneously warms up (no cooling is necessary). After approximately 100mL of recycling solution is added the voluminous precipitate of thermoplastic results. Epoxy thermoplastic is removed by filtration and can be washed with water and dried.
Note (1): The solution after thermoplastic recovery has usually pH of 7 and can be safely disposed off into the sewer. If pH is outside of neutral range (6-8) some acetic acid or sodium hydroxide needs to be added to adjust pH to neutral and than solution can be disposed of.
Note (2): After drying epoxy thermoplastic is ready for any use and can be for e.g. pelletized. Recyclamine® epoxy thermosets offer a true cradle-to-cradle solution for epoxy industry, additionally to benefits of zero-landfill manufacturing.