Biobased Epoxy Resins
Properties and Applications
Biobased epoxies are a relative new class of bio-sourced resins that are produced by epoxidation of renewable precursors such as unsaturated vegetable oils1, saccharides, tannins, cardanols, terpenes, rosins, and lignin.2 They are cured with a wide range of co-reactants, often called hardener or curative. The type of curative depends on the application and type of epoxy resin and can be biobased as well.3 Some biobased epoxies that have gained commercial use or that are currently investigated for commercial use include2
- Epoxidized linseed oil (composites, adhesives, laminates)
- Liquid epoxidized natural rubber [LENR] (epoxy composites)
- Terpene-maleic estertype epoxy [TME] (composite coatings)
- Diglycidyl ethers of isosorbide [DGEI] (epoxy resins in food industry)
- Furan diepoxy of 2,5-bis(hydroxymethyl)-furan [BHMF] (adhesives)
- Epoxidized cardanol (coatings)
The choice of resin and curing agent depends on both the process specification and performance requirements. Two important parameters are the viscosity and the glass transition temperature (Tg) of the cured resins.
The bioepoxy resins are often blended with each other and/or with
other (natural) resins as well as with fillers and fibers to
improve ease of processing and/or their end use properties. For
example, they can be blended with inorganic fillers or glass fibers
to lower cost and to
improve their mechanical properties.
Biobased epoxies can be used in many industries. Potential applications include coatings, adhesives, composites, laminates, and electronic materials such as potting compounds.
Manufacturers
1The majoirty of biobased epoxies are based on vegetable oils including soybean oil, linseed oil, canola oil, and karanja oil.
The oils can be classified as drying, semi-drying, and nondrying according to the degree of unsaturation.
2E.A. Baroncini, S.K. Yadav, G.R. Palmese, J.F. Stanzione, J. Appl. Polym. Sci., 44103 (2016)
3Some bio-based hardeners include soybean oil derived polyacids, cardanol-derived phenalkamines, and terpene-based anhydrides.