Exploring the Chemistry of Bio-Based Epoxy Resins 

Bio-based epoxy resins are a relatively new category of bio-sourced resins that are created through the epoxidation of renewable precursors like unsaturated saccharides, vegetable oils, tannins, terpenes, and lignin. In this blog, readers will learn the chemistry of bio-based based epoxy resins.

The surge in demand for sustainable products boosts market growth. This is due to the awareness among businesses and consumers about the environmental impact of conventional petroleum-based epoxy resins such as bio-based epoxy resins. In addition, according to a research report by Astute Analytica, the Global Bio-Based Epoxy Resins Market is likely to increase at a compound annual growth rate (CAGR) of 4.9% over the forecast period from 2023 to 2031.

Let's understand the chemistry of bio-based epoxy resins:

Here are two different types of products that were developed and assessed simultaneously:

Bio based epoxidized vegetable oils

Concern about the oxidation of vegetable oils that aren't saturated. The unsaturation concentration of the most intriguing oils was thoroughly analyzed to tailor the epoxidation modification properly.

A variety of epoxidized vegetable oils with epoxy contents ranging from 2.5 méq/g to 7.0 méq/g could be produced. These epoxidized vegetable oils are for research and development purposes.

The creation of epoxy-amine materials involved the evaluation and utilization of all these epoxy resins. The most promising resins were chosen based on the project's specifications for the procedures and the qualities of the finished materials.

As a result, the viscosity and glass transition temperature (Tg) of the cured resins were determined to be the most representative characteristics for the identification of the resins that had the most potential for being further developed for the project's purposes. Epoxidized castor oil, varies from other oils due to the hydroxyl groups positioned in the epoxy rings' hydroxyl position.

Identical chemical structures but differing in their epoxy function concentration are epoxidized vegetable oils. They can be made from a variety of vegetable oils, including, rapeseed or Saint John's Wort oil. When choosing the vegetable oil precursors, non-edible oils were preferred as much as feasible.

Sustainable aromatic precursors

The second method was to synthesize aromatic resins with multipurpose glycidyl ether moieties. The study in this instance was based on the chemical alteration of phloroglucinol or vanillin alcohol.

The syntheses were produced on petro-based grades for research and development and proof-of-concept testing. However, it should be noted that vanillin alcohol and phloroglucinol can also be extracted from lignin and algae, respectively. The successful synthesis of both products.

Bio-based epoxy resin preparation and curing

1 g of epoxidized vegetable oil (soybean, or their methyl esters) was combined with a quantity of lignin (LignoBoost Kraft or the solvent-extracted fractions) that had been dissolved in 2 mL of tetrahydrofuran. Ethanol is an additional solvent that can be employed. In an open flask, the mixture was agitated for one hour at 70 °C.

After that, priamine 1074 was added, the mixture was mixed for 1 minute, and then it was put into a Teflon mold. For one hour, the Teflon mold was put in a vacuum chamber (850 mbar) at 50 °C to let the solvent evaporate.