The development and comparison of bio-thermoset plastics from epoxidized plant oils

This study investigates the development of thermoset plastics from plant-based oils (e.g., linseed, soybean, cottonseed, oilseed radish, and peanut oils) using an optimal process of solvent-free epoxidation. The epoxidation of plant oils can be accomplished economically by reacting the double bonds of fatty-acids with hydrogen peroxide. During the solvent-free process catalyzed by the ion-exchange resin, we observed that the influence of several variables was important: the molar ratio of hydrogen peroxide to unsaturation, acetic acid to unsaturation, and temperature. The epoxidation of plant oils was determined from the liquid mixture and the composite matrix by thermal and spectroscopic analyses. Compounds with a higher double-bond (iodine) value showed higher oxirane oxygen percent and selectivity, and a higher hydroxyl value because of a greater possibility of attack by solutions causing side reactions. Lower iodine values indicated fewer epoxy groups and selectivity, and a lower hydroxyl value. Benzyl pyrazinium hexafluoroantimonate (BPH) yielded good thermal curing properties; as little as 1% added to the plastics produced light-weight composites. Epoxidized linseed oil promises the highest modulus and impact resistance due to the largest number of double bonds to contribute more epoxy groups and the large proportion of linolenic acids to produce epoxy groups rapidly.

► This study investigates the development of thermoset bioplastics from plant-based oils (e.g., linseed, soybean, cottonseed, oilseed radish, and peanut oils) using an optimal process of solvent-free epoxidation.
► Epoxidized oil resins can be cured by a latent hardening agent, BPH in the smallest quantity.
► Epoxidized oils such as EL, ES and EC promise the highest dynamic mechanical performance due to the largest number of double bonds available to convert into epoxy groups and the large proportion of linolenic and linoleic fatty acids to produce epoxy groups rapidly at higher selectivity.