Assessing the thermal and fungal behavior of eco-friendly epoxy thermosets derived from vegetable oils for wood protective coatings

The paper deals with the study of the obtaining, characterization and thermal and fungal behavior of a green thermoset based on epoxidized soybean oil (ESO), castor oil maleic anhydride adduct (COMA) and methyl nadic anhydride (MNA). By varying the MNA/COMA crosslinking agent ratio, resins with different degree of stiffness can be obtained suitable for green thermosets coatings. Differential scanning calorimetry (DSC) and a simultaneous TG/FT-IR/MS coupling were used to establish the crosslinking behavior, evolved gases analysis and thermal decomposition mechanisms associated with their corresponding kinetic parameters. The non-isothermal global kinetic parameters values (activation energy and pre-exponential factor) were calculated with the aid of the Friedman and Flynn-Wall-Ozawa isoconversional methods. The curves shape of the variation of activation energy versus conversion degree and first derivative (DTG) curves shapes suggest that the thermal degradation processes occurred in multi-step kinetics. Using a multivariate linear regression method the most probable thermal decomposition and crosslinking kinetic models were established. A good concordance between experimental and simulated data was obtained, confirming the correct description of the thermal mechanisms. The main identified gaseous fragments were water, carbon dioxide, saturated and unsaturated hydrocarbons and carboxylic derivatives. The decay resistance against two wood decaying strains, P. chrysogenum and A. brasiliensis was also evaluated.

Automated summary

This paper investigates the preparation, characterization and behavior of a green thermoset material based on epoxidized soybean oil, castor oil maleic anhydride adduct, and methyl nadic anhydride. Different stiffness resins suitable for green thermoset coatings can be obtained by varying the ratio of MNA/COMA crosslinking agents. The crosslinking behavior, evolved gases analysis, thermal decomposition mechanisms, and kinetic parameters were determined using differential scanning calorimetry and a simultaneous TG/FT-IR/MS coupling. The thermodynamic and crosslinking kinetic models were established through multivariate linear regression, and the performance against wood decaying strains was evaluated.