Alkyd resins are highly branched polymer with a polyester backbone which important for synthetic polymers 20. They are thermoplastic polyester resins can be synthesized by polycondensation 21 of three types of monomers of polyhydric alcohols (e.
g; glycerol), fatty acids (e.g; oleic acid) and dibasic acids (e.g; isomers of phthalic acid) or their anhydrides (e.g; phthalic anhydride) 22-24. They can be dissolved in organic solvents and have good interactions with polar substrates such as wood and steel 25. They have excellent properties such as acceptable, inexpensive to produce, high gloss, retention color, dissolved in organic solvents, excellent thermal stability, eco-friendly, excellent wetting properties, good adhesion and good interactions with polar substrates such as wood and steel 26, 27. These properties make them suitable to apply in industrial coating, adhesives, the binder for composites and anticorrosion paint.
Bio-alkyd resin contains reactive sites such as carbon-carbon double bond, a polar ester group, methylene group attached to the carbonyl site, allylic methylene attached to double bond 28.