Synthesis of tetra(2,2-hydroxyethylene) terephthalamide from PET waste and its application in synthesis of polyesteramide coating

Abstract

Purpose The purpose of this paper is to discuss the synthesis of polyesteramide resin from the monomer obtained from poly (ethylene terephthalate) (PET) waste and study of the structure – property relation for the same in polyesteramide coating. The purpose is also not only to just target the polymeric waste but also to study the effect of the structure of monomer obtained from such waste in final coating. Design/methodology/approach PET waste was depolymerised using diethanolamine to tetra(2,2-hydroxyethylene) terephthalamide (THETA). Four functional hydroxyl terminated monomers were generated having amide linkage as a structural part. THETA was used for the synthesis of polyesteramide resin along with fatty amide of oil, and concentration of the THETA was varied. The synthesised polyesteramide resin was cured with MF resin and tested for physico-chemical, thermal and anticorrosive properties. Findings PET was successfully depolymerised to monomeric level using diethanolamine as a reactive agent. It is observed that as the concentration of THETA increases, the hardness of the coating increases, as aromatic concentration increases in the coating. The amide linkage helps to improve adhesion as well as hydrophobicity because an aliphatic long chain of fatty amide and aromatic linkage of THETA helps in improving anticorrosive properties of the coating. Practical implications This method is the useful key to solve the polymeric waste problem. PET can be easily depolymerised using diethanolamine and polyesteramide resin synthesised from it. Hence, waste material can be converted into the coating by reacting it with renewable resources. Originality/value To the best of the authors’ knowledge, this is the first study which uses THETA as a monomer for the synthesis of polyesteramide resin and study of its various concentrations on coating properties. The coating is obtained from waste material; hence, polymeric waste issue is also solved, and dependency on the petroleum resources to obtain raw materials for coating is also depleted partially. The study also helps to understand the effect of the structure of monomers on the properties of the coating.