COMPARATIVE STUDY OF ALICYCLIC AND HETEROCYCLIC AMINE REACTANTS OF CARDANOL-BASED POLYBENZOXAZINE

Abstract

The bio-based benzoxazine thermosetting resins were synthesized using cardanol as a natural phenol and the bio-based amines isophoronediamine and furfurylamine. This study aims to examine the effect of amines on the performance of cardanol-based benzoxazine resins to produce polymer materials with high temperature resistance and UV protection. The primary amine on the alicyclic ring underwent a reaction with cardanol and paraformaldehyde, resulting in the formation of the oxazine structure. Concurrently, the secondary amine on the secondary carbon atom reacted with the carbonyl group of ethyl acetate, leading to the formation of an amide structure. This sequence of reactions produced a novel type of benzoxazine. The primary amine on the heterocyclic ring underwent a Mannich-like condensation reaction with cardanol and paraformaldehyde, resulting in the formation of an oxazine molecular structure that contained an additional furan ring structure. The heterocyclic ring in the cardanol-furfurylamine benzoxazine (C-fu) monomer improved the ring-closing reaction of the oxazine ring compared with the alicyclic ring in the cardanol-isophoronediamine benzoxazine (C-ip). The C-fu monomer has a higher molecular weight than the C-ip monomer. The Mn value of C-fu is greater than that of C-ip, with concentrations of Mn around 220 and 450 g/mol for C-ip and C-fu, respectively, indicating that the end groups of C-fu monomers have a higher molecular weight than the end groups of C-ip monomers. The viscosity of the C-fu monomer was lower than that of the C-ip monomer, indicating that the C-fu monomer has a wider processing window. The C-fu monomer exhibited a lower polymerization temperature (220°C) than the C-ip monomer and the poly(C-fu) has a relatively higher initial thermal resistance up to 400°C than poly(C-ip). The measurement results from UV-Vis spectroscopy showed that poly(C-fu) has higher UV protection properties compared to poly(C-ip). The study findings on various measurements indicated that C-fu and poly(C-fu) have superior properties compared to C-ip and poly(C-ip), making C-fu and poly(C-fu) suitable for use as composite material for nosecone rocket application to enhanced microelectronic devices durability and performance. Keywords: cardanol, furfurylamine, isophoronediamine, polybenzoxazine, thermal and optical properties