Synthesis and Characterization of Novel Cardanol Based Benzoxazines

Abstract

Benzoxazines are a class of phenolic compounds extensively studied in polymer science because of their properties as fiber reinforcements, fire-retardants and curing agents. In this article is described a solvent-less process, based on a Mannich reaction involving a primary amine and an aldehyde, for the preparation of new benzoxazines deriving from cardanol (a well known phenol obtained as a renewable organic resource and harmful by-product of the cashew industry). Particular attention is given to the synthesis and chemical characterization (both by 1 H NMR spectroscopy and HPLC), while the thermal polymerization process has been monitored by differential scanning calorimetry.

Renewable benzoxazine monomers from “lignin-like” naturally occurring phenolic derivatives

“…Until now, only few examples of renewable resources‐based benzoxazine materials have been reported into the literature. The most significant example is the cardanol‐derived benzoxazine . Cardanol is a monofunctional phenol present in the cashew nut shell oil and is obtained as a waste byproduct by the cashew industry.…”

Synthesis and characterization of bio‐based benzoxazines derived from thymol

“…However, petroleum‐based phenolics are nonrenewable resources and scarcity of these materials has heightened the need for novel benzoxazines that can be developed and commercialized to reduce the widespread dependence on fossil fuels . Recently, several naturally occurring phenolic compounds have been used for the synthesis of bio‐benzoxazines including cardanol, guiacol, urushiol, eugenol, vanillin, cardbisphenol, resorcinol, arbutin, lignin, chavicol, coumarin, rosin, and chalcone . These types of phenolic compounds are plant‐derived and widely found in variety of plants.…”

Cardanol Benzoxazines: A Versatile Monomer with Advancing Applications

“…are studied. Monofunctional cardanol benzoxazine is obtained when reacted with substituted aliphatic and aromatic mono‐amines such as cyclohexylamine (cha), tetrahydrofurfurylamine (thfa) allylamine (aa), 3‐aminopropyltriethoxysilane (ameo), benzylamine (ba) N,N ‐dimethylaminopropylamine (dmapa), 4‐nitroaniline (na), 2‐aminopyridine (py), 2‐amino‐5‐methylpyridine (mpy), 4‐fluoroaniline (fla), 4‐bromoaniline (bra), 4‐cyanoaniline (cna), 4‐chloroaniline (cla), 4‐aminophenol (ap), 4‐aminobenzoic acid (aba), 4,4′‐aminophenoxy itaconimide (dde‐i), or nadimide (dde‐n) . Polymer‐origin amines either of commercial origin such as polyether monoamine (Jeffamine M‐1000, ja) or modified polymeric amines such as caprolactam amine (cm‐dmapa) are also investigated …”