Cashew nuts, commonly used by food industry in confectionery and bakery products, are the the fruits of Anacardium occidentale, a small evergreen tree, native to Brazil, widely grown in the tropical areas of India, Africa, Indonesia and South Eastern Asia.
The traditional processing of nuts consists of roasting and shelling, and this step is done by hands to avoid the kernel contamination with the irritating oil contained in the nutshell, called CNSL (Cashew Nut Shell Liquid).
CNSL is a toxic and polluting waste of nuts processing with a total annual production of about 1 million tons, which require a proper disposal. Distillation of CNSL gives cardanol an alkenyl-phenol with physical and chemical properties similar to those of nonyl- and dodecyl-phenol but lacking the toxicity and carcinogenicity, associated to those two synthetic derivatives.
Cardanol is a very versatile monomer, its chemical modification results either in polymeric precursors of thermosetting and thermoplastic resins, and in polyols suitable for polyurethane formulations.
