Comparison between physico-chemical properties of the technical cashew nut shell liquid (CNSL) and those natural extracted from solvent and pressing

Abstract

Cashew nut shell liquid (CNSL) is a by-product of the cashew kernel industry, applied mainly to produce polymeric derivatives. The technical CNSL (CNSLT) was obtained industrially, extracted by roasting the cashew nut shells at temperatures between 180 and 200 °C. Two methods were used to produce natural CNSL. For the extraction of CNSLNP, the cashew nut shells were pressed at room temperature. CNSLNS was extracted in hexane at room temperature and recovered at 50 °C. A comparison was made of the composition determined by HPLC and properties generated by viscosity measurements and also by TG, DSC and IPDT (integral procedural decomposition temperature). Natural CNSLs displayed higher content of cardol and anacardic acid and lower percentage of cardanol than CNSLT. The higher content of cardanol in CNSLNS was the major difference between natural CNSLs. CNSLNP had higher levels of impurity, higher viscosity, lower thermoxidative stabilities and lower ebullition temperature. The CNSL obtained by cold solvent extraction and recovery at 50 °C better preserves the original properties of the liquid.