INFORM November/December 2025

20 • inform November/December 2025, Vol. 36 (10)

In recent years, numerous studies have emerged, focusing on bio-based, less toxic, and low-migration plasticizers derived from vegetable oils. For instance, epoxidized lin seed oil (ELO) and epoxidized soybean oil (ESBO) are widely used as non-toxic bio sourced plasticizers for PVC. However, spe cial care must be taken to ensure that these renewable resources do not displace food production. CASHEW NUTSHELL LIQUID Cashew nutshell liquid (CNSL), a non-edible oil extracted from agro-waste, has recently garnered significant attention. Encapsulated within the porous structure of the cashew nutshell (CNS), it is a viscous dark red dish-brown to greenish-yellow liquid, a byproduct of cashew processing in the industry. CNSL is one of the richest natural sources of phenols, composed of four sub stituted phenols: anacardic acid, cardanol, cardol, and 2-methylcardol. The valorization of CNSL yielded prod ucts that rival those derived from fossil fuels. For instance, cardanol-based com pounds from CNSL are recognized as a promising alternative to phthalates due to their unique natural structure and used as biobased plasticizers for PVC. Cardol esters could be an interesting plasticizer for PVC too. Indeed, the phenol content in CNSL contributes to thermal stability, while its lengthy C-15 aliphatic chain enhances plasti cizing effects. As far as we know, apart from our recent study of cardol, the exploration of renewable resources, particularly CNSL as a plasticizer for PVC, is primarily, if not exclu sively, focused on cardanol in both aca demic and industrial research. However, to obtain the desired cardanol, it must be extracted and separated from the other compounds, mainly anacardic acid and car dol. This represents a significant energy, economic, and time cost. One of the rea sons why so few studies have been carried out on cardol is that it is very difficult to obtain pure cardol. Eliminating the preliminary separa tion of cardanol from cardol would ulti mately reduce the cost of the plasticizer, thereby increasing competitiveness with petroleum-based plasticizers. Industrially, CNSL is typically distilled to isolate cardanol. Distillation yields various mixtures of car

Extraction pathways of various CNSL containing naturally different ratios of carda nol and cardol. In blue: CNSL obtained from distillation. Dashed lines represent CNSL derivatives and method used for the synthesis of CNSL-derived plasticizers. Light brown indicates pure isolated compounds contained in CNSL: Cardanol and cardol. Source: Gartili, A., et al. , JAOCS , 102, 8, 1141, 2025.