Valorization of CNSL as a Sustainable Solution for PVC Plasticization: A Comprehensive Study of Cardanol–Cardol Mixture

For the first time, a mixture of cardanol and cardol esters has been studied as plasticizers for PVC. From our previous work, it has been established that the favorable plasticizing properties of cardol for PVC materials exist. Hence, the utilization of cashew nutshell liquid (CNSL), a naturally occurring mixture of cardanol and cardol, as a PVC plasticizer presents an intriguing prospect. While major studies focused on cardanol-based PVC plasticizers, their extraction process entails time-consuming, energy-intensive, and costly steps, thereby limiting market competitiveness. The aim of this study is not to focus on pure cardol or pure cardanol, as previously conducted, but instead to focus on the naturally derived mixtures obtained through CNSL extraction. Various ester plasticizers with different alkyl length chains were synthesized from various CNSL mixtures, containing different ratios of cardanol and cardol. The chemical structure of these plasticizers was fully characterized by using ¹H NMR spectroscopy, while the rheological properties of plastisol, mechanical properties, and thermal stability of plasticized PVC films were investigated. Through this exploration, insights into the potential of CNSL-derived esters as efficient PVC plasticizers are elucidated, offering promising alternatives with reduced processing complexities and enhanced market viability.