Antioxidant Properties of Curcumin Analogues to Inhibit Thermal Degradation of Low-Density Polyethylene: Experimental and DFT Study

Curcumin can be isolated from plants (Curcuma longa) and it belongs to the ginger family. It exhibits many useful properties and acts as an antioxidant. The aim of the current study was to prepare eight curcumin analogues and investigate their antioxidant activities to inhibit the thermal degradation of low-density polyethylene (LDPE). The carbonyl index (CI) was measured to test the effectiveness of the curcumin analogues. Various doses (0.5, 1, 2, 4, and 6% wt/wt) of a mixture containing LDPE and curcumin analogues were prepared, and the CI was measured. The eight curcumin analogues were found to have good to excellent antioxidant activity against the degradation of LDPE. It was clear that the curcumin analogue derived from vanillin and acetone has the highest antioxidant activity. The density functional theory study was conducted for the eight curcumin analogues to test their reactivity and stability. Again, the global reactivity descriptors analysis showed that compound derived from vanillin and acetone was the most reactive compound to inhibit thermal degradation of LDPE.