Antioxidant Activity of Biogenic Cinnamic Acid Derivatives in Polypropylene

Abstract

Antioxidants (AOs) from natural resources are an attractive research area, as petroleum-based products can be replaced in polymer stabilization. Therefore, novel esters based on the p-hydroxycinnamic acids p-coumaric acid, ferulic acid and sinapic acid were synthesized and their structure properties relationships were investigated. The structures of the novel bio-based antioxidants were verified using NMR and Fourier-transform infrared (FTIR) spectrometry. The high thermal stability above 280 °C and, therefore, their suitability as potential plastic stabilizers were shown using thermal gravimetric analysis (TGA). The radical scavenging activity of the synthesized esters was evaluated by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Stabilization performance was evaluated in polypropylene (PP) using extended extrusion experiments, oxidation induction time (OIT) measurements and accelerated heat aging. In particular, the sinapic acid derivative provides a processing stability of PP being superior to the commercial state-of-the-art stabilizer octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

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“…Generally, cinnamic acid is composed of simple derivatives, including ferulic acid and p -coumaric acid, and is widely found in plants, including vegetables, fruits, whole grains, and honey [ 125 ]. Past studies have reported that cinnamic acid exhibits a neuroprotective effect [ 126 ], antioxidant [ 127 ], and anti-inflammatory properties [ 128 ]. When utilized in clinical practice, the administration of this compound alone recorded a low bioavailability, which restricts further development in clinical usages for AD [ 125 ].…”