Synthesis of poly vinyl chloride/chlorinated polypropylene-active natural substance derivatives for potential packaging materials application. Tannic acid, menthol and lipoic acid

A novel one step route for the synthesis of tannic acid, lipoic acid and menthol functionalized polyvinyl chloride, PVC, (PVC-Tann, PVC-Lip, PVC-Mnt) and chlorinated polypropylene, PP-Cl, (PP-Mnt, PP-Lip) was applied imparting antioxidative properties to the newly-formed materials. The resulting modified polymers were char-acterized by stress-strain mechanical measurement, 1H NMR, gel permeation chromatography (GPC) and ther-mogravimetric (TGA) analysis. Linseed oil, owing to its high linolenic acid content, was used to track the autoxidation process. The chloride functional groups were reacted with the hydroxyl/carboxylic acid of the natural compounds in the presence of a base. Linseed oil was poured into the natural compound functionalized PVC covered Petri dish to undergo autoxidation under white light.Each of the PVC-and PP-Cl-based polymers was active in delaying autoxidation. The PP-Mnt series and PP-Lip polymers all delayed autoxidation by 8 days over the PP-Cl precursor material. The autoxidation process was further confirmed by monitoring peroxide formation in the exposed linseed oil samples through differential scanning calorimeter (DSC) analysis.

Automated summary

A novel synthesis method was developed to functionalize tannic acid, lipoic acid and menthol onto polyvinyl chloride and chlorinated polypropylene, giving the materials antioxidative properties. The modified polymers were characterized and shown to delay autoxidation. The study demonstrates the potential application of these functionalized polymers in preventing oxidation.