Efficient additive package with large natural material content for the stabilization of PE

• An efficient stabilizer package was developed with large bio-based content. • The two natural antioxidants act synergistically. • The new stabilizer package offers excellent melt stability and exceptional residual stability. • Larger efficiency is achieved at smaller additive content than with commercial additive packages. An additive package with large natural material content was prepared and its stabilization efficiency was compared to that of an industrial stabilizer combination. A new phosphine-type secondary antioxidant was synthesized to increase the bio-based content of the package. The stabilization effect of the packages was studied in multiple extrusion experiments followed by the measurement of chemical structure, rheology, residual stability, and color. The interaction of the components was studied by thermogravimetry and FTIR spectroscopy. The comparison of the additive packages showed that the bio-based package offers many advantages compared to the currently used industrial package; better stabilization efficiency is achieved at smaller additive content. The natural antioxidant used, quercetin, interacts with the secondary stabilizers. Quercetin initiates the decomposition of a phosphonite stabilizer containing P(III)O bonds, but it increases the inherent stability of the newly synthesized phosphine antioxidant. The interactions result in changes in the reactions of the vinyl groups of the polymer. Besides long chain branching, other competitive reactions take place, which consume vinyl groups but do not increase viscosity. The new stabilizer package offers excellent melt stability and exceptional residual stability for the Phillips polyethylene used in this study. The main drawback of the package is the limited solubility of quercetin and the strong color of the processed material.