Processing Stabilization of Polyethylene with Grape Peel Extract: Effect of Extraction Technology and Composition

Area of Science:

• Polymer Science and Engineering
• Natural Product Chemistry
• Materials Science

Background:

• Polymer degradation during processing necessitates the use of stabilizers.
• Natural compounds, particularly polyphenols, are explored as alternatives to synthetic stabilizers.
• Grape peels are a rich source of bioactive polyphenols.

Purpose of the Study:

• To evaluate the stabilization efficiency of grape peel extracts in polyethylene.
• To compare the effectiveness of different extraction techniques (stirred tank reactor, Soxhlet, ultrasound) on extract performance.
• To assess the correlation between extract composition, antioxidant activity (DPPH assay), and stabilization performance.

Main Methods:

• Extraction of dry grape peel powder using three distinct methods.
• Characterization of extract composition, physical/chemical structure, and inherent stability.
• Incorporation of extracts and reference compounds (trans-resveratrol, Irganox 1010) into polyethylene.
• Evaluation of stabilization efficiency through multiple extrusion experiments.
• Assessment of residual stability of polymer-extract composites.

Main Results:

• Grape peel extracts exhibited similar compositions, containing various polyphenols but limited quercetin and trans-resveratrol.
• Extracts demonstrated superior processing stabilization compared to trans-resveratrol and Irganox 1010, regardless of extraction method.
• Polymers containing grape peel extracts showed poor long-term (residual) stability.
• The DPPH assay's IC50 value was found unsuitable for predicting polymer stabilization efficiency.

Conclusions:

• Grape peel extracts are effective processing stabilizers for polyethylene due to their polyphenol content.
• The structural differences of polyphenols influence both processing and long-term stabilization effects.
• Antioxidant assays like DPPH are insufficient for evaluating the efficacy of stabilizers in polymer applications.