Development of Lignin-Based Antioxidants for Polymers

Abstract

The growing interest in lignin as a potential source for biofuels and biochemicals is driven by multiple factors: (1) relative abundance, (2) absence of competition between food and fuel, and (3) recent legislation and mandates promoting a green economy. This book chapter presents a detailed literature review on how lignin fits into the growing market for antioxidants especially fpr polyolefins, and discusses previous studies on lignin as a bio-based chemical. There is a scarcity of the literature addressing the effects of adding technical lignin and its de-polymerized products in polyolefins and their antioxidant properties. In this context, the authors explored lignin de-polymerization as a promising approach to improve the reactivity of the lignin-based antioxidants for polymers (polyethylene, PE and polypropylene, PP). A proprietary hydrolytic de-polymerization process was utilized to increase the antioxidant activity of two types of technical lignin: Kraft lignin, KL (a by-product from the pulp and paper industry) and hydrolysis lignin, HL (a by-product from the pre-treatment processes in cellulosic ethanol plants). This book chapter discusses some of the results showing how de-polymerization can improve the antioxidant activity of commercial lignins, and how the mechanical properties are affected after incorporating lignin into polymer matrixes.