From Waste to Functional Additive: Toughening Epoxy Resin with Lignin

• Main Authors: Liu, Wanshuang, Zhou, Rui, Goh, Hwee Li Sally, Huang, Shu, Lu, Xuehong
• Other Authors: School of Materials Science & Engineering
• Format: Article
• Language: English
• Published: 2016
• Subjects: epoxy resin; lignin
• Online Access: https://hdl.handle.net/10356/81522; http://hdl.handle.net/10220/40860
• Institution: Nanyang Technological University

A novel approach to toughen epoxy resin with lignin, a common waste material from the pulp and paper industry, is presented in this article. First, carboxylic acid-functionalized alkali lignin (AL-COOH) was prepared and subsequently incorporated into anhydride-cured epoxy networks via a one-pot method. The results of mechanical tests show that covalent incorporation of rigid AL-COOH into epoxy networks can significantly toughen the epoxy matrix without deteriorating its tensile strength and modulus. The addition of 1.0 wt % AL-COOH gives increases of 68 and 164% in the critical stress intensity factor (KIC) and critical strain energy release rate (GIC), respectively, relative to that of neat epoxy. This article opens up the possibility of utilizing low-cost and renewable lignin feedstocks as effective toughening agents for thermoset polymers.