title: From waste to functional additive: toughening epoxy resin with lignin.
abstract: 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 (K(IC)) and critical strain energy release rate (G(IC)), 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.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Wanshuang
authors.initials: W
authors.lastname: Liu
authors.forename: Rui
authors.initials: R
authors.lastname: Zhou
authors.forename: Hwee Li Sally
authors.initials: HL
authors.lastname: Goh
authors.forename: Shu
authors.initials: S
authors.lastname: Huang
authors.forename: Xuehong
authors.initials: X
authors.lastname: Lu