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.

Synthesis and properties of an intrinsic flame retardant silicone rubber containing phosphaphenanthrene structure

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All Biomass and UV Protective Composite Composed of Compatibilized Lignin and Poly (Lactic-acid)

“…Lignin, the most abundant biomass containing aromatic rings in nature, accounts for 20–30% of wood by weights1415. Lignin has hyperbranched structure with various functional groups, such as hydroxyl, methoxyl, ether, and aldehyde groups15.…”

Epoxy resin reinforced with nanothin polydopamine-coated carbon nanotubes: a study of the interfacial polymer layer thickness

“…As literature suggests [39] , the reduction in T g of nanofiller/epoxy composites could be related to that the unfavorable interactions at the polymer matrix-hard surface interface, although there is slightly compatible PDA coating covered on CNTs surface in this study. This unfavorable interactions lead to immobile domains in the epoxy matrix, thus causing a drop in the T g value.…”