Surface Modification of Lignosulfonates for Reinforcement of Styrene-Butadiene Rubber Compounds

In this study, surface modification of lignosulfonates (LSs) was investigated for potential reinforcement of styrene-butadiene rubber compounds. Lignins are naturally occurring amorphous, highly branched polymers consisting of aromatic and aliphatic segments with polar functional groups such as hydroxyl, methoxy, carbonyl, and carboxyl. The polarity and hydrophilic nature render lignin incompatible with nonpolar rubber materials. In this study, cyclohexylamine (CA) modification of LS was evaluated for enhancement of compatibility with rubber via proton transfer and hydrogen bonding interactions. X-ray photoelectron spectroscopy data confirm attachment of CA onto the surface of LS. The cure and scorch times of rubber compounds were shortened, and the crosslink density enhanced with an increase of the amount of CA in modified LS. The tensile strength at break increased by almost 45%; the 100% modulus and elongation at break also showed significant improvements. The values of storage modulus and loss tangent increased by 13% and 18%, respectively. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40123.