Characterization of four different lignins as a first step toward the identification of suitable end‐use applications

To determine the most appropriate use of lignin, surface, structural, and thermal characteristics of lignin was investigated in this work. It was observed that kraft lignin (KL), the lignin of prehydrolysis liquor (LPHL), lignosulfonate of NSSC process (LSL), and lignosulfonates (LSs) of sulfite pulping process had 0.67, 0.25, 0.90, and 1.52–2.25 meq/g anionic charge density, and 6.3, 2.1, 10.1, and 8.8–10.1 nm hydrodynamic diameter, respectively. These results suggested that LSL and LSs could be used more effectively than other lignin as filler modifiers, flocculants, and dispersants. The combustion studies of the lignin samples suggested that KL and LPHL combusted more efficiently than other samples, as they had high heating (calorific) values of 27.02 and 19.2 MJ/kg, the apparent activation energy of 126.64 and 99.14 kJ/mol based on Flynn–Wall–Ozawa method and 122.16 and 94.73 kJ/mol based on Kissinger–Akahira–Sunose and no ash, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42336.