Lignin is the most abundant polyaromatic biopolymer and is responsible for plants' mechanical strength and timber-built structures. The complex chemical structure and the difficulty in fractionation, characterization, and modification are significant barriers to the wide-spread commercial application of lignin. Another abundant industrial waste is elemental sulfur produced as a by-product in petroleum refineries. The major drawback of using sulfur as an individual composite material is its low mechanical strength. Sulfur does, however, have numerous attractive non-mechanical properties, including hydrophobicity, antimicrobial properties, high electrical resistivity, and low thermal conductivity. Thus, it was hypothesized that durable, recyclable biocomposites could be obtained through chemically modified lignin crosslinking with sulfur. Different strategies for the chemical modification of lignin, such as chlorination and esterification with fatty acids, are discussed. Chlorolignin is one of the major toxic anthropogenic chlorinated organics in the environment yet remains as one of the most underutilized waste products of the paper and pulp industries. The chlorolignin-sulfur crosslinking was accomplished with a newly developed method called radical-induced aryl halide-sulfur polymerization (RASP), which expands the substrate scope beyond the olefins that are required for the conventional inverse vulcanization route to sulfur polymers. The esterification of lignin was carried out with another bio-based waste, unsaturated fatty acids. It was hypothesized that durable, recyclable biocomposites could be obtained by combining these three waste streams via radical-induced thermal reactions. The compatibility of these recyclable, chemically resistant, durable materials as promising candidates in sustainable composites and lignin valorization are discussed.

Biocomposites through combination of agricultural and energy production waste streams

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.