Lignin-based thermoplastic conversion process developed

Turning lignin, a plant's structural "glue" and a byproduct of the paper and pulp industry, into something considerably more valuable is driving a research effort headed by Amit Naskar of Oak Ridge National Laboratory.

In a cover article published in Green Chemistry, the research team describes a process that ultimately transforms the lignin byproduct into a thermoplastic - a polymer that becomes pliable above a specific temperature.

Researchers accomplished this by reconstructing larger lignin molecules either through a chemical reaction with formaldehyde or by washing with methanol. Through these simple chemical processes, they created a cross-linked rubber-like material that can also be processed like plastics.

"Our work addresses a pathway to utilize lignin as a sustainable, renewable resource material for synthesis of thermoplastics that are recyclable," said Naskar, a member of the Department of Energy lab's Material Science and Technology Division.

Instead of using nearly 50 million tons of lignin byproduct produced annually as a low-cost fuel to power paper and pulp mills, the material can be transformed into a lignin-derived high-value plastic. While the lignin byproduct in raw form is worth just pennies a pound as a fuel, the value can potentially increase by a factor of 10 or more after the conversion.

Naskar noted that earlier work on lignin-based plastics utilised material that was available from pulping industries and was a significantly degraded version of native lignin contained in biomass. This decomposition occurs during harsh chemical treatment of biomass.