# Valorization of Kraft Lignins from Different Poplar Genotypes as Vegetable Oil Structuring Agents via Electrospinning for Biolubricant Applications

## TL;DR

This paper explores using lignin from poplar trees to create eco-friendly lubricants by electrospinning nanofibers that structure vegetable oils.

## Contribution

A novel approach to valorize waste lignin from poplar genotypes into high-value biolubricant structuring agents via electrospinning.

## Key findings

- Electrospun poplar lignin-cellulose acetate nanofibers can structure vegetable oils into stable, gel-like dispersions.
- Nanofiber properties and lignin source affect the viscoelastic and tribological performance of the oil dispersions.
- Lignin nanofibers improve oxidative stability of vegetable oil-based lubricants.

## Abstract

This work explores the use of Kraft lignins sourced from
different
poplar genotypes (Populus alba L. “PO-10-10-20”
and Populus × canadensis “Ballotino”)
isolated by selective acid precipitation (at pHs 5 and 2.5) to produce
electrospun nanostructures that can be further employed for structuring
vegetable oils. This approach offers a new avenue for converting these
waste materials into high-value-added ingredients of eco-friendly
structured lubricants. Electrospinning of poplar Kraft lignin (PKL)/cellulose
acetate (CA) solutions yielded homogeneous beaded nanofiber mats that
were able to generate stable dispersions when they were blended with
different vegetable oils (castor, soybean, and high-oleic sunflower
oils). Electrospun PKL/CA nanofiber mats with larger average fiber
diameters were achieved using the lignins isolated at pH 5. Dispersions
of PKL/CA nanofibers in vegetable oils presented gel-like viscoelastic
characteristics and shear-thinning flow behavior, which slightly differ
depending on the nanofiber morphological properties and can be tuned
by selecting the poplar lignin genotype and precipitation pH. The
rheological properties and tribological performance of PKL/CA nanofibers
suitably dispersed in vegetable oils were found to be comparable to
those obtained for conventional lubricating greases. Additionally,
lignin nanofibers confer suitable oxidative stability to the ultimate
formulations to different extents depending on the vegetable oil used.

Lignins from different poplar genotypes
for the production
of electrospun nanostructures and the subsequent promotion of the
structuring of vegetable oils for lubricant applications.