Oil structuring properties of electrospun Kraft lignin/ cellulose acetate nanofibers for lubricating applications: influence of lignin source and lignin/cellulose acetate ratio
In the present work, electrospun Kraft
lignin/cellulose acetate nanostructures were produced,
assessed and proposed as structuring or thickening
agents of castor oil for lubricating applications.
Solutions of Kraft lignins (KL) derived from different
sources (eucalyptus, poplar and olive tree pruning)
and cellulose acetate (CA) were prepared and used as
feed for electrospinning. The rheological properties
(shear and extensional viscosity), electrical conductivity
and surface tension of KL/CA solutions influence
the morphology of the electrospun nanofibers,
which in turn is affected by the chemical structure
and composition of the Kraft lignins. Electrospun
KL/CA nanostructures consisting of filament-interconnected
nanoparticles, beaded nanofibers or uniform
nanofiber mats were able to form gel-like homogeneous
fine dispersions by simply mechanically
dispersing them into castor oil. The swelling of KL/
CA nanofibers in the percolation network was demonstrated.
The rheological, tribological and microstructural
properties of these oleogels are essentially governed by the morphological characteristics of the
electrospun nanostructures, i.e. fiber diameter, number
of beads and porosity. Rheological properties of
the resulting oleogels may be tailored by modifying
the lignin source and KL:CA weight ratio. According
to their rheological and tribological properties, KL/
CA electrospun nanostructures-based oleogels can be
proposed as a sustainable alternative to conventional
lubricating greases.This work is part of a research project (RTI2018-096080-B-C21) funded by MCIN/AEI/10. 13039/501100011033 and by “ERDF A way of making Europe”. J.F. Rubio-Valle has also received a Ph.D. Research Grant PRE2019-090632 from Ministerio de Ciencia e Innovación (Spain). The financial support is gratefully acknowledged.
Universidad de Huelva/CBUA thanks to the CRUE-CSIC agreement with
Springer Nature
