This document discusses using lignin as a feedstock to produce additives that enhance the UV resistance of plastics. Lignin is isolated from southern pine during the kraft pulping process and fractionated. A low molecular weight portion is blended with cellulose acetate. Films containing higher amounts of lignin additives showed increased stiffness and were less degraded by UV exposure, suggesting lignin forms covalent crosslinks that improve stability. The lignin structure and source affect its ability to enhance oxidative stability of materials.

1. Lignin-based UV Stabilizer for Renewable Bioplastics
Jacob Staudhammer,1 Zhenglun “Glen” Li1,2
1 BioEnergy Program, College of Agricultural Sciences, Oregon State University
2 BioEnergy Education, Advanced Hardwood Biofuels Northwest
BACKGROUND
Polyaromatic lignin is a natural component of plant cell
wall matrices. Fractionation of plant biomass during
biochemical conversion processes generates a lignin
stream which has the potential to be utilized as a
feedstock for production of value-added materials and
chemicals.
METHODS
Lignin is isolated from the kraft pulping process of
southern pine, and fractionated with acetone solvent.
The low molecular weight portion of lignin is blended
as an additive with cellulose acetate using a solvent
casting method. The addition of lignin-based additive
to the cellulose acetate does not have a significant
effect on the transparency of the material.
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Fig. 1 Process flow diagram of biomass conversion to
biofuel and renewable chemicals
Fig. 4 Cellulose acetate film with different content
(weight percentage) of lignin-based additives
RESULTS
The stiffness of cellulose acetate increases with
increased amount of lignin-based additives, which is
possibly a result of the interaction between additives
and the cellulose acetate matrix. After UV irradiation,
the stiffness of the material increases, suggesting
formation of covalent crosslinks between polymers
(Figure 5A). The samples with higher content of lignin-
based additives are less sensitive to UV degradation,
as suggested by the insignificant loss of material
ductility during UV treatment (Figure 5B).
Questions? Please contact:
Dr. Zhenglun “Glen” Li, Oregon State University
Email: glen.li@oregonstate.edu Direct: (517) 282-4731
ACKNOWLEDGMENTS
This project is supported by an Agriculture and Food
Research Initiative Competitive Grant no. 2011-68005-
30407 from the USDA National Institute of Food and
Agriculture (NIFA). Additional support was provided by
Bosky Optics LLC, and Domtar Corporation.
We propose to use lignin as a feedstock for producing
chemical additives that enhance the resistance of
plastic materials towards UV irradiation. Lignin is a
complex polymer of phenylpropanoid units (Fig. 2).
The chemical structure of lignin varies depending on
the source of the lignin and the method used for lignin
isolation. Sadeghifar and Argyropoulos reported that
lignin with higher content of phenolic hydroxyl groups
is more potent in improving the oxidative stability of
materials (ACS Sustainable Chem. Eng., 2015)
Pretreatment &
Enzymatic
Saccharification
biomass
Fermentation
of Sugars
fermentable
sugars
lignin Lignin
Fractionation
& Upgrading
UV stabilizer
Antioxidant
Biofuel
Chemicals
Fig. 2 Artistic depiction of lignin structure. Image
adapted from Green Chem., 2010,12, 1640
Fig. 3 Film of cellulose acetate containing lignin-based
additives. Films are 50 – 200 μm in thickness
0% 1% 2.5% 5%
7.5% 10% 15%
The performance of lignin-based additives is assessed
by measuring the impact of UV irradiation on the
tensile properties of the samples. Cellulose acetate
samples are cut into sample strips and exposed to UV
irradiation (1.5 W/m2) in a QUV weathering chamber
for 120 hours, and the stress-strain characteristics of
samples before and after UV treatment are measured
on an Instron tensometer. Young’s modulus is used to
characterize the change in material strength under UV
irradiation, as well as the effect of lignin-based
additives on material strength.
0
500
1000
1500
2000
2500
3000
3500
-2 0 2 4 6 8 10 12 14
TensileModulus(MPa)
Lignin %
Before UV After UV
Fig. 5A Young’s modulus of cellulose acetate samples
0%
5%
10%
15%
20%
25%
30%
0 5 10 15
ElongationatBreak
Lignin %
Fig. 5B Ductility of cellulose acetate samples
Stress
Strain
Stress-Strain Relationship Before UV Treatment
No Lignin
5% Lignin
10% Lignin
15% Lignin