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Utilization of Lignin in the Development of High-Performance Bio-based Resins

J.F. Stanzione III (Ph.D. Candidate), J. M. Sadler (Ph.D., ARL), J. J. La Scala (Ph.D., ARL), R.P. Wool (Ph.D.)

University of Delaware . Center for Composite Materials . Department of Chemical Engineering

Introduction(1)

t High-performance composites utilized in a wide-variety of industrial and governmental applications are derived primarily from petrochemical feedstocks:

²  i.e. epoxy resins and vinyl ester resins ²  i.e. carbon and aramid reinforcing fibers

t Cost and supply of these materials are extremely volatile

t Recent developments of bio-based resins include: ²  maleinized/acrylated/epoxidized soybean oil ²  methacrylated lauric and hexanoic acids

t Hurdles bio-based resins have yet to overcome: ²  have lower Tg’s relative to commercial petroleum-based resins ²  require the addition of petroleum-based reactive diluents to reduce liquid

molding resin viscosities (i.e. styrene, divinyl benzene, vinyl toluene) ²  utilize major human and animal food sources (i.e. soybeans, corn)

t Need exists to develop high-performance resins and fibers from biological sources to effectively replace petroleum-derived composites

Lignin as an Alternative Bio-based Feedstock(2)

t Structural polymer present in woody plants t Microorganism protective barrier t 18 – 25% content in hardwoods t 25 – 35% content in softwoods t 3 x 1011 tons exist in biosphere t 2 x 1010 tons generated annually t Copious paper pulping waste product t Primarily burned for energy recovery t High variability chemical feedstock t High aromatic content

²  aromaticity enhances resin structural rigidity Lignocellulose schematic.(2)

Goal of this research is to use lignin and lignin model compounds in the development of high-performance resins by

reducing its MW and/or by chemical modification to produce resins with viscosities < 2000 cP and Tgs > 120°C.

Motivation

Lignin Extraction, Structure, and Uses(3)

t Extraction methods include: ²  steam explosion cracking ²  organosolv delignification ²  alkaline or Kraft pulping

t 3-D highly aromatic structure t Kraft pulped lignin contains

hydroxyl groups typically not found in protolignin

Traditional Kraft pulping process (ht tp: / /www.sfk .ca /EN/Mi l l_Saint -Felicien/KraftProcess.php)

Proposed structure of Kraft pine lignin by Marton.(3)

t Current uses include: ²  H2O reducer in concrete ²  binding agent in animal feed ²  dust control agent ²  filler in composites and plastics ²  accounts for only 1% of total

annual lignin production

Research Method(4-6) Kraft Pine Lignin Characterization

t  Supplied by MeadWestvaco: ²  origin - Charleston, S.C. ²  Indulin® AT (January 2010 batch) ²  brown granules ²  composition = C9H7.9O2.1S0.1(OCH3)0.82

²  phenyl-propane unit MW = 178 g/mol

Fractionation Technique

kraft pinelignin (KPL)

CH2Cl2 CH3(CH2)2OH CH3OH CH3OH/CH2CL2

7:3

Fraction 1 Fraction 2 Fraction 3 Fraction 4 Fraction 5(undissolved)

dissolved dissolved dissolved dissolved

Fractionation scheme for KPL with organic solvents; undissolved lignin was dried before subjection to next solvent (horizontal arrows).(4)

Ongoing & Future Work t  Degradation of KPL in air and in high purity O2 using singlet

oxidation

t  Degradation of KPL via an olefin metathesis reaction t  Implement a “greener” fractionation technique which utilizes a

switchable-hydrophilicity solvent t  Utilize methacrylated lignin model compounds as reactive

diluents in lignin-derived resins

References (1)  S.N. Knot, Selim Kusefoglu, J.J. LaScala, G. Palmese, R. Zhou, R.P. Wool, et.al.

(Patent 2000). (2) Genome Management Information System, Oak Ridge National Laboratory. (3) Wool, R.P. & Sun, X.S. Bio-based Polymers and Composites. Elsevier, Burlington,

MA (2005). (4)  Thielemans, W. & Wool, R.P. Biomacromolecules 6, 2005, 1895-1905. (5) Mörck, R.; Yoshida, H.; Kringstad, K.P., Holzforschung, 40, 51-60 (1986). (6)  Bonini, C.; D’Auria, M.; Ferri, R., Photochem. Photobiol. Sci., 1, 570-573 (2002).

Acknowledgements This work is supported by the SERDP WP-1758 and the Army

Research Laboratory through the Cooperative Agreement W911NF-06-2-0011.

t  Followed fractionation technique of Mörck, et al.(4)

t  Fractions acetylated prior to GPC experiments.

Fractionation Results

Fraction 1 Fraction 2 Fraction 3 Fraction 4 Fraction 50

10

20

30

40

50

Fraction 1 Fraction 20.0

0.1

0.2

0.3

0.4

Yiel

d (%

)

Yiel

d (%

)

t  Hope to fractionate lignin based on MW and # of hydroxyl groups for better reaction/property control

t  Hope to degrade lignin to produce high yields of chemicals with MWs ≤ 2000 g/mol and PDIs < 1.75

t  Hope to functionalize lignin and lignin model compounds in order to chemically incorporate them into bio-based resins

t  Average % lignin recovery = 93.5 ± 1.2 t  Fraction 4 results contradict those of Mörck, et al. (still

investigating)(4)

t  Overall, as fraction # ↑, Mn ↑ and PDI ↑ (exact correlations still being investigated)

t  Methacrylated methanol fraction still largely insoluble in bio-based and petroleum-based monomers (still tweaking the methacrylation technique)

Lignin

FunctionalizedLignin

FractionatedLignin

DegradedLignin

ThermosettingResins

High-PerfomanceComposites

Lignin Model Compounds

Functionalized Lignin Model Compounds

Research method flowchart.

Phenyl-propane unit

αβ γ

Kraft pine lignin

Methacrylation Technique

Fraction # Mn (Da) Mw (Da) PDI1 309 436 1.412 1018 1382 1.453 1402 2170 1.554 1749 2828 1.645* − − −

Fractionated KPL GPC Results

* Unable to dissolve in THF

OHLignin CH3

CH2

O

OLigninCH3

CH2

O

O

OCH3

CH2+

DMAP catalyst25 - 50 °C

Argon atmosphereSolventlessn n

n ~ 7 mmol/ gram of KPL