Darshi Dissanayake_Poster IUCRC
1
NSF Industry/University Cooperave Research Center (I/UCRC) for Advanced Composites in Transportaon Vehicles Ecofriendly Nano-Composites for Automove and Aerospace Applicaons Darshi Dissanayake 1 , Hossein Toghiani 1 and Ratneshwar Jha 2 1 Dave C. Swalm School of Chemical Engineering, 2 Raspet Flight Research Laboratory, Mississippi State University Background Approach Few commercial lignins were fraconated in a precipitaon-redissoluon process to extract the high molecular weight fracon suitable for highly ordered graphene nano platelets (GnPs) producon. The effects of sequenal washing and solvaon were studied using 3 solvents acetone, methanol and tetrahydrofuran (THF). Change in glass transion temperature was studied using differenal scanning calorimetry (DSC) according to the standard ASTM E 1356-08. Fourier transform infrared spectroscopy (FTIR) was used for chemical structural analysis . Lignins samples were washed with aqueous HCl at a controlled pH to determine the possibility of sulfur removal. The treated samples were compared with as received samples in FTIR to find any change in disnct peaks. Results Fraconaon Acid washing for sulfur removal The original samples contained sulfur as S-H, sulfoxides and sulfones as it could be idenfied by the FTIR peaks at wave- numbers 2570, 1050, and 1350 cm -1 , respecvely. Acid washing could remove at least part of the sulfur in lignin bonded with hydrogen. Fig: FTIR spectra for lignin PB 1000 (blue– as received, red-treated) The path towards high strength graphene composites Studies have shown that the increase in molecular weight would increase many desired properes like tensile strength and toughness. Removing impuries will increase the rate of producon such as increasing melt spin ability which is a key issue in carbon fiber producon; moreover, sulfur removal reduces the brileness. References Saito, T., Perkins, J. H., Vautard, F., Meyer, H. M., Messman, J. M., Tolnai, B., & Naskar, A. K. (2014). Methanol Fraconaon of Soſtwood Kraſt Lignin: Impact on the Lig- nin Properes. ChemSusChem, 7(1), 221–228. Landel, R. F., & Nielsen, L. E. (1993). Mechanical Properes of Polymers and Composites, Second Edion. CRC Press. Fraconated samples were analyzed in GPC for their molecular weight distribuon. Solvent fraconaon can be used to extract the high molecular weight fracon of lignin effecvely. Solvents acetone, methanol and THF are suitable for removing low molecular fracon of lignin. The fraconaon capability of solvents vary with type of lignin. For the samples tested, fraconaon of lignin PB 1000 using acetone and lignin PB 2400 using methanol gave the best results. Sequenal dissoluon in solvents acetone and methanol followed by precipitaon will increase the average molecular weight. However in THF, the average molecular weight in second precipitate decreases. 2000 2500 3000 3500 4000 4500 ASR Acetone Methanol THF Molecular weight (Da) Effect of solvent in fractionation analysis of first precipitate PB 1000 PB 2400 PB 4000 2500 3000 3500 4000 Acetone Methanol THF Molecular weight (Da) Effect of sequential washing For Protobind 1000 First precipitation Second precipitation Lignin structure and AFM images of Graphene Lignin is an amorphous polymer present in vegetal cell wall with complex 3D randomized network. The annual lignin producon in pulp and paper industry alone exceeds 50 million tons which is currently underulized. Oak Ridge Naonal Laboratory (ORNL) has demonstrated the use of lignin as a low-cost precursor for carbon fiber producon. We are evaluang the potenal use of lignin as a starng material for graphene producon, so that it can be used as nano-reinforcements for applicaons in automove and aerospace industries. Why graphene? Mass reducon (low density and concentraon) Increased sffness (high aspect rao) Increased toughness (engineered adhesion) Electrical conducvity (electrostac painng and dissipaon, EMI shielding) Thermal conducvity, lower coefficient of thermal expansion Reduced flammability (less combusble material) Barrier to permeants (platelet morphology) Challenges Unreliable precursor to polymer producon : Complex 3D structure and structural variability depends on biomass species, the botanical origin and isolaon process; unknown reacvates and kinecs due to the presence of mulple funconal groups. Polydispersity of lignin (~200-200000 g/mol): low molecular weight lignin is unsuitable for high-end applicaons such as thermoplascs High level of impuries such as sulfur 1-3% (w/w) in Kraſt lignin and ash 4-8% in lignosulfonates Thermal instability Obtain uniform dispersion and opmize volume fracon for desired mechanical, thermal and electrical properes
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Transcript of Darshi Dissanayake_Poster IUCRC
NSF Industry/University Cooperative Research Center (I/UCRC) for
Advanced Composites in Transportation Vehicles
Ecofriendly Nano-Composites for Automotive and Aerospace Applications Darshi Dissanayake1, Hossein Toghiani1 and Ratneshwar Jha2
1Dave C. Swalm School of Chemical Engineering, 2Raspet Flight Research Laboratory, Mississippi State University
Background
Approach
Few commercial lignins were fractionated in a precipitation-redissolution process to extract the high molecular weight
fraction suitable for highly ordered graphene nano platelets (GnPs) production. The effects of sequential washing and
solvation were studied using 3 solvents acetone, methanol and tetrahydrofuran (THF). Change in glass transition
temperature was studied using differential scanning calorimetry (DSC) according to the standard ASTM E 1356-08. Fourier
transform infrared spectroscopy (FTIR) was used for chemical structural analysis .
Lignins samples were washed with aqueous HCl at a controlled pH to determine the possibility of sulfur removal. The
treated samples were compared with as received samples in FTIR to find any change in distinct peaks.
Results
Fractionation
Acid washing for sulfur removal
The original samples contained sulfur as S-H, sulfoxides and sulfones as it could be identified by the FTIR peaks at wave-
numbers 2570, 1050, and 1350 cm-1, respectively.
Acid washing could remove at least part of the sulfur in lignin bonded with hydrogen.
Fig: FTIR spectra for lignin PB 1000 (blue– as received, red-treated)
The path towards high strength graphene composites
Studies have shown that the increase in molecular weight would increase many desired properties like tensile strength and
toughness. Removing impurities will increase the rate of production such as increasing melt spin ability which is a key issue
in carbon fiber production; moreover, sulfur removal reduces the brittleness.
References
Saito, T., Perkins, J. H., Vautard, F., Meyer, H. M., Messman, J. M., Tolnai, B., & Naskar, A. K. (2014). Methanol Fractionation of Softwood Kraft Lignin: Impact on the Lig-
nin Properties. ChemSusChem, 7(1), 221–228.
Landel, R. F., & Nielsen, L. E. (1993). Mechanical Properties of Polymers and Composites, Second Edition. CRC Press.
Fractionated samples were analyzed in GPC for their molecular weight
distribution.
Solvent fractionation can be used to extract the high molecular
weight fraction of lignin effectively.
Solvents acetone, methanol and THF are suitable for removing low
molecular fraction of lignin.
The fractionation capability of solvents vary with type of lignin. For
the samples tested, fractionation of lignin PB 1000 using acetone
and lignin PB 2400 using methanol gave the best results.
Sequential dissolution in solvents acetone and methanol followed by
precipitation will increase the average molecular weight. However in
THF, the average molecular weight in second precipitate decreases.
2000
2500
3000
3500
4000
4500
ASR Acetone Methanol THF
Mo
lecu
lar
we
igh
t (D
a)
Effect of solvent in fractionationanalysis of first precipitate
PB 1000
PB 2400
PB 4000
2500
3000
3500
4000
Acetone Methanol THF
Mo
lecu
lar
we
igh
t (D
a)
Effect of sequential washing For Protobind 1000
First precipitation
Second precipitation
Lignin structure and AFM images of Graphene
Lignin is an amorphous polymer present in vegetal cell wall with complex 3D randomized
network. The annual lignin production in pulp and paper industry alone exceeds 50 million
tons which is currently underutilized. Oak Ridge National Laboratory (ORNL) has demonstrated
the use of lignin as a low-cost precursor for carbon fiber production. We are evaluating the
potential use of lignin as a starting material for graphene production, so that it can be used as
nano-reinforcements for applications in automotive and aerospace industries.
Why graphene?
Mass reduction (low density and concentration)
Increased stiffness (high aspect ratio)
Increased toughness (engineered adhesion)
Electrical conductivity (electrostatic painting and dissipation, EMI shielding)
Thermal conductivity, lower coefficient of thermal expansion
Reduced flammability (less combustible material)
Barrier to permeants (platelet morphology)
Challenges
Unreliable precursor to polymer production : Complex 3D structure and structural
variability depends on biomass species, the botanical origin and isolation process;
unknown reactivates and kinetics due to the presence of multiple functional groups.
Polydispersity of lignin (~200-200000 g/mol): low molecular weight lignin is unsuitable for
high-end applications such as thermoplastics
High level of impurities such as sulfur 1-3% (w/w) in Kraft lignin and ash 4-8% in
lignosulfonates
Thermal instability
Obtain uniform dispersion and optimize volume fraction for desired mechanical, thermal
and electrical properties
