Upload
others
View
3
Download
0
Embed Size (px)
Citation preview
Lignin-based rigid polyurethaneLignin based rigid polyurethane foam reinforced with cellulose
hi knanowhiskers
Yang Li and Arthur J. Ragauskas
School of Chemistry and BiochemistryInstitute of Paper Science and Technology
Georgia Institute of Technologyg gy
Explore the applicability of lignin in the preparation of PUObjective
Explore the applicability of lignin in the preparation of PUStudy the reinforcing effect of cellulose nanowhiskers (CNWs)
Environnmental issuesEnergy conservation
Economical utilization of waste lignin
Improve performanceof PU
OutlineOutline Introduction of major materials and techniques Oxypropylation of kraft lignin and foam formulation optimizationyp py g p Preparation of ethanol organosolv lignin-based rigid PU
nanocomposite foam Summary
2
Summary
PolyurethanePolyurethane PU is any polymer consisting of a chain of organic units joined by
urethane links.urethane links. Rigid PU foam is a highly crosslinked polymer with a closed-cell
structure.
600
700Lower densityLow thermal conductivity
100
200
300
400
500Low thermal conductivityLow moisture permeability Low cost High dimensional stability
0
100
1 2 3 4
Boardstock Sandwich panels
Refrigerationappliances
Technical insulation
High dimensional stability Good adhesive properties
3
Global market of main applications of rigid PU foam in 2000 (2.1 million tons)
Huntsman Polyurethane
Lignin structureLignin structure Three-dimensional amorphous polymer consisting of methoxylated
h l t tphenylpropane structures. 25-35 wt% in SW and 18-25 wt% in HW
OH
HOO
OH
OMe
OH
OHO
OMe
Lignin OHLignin
OHH3CO
P-coumaryl alcohol(Grasses)
HOHOOH OH
OMeO
HO
OHO
OMe
OHO
O
HO
OHH3CO
coniferyl alcohol(SW/HW/Grasses)
O O OMeMeO
HOOOHO OH
HO
MeOOMe
HO
sinapyl alcohol(HW/Grasses)
a small piece of SW lignin
OMe
OHOCH3
4
Sjostrom, E. Wood Chemistry: Fundamentals and Applications. Orlando, Academic Press, (1981).Sarkanen, K.V., Ludwing, C.H. Lignin, Occurrence, Formation, Structure and Reactions. New York, Wiley (Interscience), (1971).
Eth l l t t tEthanol organosolv pretreatment
Biomass
2:1 (v/v) of benzene:ethanol for 48 hours
1 1 wt% H2SO4 65% ethanol
Extraction
1.1 wt% H2SO4, 65% ethanol, 7:1 v/w, 170 ºC, 60 minCooking with ethanol, water, and H2SO4
Solid fraction: Cellulose
Precipitate:Ethanol Organosolv
Water-soluble fraction:SugarsCellulose
Residual ligninResidual hemicellulose
Ethanol Organosolv Lignin (EOL)
SugarsDepolymerized ligninFurfural and HMF
5X. Pan et al., Ind. Eng. Chem. Res. 2007, 46, 2609-2617.
Cellulose structure
Polymer of β-(1-4)-glucan, DP of 300-15,000 ~41wt% in SW and 42-51 wt% in HW
Cellulose molecule
Inter- and intra-molecule hydrogen bonding
6D. Klemm, H.-P. Fink et al. Angew. Chem. Int. Ed. 2005, 44, 3358-3393.A.J. Ragauskas et al. Industial Biotechnology Spring 2006
C ll l hi k (CNW)Cellulose nanowhisker (CNW)
Sulfuric acid (64% w/w) hydrolysis 10 ml acid/g pulp at 45 oC for 45 minSulfuric acid (64%, w/w) hydrolysis, 10 ml acid/g pulp, at 45 C for 45 min
Dilute with 10 fold of water Centrifugation at 12,000 rpm for 3 times
SonicationDialysis against waterCentrifugation at 10000 rpm
150-200 nm × ~10 nmBending strength of ~10 GPaBending strength of ~10 GPaYoung’s Modulus of ~150 GPa
Kevlar 156 GPa, Aluminum 70 GPa, Glass fiber 76 GPa
7500 nm
S. Beck-Candanedo et al. Biomacromolecules 2005, 6, 1048-1054.
Lignin oxypropylation
St ti t i lStarting materials: Kraft lignin (used for optimization) EOL Propylene oxide (PO) Potassium hydroxide (KOH)
Reaction parameters: 20/80/5 [w/v/%(w/w)] of lignin/PO/KOH
Lignin Tset (ºC) Tmax (ºC)
Pmax(bar)
Time( ) ( )
kraft 150 285 17.5 ~9minEOL 160 285 22.5 ~10min
8C.A. Cateto et al. Ind. Eng. Chem. Res. 2009, 48, 2583-2589.
Characterization GPC & FT IRCharacterization- GPC & FT-IRPropylene oxide oligmers (PPO) was separated from lignin polyol by extracting the product three times with hot hexane under reflux.
Lignin PPO Mnbefore Mnafterg(wt%)
before
(g/mol)after
(g/mol)Kraft 46 ± 5 1008 1732
oxykraft
EOL 45 ± 4 1082 1760kraft
Increased stretching of aliphatic CH3, CH2, CH groupsIncreased stretching of C-OIncreased stretching of C O
Chain extension reaction occurred!
9
Characterization 31P NMRCharacterization - 31P-NMRNHND NHND
Oxykraft OxyEOL
Ali h ti OH
Condensed phenolic OH
Guaiacyl phenolic OH
Condensed phenolic OH
Guaiacyl phenolic OH
Aliphatic OH Aliphatic OHcarboxylic OHcarboxylic OH
10A. Granata, D.S. Argyropoulos, J. Agric. Food Chem. 1995, 43, 1538-1544.M. Zawadzki, A. Ragauskas, Holzforschung 2001, 55, 283-285.
St ti t i l f f tiStarting materials for foam preparationHydroxyl index IOH is the weight of KOH in mg that will neutralize the
ti h d id bl f ti b t l ti ith 1 f l l
OH value IOH
acetic anhydride capable of reacting by acetylation with 1 g of polyol.
(mmol/g)Kraft lignin 5.62 351.2
k f 6 91 387 6
Dimethylcyclohexylamine (DMCHA)oxykraft 6.91 387.6
EOL 6.02 337.7oxyEOL 6 60 380 0
(DMCHA) Potassium octotate Silicon surfactant
oxyEOL 6.60 380.0
Mn Functionality IOH NCO
n-pentane
n y OH
Sucrose polyol 690 4.4 356 -Glycerol polyol 1008 3.0 246 -
11
Polymeric MDI 340 2.7 - 31.1%
Formulation of kraft lignin based PU foamsFormulation of kraft lignin-based PU foams
Percentage Lignin Sucrose Glycerol Polymeric CreamPercentage (wt%)
Lignin polyol
Sucrose polyol
Glycerol polyol
Polymeric MDI *
Cream time
0 0.00 g 25.00 g 15.00 g 36.37 g 40 sControl10 2.50 g 22.50 g 15.00 g 36.66 g 38 s30 7.50 g 17.50 g 15.00 g 37.24 g 34 s
(no oxykraft)
60 15.00 g 10.00 g 15.00 g 36.07 g 26 s100 25.00 g 0.00 g 15.00 g 39.24 g 23 sONLY
k f 100* 40.00 g 0.00 g 0.00 g 42.20 g 17 s
* The molar ratio of NCO to OH was 1.2 Replace sucrose polyol by k ft t l t
oxykraft
DMCHA Potassium octotate surfactant Pentane
oxykraft at several percentages
12
1.80 g 0.90 g 1.50 g 10.00 g
Preparation of kraft lignin based PU foamsPreparation of kraft lignin-based PU foams
Representative reactions happened during foaming
R-NH-CO
OR'+ R''-N=C=O R-N-C-O-R'
CO
O
AllophonateNH R''
p
PolyolsSurfactantCatalysts
Polymeric MDI
Pentane
Self-risingPolymerization Cure
13
Morphology and densityMorphology and density
Oxykraft content 0% 10% 30% 60% 100% 100*%Cell size (μm ) 620
±30638 ±50
610 ±30
750 ±30
750 ±20
630±±30
D it (k / 3) 29 3 30 2 29 4 30 7 30 1 29 4Density (kg/m3) 29.3 30.2 29.4 30.7 30.1 29.4
With increasing oxykraft content: Cell size was kept 620-650 μm except at 60% &100% where cell size went up to 750 μm and foam shrinkage also occurred Densities were kept ~30 kg/m3 Densities were kept 30 kg/m
14
0% 30% 60% TotalScale bar: 500 μm
Mechanical properties
0.20 0 % oxykraft10% k ft Oxykraft
contentStrength (MPa)
Modulus(MPa)
0 % 0 095±0 005 1 45±0 07
0.15
Pa
10 % oxykraft 30 % oxykraft 60 % oxykraft 100 % oxykraft
total oxykraft 0 % 0.095±0.005 1.45±0.0710 % 0.100±0.007 1.56±0.0530 % 0 112±0 006 1 58±0 05
0.10
Stre
ss, M
P total oxykraft
30 % 0.112±0.006 1.58±0.0560 % 0.101±0.004 1.13±0.01
100 % 0.085±0.009 1.11±0.03000
0.05
100 % 0.085±0.009 1.11±0.03100*% 0.137±0.009 3.41±0.390 5 10 15 20
0.00
Strain, %
Compressive stress strain curves
15
Compressive stress strain curvesIncreased by 44% 135%
P ti f EOL b d it fPreparation of EOL-based nanocomposite foams
oxyEOL DMCHA P.cat Surfactant Pentane Polymeric MDI
Control foam (w/o CNWs)
40.00 g 1.80 g 0.90 g 1.50 g 10.00 g 41.59 g
Nanocomposite foamsNanocomposite foams 1 wt% CNWs by adding 8.89 ml whiskers suspension 5 wt% CNWs by adding 44.47 ml whiskers suspension(Concentration of whiskers suspension is 0.03935 g/ml)
Method:Method:CNWs were added by directly mixing oxyEOL with whiskers suspension followed by removal of water under very high vacuum
16
Morphology and densityMorphology and density
Whiskers content 0 wt% 1 wt% 5 wt%Cell size (μm) 320±20 269±28 191±16Density (kg/m3) 33.6 37.1 62.3y ( g )
With increasing CNWs content: Cell size decreased and density were both increasedy
Control foam 1 wt% whiskers foam 5 wt% whiskers foam
17
Control foam 1 wt% whiskers foam 5 wt% whiskers foamScale bar: 500 μm
Chemical structure FT IRChemical structure - FT-IR% NH
ssio
n, %
NH
O-CONC=O
Control foam
Tran
smis
CO-NH
NC O
1% whiskers foam
T
Aliphatic CH3, CH2, CH
5% whiskers foam
4000 3500 3000 2500 2000 1500 1000 5001
C-ONHOC=O5% whiskers foam
18
Wave number, cm-1
Mechanical propertiesMechanical properties
CNW content 0 wt% 1 wt% 5 wt%Strength (MPa) 0.198±0.010 0.255±0.025 0.519±0.008Modulus (MPa) 4.07±0.24 5.35±0.19 12.82±0.14( )
0.6 0 % whiskers1 % whiskers
0.4
0.5
MPa
1 % whiskers 5 % whiskers Strength 162% , modulus 215%
0.2
0.3
Stre
ss, M
Strength 29% , modulus 31%
0 5 10 15 200.0
0.1
St i %
19
Strain, %
Compressive stress strain curves
Thermal stability – DSC & TGA
Both Tg and Td values0 wt% 1 wt% 5 wt%
Tg (ºC) 89 104 104
Both Tg and Td valuesare increased!
16 % f li i b d PU fTd (ºC) 247 263 296
0 % whiskers
16 wt% for non-lignin based PU foam EOL-based foams would give a better fire
retardant property
ss
0 % whiskers 1 % whiskers5 % whiskers
0 % whiskers 1 % whiskers 5 % whiskers
ow
Wei
ght l
os 5 % whiskers
Hea
t Flo
21 wt% char28 % h
0 100 200 300 400 500 600 700Temperature oC
0 50 100 150 200T t oC
28 wt% char24 wt% char
20
Temperature, oCTemperature, oC
DSC curves TGA curves
Summary
OxyEOL is a suitable alternative polyol to prepare rigid PU foam with a uniform cell size and low density along with reasonable mechanical strength and thermal properties.
The addition of cellulose nanowhiskers up to 5 wt% d ti ll i d th i d th ldramatically increased the compressive and thermal properties.
21
I would like to acknowledgeI would like to acknowledge
Financial support from IPST fellowship programpp p p g
22