Soy-based Polyurethane Rigid Foam - Research groups

Soy-based Polyurethane Rigid Foam - Research groups

Soy-based Polyurethane Rigid Foam
Suqin Tan
Committee Members:
Chris Macosko
Tom Hoye
Marc Hillmyer
University of Minnesota
Date: Aug. 3rd, 2010
THESIS DEFENSE
1
Polyurethane Rigid Foam
• Excellent insulating property
• High strength-to-weight ratio
• Durable
Production over 3 billion lbs/yr
Randall, D.; Lee, Steve. The Polyurethanes Book; John Wiley & Sons, Ltd. 2002
2
THESIS DEFENSE
How to Make Polyurethane Foam?
Blowing Reaction
Foam cell structure
Urea link
Gelling Reaction
polyol
Physical blowing agent is also used
isocyanate
Urethane link
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Opportunity for Bio-renewable Feedstock
 Increasing environmental conscious
Life Cycle Analysis*
• 23% reduction in total energy demand
• 61% reduction in non-renewable energy use
• 36% less global warming emissions
*Wazirzada Y. ‘ Commercialization of Bio-Polymers A Case Study’, Cargill Biobased Polyurethanes, 2009
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Polyol from Soybean Oil
Hydroformylation[2]
Epoxidation[1]
H2, catalyst
H2, CO, catalyst
MeOH, H2O
H2O2
Ozonolysis[3]
O3/ O2
NaBH4
1.
2.
3.
THESIS DEFENSE
Petrovic ZS et.al., US Patent 6,433,121; 2002
Guo A, Demydov D, Zhang W, Petrovic Z. S.
J. Polym. Environ. 2002, 10, 49.
Petrovic Z. S, Zhang W, Javni I.
Biomacromolecules. 2005, 6, 713.
5
Research Goal
• Formulate polyurethane rigid (PUR) foam from soy polyol
• Match properties of soy-based PUR foams with those of
petroleum-based PUR foams
• Understand mechanism behind property deficiencies and
develop strategies to improve them
Soy-based polyol (SBOP)
O
OH
O
OMe OH
O
O
O
OH
OH
OH
O
OMe OMe
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6
Can We Make PUR Foam From Soy Polyol?
Foam formulation
Foaming steps
Chemical
Weight (pbw)
Polyol
(petro / soy)
100
1.
Water
1.9
Gelling catalyst
2.1
Polyol
Catalysts 2.
n-pentane
Water
Surfactant
Blowing catalyst
0.5
Surfactant
1.6
n- pentane
9.6
Isocyanate
(ISO index=110)
126.7
3.
isocyanate
10-15 seconds
2500 rpm
stirrer
800 mL
container
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Yes! But...Glycerol is Needed
Control I
Chemical (pbw)
Control I
SBOP I
(w/ glycerol)
Polyol
(petro/ soy)
100
100
Water
1.9
1.9
glycerol
--
16
Gelling catalyst
2.1
3.7
Blowing catalyst
0.5
1.1
Surfactant
1.6
2.2
n- pentane
9.6
16
Isocyanate
(ISO index=110)
126.7
140.8
SBOP I
(w/ glycerol)
SBOP I
(w/o glycerol)
ISO index=100
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Foam Properties Comparison
Foam
Control I
40.3±0.6
SBOP I
(w/o glycerol)
61.2±7.9
SBOP I
(w/ glycerol)
41.8±0.2
Density
(kg/ m3)
Tg
( °C)
k value
(mW/m∙K)
Δk*
(mW/m∙K)
Compressive strength
(kPa)
Cell size
(um)
140±4.4
144±2.4
216±4.4
23.3±0.3
36.3±3.5
22.8±1.2
2.60
N/A
4.62
208
190
206
342±46
poor
300±81
* Δk= k60-k0
By adding glycerol, soy foams have comparable density and k value, much higher Tg and
compressive strength, and smaller average cell size
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Thermal Conductivity (k value) Aging
Foam k value aging test:
Sample size: 2.5”*2.5”*2.5”
Temperature: 70 °C
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Surfactant
Cloud point test
Surfactant structure: polydimethysiloxane
polyether graft copolymer
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Surfactant hydrophobicity:
7105>9204>3805>8404
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Can Surfactant Help?
Increasing surfactant hydrophobicity
7105>9204>3805>8404
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Foam k value aging test
12
Foams from Different Surfactants
Foam property
Control I
SBOP I_8404
SBOP I_3805
SBOP I_9204
SBOP I_7105
Density
40.3±0.6
41.8±0.2
43.2±0.1
46.7±0.1
47.0±0.2
Tg ( °C)
144
218
206
208
193
k value
23.3±0.3
22.8± 1.2
25.5±0.5
24.9± 0.7
27.8± 0.6
208
206
173
245
206
342±46
301± 81
271±72
227±59
302±108
(kg/m3)
(mW/mK)
Compressive
Strength (kPa)
Cell size (um)
Soy foams have higher density and k value with increasing
surfactant hydrophobicity
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Soy-based Foams from Glycerol Aided Formulation
• Results summary
– By adding glycerol, soy-based PUR foams had comparable
density and k value, much higher Tg and compressive strength,
and smaller average cell size
•
Problem
– High glycerol level is not favored (friability, flammability)
•
Next step
– Develop new foam formulation
– Partial & complete SBOP substitution
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Glycerol Free Route to Make PUR Foams
Polyol
OH number
(mg KOH/g)
Molecular Weight
(g/mol)
Functionality
Viscosity
(mPa∙s)
Acid Value
(mg KOH/g)
Water content
(ppm)
Manufacture
/Resource
Control I
Control II
Jeffol ® SD-361 Jeffol® FX31-240
360
240
SBOP
240
690
700
1200
4.4
2500
3.0
250
4.4
8900
--
--
1.7
--
--
3000
Huntsman
Huntsman
Experimental
(Cargill)
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Glycerol Free Formulation
New Foam formulation
Chemical
Weight (pbw)
Polyol
(petro / soy)
100
Water
2.6
Diethylene glycol
6.0
Gelling catalyst
4.0
Blowing catalyst
1.0
Surfactant
2.0
n- pentane
8.0
Isocyanate
(ISO index=125)
130
Control,25% , 50% , 75% , 100% SBOP
ISO index=100
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Foam Properties
Foam
Control II
25% SBOP II
50% SBOP II
75% SBOP II
100% SBOP II
Density
(kg/m3)
39.5±0.8
39.7±0.9
39.8±1.1
41.3±1.3
46.4±2.0
Tg
(°C)
98
107
123
134
142
k value
(mW/(m∙K))
24.4±0.04
--
25.4±0.14
--
24.7±0.07
Compressive
strength
(kPa)
115
--
138
--
170
Cell size
(um)
431±91
392±84
390±102
375±128
386±102
Soy foams have comparable density and k value, much higher
Tg and compressive strength but smaller average cell size
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Foam Aging Test
Sample size: 2.5”*2.5”*2.5”
Aging condition: oven, 70°C
Foams from 100% SBOP aged faster
than control foams
Comparison between experimental and
predicted foam aging
Modesti M, Lorenzetti A, Dallacoua C. Polym. Eng. Sci. 2004, 44, 2229
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Foam Aging: Different Gas Permeabilities
b
gas
k value
(mW/mK)
N2
24.6
O2
24.9
CO2
15.3
n-C5H12
13.7
Mean partial pressure of physical blowing agent (245fa), CO2, air and total cell
pressure during aging
Modesti M, Lorenzetti A, Dallacoua C. Polym. Eng. Sci. 2004, 44, 2229
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Gas Permeation: Thin Film
• Polyurethane thin film
– eliminate cell structure issue
– study gas permeation of polyurethane solid
Polyol
DEG
acetone
isocyanate
Film cure
cut
HDPE sheet and aluminum frame
THESIS DEFENSE
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Nitrogen Permeation
Barrer is a non-SI unit of gas permeability, 1 Barrer=10-10 (cm3 O2) cm·cm-2 s-1
cmHg-1, here ‘cm-3O2’ is a molar quantity of O2
100 % Soy-based PUR films had much higher N2 permeation
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Proposed Mechanism
Permeation rate of gases decreases as:
• polymer structural symmetry increases
• polymer cohesive energy density increases
Permeability of polymer films to O2 at 25-30 °C
Polymer
δ
(Cal/cm3)1/2
O2
permeability
(Barrer)
Polymer
δ
(Cal/cm3)1/2
O2
permeability
(Barrer)
1,4polybutadiene
8.3
191
Polyvinylidene
chloride
9.7
(PVC)
0.05
Natural rubber
8.1
5000
1,4polybutadiene
8.3
191
Comyn, J. Polymer Permeability. Elsevier Applied Science Publishers, London and New York, 1985.
Hiemenz C. P, Lodge P. T. Polymer Chemistry. CRC Press. 2007.
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Soy-based Polyol vs. Petroleum-based Polyol
polyol structure comparison
Control
Mw= 700 g/mol
fn= 3.0
SBOP
Mw= 1200 g/mol
fn= 4.4
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Polymer Cohesive Energy Density: Swelling Test
DMF (δ=12.14 (Cal/cm3)1/2)
THESIS DEFENSE
Qt :mole percent uptake at time t
ni:moles of solvent taken up at
time t;
mi:dry mass of the sample;
Q∞ :mole percent uptake at
equilibrium.
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Polymer Solubility Parameter
solvent
δ
(Cal/cm3)1/2
chloroform
9.21
tetrahydrofuran
9.52
Dichloromethane
9.93
Pyridine
10.61
N, Ndimethylformamide
12.14
methanol
14.28
The plot of the equilibrium degree of swelling vs. solvent
solubility parameter
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Research Summary & Future Direction
• PUR foams were made from soy polyol
Compared with control foams/films:
– all soy foams had comparable density and initial k value, much higher Tg
and compressive strength and smaller average cell size
– 50% soy foams had similar k value aging
50% soy thin films had comparable N2 permeation
– 100% soy foams aged much faster than petro-based foams
100% soy thin film had much higher N2 permeation
• Future Work
– Proposed mechanism: polymer cohesive energy density
• lower polymer cohesive energy density leads to higher N2 permeation
for soy-based PUR thin films
• introduction of polar side groups into soy polyol to increase polymer
cohesive energy density
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Acknowledgements
• Financial support :
• Collaborators: Tim Abraham, Don Ference, Dave Henton, Wei Zhang
& BiOH labs (Cargill)
•
Advisors Chris Macosko & Tom Hoye, Committee members
•
Macosko research group & polymer group
• Undergraduate researchers: Jason Zhang, Darius Jaya
•
Machine shop, staff and administrative assistants
•
Family and friends
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Questions and Comments
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Needle Probe Method
(top) scheme of needle probe setup for k
value measurements
(right) Pulse/temperature measuring
circuit
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Needle Probe Method
Thermal Conductivity Estimation vs. tm
0.7
0.6
0.5
K [W/m-K]
0.4
0.3
0.2
0.1
0.0
2000
7000
12000
17000
22000
tm [mS]
k value versus time curve from needle probe measurement
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Adiabatic Temperature Rise
Original temperature profile (formulation I w/o pentane added)
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Adiabatic Temperature Rise
Temperature profile comparison for Control A foaming with or without pentane added
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Adiabatic Temperature Rise
p ( NCO ) 
Trxn 
Q

C p mT
H r , u
r Tm
Trxn
mw
m
 H r , r OH f n
Mw
M OH
C p mT
p: isocyanate conversion
r : stoichiometric ratio of functional groups, which is unity in this case
∆Tm : temperature rise during foaming measured via thermocouple
∆ Trxn : maximum temperature rise based on an adiabatic reactor
Q : total amount of heat generated
∆ Hr (J/g) : heat of reaction, the heat of reaction for urea and urethane formation were
taken as –125.5 kJ/mol and –93.9 kJ/mol
m (g) : reactant mass
Cp (J/g/oC):specific heat capacity of foam, which is 1.8
M (g/mol): molecular weight
fn : polyol functionality,
the subscripts, u,r, w, OH, and T indicate urea, urethane, water, polyol and total,
L. Zhang, Ph. D Thesis, Univeristy of Minnesota, 2008.
respectively.
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SEM Images (formulation I)
Control I
SBOP I w/o glycerol
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SBOP I w/ glycerol
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34
Cell Size Analysis
ImageJ analysis
N. C. Hilyard, A. Cunningham. Low density cellular plastics-Physical basis of behaviour,
Chapman & Hall, 1994.
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SBOP I_7105
SBOP I_3805
Control I
SBOP I_8404
SBOP I_9204
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SBOP I_3805
SBOP I_7105
25.11 mW/mK
43.2 kg/m3
dn=271 um
SBOP I_8404
25.87 mW/mK
41.8 kg/m3
dn=300 um
27.19 W/mK
47 kg/m3
dn =302 um
control
24.06 W/mK
40.3 kg/m3
dn =342 um
SBOP I_9204
26.18 W/mK
46.7 kg/m3
dn =226 um
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Cloud Point Test
Cool down
until clear
again
Water bath
(80°C)
0.1 % surfactant solution
(DI water as the solvent)
T. Inoue, H. Ohmura, D. Murata. J. Colloid Interface Sci 2003, 258, 374.
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Dynamic Mechanical Analysis (formulation I)
DMA curves showing G’ (left) and G” (right) as a function of temperature
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Tg Determination (formulation I)
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25% SBOP II
50% SBOP II
Control II
75% SBOP II
100% SBOP II
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50% SBOP II
25% SBOP II
75% SBOP II
Control II
100% SBOP II
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Dynamic Mechanical Analysis (formulation II)
DMA curves showing G’ (left) and G” (right) as a function of temperature
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Tg Determination (formulation II )
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IR Analysis of Polyurethane Thin Film
IR spectrum comparison of freshly made and cured polyurethane thin films:
(left) control II, (right) SBOP II.
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