department of chemical engineering and chemistry 1/24 thermoreversible crosslinking of maleic...
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/department of chemical engineering and chemistry 1/24
Thermoreversible crosslinking of maleic
anhydride-grafted ethylene-propylene
copolymers
An evaluation of hydrogen bonded and ionic networks
Sun Chunxia
March 2005
Coaches:
Mark van der Mee
Han Goossens
/department of chemical engineering and chemistry 2/24
Contents
1)Introduction: crosslinking of rubbers2)Objectives3)Modification with alkylamines - Preparation - Results - Conclusions4)Modification with metal acetylacetonates
- Preparation- Results- Conclusions
5)Future work
/department of chemical engineering and chemistry 3/24
Crosslinking of rubbersCrosslinking of rubbers
Crosslinking transforms non-elastic base material into an elastic material
Two main commercial technologies:1) Sulphur vulcanisation:
2) Peroxide curing
s s
s s
sulphur
heating
Why?
How?
/department of chemical engineering and chemistry 4/24
Crosslinking of rubbers
• Prevents processing in the melt
• Complicates recycling of scrap &
used products
Problems:
х
/department of chemical engineering and chemistry 5/24
Thermoreversible crosslinking
Thermoreversible crosslinking of
rubbers:
Low temperature: crosslinked material
High temperature: crosslinks weaken or disappear
Result: A crosslinked elastomer at service temperature
that can be processed at elevated temperatures!
heating
cooling
/department of chemical engineering and chemistry 6/24
Crosslinking of rubbers
Microphase separation into MAn-rich domains
– Driving force is strong attraction between MAn groups
and strong repulsion between polar MAn groups and
apolar EPM chains
– Domains act as physical crosslinks, increasing network
density
0.1
1
10
100
1000
-100 -50 0 50 100Temperature (ºC)
Stor
age
Mod
ulus
(MPa
) EPM
MAn-g-EPM
/department of chemical engineering and chemistry 7/24
Thermoreversible crosslinking
NH
NN
NH2
ZnAc2
O OO
Multiple Hydrogen
Bonding
(2) Melamine
(1) NH3 Triple Hydrogen
Bonding unit
Ionomer
Ureidopyrimidinone
Quadruple Hydrogen Bonding unit
Diol
Reversible ester XL formation
(1) Furfuryl amine
(2) Bismaleimide
Diels-Alder reaction
Diamine
Reversible amide XL formation
(1) Terpyridine
(2) Metal
Metal-Ligand complex
Several thermoreversible crosslinking techniques
/department of chemical engineering and chemistry 8/24
Thermoreversible crosslinking
Hardness [ Sh. A]
E-mod [MPa]
TS [MPa]
EB [%]
CS23C
[%] CS70C
[%] MAn-g-EPM 38 1.6 0.4 550 88 100 MI-g-EPM 49 2.0 0.7 450 76 100 ATA-imide 52 2.4 1.2 310 76 100 ATA-AA 54 2.5 1.4 340 38 86
MA-g-EPM 54 2.8 1.6 320 59 100 MAA-g-EPM 57 3.4 6.1 590 24 60 ATA-imide + CoAcac
51 2.4 7.5 720 - 56
Previous work in this project
So far, pure HB is very weak !
/department of chemical engineering and chemistry 9/24
Thermoreversible crosslinking
How to improve it ?(1)Combination with ionic
interactions
(2)Arrays of HB:N
O N N NR
O
H H
H
N
ONNNR
O
HH
H
Ureidopyrimidinones
(UPy’s)
(E.W. Meijer et al.)
/department of chemical engineering and chemistry 10/24
Objectives
1) Modification of MAn-g-EPM with primary amines to an amide-salt Significantly improves properties with NH3, which is highly volatile
DECREASE IN PROPERTIESImide formation will occur at elevated temperatures
DECREASE IN PROPERTIES
2) Addition of metal acetylacetonates (MeAA) to MAn-g-EPM based
imides
Modification of MAn-g-EPM with 3-amino-1,2,4-triazole (ATA) only slightly improves
the properties
Addition of different MeAA to the ATA-imide introduces ionic interactions
Objectives
ATA
Use less volatile primary amines (C3, C6, C10, C18)
Study the mechanism for different metals (Co & Zn) and different imides
/department of chemical engineering and chemistry 11/24
Results (I)-Alkylamines
OO
O OH NH
OO
R
1eq R-NH2
o- NH
OO
RRNH3+
O
N
R
excess R-NH2
TMAn-g-EPMamide-acid amide-salt
imide
O
Compression moulding
at 180 ºC for 20 minutes
Modification of maleic anhydride-grafted EPM with alkylamines
Preparation
Solution in THF at R.T.
/department of chemical engineering and chemistry 12/24
Results (I)- Alkylamines
1900 1800 1700 1600 1500 1400 13000.00
0.05
0.10
0.15
0.20
Inte
nsity
(a.
u.)
Wavenumber [cm-1]
MAn-g-EPM decylamine hexylamine propylamine octadecylamine
Peak position
(cm-1)
Peak
assignment
1865 Anhydride
1785 Anhydride
1710 Acid
1640 Amide I
1555 Amide II
Synthesis
1 eq AlkylamineOH HN
OO
R
/department of chemical engineering and chemistry 13/24
Results (I)- Alkylamines
1900 1800 1700 1600 1500 1400 13000.00
0.05
0.10
0.15
0.20
Inte
nsity
(a.
u.)
wavenumber [cm-1]
hexylamine 1eq hexylamine 2eq hexylamine 5eq hexylamine 10eq
FTIR spectra hexylamine
modified MAn-g-EPM
FTIR spectra octadecylamine
modified MAn-g-EPM
Different ratios
/department of chemical engineering and chemistry 14/24
C10 > C18 > C3 > C6
Results (I)- Alkylamines
•Significant improvement in
tensile properties
•Trends in TS and modulus not
consistent with alkyl length
Two competing effects:
Long tails disturb aggregate
formation
- poor properties
Long tails can crystallize
- improved properties
Tensile tests
1 eq Alkylamine
0
0.4
0.8
1.2
1.6
2
0 200 400 600 800 1000
Engineering strain [%]E
ngin
eerin
g st
ress
[MP
a]
MAn-g-EPMhexylaminepropylamineoctadecylaminedecylamine
/department of chemical engineering and chemistry 15/24
Results (I)- Alkylamines
hexylamine octadecylamine
• Modulus and TS increase with increasing
amount of alkylamine
• C18 > C6 crystallization?
Different ratios
0
0.4
0.8
1.2
1.6
2
2.4
2.8
3.2
3.6
4
0 200 400 600 800 1000Engineering strain [%]
Engin
eerin
g str
ess [
MPa
]
MAn-g-EPM
octadecylamine 1eq
octadecylamine 2eq
octadecylamine 5eq
0
0.4
0.8
1.2
1.6
2
2.4
2.8
3.2
3.6
4
0 200 400 600 800 1000Engineering strain [%]
Engin
eerin
g str
ess [
MPa
]
MAn-g-EPMhexylamine 1eqhexylamine 2eqhexylamine 5eqhexylamine 10eq
/department of chemical engineering and chemistry 16/24
Results (I)- Alkylamines
• Imide formation gives poor properties
• Poor properties of C18-imide:
No significant crystallization!
Imide of alkyl-amide acids
OH NH
OO
Ramide-acid
O
N
R
imide
OCM
180 oC, 80 bar
/department of chemical engineering and chemistry 17/24
Results (I)- Alkylamines
• FTIR spectroscopy can be used to study reaction of MAn-g-EPM with
amines
• Modification with different primary amines improves the tensile
properties
significantly
• Modulus and TS increase with increasing amount of alkylamine
• Imide formation leads to poor properties
Conclusions
/department of chemical engineering and chemistry 18/24
Results (II)- Metal acetylacetonates
• Metal acetylacetonate (CoAA or ZnAA) added to imide (ATA
or
C3) in THF at RT
• Definition of 1 eq and 2 eq MeAA:
1 eq MeAA: adding enough metal to coordinate with all the
oxygen atoms from the imide groups, assuming a
fourfold coordination
2 eq MeAA: adding the double amount of metal
HB with ionic interaction systems
Preparation
O
N
R
imide
O
/department of chemical engineering and chemistry 19/24
Results (II)- Metal acetylacetonates
1 eq MeAA to ATA-imide 2 eq MeAA to ATA-imide
Tensile tests
0
1
2
3
4
5
6
0 100 200 300 400 500 600Engineering strain [%]
Engin
eerin
g stre
ss [M
Pa]
MAn-g-EPMATA-imideATA-imide+2eq CoAAATA-imide+2eq ZnAA
0
1
2
3
4
5
6
0 100 200 300 400 500 600Engineering strain [%]
Engin
eerin
g str
ess [
MPa
]
MAn-g-EPMATA-imideATA-imide+1eq ZnAAATA-imide+1eq CoAA
/department of chemical engineering and chemistry 20/24
Results (II)- Metal acetylacetonates
1 eq of MeAA to propylimide 2 eq of MeAA to
propylimide
Tensile tests
0
0.5
1
1.5
2
2.5
3
0 100 200 300 400 500 600 700 800Engineering strain [%]
Engin
eerin
g str
ess [
MPa
]
propylimide
MAn-g-EPM
propylimide+1eq CoAA
propylimide+1eq ZnAA
0
0.5
1
1.5
2
2.5
3
0 100 200 300 400 500 600 700 800Engineering strain [%]
Engi
neer
ing
stre
ss [M
Pa]
propylimide
MAn-g-EPM
propylimide+2eq ZnAA
propylimide+2eq CoAA
/department of chemical engineering and chemistry 21/24
Results (II)- Metal acetylacetonates
N
OO
N
NNH
Co
Zn
N
OO
C3H7
Mechanism for coordination
ATA-imide propylimide
ATA-imide : 1eq Co >> 1eq Zn; 2 eq Zn ≈ 2 eq Co; 2 eq Zn > 1 eq Zn
C3-imide : Co ≈ Zn; 1 eq > 2 eq
/department of chemical engineering and chemistry 22/24
Results (II)- Metal acetylacetonates
Following mechanism was proposed to explain the results:
• In propylimide, Co and Zn can only weakly coordinate with O,
leading to comparable properties
• In ATA-imide, additional strong coordination with N from the
ATA-ring is
possible. Two different situations:
– Co likes to coordinate with N, so good properties are obtained for
both low and high amounts
– Zn likes to coordinate with O, so an excess of Zn has to be added to
force strong coordination with N to get good properties.
Conclusions
/department of chemical engineering and chemistry 23/24
Future work
• The effect of the tail length and the amount of the primary
amines on the properties will be further investigated
• The influence of temperature and amount of
octadecylamine on crystallization and mechanical properties
will be studied
• Other systems of HB combined with ionic interactions will
be prepared and evaluated, trying to avoid imide formation
•The exact coordination mechanism of MeAA modified MAn-
g-EPM will be further investigated by EXAFS
EXAFS can get information about coordination around metals
Future work
/department of chemical engineering and chemistry 24/24
Acknowledgements
• Otto van Asselen
• Jules Kierkels
• All other colleagues of SKT
Acknowledgement
/department of chemical engineering and chemistry 25/24
Structures and Names
OH OHOO
O NH2
OO OONH
OH NHOO
NN
NH
NOO
NN
NHNH4
MA-g-EPM MAA-g-EPM MI-g-EPM ATA ATA-imide
+
/department of chemical engineering and chemistry 26/24
Mechanism of 4 fourfold coordination
N
OO
N
NNH
N
O O
N
NHN Co
N
OO
N
NNH
N
O
ON
N
HN
Co
NO
O
N
NHN
ATA-imide +1 eq CoAA ATA-imide +2 eq CoAA
/department of chemical engineering and chemistry 27/24
Mechanism of 4 fourfold coordination
N
OO
N
NNH
N
O
ON
N
HN
Zn
NO
O
N
NHN
N
O
O
N
N
NH
N
O
ON
N
HN
Zn
NO
O
N
NHN
N O
O
N
NNH
ATA-imide + 1 eq ZnAA ATA-imide+ 2 eq ZnAA
/department of chemical engineering and chemistry 28/24
Future work
OOO OH NH
OO
R
1eq R-NH2
o- NH
OO
RRNH3+
ON
R
excess R-NH2
TMAn-g-EPMamide-acid amide-salt
O
OH HNOO
NN
NH
NOO
NN NH
ATA (amide-acid)
ATA-imide
MeAA
o- NH
OO
RM+
imide
ionomer
base
R:H, C3, C6, C10, C18
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