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Thermomechanical Properties of POSS-Polymer Hybrids
Andre Lee, H.P. Geng (MSU)
S.H.P.;R.L.B.;T.S.H.;S.A.S (AFRL)
J.D.L;J.S. (Hybrid-plastics)
F.J.F. (UCI)
Sept. 8th, 20001st POSS workshop
Outline
• Experimental Approach
• Materials
• Results
• Summary
Us
e
Te
mp
er
at
ur
e
&
Ox
id
at
io
n
Re
si
st
an
ce
Toughness, Lightweight &Ease of Processing
•Hybrid plastics can bridge the barrier between ceramics and polymers
HYBRID PROPERTIES
SPACE
Polymers
Ceramics
Hybrid Inorganic/Organic Polymers
Experimental Approach
• Hybrid Polymers
POSS macromer contain reactive sites (monofunctional, difuncational or multifunctional) is added to organic monomer to form either linear copolymers of hybrid polymeric networks. Since the inorganic phase is chemically attached to the organic phase, it is expected the POSS domain to be homogeneous.
• Nano-Composites
POSS macromer contain no specific reactive sites is mixed with polymer directly. The mixing process range form twin-screw compounding or common solvent solution mixing. The dispersion of POSS macromers depend on the miscibility between polymer and POSS macromer. Property of composite can be affect by the interactions between polymeric matrix and the reinforced POSS fillers.
Physical Aging of Polymeric Materials
VH
T
liquid
Glassy
POSS-Epoxy Material:
Si O Si
O
Si OSi
O
OOO O
SiSi
O
SiSi O
O O
R
R
R
RR
R
R
O
OO
OH
OOOO
OO
O O
H2N C
CH3
H
O CH2
CH
CH3
NH2
Si O Si
O
Si OSi
O
OOO O
SiSi
O
SiSi OO O
R
R
R
RR
R
R
HN C
CH3
H
O CH2
CH
CH3
NH
OH
NH
C
CH3
H
O CH2
CH
CH3
POSS-epoxy prepolymer
NH2
+
100 °C24hrs
CH2
POSS-reinforced epoxy resin
CH
+
CH2
60 °C3hrs
OH
R = c-C6H11 (cyclohexyl), c-C5H9 (cyclopentyl)
O
DGEBPA n~ 0 - 0.5
(CH2)4
n
O
BDGE
CH2
x
CH
JEFFAMINE D-230
CH2
OHx x
10-1
100
101
10-1 100 101 102 103 104 105 106 107
DGEBA/D230/Heloxy67/10%POSS
Rel
axat
ion
Mod
ulus
(G
Pa)
Time (Seconds)
T=63.9oC
ε=0.1%
Small-Strain stress relaxation:
10-2
10-1
100
101
10-1 100 101 102 103 104 105
DGEBA/D230Heloxy67/x%POSS
Rel
axat
ion
Mod
ulus
(GP
a)
Time (Seconds)
ta=64 hours
T=63.9oC
ε=0.1%
9%POSS
5%POSS
0%POSS
Effect of POSS on the relaxation modulus:
102
103
104
105
106
10-1 100 101 102
Cha
ract
eris
tic R
elax
atio
n Ti
me
(Sec
onds
)
Aging Time (Hours)
DGEBA/D230/Heloxy67/x% POSS T= 54.1oC ε=0.1%
9 % POSS
5 % POSS
0% POSS
Effect on the aging rate of epoxy resin:
10
100
10-1 100 101 102
Cha
ract
eris
tic R
elax
atio
n T
ime
(Sec
onds
)
Aging Time (Hours)
5
30
70
T = Tg - 9oC
9%POSS
0%POSS
Effect on the structural equilibrium:
Summary on POSS hybrid copolymers
• The POSS retard the motion of entire polymer chain, which slows all time-dependent properties. For epoxy containing POSS, the rate of physical aging is not affected, but the time to reach structural equilibrium increases as amount of POSS increases. The presence of POSS also enhanced the observed glass transition temperature.
• For PMMA-POSS copolymers, the observed Tg also increase with amount of POSS segments within the copolymer. Furthermore, the POSS segment acts like “crosslinking” junction, which means the copolymer behave more like a crosslinked solid at temperature above Tg rather than like an entangled polymer melt.
TGA of POSS(cyclopentyl8) Black curve; PDMS matrix Green curveBlend of POSS(20wt%)/PDMS Red curve
TGA of POSS(cyclohexyl8) Black curve; PDMS matrix Green curveBlend of POSS(20wt%)/PDMS Red curve
TGA of POSS(Vinyl8) Black curve; PDMS matrix Green curveBlend of POSS(20wt%)/PDMS Red curve
TGA of POSS(Phenethyl8) Black curve; PDMS matrix Green curveBlend of POSS(20wt%)/PDMS Red curve
TGA of POSS(Styrly8) Black curve; PDMS matrix Green curveBlend of POSS(20wt%)/PDMS Red curve
TGA of POSS(cyclopentyl7Vinyl1) Black curve; PDMS matrix Green curveBlend of POSS(20wt%)/PDMS Red curve
TGA of POSS(cyclopentyl7styryl1) Black curve; PDMS matrix Green curveBlend of POSS(20wt%)/PDMS Red curve
Summary on POSS-Polymer Blends
• Depending on the the organic group surrounding the inorganic cage, it is possible for POSS macromer to “dissolve” in the polymeric matrix.
• With proper selection of POSS macromers, it is possible to improve the thermal degradation resistance of polymers.
• With proper selection of POSS macromers, it is possible to improve the heat deflection temperature of polymers.
• There is a general lack of understanding of property improvement observed in POSS-polymer blends.
Size & Shape
POSS Blending
POSS Polymer Incorporation
Si
Si
O
O
Si
Si
Si
Si
O
O
OSi
Si
O
OO
OO
R R
R
R
R
R
R
O
R
Si
Si
O
O
Si
Si
Si
Si
O
O
O
O
SiO
Si
O
OO
OO
R R
R
R
R
R
RSi
Si
O
O
Si
Si
Si
Si
O
O
O
O
SiO
Si
O
OO
OO
R R
R
R
R
POSS Bead POSS Pendent POSS Crosslinking
size
shape
solubility
• Maximizing property enhancements through changes at the nano level
• Polymer miscibility vs. POSS/POSS interactions
Concerted Research Effort:
Structure-Property Relationships
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