Upload
cymy
View
220
Download
0
Embed Size (px)
Citation preview
8/13/2019 15 PolyProp
1/12
Polymers 1m
0 3. nm 104chain units long molecules
H
CH
H
CH
H
CH
H
CH
H
CH
H
CH
H
CH
H
CH
O
CH2OH
HO OH
O
thin, flexible
polyethene
apolar
hydrophobic
thick, rigid
cellulose polarhydrophylic
10nm
coiled
O
CH2OH
HO OH
O
O
CH2OH
HO OH
O
8/13/2019 15 PolyProp
2/12
HCH
HCH
HCH
HC
HCH
HCH
CH
HCH
HCH
entanglement
Cross Links
cross links make a polymer insoluble
8/13/2019 15 PolyProp
3/12
crystalline
(no diffusion)
amorphous
with some space
open, that allowsmotion of permeants
0 < crystallinity < 1
depends on the
polymer and its his torydimensions 10 nm
Crystalline and Amorphous
8/13/2019 15 PolyProp
4/12
108
106
104
modulus of
elasticity
EN m 2
200 300 400 500
Tg Tm
glass rubber liquid
temperature
T
K
glass transition
melting
temperature
rigid creeping
flow
1010
102
with cross
linking
Glass Transition Point
8/13/2019 15 PolyProp
5/12
8/13/2019 15 PolyProp
6/12
polymer (1) solvent (2)
solvent
activitya2
10 2 100
volume fraction
2
101
100
10 1
10 2
polymer and solvent
fit on a 3D lattice
factor 2.71
a V
V2 2
2
1
11
exp
V V2 1
linear
Flory-Huggins
8/13/2019 15 PolyProp
7/12
V
V
2
1
10 2
10 3
10 4
solvent
activity
10 2
10 4
10 6
10 0
10 2 100
10010 2volume
fraction
2
mole
fraction x2
a2 activity is a simple functionof the volume fraction
strong volume and non-
ideality effects if we usemole fractions
Do not use the
Polymer to defineMole Fractions
8/13/2019 15 PolyProp
8/12
a V
V2 2
2
1
1 1
21
exp
non-ideality parameter
0 solvent and polymerdislike each other
0 solvent and polymer
are similar
solvent and polymer
attract each other
0
solvent
activitya2
10 2 100
volume fraction
2
101
100
10 1
10 2
2
1
0-1
demixing!Non-ideality
8/13/2019 15 PolyProp
9/12
Swelling (1)
a BV
VC2 2 1 1
2 21
1 3
expB nc
1
2
number of chain units
between each cross link
a cross linked polymer:
little springs under an
internal stress
solvent
8/13/2019 15 PolyProp
10/12
Swelling (2)
1.0
0.1
0.01
0.0 1.0 2.0
0
1
2
swelling parameter
gels, protein separation media
reverse osmosis
pervaporation
gas separations
(high pressure)
2
BV
VC
2
8/13/2019 15 PolyProp
11/12
Solubility of Vapour in Polymer
activity of vapour 2 activity of 2 in polymer
a p
p2
2
2
a BV
VC2 2
21
exp
1
1
equilibrium
a a2 2
2 2
22
1
1
p
p BV
VCexp
Henry coefficient
8/13/2019 15 PolyProp
12/12
Distribution between Solvent and Polymer
polymer (1)
solvent (2)
solute (3)
1 02large
3small
12
3
equilibrium calculation: a a2 2
a a3 3
a V
VB
V
VC3 3 1
3
2
23
1
1 31
exp
swelling: Fig 15.10
a
V
V3 3
3
2
21 exp
3
3 constant
volume distribution
(Nernst) coefficient