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1
Polymer Thermodynamics
Prof. Dr. rer. nat. habil. S. Enders
Faculty III for Process ScienceInstitute of Chemical EngineeringDepartment of Thermodynamics
Lecture
0331 L 337
1. Introduction and Basic Thermodynamics
2Polymer Thermodynamics
Lectures Friday 12.00 – 14.00 o‘clock14.00 – 16.00 o’clockRoom: BH-N 243
schedule
from 12. of April until 17. of May 2013
3Polymer Thermodynamics
Contact Information:Tel.: 030 314 22755 Fax: 030 314 22406 E-Mail: Sabine.Enders@tu-berlin.deaddress: TU Berlin, Sekr. BH 7-1, Ernst-Reuter Platz 1, 10587 Berlin
Consulting hours: Monday 14-15 o’clock, room BH 703
Prof. Dr. rer. nat. habil. S. EndersFaculty III for Process ScienceInstitute of Chemical EngineeringDepartment of Thermodynamics
http://www.thermodynamik.tu-berlin.deactual information's:
News Lecture presentations and exercises Internet Links
Lehre → Polymer Thermodynamics
4
Polymer ThermodynamicsRecommended literature
• J. Bicerano, Prediction of Polymer Properties, Marcel Dekker, 1993.• H.G. Elias, Makromoleküle; Band 2, Physikalische Strukturen und Eigenschaften,
Wiley-VCH Verlag, 2000.• K. Kamide, Thermodynamics of Polymer Solutions Phase Equilibria and Critical
Phenomena, Elsevier, 1990.• P.J. Flory, Principles of Polymer Chemistry, Cornell University Press 1953.• G. Astarita, S.I. Sandler, Kinetic and Thermodynamic Lumping of Multicomponent
Mixtures, Elsevier, 1991.• D.W. van Krevelen, Properties of Polymers, Elsevier, 1990.• R.P. Danner, M.S. High, Handbook of Polymer Solution Thermodynamics,
American Institute of Chemical Engineers, USA, 1993. • R. Koningsveld, W.H. Stockmayer, E. Nies
Polymer Phase Diagrams: A TextbookOxford University Press (2001) ISBN-13: 9780198556343.
• L.H. Sperling, Introduction to Physical Polymer Science, 3 rd. Ed., Wiley –Interscience (2001).
5Polymer Thermodynamics
Examination
oral, individual examinationduration 30 minutescontent: topics of the lecturePlease, bring along student ID and personal IDPlease, make a appointment in my office or via email
characteristic feature
Time: 21. of May until 24. of May 2013
6Polymer Thermodynamics
„If you do not know thermodynamics youwould not get a bad design, you would get a wrong design!“
M. Parker, CEO Dow Chemical Company (2002)
Why do we need polymer thermodynamics ?
7Polymer Thermodynamics
Why do we need polymer thermodynamics ?
polystyrene
Which liquid can be put in cups made from polystyrene ?
Interaction of liquids (solvent) with polymers
solubility of polymersthermic stability of polymers
8Polymer Thermodynamics
Why do we need polymer thermodynamics ?
Polymer Production: based on Petrol (Petrol distillation)
Which polymers can be produced ? At which temperature ? Is the polymerization reaction a voluntary process ?Which solvent should be used ?
rubber productionplant
monomer
9Polymer Thermodynamics
Why do we need polymer thermodynamics ?
The most industrial polymer production processes take place in solutions.How it is possible to remove the solvent ?Which solvent should be used ?How can we avoid undesired phase separation in the production plant ?What are the thermodynamic properties (i.e. heat capacity, vapor pressure)
of polymer solutions?
10Polymer ThermodynamicsWhy do we need polymer thermodynamics ?
1. example: foam polystyrene = expanded polystyrene = EPS
Application of EPS
construction (heat, sound and tension insulation)
street buildinginsulating slab
11Polymer ThermodynamicsWhy do we need polymer thermodynamics ?
1. example: foam polystyrene = expanded polystyrene = EPS
Application of EPS
safety helmet for bikers
blister packaging material of any shape
polystyrene plant (Dow Chemical Company)
Thermodynamic task: Description of the involved phaseequilibria during the whole production process.
12Polymer Thermodynamics
Why do we need polymer thermodynamics ?
1. example: foam polystyrene = expanded polystyrene = EPS
Expansion: Polystyrene particle having a diameter of 1mm will be expanded using pentane.
first step: Heating of PS to 100-120°C(T>Tg) using hot water vapor
second step: Pentane will be evaporated and pressed into polymer particles. This leads to new particle (pearls) having a diameter of 3 mm.
Thermodynamic task: Can we predict the glass temperature
of polymers?What is the vapor pressure of pentane?Does the interfacial properties play an
important role?
13Polymer ThermodynamicsWhy do we need polymer thermodynamics ?
1. example: foam polystyrene = expanded polystyrene = EPSExpansion: Polystyrene particle having a diameter of 1mm will be expanded using
pentane.Third step: Expanded polymer particle will be given in the desired forming.Fourth step: Little holes will be made on the polymer wall.Fifth step: Hot air will be pressed in the system in order to remove the pentane.Sixth step: Heating the polymer well above the glass transition temperature in
order to increase the volume by the factor 2 – 2.5.Seventh: Cooling down the whole system. The foam takes his final shape.Eight: The product will be stored several days in order to allow the completely remove
of pentane.Thermodynamic task: At which conditions will the air be able to replace pentane ?How will the volume of the polymer be changed during heating and cooling procedures?Does a special interaction between the polymer and the fluid play a role ?At which temperature can the critical state of the gas be found ?Is there a potential for simplification or improvement of the process ?What is the role of permeation in the procedure ?
14Polymer Thermodynamics
Why do we need polymer thermodynamics ?
Foaming of Polymers
Thermodynamic task:It is possible to use an alternative gas (hydrogen, nitrogen, carbon dioxide)?At which pressure can the foaming process be carried out ?
1. example: foam polystyrene = expanded polystyrene = EPS
15Polymer Thermodynamics
Why do we need polymer thermodynamics ?
2. example: polymers for medical applications
glasses, contact lenses, denture
valve, blood vessels, disc, artificial nervesdialysis membranes, dialysis tubes, artificial hip joint endoprosthesisimplant for skin
artificial knee joint
others 11%
16Polymer Thermodynamics
Why do we need polymer thermodynamics ?
2. example: polymers for medical applications
Application: bags for blood, drug-formulations,safety gloves, tubes, blister-package
Advantage: suitable for thermic formability,high flexibility, excellent chemical resistance, very low potential for allergy
Disadvantage: phthalates is used as softener, but they can be toxic (teratogen and cancerogen) for humans
Challenge for thermodynamics:How can we produce ultra pure PVC with a negligible amount of softener ?What is the relation between polymer properties (i.e. molecular weight distribution ) and flexibility ?Can we use phase equilibria (demixing of polymer solution) to make tailor-made polymers?Which procedure can be applied for sterilization ?
PVC = poly(vinyl chloride)
17Polymer Thermodynamics
Why do we need polymer thermodynamics ?
2. example: polymers for medical applications
PE – poly(ethylene)
Application: foil, packaging, containerstubes, bottles, implant (knee, hip)
Advantage: excellent chemical resistancehigh stiffness
Challenge for thermodynamics:How we can produce ultra pure PE ?What are the relations between polymer properties (i.e. molecular weight distribution )and other physical properties, like permeation, solubility?
Can we use phase equilibria (demixing of polymer solution) to made tailor-made polymers?Which procedure can be applied for sterilization ?LDPE is produced via high-pressure polymerization. What do we know about the influence of pressure on the phase equilibria ?
18Polymer Thermodynamics
Why do we need polymer thermodynamics ?
2. example: polymers for medical applications
PS = polystyrene
Application: package, infusion equipment, tubes
Advantage: chemical resistanceexcellent deformability excellent transparence
Thermodynamic challengeHow can we produce tailor-made polymers basedon polystyrene, maybe copolymerization?Which copolymer should be applied for which purpose?What is the influence of chemical composition onthe properties of the copolymer ?
19Polymer Thermodynamics
Why do we need polymer thermodynamics ?
2. example: polymers for medical applications
Application: artificial thread, artificial tissuemembranes for dialysisheart valve, syringe
Advantage: chemical resistanceexcellent deformability
Challenge for thermodynamics:How can we produce ultra pure PP ?What are the relations between polymer properties (i.e. molecular weight
distribution ) and other physical properties, like permeation, solubility chrystallinity?
Can we use phase equilibria (demixing of polymer solution) to made tailor-made polymers?
Which procedure can be applied for sterilization ?
PP = polypropylene
20Polymer Thermodynamics
Why do we need polymer thermodynamics ?
2. example: polymers for medical applications
PLA = poly(lactic acid) O R C
O
O R1 O C
O
R2 C
O nI II
R = CH-CH3Advantage: biological degradation is possibletwo optical isomers poly( L-lactic acid) and poly( D-lactic acid)
Properties: partial crystallinemelting temperature 180°C
Properties: amorphousmelting temperature 75°C
copolymerization in order to tune the physical properties
Thermodynamic challenge: What is the influence of copolymer composition onphysical properties (chrystallinity, degradation, pH-stability)?
Application: tissue-engineering,artificial bone and articular
21Polymer Thermodynamics
Why do we need polymer thermodynamics ?
2. example: polymers for medical applicationsPLA = poly(lactic acid) as controlled drug delivery systems
encapsulation of drugs
Diseases: chemotherapy, hormone therapy
Advantage: long-term therapy over monthsis possible
Thermodynamic challenge: Can we predict the maximal amount of drug in the polymerparticles? Do we have any influence on this amount ?What do we know about the involved swelling equilibria ?How can we optimize the degradation behavior ?
22Polymer Thermodynamics
Why do we need polymer thermodynamics ?
Let us start to learn something about polymer thermodynamics !
The department of Thermodynamics und Thermic Engineering wishes you a lot of fun with thermodynamics and complete success.
Let us start to repeat the basics of thermodynamics, namely some basic terms, the first and second law of thermodynamics.
23Polymer Thermodynamics
Basic terms of Thermodynamics
System and SurroundingSystem: certain sector of matter containing a large number of particles (1023) Examples: content of beaker, content of thermos bottle, chemical reactor, steam engine
system surrounding
material transfer energy transfer
open system closed system isolated systemFor heat and work holds the definition that heat or work put into the system has a positive sign. 0
0from surrounding to system dW or dQ endothermicfrom system to surrounding dW or dQ exothermic
24Polymer Thermodynamics
phase: Phase is a substance (pure phase) or a mixture of substances having spatial constant properties. The area, where the properties will bechanged is called interphase.
Liquid L
Vapor V
L
Vvapor density
V
liquid densityL
interphase
Basic terms of Thermodynamics
Phase
25Polymer Thermodynamics
phase: Phase is a substance (pure phase) or a mixture of substances having spatial constant properties. The area, where the properties will bechanged is called interphase.
Solid S
Liquid L
S
Lliquid density
L
solid densityS
interphase
Basic terms of Thermodynamics
Phase
26Polymer Thermodynamics
phase: Phase is a substance (pure phase) or a mixture of substances having spatial constant properties. The area, where the properties will bechanged is called interphase.
Liquid 2 L2
Liquid 1 L1L1liquid density
L1
liquid densityL2
interphase
Basic terms of Thermodynamics
Phase
Example:oil + water
L2
27Polymer Thermodynamics
state: Thermodynamic state of system is characterized by its state variables(i.e. temperature, pressure, density, composition, energy).
Basic terms of Thermodynamics
State
state functions (i.e h,u,f,g,s) depend on state variables (i.e. T,P,V, ni).
General: z=f(x,y)Change of state functions dz exact differential
0 0
( , ) ( , ) ( , ) ( , ) ( , ) ( , )lim lim
( , ) ( , )( , ) ( , ) ( , ) (
( , ) ( , )( , )
, )
x yy x
y
y x
x
z x y z x x y z x y z x y z x y y z x yx x y y
z x y z x ydx z x dx y z x y
z x y z x ydz x y d
dy z x y dy z x yx y
x dyx y
exact differential
28Polymer Thermodynamics
state: Thermodynamic state of system characterized by its state variables(i.e. temperature, pressure, density, composition, energy).
Basic terms of Thermodynamics
State
state functions (i.e h,u,f,g,s) depend on state variables (i.e. T,P,V, ni).
General: z=f(x,y)Change of state functions dz exact differential
, ,, q s r qr s
z z zdz dq dr dsq r s
partial differential coefficient related to experimental quantities
i.e. PP
P P T P
H S c H Vc V TT T T P T
29Polymer Thermodynamics
Basic terms of Thermodynamics
Statestate functions: example
y
x
z(x1,y1)
z(x2,y2)
Y
Z dXX
X
Z dYY
2 23( , ) 3 22
z x y x xy y
6 2
2 3
6 2 2 3
y x
y
x
z zdz dx dyx y
z x yx
z x yy
dz x y dx x y dy
30Polymer Thermodynamics
Basic terms of Thermodynamics
State
31Polymer Thermodynamics
Basic terms of Thermodynamics
State
Z = Zend - Zbeginning
state functions are not dependent on the route
0 5 10 15 20-100
-80
-60
-40
-20
0
20
40
60
80
state at end
state at beginning
route 1 route 2 route 3
f(X)
X
Z = Z = 2Z=3Z
32Polymer Thermodynamics
Basic terms of Thermodynamics
State – Functions
Calculation of changes in state functions
2 23( , ) 3 22
z x y x xy y
change in state = state at end – state at beginning
i.e. state at beginning: x=2, y=4state at end: x=5, y=1
(5,1) (2,4) 86.5 52 34.5z z z
Example:
33Polymer Thermodynamics
Basic terms of ThermodynamicsState – Change
i.e. What is the change in volume, if the substance is transferred from state V(P,T,n) into state V(P+DP, T+DT,n) ?
2, , ,P n T n P T
V nR V nRT V RTT P P P n P
, , ,
( , , )
P n T n T P
V f T P nV V VdV dT dP dnT P n
nRTPV nRT VP
2
nR nRT RTdV dT dP dnP P P
Ideal gas law:
34Polymer Thermodynamics
Basic terms of Thermodynamics
State – Functions
Z = Zend - Zbeginning
Law of Schwarz: The sequence of differentiation can be interchanged.
qr
z zdz dq drq r
for
2 2z zq r r q
( , )z f q r is valid
qr q r
z zr q q r
state functions depend not from the route
35Polymer Thermodynamics
Basic terms of Thermodynamics
State – Functions
Z = ZEnd - ZBeginning
( , ) ( , ) ( , ) ' ' '
( , ) ( , )( , )
( ,
( , ) ( , ) ( , ) ( , )
) ( ,, )
,
(
)
)
(
y x
y x
z x y f x y g x y y uv vu
with
f x y f x ydf x y dx dyx y
g x y g x yd
dz x y g x y df x y f x y dg
g x y dx dy
x y
x y
Rule for differentiation of products
36Polymer Thermodynamics
Basic terms of ThermodynamicsState – Quantities
state quantities can be extensive or intensive.
Extensive state quantities will double their value if two equal systems will be united toone new system.
i.e. mass m, volume V, energy U
Intensive state quantities will keep their value if two equal systems will be united toone new system.
i.e. temperature T, pressure P, molar volume v, specific volume vsp
molar quantities
Vvn
n = amount of substance
specific quantities
spV vvm M
m = mass, M = molar mass
density [g/l]concentration [mol/l]
37Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
The equilibrium state is the final state of the process. At equilibrium no changes can be observed, experimentally.
state 1 state 2 state 3process process
38Polymer Thermodynamics
Basic terms of Thermodynamics
ProcessesProcesses: Transfer from initial (beginning) state to the final (end) state.
Process quantities: depend on the routethey are related to a process and not to a systemi.e. work and heat
extensive quantitiesi.e. work W, heat Q
intensive quantitiesi.e. molare enthalpies of chemical reactions
no heat exchangeconstantvolume
constanttemperature
constantpressure
adiabaticisochoreisothermisobar
39Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
heat and workfrom mechanics
dW Fds
force route
i.e. to uplift of mass m from the height h1 to the height h2
2 2
1 1
2 1( )h h
HUBh h
W Gdh mg dh mg h h i.e. Acceleration of mass m from speed v=0 to speed v1
1 1 121
0 0 0
12
s v v
BedvW mads m vdt mvdv mvdt
WHUB=mg(h2-h1)
h2h1
mg
h
WBe=mV12/2
V1
mV
V
dv dsa vdt dt
40Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
V1
V2s2
s1
weight G area A
During expansion of an ideal gas against an outside acting force F caused be the weight, G, the work is given by:
2
1
2
1
2
1
S
VolS
V
Vol
V
VolVV
W Fds F PA dV Ads
dVW PAA
W PdV
V2
V1
pV
dW Fds
force routethermodynamics: mechanical work Wvol caused by themovement of the system limits via volume change
Mechanical work is always connected with a vectored movement of particles.
ds
41Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
V1
V2s2
s1
weight G area A
2 2
1 1
S V
VolS V
W Fds PdV
Thermodynamics: mechanical work, Wvol
The sign of mechanical work:
2 1
1 2
0 0
0 0
Vol
Vol
V V V W
V V V W
→ work done by the system
→ work done on the system
ds
system
surrounding
42Polymer Thermodynamics
Basic terms of Thermodynamics
Processesmechanical work at constant extern pressure (i.e. atmospheric pressure)
2 2
1 1
2 1
2 1 0
S V
VolS V
Vol
Vol
W Fds PdV
W P V VV V W
V1
weight G
P
V2
weight G
P
state 1 state 2
The work is done by the system.
43Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
2
1
2 2
1 1
2
1
1 2
1
ln
0
V
VolV
V V
VolV V
Vol
Vol
W PdV mit PV nRT
nRTW dV nRT dVV V
VW nRTV
V V W
V2
weight G
P2
state 2
V1
weight G
P1
state 1
mechanical work at variable extern pressure
The work is done on the system.
44Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
21 2
1 1 2
lnVolV nRT nRTW nRT P PV V V
mechanical work at variable extern pressure
P1
P2
nRTPV
Isotherme
V2
V1
P
V
45Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
Two groups of hikers would like to go to mountain. The first group takes the direct way. The second group uses the serpentines.On the top of the mountains both groups have the same state (the same height), but the second group has done more work.
Change in state variables (i.e. height): depends not on the routeChange in process quantities (i.e. work): depends on the route
46Polymer Thermodynamics
Basic terms of Thermodynamics
ProcessesHeat: is equal to the change of energy related to the energy of molecular motion.
- process quantity depends on the way- is related to processes and not to systems
heat exchanges withchange of temperature
heat exchanges withoutchange of temperature
dQ TCdheat capacity C
i.e. Heating of liquid in beakerlatent heat i.e. phase change,
chemical reactionsolution, adsorption
dQ qdq molare heat of reaction reaction coordinate
dQ < 0 exothermicdQ > 0 endothermic
Ccn
specific heat capacity: spCcm
47Polymer Thermodynamics
Basic terms of Thermodynamics
Processes
ice-20 0 20 40 60 80 100
Hea
t Q
T [°C]
water + ice
water
water + vapor
vapor
48Polymer Thermodynamics
Basic terms of Thermodynamics
Processeswork heat
49Polymer Thermodynamics
Basic terms of Thermodynamics
Equilibrium
a) thermic equilibrium: TI = TII = ... = T constant temperature
b) mechanical equilibrium: PI = PII = ... = P constant pressure
c) material equilibrium: iI= i
II= ... = in
The chemical potential of the component, i, is equalin all present phases.
50Polymer Thermodynamics
Basic terms of Thermodynamics
Equilibrium
PotE mgh
stable
EPot global minimum
stable against all
perturbations
instable
EPot global maximum
instable against all
perturbations
metastable
EPot local minimum
stable against small
perturbations
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