Natural Weathering of Polymers – Dose-Response-Functions

Natural Weathering of Polymers –Dose-Response-Functions of Air-Pollution Effects for

Service Life Prediction

Thomas Reichert, Ute Pohsner

CEEES Workshop, 22nd September 2006, London, United Kingdom

Seite 2

Dose-Response-Functions of Air-Pollution Effects for Service Life Prediction

Goals The mapping of air pollution effects onmaterials shall depict the deteriorationpotential of air pollution and the resultingeconomic damage. Therefore the dose-response functions for the deteriorationcaused by environmental effects have tobe determined.

On the basis of the mapping results effectiveand cost efficient decreasing anddiminishing strategies for air pollutioncould be developed and concluded.

3

Universität StuttgartInstitut für Energiewirtschaft und Rationelle Energieanwendung IER

Bert Droste-Franke, IER University of Stuttgart GreenSense_Hamburg_01.ppt

Method for economicdamage evaluation

Damage ∆Z

Surface Fraction∆a = ∆Z / Zkrit = 1 / t

Additional Restoration Areas O * a

Economic Damages

Air pollution concentrations,acid rain, dose-response-functions

Climatic Data

Critical Damage Zkrit

Material Surface O

Area SpecificRestoration Costs

Seite 4


Investigated Materials

1. Polyurethane PUR (car spoiler)2. Polyvinylchloride PVC (window frames)3. Fiber Reinforced Polyester PES-GFK (roofs, boats)4. Alkyd resin based Lacquer (metal protections)

Criteria for Investigation:1. Long using time 2. Application in urban areas3. Large economic relevance4. Different application areas and branches

Seite 5


Polyurethane PUR (Car spoiler)

Two component polyurethane lacquer;The PUR-specimen is designed with ablack substrate material (PUR) and apainted white PUR-lacquer. The lacquersystem is a light-grey base lacquer and aalpine white, high glossy finishinglacquer.

Seite 6


Polyvinylchloride PVC(window frames)

Additional to the base polymera lot of additives are added:stabilizers, emulators, fillers,pigments, UV-absorber andmodifiers.

Seite 7


Fiber Reinforced PolyesterPES-GFK (roofs, boats)

A low viscose, middle reactive polyesterresin (Basis Palatal 5).With tailored additives the material getgood optical and mechanical properties.The specimen have seven fiber fleecelayers.

Seite 8


Alkyd resin based lacquer(metal protection)

Corrosion protection lacquer for metalsurfaces.The specimen have a 2 mm thick steelplate with a ground layer and a alkydresin based lacquer.

Seite 9


Natural weatheringstation with testrack and airpollution andclimaticmeasurementstation(Rhine harbor Kehl)

Seite 10


Locations of thenatural weatheringstations

R o s t o c k

H a m b u r g

H a n n o v e r

B o n n

M u n c h e n

D r e s d e n

B e r l i no

o

o

o

oo

oo

Seite 11


Averaged Air Pollution Concentration (05.92-04.00) at the Natural WeatheringLocations

Diagramm einfügen!

0102030405060708090

FR -Mitte KA-Mitte Keh l-Hafen MA-Nord Rasta t t Bo t trop Waldh o f Schau inslan d

Sch we fe ld io xid Sticksto ffmo n o xid Sticksto ffd io xid Ozo n

Lu ftsch a d sto ffko n ze n tra tio n in µg /m³

Seite 12


Investigation Methods

Morphological- Microscopy on Cuts and Grindings- Scanning Electron Microscopy

Mechanical- Surface Hardness- Tear Resistance- Elongation at Break

Optical- Visual Inspection- Color Change- Surface Roughness

Analytical- FT-IR-Spectroscopy- Mol-Mass-Distribution

Seite 13


Microtome cuttings of8 years natural weatheredPVC – specimen

(after a dying process with acridineorange)

(Enlargement 520:1)

Seite 14


Dose-Response-Functions ?

Material Property = Fkt (t, Hglob, U, T, [SO2], [NOX], [O3], N ...)

t = Exposition timeHglob = RadianceU = Relative humidityT = Temperature[SO2] = Concentration of sulphur dioxide[NO2] = Concentration of nitrogen dioxide[O3] = Concentration of ozoneN = Amount of rain (acid rain)

Seite 15


UN ECEICP Materials

Carousel with stonematerials

Unshelteredpanels

Sheltering boxcontaining

panels,carousels with

stone materialsand aluminium

box with theelectric contact

materials

Quelle: Tidblad

Seite 16


Dose-Response-Functions for Metals

K = dry (T, Rh, [SO2], [NO2], [O3], t) + wet (Rain, [H+], t)Where K is the corrosion rate, T is the temperature in degree C, Rh is the relative humidity in %, [Gas] is the concentration in µg/m³ (SO2, NO2 and O3), t is the weathering time in years, Rain is the amount of rain and precipitation in mm and [H+] is the measured value correlated to the acid rain mg/l.

(Source: Tidblad et. al)

Seite 17


Dose-Response-Functions for Polymers

1. Step:According Guillet et. al. /Rabek/ it is possible to assume for the surface materialproperties of a polymer a proportional effect to the incoming global radiation,cause the possibility of a chain scission is proportional to the amount of incomingphotons.

MP ~ P1•G•tP2

G = radiance [W/m²] t = exposition time

MP = Material PropertyP1, P2 = Parameters

Seite 18


Dose-Response-Functions for Polymers

2. Step:Additional to the photo-inducted ageing the influence of the humidity, precipitation and airpollution lead to a damage of the polymer. During the life cycle the polymer product takesup water vapor and gases till the saturation level is reached by constant environmentalconditions. In alternating environmental conditions the penetration depth PD of gases andwater vapor is dependent from the periodicity Tp of the parameter and the temperaturedependent diffusion coefficients Di(T)

PD ~ (Di(T)•Tp/π)1/2

MP ~ P1[Gas1]tP1(D1(T)T1/π)1/2 + ...+ PN[GasN]tPN(DN(T)TN/π)1/2

Seite 19


1,00E-09

1,00E-08

1,00E-07

1,00E-06

1,00E-05

0 20 40 60 80 100 120 140

Surface Temperature [°C]

Coe

ffic

ient

[cm

²/s]

0 5 10 15 20 25 30

Air Temperature [°C]

Permeationskoeffizient Arrhenius D*T Linear (D*T)

Seite 20


Damage depth of PUR

Penetration depth in PUR = 0,5777 + 0,4900•(G •t)1/2

+ 0,0253•(10-9•T•108/π)1/2•rH•t+ 0,0184•(10-9•T•108/π)1/2•[NO2]•t+ 0,0122•(10-9•T•108/π)1/2•[O3]•t

With: Penetration depth in PUR in µmG = radiance (averaged annual value in W/m²)t = exposition time in yearsT = averaged annual air temperature at location (in °C)rH = averaged annual relative humidity at location (in %)[NO2] = averaged annual concentration for NO2 in µg/m³[O3] = averaged annual concentration for Ozone in µg/m³

Seite 21


Plot of Eindringtiefe von Lugol _scher L

predicted

obse

rved

0 3 6 9 12 150

3

6

9

12

15

R2 = 89,60 %

Damage depth of PUR

Seite 22


Damage depth of PUR

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Exposition Time [a]

Pene

trat

ion

Dep

th in

µm

ConstantRadiation-PartHumidity-PartOzone-PartNO2-Part

T = 20°CrH = 60%NO2=50 µg/m³SO2=40 µg/m³O3 =50 µg/m³

Seite 23


Damage depth of PUR

0

10

20

30

40

50

60

70

80

90

Pene

trat

ion

Dep

th in

µm

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25Exposition Time [a]

NO2-PartOzone-PartHumidity-PartRadiation-PartConstant

Seite 24


Color Change of Polyester GFK

Delta E = 0,4383 + 0,5979•(G •t0,4)1/2

+ 0,0354•(10-9•T•108/π)1/2•rH•t0,65

+ 0,0064•(10-9•T•108/π)1/2•[SO2]•t0,65

+ 0,0195•(10-9•T•108/π)1/2•[O3]•t0,65

With: Delta E (without dimension)G = radiance (averaged annual value in W/m²)t = exposition time in yearsT = averaged annual air temperature at location (in °C)rH = averaged annual relative humidity at location (in %)[SO2] = averaged annual concentration for SO2 in µg/m³[O3] = averaged annual concentration for Ozone in µg/m³

Seite 25


Plot of DeltaE_PES_mL

predicted

obse

rved

0 4 8 12 16 200

4

8

12

16

20

R2 = 91,68 %


Seite 26



0

2

4

6

8

10

12

14

16

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Exposition Time [a]

Del

ta E

ConstantRadiation-PartHumidity-PartSO2-PartOzone-Part

T = 20°CrH = 60%NO2=50 µg/m³SO2=40 µg/m³O3 =50 µg/m³

Seite 27



0

5

10

15

20

25

30

35

Del

ta E

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25Exposition Time [a]

Ozone-PartSO2-PartHumidity-PartRadiation-PartConstant

Seite 28


Plot of Eindringtiefe von Acridinorange

predicted

obse

rved

0 4 8 12 160

4

8

12

16

R2 = 81,43 %

Damage Depth of PVC

Seite 29


0

5

10

15

20

25

30

35

Eind

ring

tiefe

in µ

m

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Expositionszeit in Jahren

Tiefenschädigung von PVC

NO2-PartOzone PartSO2-PartHumidity PartRadiation Part

Damage Depth of PVCT = 20°CrH = 60%NO2=50 µg/m³SO2=40 µg/m³O3 =50 µg/m³

Seite 30


Conclusion

Dose-Response-Functions for Material Properties changed by climaticeffects (solar radiation, humidity, temperature, air pollutants) havebeen developed.

Calculations of material damage and the different quantities from eachenvironmental parameter are possible.

Comparisons of different climatic situations are possible.

With the aid of a lifetime criteria an estimation of the lifetime of thematerial is possible.

The application to other polymer materials should be proved.

Dr.-Ing. Thomas [email protected]

Fraunhofer-Institut für Chemische Technologie ICT

76327 PfinztalGermany

www.ict.fhg.de

Thank you for your attention !

Documents

Natural Weathering of Polymers – Dose-Response-Functions