TPO – Long Term PfPerformance · 2013. 1. 12. · 11/1/2010 13 11 TPO, PVC, KEE, and EV single ply membranes – subjected to long-term UV exposure “On average, the TPO membranes

11/1/2010

1

TPO – Long Term P fPerformance

A Panel Discussion

MRCA National Conference - 2010

2010 National Conference

Panel Members

Helene Hardy Pierce GAF MaterialsHelene Hardy Pierce – GAF Materials CorporationDwayne Wacenske – Firestone BPTom Taylor – GAF Materials CorporationCo po at oRandy Ober – Carlisle SyntecRene Dupuis – SRI Consultants


11/1/2010

2

Introduction

MRCA / NRCA Lab WorkMRCA / NRCA Lab WorkMRCA 2005 TPO Field StudyMRCA TPO Advisory 2010

Response to localized high solar or thermal loading issuesg


5

10

4 Year Old TPO Sample (Test Cut 1) Softening Point of Thermoplastics

PP

-5

0

5

Hea

t Flo

w E

ndo

Up

(mW

)

Onset = 150.8ºF

Peak = 176.9ºF

Onset = 294.6ºF

Peak = 316.9ºF PE

-10

5

115 135 155 175 195 215 235 255 275 295 315 335 355 375 395

Temperature (ºF)

Area = 16.5 mJDelta H = 1.736 J/g


11/1/2010

3

0

5

New TPO Sample

-10

-5

Hea

t Flo

w E

ndo

Up

(mW

)

Onset = 219.0ºF

Peak = 238.1ºF

Onset = 260.0ºF

Peak = 285.3ºF

PEPP

-15115 135 155 175 195 215 235 255 275 295 315 335 355 375 395

Temperature (ºF)



11/1/2010

4

11/1/2010

5

MRCA TPO ADVISORY 2010


If situations exist that may commonly elevate temperatures over 160 degrees or increase solar loads beyond “ l” i i l l d ti“normal” incoming solar load, question the manufacturer as to the suitability of their product for the situation; consider changing the product to a material that will clearly withstand the loading; consider changes in design to forestall the loading.


11/1/2010

6

Helene Hardy Pierce – GAF Materials Corporation


Historical Background


11/1/2010

7

History of TPO…Europe since late 1980’spU.S….

First generation late 1980’s as a “thermoplastic elastomer” Marketed as “thermoplastic


p(poly)olefins” since very early 1990’s

Approaching 20 years in-service…

Think About Types of Adopters…

Technology Enthusiasts/VisionariesTechnology Enthusiasts/Visionaries (innovators)

Pragmatists (early majority)Conservatives (late majority)Skeptics (laggards)


p ( gg )

11/1/2010

8

The U.S. Commercial Membrane Roofing Market

2009-2010 Estimate

32%25%

Other SinglePlyAsphaltic

TPO


43%

Source: Consensus of the three manufacturers on this panel and values are provided as an indicator of relative market use

Almost 20 Years…


11/1/2010

9

Yet Still, Many Consider…

TPO =


So How Have We “Looked At” TPO?

The first part of a multi-year research project… published in 1998


11/1/2010

10

Strength/elongation andStrength/elongation and thermogravimetry to evaluate in-service TPO membranesCompared with the proposed properties in the “draft” TPO standard


Proposed improvements to the draft standard

More Recently…

18 Months ago at the 2009 IRE…


11/1/2010

11

UV/Artificial aging workAlgae/fungus resistanceWelding optimizationCompatibility of adhesives with TPO


membranes

Over Time

Most should be familiar with the WSRCA 7


year TPO study…

11/1/2010

12

White 60 mil TPO membranesTest patches show weldability after agingShowing good in-service performance


Showing good in-service performanceIn general, all seams are performing well

Owner Generated L kLook


11/1/2010

13

11 TPO, PVC, KEE, and EV single ply membranes –subjected to long-term UV exposure

“On average, the TPO membranes have a greater propensity for retaining physical properties when

d t PVC KEE d EV b


compared to PVC, KEE, and EV membranes. Substantial variations, however, were observed within the TPO group.”

Dwayne Wacenske –Firestone Building Products


11/1/2010

14

EVO UTION OF THE ASTMEVOLUTION OF THE ASTM STANDARD FOR TPO MEMBRANE


ASTM

ASTM members include:ASTM members include:Producers (including chemical companies)Users – ContractorsGeneral Interest – UL, FM, NRCA, Consultants

ASTM is a consensus organization e gASTM is a consensus organization, e.g. there can be no persuasive negative votes


11/1/2010

15

ASTM Standard for TPO

Work started in the early ‘90s to createdWork started in the early 90s to created a TPO StandardIt took over 10 years and 36 drafts to come to a consensus.ASTM D6878 was finally published in S 68 8 as a y pub s ed2003.


ASTM D6878

Standard for TPO Roofing MembranesStandard for TPO Roofing MembranesSpecifies:

DimensionsPhysical propertiesDurabilityy

11/1/2010

16

Physical Properties

Breaking StrengthBreaking Strength Elongation at BreakTearing StrengthBrittleness PointWater AbsorptionWater Absorption


Dimensions

The standard providesThe standard providesMinimum thickness of 39 milsMinimum thickness over the scrim of 12 milsTolerances for width and length are +3% -0%0%


11/1/2010

17

Durability PropertiesOzone ResistanceOzone ResistanceHeat Aging

Oven temperature is 116°C (240°F)Duration is 28 days

Weather ResistanceXenon arc apparatusChamber temperature is 80°C (176°F)Exposure is 10,080 kJ/m²This was increased from 5,040 in 2006


Durability TestsTPO EPDM PVC KEE

ASTM Standard D6878 D4637 D4434 D6754X AXenon ArcTemperature 80°C 80°C 63°C 63°CHours @ 0.35 W/m² 8,000 4,000 5,000 5,000Oven AgingTemperature 116°C 116°C 80°C 80°CDays 28 28 56 56

Note: The Arrhenius equation predicts that for every 10°C rise in temperature, the chemical reaction rate doubles.Thus, 28 days at 116°C is equivalent to 340 days at 80°C.

11/1/2010

18

Summary of D6878

Adopted in 2003Adopted in 2003In 2006, weathering requirement was doubled.2008 – Clarification was made on the Water Absorption test methodate bso pt o test et od2010 – Evaluating increase in Heat Aging requirements


Tom Taylor – GAF Materials Corporation


11/1/2010

19

Predictors to Long Term Performance


Overview…White TPO membranes are generally performing wellperforming well

There have been examples of TPO aging faster than predicted


We will look at what causes TPO to age, and why there is a push to raise the standard

11/1/2010

20

Sunlight… Is it just about UV?

There are 3 parts –Visible light

Helps us to see

HeatKeeps us warm


Ultraviolet (UV)Gives us a tan, if we’re carefulBurns us if we are not careful…or worse!

So…

We all know UV is badWe all know UV is bad


11/1/2010

21

But…

We didn’t think that heat was badWe didn t think that heat was bad.

So what changed ?


So what changed…?

Field Performance!

As TPO installations have grownAs TPO installations have grown exponentially, the small percentage of premature aging issues has become a noticeable number


11/1/2010

22

Why would a TPO membrane fail earlier than expected?

These roofs have a few things in common. Either

Nearby highly reflective surfacesor


orBuild up of dark dust and debris

One Example……………

This was white TPO..


...covered with blackdust

11/1/2010

23

Temperatures as high as 180°F !


Premature Failure…

Erosion downto the scrim!


!!!

11/1/2010

24

It got us thinking -…what about solar?


Between panels…180°F

Under the black edge…200°F


11/1/2010

25

TPO is getting far hotter than we

Connecting the Dots……..

TPO is getting far hotter than we anticipated

High heat appears to be aging membranes quickly


y

Let’s investigate and improve…

What About Oven Aging?

Testing at 200°F may take yearsTesting at 200 F may take years

300°F is getting close to the melt temperature of some of the polymers


240oF is what’s in the standard

Let’s look at the highest possible temperature…

11/1/2010

26

80 mil TPO – 280°F Exposuretime to cracking…A

(2008)B

(2008)C

(2009)D

(2008)E

(2009)40 days 40 days 87 days

(80 days -1stcrack on cap)

68 days 48 days


60 mil TPO – 280°F Exposuretime to cracking…

A(2008)

B(2009)

C(2009)

D(2009)

E(2009)( ) ( ) ( ) ( ) ( )

40 days 91 days(54 days -1st crack)

77 days 28 days 20 days


11/1/2010

27

45 mil TPO – 280°F Exposure time to cracking…

A(2008)

B(2005)

C(2008)

D(2009)

E(2008)

F(2008)

G(2009)

40 days 28 days 40 days 107 days 82 days 54 days 20 days


So, what does this tell us?Large differences exist between manufacturersLarge differences exist between manufacturers

Some of the earliest failures seem to correlate with failures in the field

Was 280°F too high…?


Let’s look at this temperature compared to the 240oF in the current standard…

11/1/2010

28

240 versus 280 data…a fairly good correlation!

600

R2 = 0.8803

300

400

500

s to

Cra

ckin

g in

240

F


100

200

10 20 30 40 50 60 70 80 90

Days to Cracking in 280F

Day

s

So, what’s the right standard?280°F 240°F

(X) (Y)

Oven Aging

Product (and

Actual Days to Crack(X) (Y)

A, 45mil 20 212B, 45 mil 28 229C, 60 mil 31 212D, 80 mil 34 212E, 60 mil 37 296F, 80 mil 40 296G, 80 mil 48 344

(and thickness)


G, 80 mil 48 344H, 80 mil 68 399I, 60 mil 76 399J, 80 mil 80 369 – no cracking

yetK, 60 mil 85 392 – no cracking

yet

11/1/2010

29

We can also predict how long it will take to crack due to heat aging…

280°F 240°F 240°F 200°F Predicted Days to Crack

Oven Aging

Product Actual Days to Crack(X) (Y)

A, 45mil 20 212 200 941B, 45 mil 28 229 232 1017C, 60 mil 31 212 244 941D, 80 mil 34 212 255 941E, 60 mil 37 296 267 1314F, 80 mil 40 296 279 1314G, 80 mil 48 344 311 1527

Predicted Days to CrackProduct (and

thickness)

Actual Days to Crack


H, 80 mil 68 399 389 1772I, 60 mil 76 399 421 1772J, 80 mil 80 369 – no cracking

yet437 1939

K, 60 mil 85 392 – no cracking yet

457 2027

Let’s put it in field exposure terms…

280°F 240°F 240°F 200°F Predicted Years

200°F Field Exposure

Predicted Days to Crack

Oven Aging

Product Actual Days to Crack(X) (Y) (assuming

6 hrs/day at 200F)A, 45mil 20 212 200 941 10B, 45 mil 28 229 232 1017 11C, 60 mil 31 212 244 941 10D, 80 mil 34 212 255 941 10E, 60 mil 37 296 267 1314 14F, 80 mil 40 296 279 1314 14G, 80 mil 48 344 311 1527 17

(and thickness)


H, 80 mil 68 399 389 1772 19I, 60 mil 76 399 421 1772 19J, 80 mil 80 369 – no cracking

yet437 1939 21


457 2027 22

11/1/2010

30

280°F 240°F 240°F 200°F Predicted Years

200°F Field Exposure

Predicted Days to Crack

Oven Aging

Product Actual Days to Crack

So what is right for an oven aging standard?

(X) (Y) (assuming 6 hrs/day at 200F)

A, 45mil 20 212 200 941 10B, 45 mil 28 229 232 1017 11C, 60 mil 31 212 244 941 10D, 80 mil 34 212 255 941 10E, 60 mil 37 296 267 1314 14F, 80 mil 40 296 279 1314 14G, 80 mil 48 344 311 1527 17

(and thickness)


,H, 80 mil 68 399 389 1772 19I, 60 mil 76 399 421 1772 19J, 80 mil 80 369 – no cracking

yet437 1939 21


457 2027 22

Suspected field issuesProposed safe zone – 50+ days at 280°F

Heat Aging…Let’s recap…

What should the test temperature be?What should the minimum test time be?

Any test should be complete in a reasonable time…days not years

280°F is aggressive, shows differences, enables manufacturers to rapidly test


p y

56 day minimum will prevent early failures

11/1/2010

31

So, is that it…?

Not Quite…Not Quite…

Further questions are:How precisely do we need to hold at 280F?Do different labs get the same results

A round robin is clearly warranted


y

And let’s not forget…

What about UV AND Heat?

We’ve looked at UV aging followed by Heat Aging


11/1/2010

32

Its really telling us how much stabilizer is left after UV exposure…

QUV exposure=14251 kJ/m2

100po

sure

40

60

80

king

in 2

80F

afte

r QU

V Ex

p


QUV exposure=32516 kJ/m2

0

20

0 20 40 60 80 100 120 140 160 180

Days to Cracking in 280F

Day

s to

Cra

ck

UV + Heat has a strong correlation toUV + Heat has a strong correlation to Heat Aging alone…

Is there a way to look at accelerated field testing to verify the accelerated lab


test g to e y t e acce e ated abtesting?

11/1/2010

33

Enter the UAWS*


* Ultra Accelerated Weathering System (Atlas Material Testing)

UAWS29 reflectors –29 reflectors

Can heat to the polymer melting point!

UV level is 17,000 MJ/m2/yearSouth Florida sees 280 MJ/m2/year!

So 6 months at UAWS could predict 25 to 30


So, 6 months at UAWS could predict 25 to 30 years in south Florida!

Let’s take a look…

11/1/2010

34

So, how hot does UAWS get?

200

220F

TPO Maxi Surface Temp on Atlas UAWS, AZ

80

100

120

140

160

180

Max

imum

Tem

pera

ture

Maxi Ambient Temp AZ


40

60

3/28/2009 5/17/2009 7/6/2009 8/25/2009 10/14/2009 12/3/2009 1/22/2010 3/13/2010 5/2/2010

M Maxi Ambient Temp - AZ

Right up at levels that cause issues!

Preliminary Results…We loaded TPO with stabilizers…

TUVR, MJ/m2 South Florida Equivalence

280°F Heat Aging

60 mil 13,441 48 years 154 days

80 mil 12 374 44 years 184 days


80 mil 12.374 44 years 184 days

These stabilizers are the advanced stabilizers being used today!

11/1/2010

35

So, what’s the message?

Heat aging is telling us how robustHeat aging is telling us how robust these membranes are!Exceptional heat aging ability equates to exceptional UV aging

M b h b h


Membranes that pass a robust heat aging standard are going to perform well under all conditions!

So, Let’s Put it all Together

UV Aging the standard has been improvedUV Aging – the standard has been improvedTesting shows everyone is easily meeting/beating D6878No evidence has been found for field failures in high UV conditions


But…

11/1/2010

36

Heat aging shows large differences between membranesmembranesHeat is now known to be causing some early aging of membranes in the fieldHigh temperature aging appears to predict general life expectancy of membranes


So, what should the standards be?

Randy Ober – Carlisle Syntec


11/1/2010

37

Raising the Bar for TPO Membrane Performance


“RAISING THE BAR” FORRAISING THE BAR FOR TPO ROOFING MEMBRANE PERFORMANCE

ASTM D6878December 2009

11/1/2010

38

11/1/2010

39

11/1/2010

40

ASTM D6878

TPO StandardTPO StandardHeat AgingRequirements

28 days @ 240º28 days @ 240º F

Samples Heat-Aged at 275°F

7 WEEKS(26 WEEKS @240 F)



15 WEEKS(59 WEEKS @240 F No Failure)

11/1/2010

41

Proposal to ASTM Task Group

Add “ t ” h t i i t ithiAdd “extreme” heat aging requirements within ASTM D6878 to 275 degrees FIncrease heat aging duration to minimum 8 weeks (56 days) without cracking around 3” mandrelIncrease the performance of the TPO industryIncrease the performance of the TPO industry

June 2010

Does heat aging at 275 F change the mechanismDoes heat aging at 275 F change the mechanism for failure?Higher the temp, the less likely the heat aging test will represent real life…Could analytical tests be conducted on heat aged samples (tested at different temps to determine if failure mechanisms are the same)?What sort of heat aging data is available?

11/1/2010

42

June 2010 ASTM Task Group

Does heat aging at 275 F change the mechanismDoes heat aging at 275 F change the mechanism for failure?Higher the temp, the less likely the heat aging test will represent real life…Could analytical tests be conducted on heat aged samples?What sort of heat aging data is available?

June 2010 ASTM Task Group

Should 240 F be used just at a longer duration?What duration should be required?Can additional test data be generated?

11/1/2010

43

180

200

275 F Heat Aging Data

40

60

80

100

120

140

160

Lab A

Lab B

Lab C

0

20

40

A 45 mil

A 60 mil

B 60

mil

B 80

mil

C 45

mil

D 60 mil

D 80 mil

E 45

mil

F 60

mil

F 80

mil

G 60 mil

G 80 mil

H 60 mil

H 80 mil A B C D E F A B C D

October 2010

Task group conference callHeat aging data reviewedRound robin heat aging testing initiatedBallot has been issued for heat aging at 275 F / 56 days

11/1/2010

44

Dwayne Wacenske –Firestone Building Products


INSTALLATION PRACTICES THAT AFFECT SINGLE-PLY PERFORMANCE


11/1/2010

45

Installation Practices

Installation practices affect the long-termInstallation practices affect the long term performance of the roofing system.Initially the roof may be fine, but some problems can arise years later.With thermoplastic membranes, these practices usually relate to the hot-airpractices usually relate to the hot air welding of the seams.This applies to both TPO and PVC.


Test WeldsAt least twice dailyy

Start of the day After lunchWhenever the machine is restarted

ProcedureWeld scrap membraneAllow the seam to coolPull the seam apartCheck for proper weldCheck for drag marks


11/1/2010

46

Weld Failure ModesCohesive FailureFails within one plies

Adhesive FailureFails between the 2 plies

Good Weld

Bad Weld

Excessive Heat

Overheating the membrane byOverheating the membrane byAir temperature too highWelder speed too low

Excessive heat during the welding process can consume polymer p p ystabilizer, then it is not available for long-term stabilization.


11/1/2010

47

Ideal Welder Settings

Lowest temperature that providesLowest temperature that provides consistent cohesive failures (Good Seams) at production speeds


Welder Drag

Improper alignmentImproper alignment of the hot-air nozzle can create gouges in the membrane outside of the seam.These marks can

Drag Lines

These marks can lead to issues in the future.


11/1/2010

48

Proper Nozzle Alignment

NozzleNozzle should be as

close as possible and parallel to the

roller


Inside edge of nozzle should be aligned with the edge of the roller.

Probing Seams

Care must be taken when Probing SeamsCare must be taken when Probing SeamsUse a blunt probeProbes sharpen with use and must be occasionally dulled

Using a sharp probe can scar the membrane in a vulnerable area – the seamsKeep the tip of the probe horizontal


11/1/2010

49

Scars from ProbingCross Section of Membrane

Welding Walk Pads

Care must be taken toCare must be taken to not overheat membrane when welding walk padsThickness of walk pads does not always

i hrequire extra heat to get a good weldPerform test welds


11/1/2010

50

Creases in the Membrane

Hard creases made during installationHard creases made during installation can result in surface cracks in the membrane years later.Membrane can be folded back for applying adhesive or fasteners, but weight should not be placed on the fold to hold it in place.


Avoiding CreasesDon’t place weight on the

foldDo place the weight away

from the fold


11/1/2010

51

Result of CreasingFrom the Western States Test Roof in San Antonio after 7 years


Surface Crazing

Damage to the Membrane

Care must be taken to prevent damageCare must be taken to prevent damage to the surface of the membrane

Do not drag equipment over the membraneUse cover boards under generators or other equipment to prevent damage


11/1/2010

52

Summary

Localized High Heat Issues Can OccurLocalized High Heat Issues Can Occur In The Field UnintentionallyReviewed History of TPO Issues

Lab and Field StudyAdvisoryy

History of TPO Evolution of the ASTM Standard for TPO Membrane


Summary

Predictors for Long Term PerformancePredictors for Long Term PerformanceModifying the Current ASTM Standard

Proposed Increases in Time and Temperature for Heat Aging

Field Installation Techniques and Good qPractices


11/1/2010

53

Questions?


Documents

TPO – Long Term PfPerformance · 2013. 1. 12. · 11/1/2010 13 11 TPO, PVC, KEE, and EV single ply membranes – subjected to long-term UV exposure “On average, the TPO membranes