Durability of Building and Construction Sealants and Adhesives Volume 2 Andreas T Wolf

8/20/2019 Durability of Building and Construction Sealants and Adhesives Volume 2 Andreas T Wolf

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S T P 4 8 8

D u r a bi l i t y o f B u i l d i n g a n d C o n st r u c t i o n Sea l an t s a n d

A dh esi v es: nd V o l u m e

Andreas T Wolf editor

ASTM Stock Number: STP1488

I N T E R N T I O N L

ASTM

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PO Box C700

West Conshohocken, PA 19428-2959

Printed in the U.S.A.


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L i b r a ry o f C o n g r e s s C a t a l o g in g - i n - P u b l ic a t i o n D a t a

Durab i l i ty o f bu i ld ing and con s t ruc t ion sea lan ts and adhes ives / Andreas T. Wo l f, ed .

p. cm . - (STP 1488)

ISBN: 0 -8031-3414-2

ISBN: 978-0 -8031-3414-0

1 . Bu i ld ing m ate r ia ls -Tes t ing -Congresse s . 2 . Sea l ing compoun ds-Tes t ing -C ongresse s . 3 . Se a l ing

co mp o u n d s -De te r i o ra t i o n -Co n g re sse s .

2 .4 . Adh es ives-Tes t ing -Congress es . 5 . Adhes ives-De te r io ra t ion -Co ngresses . I . Wo l f A . T .

(Andre as T. ) I II Ser ies : AST M

3. spe cia l techn ica l publ icat ion ; 1488.

TA4 1 8 .3 6 .D8 7 2 0 0 6

P h o t o c o p y R i g h t s

A u t h o r i z a t i o n to p h o t o c o p y i te m s f o r i n te r n a l , p e r s o n a l, o r e d u c a t i o n a l c l a s s r o o m u s e , o r

t he in t erna l , persona l , o r educa t iona l c lassro om use o f spec i f ic c l i en t s , i s g ran ted , by t he

Am er ican S oc ie t y f o r Tes t ing and M at er ia ls In t ernat iona l (AS TM ) p rov ided t ha t t he appropri -

a t e f e e i s p a i d to t h e C o p y r i g h t C l e a r a n c e C e n t e r , 2 2 2 R o s e w o o d D r iv e , D a n v e r s , M A 0 1 9 2 3 ;

Tel : 978 -750-84 00; on l ine: ht tp JhNw w.copyr ight .com/ .

P e e r R e v i e w P o l i c y

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The au thors add resse d a l l o f the rev iewers ' com m ents to the sa t is fac tion o f bo th the techn ica l

ed i to r (s ) and the AS TM In te rna tiona l Co m m i t tee on Pub l ica tions .

The qua l i t y o f the pape rs in th is pub l ica t ion re f lec ts no t on ly the o bv ious e f fo r ts o f the au-

thors and the techn ica l ed i to r (s ) , bu t a lso the work o f the p eer rev iewers . In keep ing w i th long-s tand-

ing pub l ica t ion p rac t ices , AST M In te rna t iona l ma in ta ins the anon ym i ty o f the pe er rev iewers . The

ASTM In te rna tiona l Co m m i t tee on Pub l ica t ions ackn ow ledge s w i th apprec ia t ion the i r ded ica t ion and

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April, 2006


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oreword

Th is pub l ication Du r ab i li ty o f Bu i l d ing an d C ons t r uc t ion S ea lan t s an d Adhes ives conta ins

papers p resen ted a t t he second sympos ium o f the same name he ld in Reno Nevada on 15-

16 June 2005. The sympos ium wa s spons ored by the ASTM Internat iona l Com mi t tee C24

on Bui ld ing Seals and Sealants . The sympos ium chai rman was Andreas T . Wol f o f Dow

Com ing GmbH W iesbaden Germany.

iii


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ontents

O v e r v i e w

FACTORS INFLUENCING THE DURABILITY OF SEALED JOINTS AND ADHESIVE FIXATIONS

R e d u c i n g M o d u l u s o f S e a l a n t s t o I m p r o v e D u r a b i l i t y - - J . M . K LOSOW SKIAND J. E . PLOTT

Q u a n t i f i c a t i o n o f D i f f e r en t i al T h e r m a l M o v e m e n t i n I n s u l a t i n g G l a s s E d g e S e a l s U s i n g

F i n i t e E l e m e n t A n a l y s i s - - J . E . STEW A RT,W . R . O BRIEN, AND A . T . WO LF

R e d u c i n g T i n a n d A m i n o s i l an e C o n c e n t r a t i o n i n S i li c o ne E l a s t o m e r i c C o a t i n g t o

I m p r o v e I t s D u r a b i l i t y - - Y . CA I

DURABILITY STUDIES OF SEALANTS AND ADHESIVES

F o r m u l a t i n g H i g h W e a t h e r a b i l i t y S e a l a n t s : P o s s ib i l it i es a n d C h a l l e n g e s - - C . URBAN

T. MATSUMOTO, S. TOM ARI,AND F . ADELEU

N e w D u r a b l e S e a l a n t o f T e l e ch e l ic P o l y a c r y l a t e - - Y .

M A S A O K A Y . NAKAGAWA

T . HASEGAWA,AND H . ANDO

S e i sm i c P e r f o r m a n c e o f T w o - S i d e S t r u c t u r a l S i l ic o n e G l a z i n g S y s t e m s - - A .

M .

MEMARI

X . CHEN, P. A . KREMER, AND R . A . BEHR

DEVELOPMENT OF NEW T EST METH ODS AND PERFORMA NCE-BASED SPECIFICATIONS

D e v e l o p m e n t o f a P r a c t i c a l M e t h o d t o E v a l u a t e t h e F a t i g u e P r o p e r t i e s o f S t r u c t u r a l

S i l i c o n e G l a z i n g A d h e s i v e s - - L . D . C ARB ARY ,E. D . B ULL, AND S. S. MISHRA

S t a n d a r d s D e v e l o p m e n t f o r I m p e r m e a b l e , C o n s t r u c t ib l e , a n d D u r a b l e W a t e r p r o o f i n g - -

J. C. STRONG,J. R . KOVACH, AND V . S. ENG

S t u d y o f W e a t h e r a b i l i t y o f C o n s tr u c t io n S e a l a nt s w i t h N o v e l T e st in g M e t h o d - -

N . ENOMOTO, A . ITO , I. SH1MIZU,T. MATSUMURA,Y . TAKANE,AND K . TANAKA

P r o p o s e d D e s ig n a n d M e t h o d f o r P r o v i d i n g S e a le d J o i n t P e r f o r m a n c e u n d e r R e l a t iv e

S t o r y D i s p l a c e m e n t - - H . M IY AU CHIAND K . TANAKA

U s e o f O p t i c a l I m a g i n g / I m a g e A n a l y s i s S y s t e m f o r t h e Q u a n t i t a t i v e A n a l y s i s o f S u r f a c e

C h a n g e s I n d u c e d b y O u t d o o r W e a t h e r i n g o n S e a l a n t s - - A . T . W O L F, S . SU GIYA MA ,

AND F. LEE

vi i

16

23

31

4 0

53

63

8 2

91

102

N o n - d e s t r u c t i v e F i e ld T e s t in g o f I n s t a l l e d W e a t h e r p r o o f i n g S e a l a n t J o i n t s

-

Q u e s t i o n s a n d A n s w e r s - - D . H U FF 1 13


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O v e r v i e w

STP1488-EB/APR. 2006

I n t r o d u c t i o n

The Second ASTM Symposium on Durability of Building and Construction Sealants and Adhesives

(2005-DBCSA) was held on June 15-16, 2005 in Reno, Nevada. The symposium brought together ar-

chitects, engineers, scientists - researchers and practitioners. Their aim was to transfer new ideas,

gained from laboratory research and field work, to the study of sealant and adhesive durability and

the development of new products and test methods.

Nineteen papers were presented at the symposium. This book contains a selection of twelve sympo,

sium papers published by the Journal of ASTM Internat ional (JAI) prior to February 2007. JAI is an

online, peer-reviewed journal for the international scientific and engineering community. Publication

in JAI allows rapid dissemination of the papers as soon as they become available, while publication

in this Special Technical Publication (STP) is intended to provide easy access to the condensed in-

formation in a single volume for future reference.

Since the commercial introduction of the first elastomeric sealants and adhesives about fifty years

ago, major advancements have been made in our understanding of their durabil ity and the factors gov-

erning it. The progress of sealant and adhesive technology in building and construction structures has

brought with it many new materials, products, systems, designs and concepts. It has also brought an

awareness of new or formerly unrealized problems relating to the durability of building and con-

struction sealants, which ASTM C 24 Committee on Buildings Seals and Sealants is addressing.

Against a background of national and internationalefforts to harmonize testing and approval of build-

ing materials and structures, ASTM C 24 Committee has been looking for ways of bringing together

the experience of international experts gathered in the application and testing of building and con-

struction sealants.

The current series of ASTM symposia on Durability of Building and Construction Sealants and

Adhesives is a continuation of tri-annual symposia which were inaugurated by the RILEM Technical

Committee 139-DBS Durabili ty of Building Sealants in 1994. Today, this continuing series of sym-

posia provides the best scientific forum globally in the building and construction industry for peer-re-

viewed papers on all aspects of sealant and adhesive durabil ity.

As with most scientific disciplines, substantial advances often occur through a series of small steps,

rather than in giant leaps. This is also the case for the papers presented at the ASTM Symposium on

Durability of Building and Construction Sealants and Adhesives (2005-DBCSA). Many of the papers

reflect progress reports on on-going research.

This volume contains twelve contributions reflecting the wide spectrum of current state-of-the-art re-

search into sealant and adhesive durability. The symposium papers cover the following topics:

9 Factors Influencing he Durability of Sealed Joints and Adhesive Fixations

9 Durability Studies of Sealants and Adhesives

9 Development of New Test Methods and Performance Based Specifications

C opyr igh t 9 2 0 0 6 b y A S T M I n te r n a ti o n a l w w w . a s t m . o rg

v


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Below is a short overview of the papers which were published in JA in the above three categories.

F a c t o r s I n f l u e n c i n g t h e D u r a b i l i t y o f S e a l e d J o i n t s a n d d h e s i v e Fixations

While our understanding of the factors influencing the durability of sealed joints and adhesive fixa-

tions has progressed substantially over the past decades, there is still much to learn. A number of pa-

pers therefore focus on this topic.

The modulus of a sealant is a key property influencing the durability of weatherproofing joints that

undergo movement. For sealants subjected to cyclic movements, formulation changes resulting in a

reduction in modulus will provide higher durability, if sealant fatigue and other performance proper-

ties, such as adhesion, are not simultaneously degraded. J. M. Klosowski and J. E. Plott show the util-

ity of a melamine resin additive in reducing the modulus of polyurethane and silicon-curable

polyether sealants. The authors demonstrate that addition of relative small amounts of the melamine

resin results in modulus reduction and improved adhesion in the specific sealants studied. However,

the short-term nature of the study does not allow a sound assessment of the long-term durability of

these sealants, since potential negative effects of the additive on the long-term behavior of physical

properties were not studied.

Differential thermal movement between the spacer frame and the glass panes is a key contributor to

the aging of the insulating glass edge seal and of the insulating glass unit (IGU) itself. Using finite el-

ement analysis, J. E. Stewart, W. R. O'Br ien, and A. T. Wolf model the thermal movements occur-

ring in the edge seal of a large IGU as a result of temperature variations (-30~ to +60~ for three

commercially available spacer bars of different material (aluminum, galvanized steel, and stainless

steel) and corner design (corner keys or bent comers). As expected, at the low temperature, the cor-

ners are pulled inward, resulting in a bending angle >90~ while at the high temperature, the corners

are pushed outwards, resulting in a bending angle


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curable sealants based on polypropylene oxide or polyacrylate backbones and mixtures of these two

backbones. As expected, binder and stabilizer have the most notable influence on weathering resis-

tance; however, catalyst, titanium dioxide, and plasticizer also affect the weathering behavior. For op-

timum weathering performance, all raw materials influences need to be carefully tested.

Combinations of raw materials, especially in the case of stabilizers, may have synergistic effects, but

may also reduce the weathering resistance. The authors also highlight the fact that a minimum of

1500-2000 hours of accelerated weathering should be used to assess the durability of construction

sealants, and that for more demanding applications, 5000 hours, 10 000 hours, or an even longer du-

ration of accelerated weathering may be required.

The second paper by Y. Masaoka, Y. Nakagawa, T. Hasegawa, and H. Ando also deals with the dura-

bility of silane curable organic sealants. In this paper, the authors discuss the durability and perfor-

mance of sealants based on a novel telechelic silane curable acrylate polymer in contact with photo-

catalytic self-cleaning glass. Conventional sealants, when used in this application, often lack

sufficient weatherability or involve the risk of hydrophobic staining of the self-cleaning glass.

Sealants based on the novel telechelic silane curable acrylate polymer retain good adhesion to the

self-cleaning glass even after more than 10 000 hours of exposure to UV irradiation in a super-accel-

erated xenon-arc weathering machine. Based on outdoor exposure of the test samples for two months

and measurement of contact angles before and after exposure the authors conclude that these novel

sealants have very low staining potential on photocatalytic coatings.

Since its introduction nearly four decades ago, structural silicone glazing (SSG) has become a popu-

lar glazing method for curtain wall construction. The major difference between SSG systems and the

more widely used 'dry-glazed' systems is that glass lights or panels in SSG systems are adhered to

the supporting glazing frame with structural silicone sealant along either two edges of the glass panel

or all four edges. It is generally believed that SSG systems perform well in seismic regions due to the

'resil ient attachment' of glass to the glazing frame. This notion has merits in four-sided SSG systems,

but has not been previously substantiated for two-sided systems, wherein the top and bottom edges

are typically captured in metal glazing pockets. The research presented by A. M. Memari, X. Chen,

P. A. Kremer, and R. A. Behr in their paper therefore is aimed at characterizing the serviceability and

ultimate behavior of two-sided SSG curtain walls under cyclic racking displacements. Serviceability

drift capacities corresponding to damage states such as gasket distortion, weather-seal and structural

seal failures leading to air leakage and glass cracking are identified. Based on the results obtained in

this study and comparisons with data collected during comparable studies on dry-glazed curtain

walls, the authors conclude that serviceability and ultimate drift capacities of two-sided SSG systems

under seismic conditions are significantly higher than their dry-glazed counterparts.

D e v e l o p m e n t o f N e w T e s t M e t h o d s a n d P e r f o r m a n c e a s e d S p e ci fi ca t io n s

The final section of the collated symposium papers reviews attempts at developing new test methods

for assessing the durability of sealants and adhesives, and, at reaching the ultimate goal, the devel-

opment of performance-based specifications.

Structural silicone sealants are used to attach glass or other panels to curtainwall framing systems.

These sealants must possess sufficient structural strength to carry the wind-loads but must also have

sufficient movement capability to resist the fatigue caused by cyclic shear movement. Cyclic shear

movement is induced in the structural sealant by differences in the thermal expansion between the

glazing panel and the curtainwall substructure undergoing variations in temperature. Temperature

variations occur in response to changes in atmospheric conditions (clouds, rain, etc.), as well as di-

urnal or seasonal climate changes. Assuming the occurrence of a cyclic shear exposure event twice a

day, a structural sealant is exposed to 36 525 cycles over a period of 50 years. In their paper, L. D.

Carbary, E. D. Bull, and S. S. Mishra expose nine silicone sealants with rated movement capabilities

of 12.5 , 20 , 25 and 50 to at least 36 000 cycles of cyclic shear movement with 15 strain at

a rate of five cycles per minute. It should be noted that realistically, thermal movement displacements

for in-service curtainwalls will rarely approach strains of 15 . Products with a movement capability


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of 12.5 have been performing without failure for many years lending credence to this point. While

the tested structural silicone sealants experience degradation as a result of the cyclic shear exposure,

the degradation is small enough not to induce rupture, if the sealants are not strained beyond their

movement capability. The sealants with higher movement capability show less susceptibility to

degradation than sealants with lower movement capability. The authors suggest that this test method

can provide a basis and a model from which to further study fatigue and to provide some guidelines

and understanding of how the structural silicone sealants react to repetitive loading. They also spec-

ulate that further development of this method may result in its inclusion in the ASTM C1184

Specification for Structural Silicone Sealants.

The expectations of building owners for waterproofing systems are simple. Waterproofing must pre-

vent the passage of water (impermeability), must be capable of successful installation under typical

construction conditions (constructability), and must continue to provide waterproofing for the life of

the structure (durability). The realization of these expectations is thwarted, in part, by a lack of con-

sensus on how these features are defined, tested, and compared to performance-based criteria. J. C.

Strong, J. R. Kovach, and V. S. Eng in the first part of their paper investigate important properties of

waterproofing materials commonly used on plazas and below-grade walls and review the acceptance

criteria of ASTM International,Canadian General Standards Board (CGSB), and International Code

Council (ICC) Evaluat ion Services (ES) standards for waterproofing systems. In order to overcome

the discrepancies between these standards, the authors recommend an open dialogue between the

groups responsible for waterproofing material specifications in ASTM, CGSB, and the ICC ES. In

the second part of their paper, the authors contribute two exploratory studies on the initial leakage re-

sistance of bentonite waterproofing and the water absorption in cold liquid-applied waterproofing.

Based on this testing, the authors suggest specific improvements in the relevant standards.

In November 2000, the Architectural Institute of Japan (AIJ) established a subcommittee chartered

with developing an accelerated weathering test method suitable for assessing the durability of

sealants. In their paper, N. Enomoto, A. Ito, I. Shimizu, T. Matsumura, Y. Takane, and K. Tanaka re-

port interim results obtained with the proposed test method. In this method, the weatherability of

sealants is studied using newly developed test specimens, which enable exposure of the cured sealants

to simultaneous compression and extension in a single test specimen. The study comprises twenty-

four sealants of seven chemical types commercially available in Japan. Interim results are reported

after twelve months of natural outdoor weathering at three exposure sites in Japan (north: Hokkaido,

central: Chiba, and south: Okinawa) and 3500 hours of artificial accelerated weathering with xenon

lamp and carbon flame weathering devices. The interim results confirm that the surface degradation

of sealants is accelerated by the additional movement cycles, and that the differences in the degrada-

tion among the sealants are becoming observable after the current exposure durations.

In their paper, H. Miyauchi and K. Tanaka propose a new design and service life assessment method

for sealed joints exposed to seismic events. The paper is the culmination of several years of research

by the two authors. In this research, the fatigue resistance of sealed joints to relative story displace-

ment movements caused by earthquakes was studied experimentally and analytically. The authors

now propose a new joint design method, which provides adequate sealed joint performance over the

join t' s service life. The design method is based on three criteria, i.e., type of sealant, effect of cross-

sectional size and shape of the sealed joint, and fatigue resistance of the sealant at intersectional zones

of sealed joints to the sliding and rocking motions of curtain wall panels. The process of sealed joint

design considers the relationship between the number of cyclic movements to which the sealed joint

is exposed during its service life and the number of cycles to crack initiation in the sealed joint as ob-

served in the fatigue test method developed by the authors. Finally, he approach suggested by the au-

thors allows the calculation of the accumulated damage level and the expected service life of a sealed

joint.

In their paper, A. T. Wolf, S. Sugiyama, and F. Lee report on the use of an optical imaging and im-

age analysis system in the assessment of surface changes induced in sealants by outdoor weathering.

The method allows quantification of four distinct surface defects in the samples, namely cracking


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crazing), visual color change, spatial uniformity of deterioration due to dirt pick-up and uneven

color change, or both), and overall surface texture. Chalking and dirt pick-up, as rated visually prior

to the evaluation, cannot be accurately assessed with the digital imaging technique employed. The

analysis shows that surface cracking and crazing generally can be well characterized using the auto-

mated image analysis system. While this study represents a step in the right direction, the authors sug-

gest that further investigations are needed to develop an automated surface characterization method

for sealants.

With current expectations for building exteriors to prevent all air and water entry into the building in-

terior, the need for a near perfect seal of weatherproofing sealant joints has reached new levels of in-

tensity. The need for better field tests has increased accordingly. To reach these goals, ASTM C-

1521-02a Standard Practice for Evaluating Adhesion of Installed Weatherproofing Sealant Joints has

been developed and adopted. The practice outlines a nondestructive procedure. The advantage of this

methodology is that it allows an unlimited amount of testing to be conducted. While the procedure

does not specify a specific instrument to induce the strain on the sealant/substrate bond-line, a device

able to accomplish this procedure in a uniform, controlled, and calibrated fashion has been developed.

The paper by D. Huff outlines a description of the device and its capabilities. The paper also provides

a discussion of the use of statistical sampling when the option of complete testing is not feasible or

required.

l o su r e

As we publish this volume, I look forward to the next Symposium on Durability of Building and

Construction Sealants and Adhesives 2008-DBCSA) and the associated flurry of papers in this dy-

namic industry. I encourage all readers to participate in the work of ASTM C24 committee, to attend

the future symposia and to contribute new papers. Your participation and feedback help to advance

the industry and, as a result, we will all benefit from improvements to our buil t environment.

In closing, I would like to gratefully acknowledge the outstanding quality of the contributions made

by the authors as well as the dedicated efforts of the 2005 session chairpersons, the peer reviewers,

and the staff of ASTM and AlP, who all helped to make the 2005 symposium and the publication of

the associated papers possible.

Andreas T. Wolf

Wiesbaden, Germany


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Factors Influencing the Durability of Sealed

Joints and dhesive Fixations


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Jerome M Kloso wski I and John E Plott2

Journa l o f ST M In te rna t iona l Vol. 3, No. 4

Pap er ID JA113415

A va i lab l e on l i ne a t w ww.as tm .o rg

R e d u c i n g M o d u lu s o f S e a l a n t s t o I m p r o v e u r a b il it y

ABSTRA CT The premise i s that i f one reduces sea lant fa t igue by lowering mod ulus whi le leaving o th er

characteristics of a sea lant unchanged, i ts durabi li ty wi l l improve. Reducing sea lant fat igue is seen as a

pos it ive cons eque nce of lower ing the modulus o f e las ti ci ty o f a sea lant . The d ata sho ws the e f fec t o f

incorporat ing a modulus modi fier in one - and two-p ar t s tanda rd cur ing) ure than e sea lants and a one -par t

s i lane cur ing po lyether sea lant . Th is a pproach lowers m odulus w i th no o r m in imum reformulat ion.

KEYWORDS sealant, addit ive, adh esion, m odulus, elongat ion, mo vem ent, durabi li ty

n t r o d u c t i o n

M o s t s e a l a n t s a r e n o t u s e d a s s t r u c t u r a l a d h e s i v e s . T h e m a j o r i t y o f s e a l a n t s a re i n t e n d e d t o fi ll h o l e s a n d

j o i n ts a n d m o v e w h e n t h e j o i n t m o v e s a n d a d h e r e t h e w h o l e t i m e . S e a l a n ts t h a t a r e s o m e w h a t s o f t er b u t

r e m a i n e l a s t o m e r ic a r e m o r e s u i t e d f or t h o s e a p p l i ca t io n s h a v i n g h i g h j o i n t m o v e m e n t l i k e e x p a n s i o n

j o i n t s , c u rt a i n w a l l s, h i g h w a y p a v e m e n t j o i n t s , p a r k i n g d e c k s , a n d b r i d g e s . F o r e x a m p l e , a s e a l a n t th a t c a n

t a k e + / - 2 5 % j o i n t m o v e m e n t is c o n s id e r e d m o r e u s e f u l a n d c a n b e u s e d i n m o r e a p p l ic a t io n s t h a n a

s e a la n t + / - 1 2 . 5 % o r + / - 2 0 % j o in t m o v e m e n t . T h a t is tr u e r i gh t u p th e li ne , w i t h + / - 3 0 , 4 0 , a n d 5 0 %

j o i n t m o v e m e n t al l b e i n g m o r e u s e f u l . T h e r e fo r e , a d d i t i v e s th a t l o w e r t h e m o d u l u s o f e la s t i ci t y c a n b e v e r y

u s e f u l i f i n d e e d t h e y l o w e r t h e m o d u l u s o f e l a s ti c i ty a n d a r e a c c o m p a n i e d b y h i g h e r e l o n g a t i o n . T h e k e y

b e n e fi t s e e n i s th a t th e y a re m o r e c a p a b l e o f h a n d l i n g h i g h e r jo i n t m o v e m e n t w h i l e l e s s e n i n g s t r es s e s o n

t h e s u b s t r a t e s r e s u lt i n g i n g r e a t e r d u r a b il i ty a n d l o n g e v i t y . T h i s i s e s p e c i a l ly i m p o r t a n t i f t h e s u b s t r a t e i s

r e la t i v el y w e a k l ik e E x t e r i o r I n s u l a ti o n F i n i s h e d S y s t e m ( E I F S ) o r w i t h m a n y c e m e n t a t i o u s s u r fa c e s . In

e s s e n c e , t h e j o i n t l a s ts l o n g e r w h e n l e s s s t r e s s i s i n t ro d u c e d . W h e n j o i n t s l a s t l o n g e r, b u i l d i n g s l a s t lo n g e r .

T o t h a t e n d , a m e l a m i n e t y p e a d d i t i v e w a s e v a l u a t e d i n d i f f e r e n t c o n c e n t r a t i o n s a n d s o l v e n t s w i t h

s e v e r a l s e a la n t t y p e s to s e e i f a b e n e f ic i a l c h a n g e i n p e r f o r m a n c e c o u l d b e a c h i e v e d .

P r o c e d u r e

A m e l a m i n e t y p e a d d i t iv e s u p p l i e d b y T h e C . P . H a l l C o m p a n y ( C h i c a g o , I l li n o is ) w a s a d d e d a t l e v e l s

r a n g i n g f r o m 0 . 3 to 6 . 0 % s o l i d s in s o l u t i o n to v a r i o u s s e a l a n t s i n c l u d i n g a o n e - a n d t w o - p a r t u r e t h a n e

s e a l a n t , a n d a o n e - p a r t s i l a n e c u r i n g p o l y e t h e r s e a l a n t .

S o l u t i o n c o n c e n t r a t i o n s w e r e m a i n t a i n e d a t 8 5 % s o l i d s a n d 1 5 % s o l v e n t ; s o l v e n t t y p e s i n c l u d e d

2 - e t h y l h e x a n o l ( 2 E H ) a n d M e t h y l i s o b u t y l k e t o n e ( M I B K ) . T h e s t u d y l o o k e d a t c h a n g e s in s e a l a n t p h y s i -

c a l p r o p e r t i e s a n d c h a n g e s i n s u b s t r a t e a d h e s i o n . P h y s i c a l p r o p e r t y t e s t i n g i n c l u d e d s e a l a n t r e s i l i e n c e a s

m e a s u r e d w i t h a p l a s t o m e t e r , a n d t h e s e a l a n t s t re s s / s tr a i n r e l a t i o n s h i p a s m e a s u r e d f r o m s t r e s s i n g ty p i c a l

C 7 1 9 ( o r I S O 9 0 4 7 ) c o n f i g u r e d s e a l a n t j o i n t s . T h e a d h e s i o n w a s s t u d i e d a f t e r 2 1 - d a y c u r e u s i n g t h e

9 0 d e g p e e l t e s t d o n e a t a m b i e n t c o n d i t i o n s a n d t h e n a t 7 - , 1 4- a n d 2 1 - d a y 5 0 ~ w a t e r i m m e r s i o n s . T h e

p e e l t e s t w a s a p p r o p r i a te f o r t h is s t u d y s i n c e it is c o m p a r i n g a p r o d u c t t o i t s e l f a n d v a r i a t i o n s w i t h i n a

g i v e n f o r m u l a .

Manuscript received May 23, 2005; accepted for publication October 20, 2005; published online February 2006. Presented at

ASTM Symposium on D urabili ty of Building and Construction Sealants and A dhesives, Second Symposium o n 15-16 June 2005

in Reno NV" A. T. Wolf Guest Editor.

1 . ' ' . ' . . . . .

President of Klosowski Scientif ic Inc., Ch ief Che ml st--E ng me enn g Diagnostics Inc., FA STM, Retired Senior Scientist , Dow

Com ing Corporation, Klosowski Scientifc Inc., 30 31 State Street Rd., Bay City, Michigan 48706.

2 President, The Performance Strategy G roup, ww w.performancestrategygroup.com, Registered P rofessional Engineer, Certified

New Product Development Professional, John E. Plou, PE LLC, 6000 Woodpark Drive, Midland, MI 48640.

Copyrigh! 9 2006 by ASTM Intemaliona]. 100 Bait H arbor Drive, PO Box C7 00, WestConshoht,x~ken.PA 19428-2959.


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D U R B IL ITY OF BU IL D IN G C ON STR U C TION

T A B L E l~A dd itiv e adhesion test i ttg of ra o-part uretlume sealant (d 0 and 9 days we t ) .

C onc lx~ t e Gh t s s Ky n ' a r~ P V C A l u m i n u m ~

d r y 9 d w e t d r y 9 d w e t d r y 9 d d r y 9 d d r y 9 d

w e t w e t w e t

C o n t r o l 5 4 t o 5 5 5 2 0 - 1 5 5 5 5

2 - E H ( a l c o h o l o n l y l a t 0 . 2 6 c k 5 5 5 t o 4 4 t o 5 3 3 5 4 5 5

R e s i n 2 - E H a t 0 . 3 9 ~ 4 4 t o 5 5 5 2 0 - 1 5 5 5 5

R e s i n i n 2 - E H a t 0 . 6 5 c ~ 4 4 t o 5 5 5 2 1 5 5 5 5

R e s i n i n 2 - E H a t 1 .7 % 5 5 4 t o 5 5 3 0 - 1 5 5 5 5

N o t e : T h e r e s i n a d d i t i v e w a s 8 5 ~h s o l i d s , 1 5 % 2 E H s o l v e n t . 5 = c o h e s i v e f a i l u r e . 4 = p a r t i a l c o h e s i o n , 3 = s t r o n g a d h e s i o n b u t a d h e s i v e f a il u r e ,

2 = m o d e r a t e a d h e s i o n , I = w e a k a d h e s i o n , 0 = n o a d h e s i o n

U n p r i m e d

For one part sealants, 94 g of sealant was put into the disposable cups that go with the (DAC) 150

mixer and 0.65, 1.7, 4.0, 6.0 % additive solution was added. Each time it was mixed in gently by hand, and

then mixed for 26 s, the top removed, scrapped down, and mixed again for 26 s. The head space was

purged with an inert gas and the container was sealed and left to sit for 24 h to equilibrate. A 10 cc syringe

with the bottom removed was used to draw the sealant and inject it into the test joints. The joints had

Teflon~3 spacers and were 12 mm by 12 mm by 50 mm (89 by 89by 2 in.). Separately, a 3 nun (1/8 in.)

thick slab of the same sealant was prepared by tooling the sealant between 3 mm (1/8 in.) spacers to

check cure rate and durometer. For each test, a control was made and handled in the same manner.

The two-part sealants were handled in a similar fashion with the additive introduced into the base,

allowed to equilibrate for 24 h. The pigment and activator were then added, mixed 12 s, scrapped down,

mixed again for 12 s and then placed into joints and into a slab as done with the one part sealants.

The additive in 2EH represented 0.3, 0.65, and 1.7 % of the total sealant formulation; the additive in

MIBK represented 4.0, 5.0, and 6.0 % of the sealant formulation. The resin additive was 85 % solids and

15 % solvent in each case. In each set of experiments, a separate experiment was run using 2EH and

MIBK in the amount that is present in the additive solution.

No attempt was made to optimize the order of addition, sealant equilibration time or other manufac-

turing variables.

With each sealant and additive combination, an adhesion study was done on concrete, EPDM, glass,

Kynar, PVC, cold rolled steel, anodized aluminum and brass. For this study, the concrete was wiped free

of dust; the EPDM was wiped with xylene; the glass cleaned with IPA/water; the Kynar was wiped with

MIBK, and the cold rolled steel with toluene. In each case the surface was cleaned twice, using the two-rag

method each time, one to wipe it on and the other to wipe it off. These were than coated with approxi-

mately 88 n. thick by I in. wide sealant in strips and cured for 21 days. The adhesion was checked by

forming a tab and pulling at 90 deg to the surface noting the resistance to the pull and the mode of failure.

After the initial check, the samples were put into a 50~ water bath for one week, then checked, then

re-immersed and rechecked on a periodic basis (e.g., 9-days wet (two-part urethane), 21-days wet (one-

part urethane), 35-days wet (one-part silane curing polyether). These results were then compared to the

control (without additive). Tables 1-3 represent the data generated from these experiments with various

additive levels and solvent types.

i s c u s s i o n

For purposes of this evaluation, adhesion data was based on the following number scale: 5 equals cohesive

failure, 4 equals partial cohesion, 3 equals strong adhesion but adhesive failure, 2 equals moderate adhe-

sion. 1 equals weak adhesion and 0 equals no adhesion, that is, the sealant almost falls off the substrate.

Tables 1-3 show the adhesion results for both one- and two-part urethane sealants and one-part silane

curing polyether for the control and with various additive levels and solvent types.

In all cases, the additive did not hurt adhesion, and with several substrates, adhesion was improved.

Pictures of actual samples tested are also shown in Figs. 1-3.

Standard cure, two-part urethane control on aluminum joint (left) showing 100 % adhesive failureand

S T e f l o n~* i s a r e g i s t e r e d t r a d e m m k t ) f t h e D u P o n l C o r p o r a t i o n . I ) ,


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KLOSOWSKI AND PLOTT ON SEALANTS

TABLE

2--Additive adhesion testing of one-part nrethane sealant dry and 21 days wet).

Concretea EPDM Glassa Kynara PVC

dry 21d dry 21d dry 21d dry 21d dry 21d

wet wet wet wet wet

Control 3 3 1 5 2 5 1 4 2 3

2-EH at 0.35 % 5 5 2 5 3 5 2 5 3 5

Resin in 2-EH at 0.65 % 3 5 1 5 2 4 I 3 3 4

Resin in 2-EH at t. 1% 3 5 1 5 3 4 l 4 1 4

Resin in 2-EH at 1+7 % 3 5 1 5 3 5 1 4 l 5

Resin in 2-EH at 2.2 % 3 5 1 5 3 5 1 5 2 5

Resin in 2-EH at 2.8 ch 5 5 2 5 5 5 2 5 2 5

Note: The resin additive was 85 % solids, 15 % 2EH solvent; 5=cohesive failure, 4=parti',d cohesion, 3=strong adhesion but adhesive failure,

2=moderate adhesinn, 1=weak adhesion, 0=no adhesion

aUoprimed

1 .7 % add i t ive in 2EH ( r igh t ) in the s ame fo rmula t i on s how ing 100 % cohes ive f a i lu r e .

S tandard one- pa r t u r e thane con t ro l on concre te jo in t ( l e ft ) s how ing 100 % adhes ive f a i lu r e ; ve r s us 1 .7

% add i t i ve in 2EH in the s ame fo rmula t ion ( r igh t ) s how ing 100 % adhes ive f a i lu r e .

TABLE

3--Additive adhesion testing o f one-part silane curing polyether dr), and 35 days wetj,

Concrete ~ EP DM Glassa Kynar~ PVC~ Steel~ Aluminum Brass

dry 35d dry 35d dry 35d dry 35d dry 35d dry 35d dry 35d dry 35d

wet wet wet wet wet wet wet wet

Control 5 2 0-1 0 5 5 3 3 1 t 5 2 4 5 2 0

Resin in MIBK at 4.0 % 5 2 0-1 0 5 5 3 5 0 0 5 3-4 5 5 4-5 2

Resin in MIBK at 5.0 % 5 2 0 0 5 5 2 3 0 0 5 3-4 5 5 3 2

Resin in

MIBK

at 6.0 % 5 2-3 0 0 5 5 2 3-4 0 0 4-5 2 2-3 5 2-3 1-2

Note: The resin additive was 85 % solids, 15 % MIBK solvent. 5=cohesive failure, 4=partial cohesion, 3=strong adhesion but adhesive failure,

2= moderate adhesion, 1= weak adhesion, 0= no adhesion

aUnprimed

F I G .

1 - - T w o - p a r t u r e t h a n e o n a l u m i n u m l e ~ ) a n d w i t h a d d i t i v e r ig h t) .

F I G .

2 - - O n e - p a r t u r e t h a n e o n c o n c r e t e l e ft ) a n d w i th a d d i t i v e r ig h t) .


19/132

DURA BILITY OF BUILDING CONSTRUCTION

FIG. 3- -l -p ar t silane curing poly ethe r on concrete left) and with additive right).

One-p art s i lane curing polyeth er control on concrete join t (left ) showing 40 cohe sive fai lure versus

4.0 addit ive in MI BK (f ight) showing 70 cohes ive fai lure.

The pho tos re inforce the prev ious comme nt tha t the addi t ive so lu tion does no t harm adhes ion and may

have some improvement .

Addit ional test ing was done to val idate the effect of the addit ive on sealant modulus. Within an

opt imum range of addi t ive leve l - - th a t is , 1 .7 in 2EH for one- and two-par t u re thane sea lan ts, and 4 .0

to 6 .0 in MIB K for one-par t s i l ane cur ing po lye ther sea la n t - - th e e longa t ion increased approximate ly 60

percen t . Wh en the equiva len t amount o f so lvent was used wi thout addit ive , t ens i le fo rce was lowered

but no resul tant increase in elongat ion was seen. See Figs. 4-6.

onclus ions

The data indicates that relat ively low levels of the addit i ve- - th at is , 1 .7 in 2EH for one- and two-part

ure thanes, 6 .0 in MIB K for s i l ane cur ing po lye ther sea lan ts - - lowe rs sea lan t modulus wi thout nega t ive ly

affect ing substrate adhesion. 2EH (alcohol) by i tself lowered the pul l force but did not increase sealant

elongat ion versus the addit ive in solvent which did. In separate controls , the addit ive in MIBK was also

evaluated and found to be useful in lowering modulus and increasing sealant e longat ion in one-part s i lane

curing polyether sealants . In data not shown in this paper , the addit ive in both 2EH and M IBK lowered the

modulus in proport ion to the concentrat ion level used while increasing elongat ion to produce a very

interest ing product w ith enhan ced join t mo vem ent ab i l i t ies leading to increased sealant durabi l i ty . In other

E lo n g a t i o n ( % )

0 100 200 300 400 SO0 600 700

2 - p a r t

U r e l : h a n e S e a l a n t T e s t R e . s u i t s

: I

0.99MPa

[ V ~ i I

.... / INCREASEWlTH ADDITIVE I .. .. .. .. .. .. .. .. .. .. i IO,86MPa

[ 1 :: : :: ::

i / ~ Cont rol for t r ia l set

i i I

i A.- ~, Average O'69$Mpa @ 90% el~176 peak f~ 3 trials i t . .. . .. .

9 ~;~ /~ 2EH {al tohoi only) , te i l lant

t a c k y a n d

uncured

[ ~< i J f ~ ~ Average O.624MPa @ 94% elongation peak for 3 trials : i O.57MPo

Z J ~ ' ; : ~ ] ~ : 1

Average 0.49/MPa O 153~

elongation peak for

3 tr ials o .. .. . i?

!.' :

' ' . i ;

: / ~1 1 i: t i

. . . . . . . . . ~ : ~ o.14Mpa

FIG. 4 Elong ation compa rison of two-part, urethane seal ant unprimed) with and withou t additive.


20/132

K L O S O W S K I A N D P L O T T O N S E A L A N T S 7

r " I E l o n g a t i o n ( % l

0 1 0 0 2 0 0 3 ~ 0 4 0 0 5 0 0 6 0 0 7 0 0

I i : i : / ~ _ . . . L " c o n t r o i f o r t r i a l s e t : : i I . . . . .

I i i / F i ' ~ ' | A v e r a g e 1 , 0 1 4 N e e @ Z 6 3 % p e a k e l o n g a t i o n f o r t r i a l s e t

I - ' : . . .. .. .. .. .. . . . . . . . . : . . .. . .. . . .. . J i A ~ , = ~ a , ~ 5 ~ . ~ , , : O . ~ A i i o ~ . . ~ o , , ~ . ,

i i ' 1 I N C R E A S E W I T H A D D I T I V E i '

; I = - i

! " ; : ; i o , 7 1 i v l p a

.............. :: o SZ M:~ . %

J H i i i l

/ ~ : a - P a r t U r e t h a n e S e a l a n t T • t R e s u l t s

o . o o M p a

FIG. 5--Elongation comparison of one-part, urethane sealant unprimed) with and without additive.

E l o n g a t i o n ( % )

0 t 0 0 2 0 0 ] 0 0 4 0 0 5 0 0 6 0 0 7 0 0

0 , 9 g M P a

l - l i n d S i l e n e C u r e P o l y e t h e r S e a l a n t T e s t

R e s u l t s

; 0 , B 6 M P a

A V E R A G E 5 7 % E L O N G A T I O N

L N C R E A S E W I T H A O B T V E ) . . . . . . . . 0 , 7 1 M P a

C o n t r o l f a r l h r i a l

A v e r a g e 0 , 4 7 3 M P a @ 3 8 9 % p e a k e l o n g a t i o n f o r t r ia l ~

W i th 6 . 0 % a d d i t i v e i n M T i tK m i x e d i l l

. : , , , A v e r a g e 0 . S Z O H P a ~ 0 1 1 ~ o p e a k ~ o n g a t l

0 . 4 3 ~ l P a M =

0 . 2 8 M P a

B a s e I I

l

9 ! o . o o M p a

F IG

6--Elongation comparison of one-part, silane curing polyether sealant unprimed) with and without

additive

data not shown in this paper, higher levels of 2EH (alcohol) inhibited cure rate and caused the surface to

remain tacky for extended periods. For this reason, MIBK was substituted for 2EH when additive con-

centrations above 1.7 were used. As shown in these tables, lower concentrations of additive were

especially useful in one- and two-part urethane formulations in that they had little effect on cure rate or

tackiness or adhesion but a significant effect on movement ability and modulus of elasticity. Also, higher

concentrations of additive in MIBK were more useful in the silane curing polyether sealants again with

little effect on cure rate, tackiness or adhesion but a significant effect on movement ability and modulus.

A key observation is that the melamine type additive, while having a pronounced effect on physical

properties, had no detrimental effects on adhesion. These could be very useful in extending the sealants

joint movement capabilities into the higher movement (+ /- 50 ) ranges.

To the extent that joint movement ability, enhanced by lowering sealant modulus and increasing


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D U R ABIL ITY OF BU IL D IN G C ON STR U C TION

elongat ion is a factor in joint durability an additive like this could contribute to increased durability and

broaden the range of application.

e m a r k s

The melamine type additive is a proprietary material available from C. P. Hall Inc of Chicago IL.

Urethane sealants were commercially available; suppliers did not wish to be identified at this time.

One-part silane curing polyether sealant was a proprietary product from a supplier also not wanting to

be identified at this time.

Adhesion substrates of glass aluminum and concrete were the standard ASTM specimens. The others

were commercially available both off the shelf.

The mixer used was a DAC 150 an early version of the centrifugal mixers available from Flacktek

Inc. of Landrum South Carolina.

All solvents were commercial grade from local hardware stores.

Stress/strain testing was done on an Instron run at a crosshead speed of 2 in. per minute.


22/132

J ou r na l o f A S TM I n t e rna t i ona l Vol. 3, No. 8

Pap er ID JAI13121

A va i lab l e on l i ne a t w ww.as tm .o rg

J a m e s E . S t e w a r t , 1 W i ll i a m R . O B r i e n , 2 a n d A n d r e a s T . W o l f f

Q u a n t i f i c a t i o n o f D i f f e r e n t i a l T h e r m a l M o v e m e n t i n I n s u l a t i n g

G l a s s E d g e S e a l s U s i n g F i n it e E l e m e n t n a l y s i s

A B S T R A C T :

Di f ferent ia l thermal movement between the spacer f rame and the g lass panes is a key

contr ibutor to the aging of insulat ing glass ed ge sea l and o f the insulating glass uni t IGU) i tsel f. Using f in i te

e leme nt ana lys is FEA) the autho rs modeled the therm al mo vem ents occurring in the edge sea l o f a large

IGU 1 .5 • m 2) as a resul t o f t em pera tu re va r i a ti ons -3 0~ to +60~ fo r t h ree com m erc i a ll y ava i lab l e

space r bars o f d i fferent material a nd des ign. T he m odel wa s based on ny lon co rner keys for the a luminum

and galvanized

s t e e l s p a c e r s

and b ent corners for the s ta in less s tee l spacers . The ny lon corne r keys were

assum ed to be so lid and f i rm ly bonded to the spacers ; whe reas the bent corners we re mode led as so lid ,

bent me ta l corner keys , a lso fi rm ly bonded to the spacers . S ince ac tua l be nt corners are ho l low, the mod el

tends to overes t imate the s t resses for th is corner des ign. A s exp ected, a t the low temperature , the corn ers

are pu lled inward, resu lt ing in a bending angle >9 0~ whi le a t the h igh tempe rature, the corners are pushed

outw ards , resul ting in a bending an gle < 90 ~ M oni toring the cha nge s occurr ing in the thickness of the

poly isobuty lene pr imary sea l a long the c imu mferen ce of the IGU, the authors found tha t the s ta in less s tee l

spac er bad, by far , the leas t e f fec t on the cha nge in the c ross-sec tional area, whi le the a luminum spac er

had the most substant ia l e f fec t . Th is f ind ing is in keeping w i th the expected per formance based on the

d if ference in therma l expans ion coeff ic ients betw een s pac er mater ia l and f loat g lass . Thus, cha nge s in the

effective cross-sect ional are a of the pr imary sea l ava i lable for di ffusion that ar ise f rom di f ferent ial therm al

movements , are l ike ly to acco unt for the observe d per form ance d i fferences of IGU s hav ing d i f ferent spacer

m a t e r i a l s .

K E Y W O R D S : I ns u la t in g g l a s s u n it d if fe r en t ia l t h e r m a l m o v e m e n t s p a c e r f in i te e l e m e n t a n a l y s i s

n t r o d u c t i o n

I n s u l a t i n g g l a s s u n i t s ( I G U s ) a r e e x p o s e d t o a v a r i et y o f e n v i r o n m e n t a l f a c to r s , s u c h a s t e m p e r a t u r e a n d

a t m o s p h e r i c p r e s s u r e f l u c t u a ti o n s , w i n d l o a d s , w o r k i n g l o a d s, s u n l i g h t , w a te r , a n d w a t e r v a p o r t h a t n e g a -

t i v e l y a f f e c t s t h e i r s e r v i c e l if e [ 1 ]. D u r i n g s e r v i c e , t h e e d g e s e a l o f t h e g l a z e d I G U i s e x p o s e d t o a

m i c r o c l i m a t e w i t h i n th e w i n d o w f r a m e o r cu r t a i n - w a l l c o n s t r u c t i o n t h at s t r o n g l y d e v i a t e s f r o m t h e a m b i e n t

c l i m a te . T w o m a j o r s t u d i e s h a v e b e e n c o n d u c t e d i n a n e ff o r t t o m o n i t o r t h i s m i c r o c l i m a t e i n t e r m s o f

e d g e - s e a l t e m p e r a t u r e , m o i s t u r e , a n d p r e s e n c e o f l iq u i d w a t e r o v e r a p e r io d o f s e v e r a l y e a r s [ 2 ,3 ] . W h e r e a s

i n C e n t r a l E u r o p e e d g e - s e a l t e m p e r a t u r e s o f c l e a r g l a s s 1 G U s s e l d o m e x c e e d 4 0 - 5 0 ~ f o r t i n te d o r

c o a te d g l a s s u n i t s o r in w a r m c l i m a t e s s er v ic e t e m p e r a t u r e s m a y w e ll r ea c h 8 0 ~ a n d a b o v e f o r p r o l o n g e d

p e r i o d s o f t i m e [ 4 ].

I n o rd e r t o w i t h s t a n d t h e s e e n v i r o n m e n t a l l o a d s , a n I G U e d g e s e a l m u s t h a v e t h e f o l l o w i n g p r o p e r ti e s :

9 D u r a b i l it y , i. e. , r e s i s t a n c e a g a i n s t e n v i r o n m e n t a l f a c t o r s ( b o th i n t e r m s o f p h y s i c a l p r o p e rt i e s a n d

a d h e s i o n ) .

9 S t r u c tu r a l s t r e n g t h t h a t c o n s t r a i n s m o v e m e n t i n t h e e d g e - s e a l t o m i n i m i z e c h a n g e s i n t h e ef f e c-

t i v e c r o s s - s e c t i o n a l a re a o f t h e p r i m a r y s e a l a v a i l a b le f o r d i f f u s i o n .

9 L o w m o i s t u r e - a n d g a s - p e r m e a b i l i t y u n d e r se r v i c e c o n d i t i o n s .

D i f f e r e n ti a l t h e r m a l m o v e m e n t b e t w e e n t h e s p a c e r a n d t h e g l a s s p a n e s i s a k e y c o n t r i b u t o r t o th e a g i n g

o f t h e i n s u l a t i n g g l a s s e d g e s e a l a n d o f t h e I G U i ts e lf . R e p e t i ti v e s h e a r a n d t e n s i l e c y c l i n g i n d u c e s a

p u m p i n g e f fe c t in t h e p o l y i s o b u t y l e n e ( P IB ) p r i m a r y s e a l th a t o v e r t im e d i s p l a c e s t h e p r i m a r y s e a l a n d

Manu script received May 5, 200 5; accepted for publication May 4. 2006; published online June 2006. Presented at AST M

Symposium on Durabili ty of Building and Construction Sealants and Adhesives on 15-16 June 2005 in Reno, NV:

A. 1". W olf, Gue st E ditor.

1 Senior Engineer, Dow C orning Corporation, M idland. MI 4868 6.

2 Marketing Specialist, Dow Com ing Corporation, Midland, M I 48686.

3 Scientist, Dow Co min g Gm bH, 65201Wiesbaden, Germany.

Copyright 9 2006 by ASTM International, 100 Barr Harbor Drive, PO Box C 700, WestConshohocken,PA 19428-2959.


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1 DURABILITY OF BUILDING CONSTRUCTION

FIG. 1 Glas s pane e lement modeled .

generates voids, resul t ing in an increased leakage rate of the IGU. D epend ing on the physical propert ies of

the secondary seal , the mechanical cycl ing may also induce fat igue aging in the edge seal . Final ly, the

different ial thermal movement also affects the opening of the primary and secondary seals and, therefore,

the effect ive cross sect ion through which diffusion of water vapor and f i l l gases occurs. Therefore, a

quanti ta t ive evaluat ion of the magnitude of different ial thermal movements in an 1GU edge-seal configu-

rat ion is essent ial in predict ing the service l i fe of an IGU.

Finite Element Analysis FEA) Evaluation

Using f in ite e lement ana lys is (FEA) the au thors modeled the thermal movem ents occur r ing in the edge sea l

of a large IGU as a resul t of temperature variat ions for three commercial ly avai lable spacer bars of

different mater ial and design.

Model ing Cons iderat ions

An IGU window size of 1.49 m (58.8 in.) by 2.13 m (84 in.) was chosen for the FEA modeling. This s ize

simulates a large sl iding glass door, w ith the same aspect rat io (1.42857) as the 0.35 m (14 in .) by 0.50 m

(20 in.) test panes. Taking advantage of symmetry, the model needs only to take one quarter of the ful l

s ize into account . In the model , the pane is supported along the bot tom perimeter edge as shown by the

arrows in Fig. 1. Element nodes on symmetry planes are constrained to remain on the symmetry planes.

Galvanized s tee l and a lum inum spacers a re modeled wi th d imens ions 12.3 mm (0 .485 in . ) wide and

8 mm (0 .315 in . ) deep and a wal l th ickness of 0 .4 mm (0 .016 in . ) for a luminum and 0 .5 m m (0 .020 in . )

for galvanized steel . Comer keys for galvanized steel and aluminum spacers are modeled as sol id polya-

mide (Nylon< ~6) keys that are bon ded to the spacers ( the mode l does not a llow for any sl ippage betwe en

the spacer and the corner keys) . Figure 2 shows the spacer and corner key designs and dimensions chosen.

The stainless s teel spacer is modeled with dim ension s of 11.5 mm (0.454 in.) wide and 6 mm

(0.235 in. ) deep with a wall thickness of 0.2 mm (0.01 i n.) . The corner key is mod eled as bon ded to the

spacers and as a sol id. The actual corner key is hol low an d the m etal is spl it a t the inner radius, therefore

the stress predicted by the m odel is much hig her than the actual s t ress expected in service. Figure 3 shows

the stainless s teel spacer and corner key designs and dimensions chosen.

The edge sea l o f the ga lvanized s tee l and a luminum spacer i s modeled wi th the secondary sea l

constrained by bon ding to the spacer and the glass panes, but not to the nylon corner key, ref lect ing the

fact that secondary sealants general ly have poor adhesion to plast ic corner keys. For the s tainless s teel

spacer , the edge seal is mod eled with the secondary seal constraine d by bon ding to the glass panes and

the spacer, as was the ca se for the galvanized steel and alu minu m spacers . However, the corne r keys in this

instance are bonded to the secondary seal as well as the edges in contrast to that described for the other

two spacer types.

The secondary sea lan t th ickness- -measured as coverage above the spacer - - i s assumed as 6 mm. The

glass thickness is modeled as 6 mm (0.236 in.) and a 0.3 mm (0.019 in.) gap is assumed for the primary


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STEWART ET AL O N DIFFERENTIAL THE RM AL MO VEM ENT 11

FIG. 2--Spacer aluminum and galvanized steel) and corner key designs and dimensions.

seal. The polyisobutylen e PIB) mater ial itself was no t modeled, due to the low streng th of the mater ial .

Figure 4 shows the edge-seal configurat ions for the aluminum and galvanized steel spacers and the

stainless steel spacer.

FIG. 3--Stainless steel spacer and corner key designs and dimensions.

FIG. 4~Edge-seal configurations fo r aluminum and galvanized steel and stainless steel spacers.


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FIG. 5-- Co rn er deflection o f aluminum spacer fra me exaggerated by facto r o f 100).

Characterization of Material Properties

For materials that display an almost linear stress-strain response within the given range of loads, such as

glass, aluminum, and steel, the key physical properties required for FEA modeling- -Young 's modulus of

elasticity and Poisson's ratio--are available in a number of engineering handbooks [5]. The response of

elastomeric seals and sealants, however, generally is nonlinear, even at lower strains. For silicone sealants,

which by nature are closer in behavior to ideal elastomers, nonlinear response must be considered once

strains exceed the range of about -15 % to +30 %. Linear FEA modeling becomes fairly inaccurate

outside this limited range; therefore, a nonlinear stress-strain curve is required for the characterization of

sealant behavior.

Uniaxial tensile and compressive stress relaxation testing was used to determine the behavior of two

silicone insulating glass sealants (DOW CORNING 982 and DOW CORNING 3-0117) 4 within the func-

tional range of strain of the materials. These tests characterize the s tress-strain behavior of the sealant at a

specific temperature and after the sealant has had time to relax under strain. This approach is more

representative of a quasistatic des ign condition where the applied sealant strains occur slowly, providing

sufficient time for the sealant to relax and reach a uniform temperature [6]. The tensile and compressive

stress-strain curves are used with a curve fit program to create coefficients for a material constitutive

equation. The constitutive equation provides strain energy density material functions for the elastomer

portion of the model.

FEA Calculations

FEA is a numerical method for predicting the deformation of a part. Essentially, the part is broken down

into a number of discrete entities or elements. A simultaneous analysis is performed on each individual

element and the effect an element has on the neighboring elements. AI~AOUS M, a commercial ly available

finite element analysis (FEA) software program,5 was used for the modeling. FEA calculations were

carried out to simulate the deformation of the edge seal for IGUs exposed to temperatures of

-3 0~ (- 22~ and +60~ (+I40~ IGUs with galvanized steel and aluminum spacers were modeled

with DOW CORNING 982 as the secondary sealant; units with stainless steel spacer were modeled with

DOW CORNING 3-0117 sealant.

Results and iscuss ion

As expected, at the low temperature, the corners are pulled inward, resulting in a bending angle greater

than 90~ whereas at the high temperature, the corners are pushed outward, resulting in a bending angle

less than 90 ~ Figure 5 shows, as an example, the deformed corner shapes for the aluminum spacer at the

low and high temperatures exaggerated by a factor of 100.

Simultaneously, the primary seal (PIB) cross section decreases at the low temperature and increases at

the high temperature. Figure 6 shows the pumping effect occurring in the PIB primary seal as a result of

the thermal cycling. The aluminum spacer, having a larger coefficient of thermal expansion (c.t.e.), com-

4Dow Coming Corporation, West Salzburg Road, Midland, MI 48686.

5a~a,4osl ~l Software, HKS Michigan, 14500 Sheldon Road, Suite 160, Plymouth, MI 48170-2408.


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STEWART ET AL ON DIFFERENTIAL THERMAL MOVEMENT 13

FIG. 6 - - P u m p i n g o f P 1B p r i m a r y s e a l a s a r e su l t o f t h e r m a l c y cl in g .

bined with the sealant (DOW CORNING 982) having a high modulus and larger coefficient of thermal

expansion, has the greatest effect on the corner of the IGU resulting in a large change in cross-sectional

area during the change from hot to cold. Monitoring the changes occurring in PIB primary seal thickness

around the circumference of the IGU, the authors found that the s tainless steel spacer had, by far, the least

effect on the change in cross-sectional area, while the aluminum spacer had the largest effect, see Table 1.

The spacer design and the material choices (spacer, sealant) also have a pronounced effect on the

nominal strain distribution in the edge-seal. Figures 7-9 show the nominal strain distribution in the edge

seal for the aluminum, galvanized steel, and stainless steel spacers at the cold (- 30 ~ and hot

(+60~ temperatures.

As can be seen, the maximum strain for the aluminum and galvanized steel spacers occurs in the

primary seal region, while the stainless steel spacer results in a more even strain distribution. This finding

is in keeping with the expected performance based on the difference in thermal expansion coefficients

between spacer material and float glass. Thus, changes in the effective cross-sectional area of the primary

seal available for diffusion that arise from differential thermal movements, are likely to account for the

observed performance differences of IGUs having different spacer materials.

TABLEI--Deformation of PIB primary seal as a function of spacer material

Deformationof PIB seal, %, lbr spacermaterial

Temperature, C aluminum galvanized stainless steel

+60~ +51% +42% +6%

-30 ~C -60% -36% -4%

F I G. 7 No m i n a l st r a in d i s tr i b u ti o n in e d g e s e a l a l u m i n u m s p ac e r, D O W C O R NI NG 9 8 2) .


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FIG. 8-- No mi na l strain distribution in edge seal galvanized steel spacer, DO W CORN ING 982).

Summary and onclusions

Differential thermal movement between the spacer frame and the glass panes is a key contributor to the

aging o f insulating glass edge seal and of the insulating glass unit IGU) itself. Repetitive shear and tensile

cycling induces a pum ping e ffect in the polyisobutylene PIB) primary seal. This pumping effect may over

time displace the prim ary seal and generate vo ids, resulting in an increa sed leakage rate of the 1GU, as has

been obse rved on IG units exposed to accelerated testing or in-service conditions see references cited in

[1]). Depen ding on the physical properties of the secondary seal, the mechanical cycling may also induce

fatigue aging in the edge seal. Finally, the differential thermal movement also affects the opening of the

primary and secondary seals and, therefore, the effective cross section through which diffusion of water

vapor and fill gases occurs.

FIG. 9 Nom ina l strain distribution in edge seal stainless steel spacer, D O W CO RN ING 3-0117).


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STEWART ET AL ON DIFFERENTIAL THERMAL MOVEMENT 15

The FEA mode l ing pe r fo rmed by the au thors conf i rmed tha t , a s expec ted , a t the low tempera tu re , the

corners o f the spacer f ram e a re pu l led inward , re su l t ing in a bend ing ang le g rea te r than 90~ wh ereas a t the

h igh tem pera tu re , the co rners a re pushed ou tw ard , re su l t ing in a bend ing ang le le ss than 90 ~ M oni to r ing

the changes occur r ing in P IB p r imary sea l th ickness a long the c i rcumferen ce o f the IGU , the au thors found

tha t the s ta in less s tee l spacer had , by fa r , the leas t e f fec t on the change in the c ross -sec t iona l a rea , whereas

the a lum inum spacer had the mos t substan tial e f fec t . Th is f ind ing i s in keep ing w i th the expec ted pe r fo r -

ma nce based on the d i f fe rence in the rmal expans ion coef f ic ien ts be tw een sp acer mate r ia l and f loa t g lass .

Thus , changes in the e f fec t iv e c ross -sec t iona l a rea o f the p r imary sea l ava i lab le fo r d i ffus ion tha t a r i se

f rom d i f fe ren t ia l the rmal movements , a re l ike ly to accoun t fo r the obse rved pe r fo rmance d i f fe rences o f

1GUs hav ing d i f fe ren t spacer mate r ia ls .

e f e r e n c e s

[1 ] W olf , A. T ., S tud ies in to the L i fe -E xpec tancy o f Insu la t ing Glass Un i t s , Build. Environ., Vol. 27,

No. 3 , 1992, pp. 305-319.

[2 ] Fe ldm eie r , E , H e in r ich , R. , Hepp , B. , Schmid , J. , and S t ie ll , W. , The Aging Behavior of Insulating

Glass (in German), Ins t i tu te fo r Window Techno logy ( IFT) , Rosenhe im, Germany , 1984 .

[ 3] Gr a v in , S. L . , a n d W i ls o n , J . , E n v i r o n m e n ta l Co n d i t i o n s in W in d o w F r a m e s w i th Do u b le - G la z e d

Un i t s , Constr. Build. Mater., Vol. 12, 1998, pp. 289-302.

[4] Jacob , L ., and D 'C ruz , J . , Funda men ta l Con cep ts fo r the Des ign , Man ufac tu re and Tes t ing o f IG

Un i t s f o r W a r m Cl im a te , Glass Processing Days 13-16 June 1999, Tam glass L td . Oy , J . V i tkala , ed . ,

Tampere, Finland, 1999.

[5] Chemical Engineers Handbook, 5 th ed . , R . H. Pe r ry and C. H. Ch i l ton , eds . , McGraw-Hi l l Book

Com pany , New York , 1973 .

[6 ] Wo lf , A. T. , and Cle land-Hos t , H. L . , M ate r ia l P roper t ie s fo r Use in FE A M ode l ing : Sea lan t

Be h a v io r w i th Am b ie n t L a b o r a to r y C l im a te Ag in g , Durability of Building and Construction Seal-

ants and Adhesives, ASTM STP 1453,ASTM In te rna t iona l , A. T . Wolf , ed . , Wes t Conshohocken , PA,

2004 , pp . 372-384 .


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Y u h a o a i I

Journ al of AST M International No ve mb e r /De ce mb e r2005

Vol.

2 No. 10

Pap er ID JAI13126

Ava i lab le on l ine a t w ww .as tm.o rg

R e d u c i n g T i n a n d m i n o s i la n e C o n c e n t r a t io n in S i li c o n e

E l a s t o m e r i c C o a t i n g t o I m p r o v e i t s D u r a b i l i t y

ABSTRACT

This study evaluated the impacts of t in and amino-functional si lane on the long-term

durability of a silicone coating material.

A n experimental design was applied. Tin an d amin osi la ne 's concentrat ions were the variables.

Laboratory-made samples were tested for initial mechanical properties. Samples were further placed in

the QU V accelerated weathering cha m ber (fluorescent U V and condensat ion method) an d tested

periodical ly for tens i le and elongation propert ies with in the durabili ty evaluation.

Based on the observations of the material and the measurements of mechanical propert ies, the

concentrat ion of t in in the formulat ion h as the m ost influential impact on durabil ity. T he high er the

concentrat ion of t in, the faster the chalking. The concentrat ion of the aminosi lane also showed similar

impacts o n the durabili ty, bu t not as significant as t in.

This s tudy suggested tha t i t i s feas ible to reduce bo th t in and a min osi lane 's amount by 30 % w i thout

significant impacts on the material 's propert ies, and this may improve the coating's durabil i ty by more

than 50 %. T his finding ma y also apply to si licone sealant and adhesives.

K EY W O RD S: Sil icone coating, durabili ty, Q UV , mechanical property, t in catalyst, aminosi lane

I n t r o d u c t i o n

S i l i c o n e m a t e r i a l s h a v e a n u n u s u a l c o m b i n a t i o n o f p r o p e r t i e s t h a t a r e r e t a i n e d o v e r a w i d e

t e m p e r a t u r e r a n g e ( - 1 0 0 t o 2 5 0 ~ T h e y h a v e g o o d lo w te m p e r a t u r e f le x ib i li ty . T h e y a re v e r y

s t ab l e a t h i g h t e m p e r a t u r e , d u r i n g o x i d a t i o n , i n c h e m i c a l a n d b i o l o g ic a l e n v i r o n m e n t s , a n d w h e n

s u b j e c t to w e a t h e r i n g . S i l i c o n e s a ls o h a v e g o o d d i e l e c tr i c s t r e n g t h a n d w a t e r r ep e l l e n c y . S i l i c o n e

m a t e r i a l s a re p r o d u c e d i n t h e f o r m s o f f lu i d s, re s i n s , a n d e l a s to m e r s . A m o n g t h e m , e l a s t o m e r

a p p l i c a t i o n s i n c l u d e s e a l a n t s , c o a t i n g s , a d h e s i v e s , g a s k e t s , t u b i n g , h o s e s , e l e c t r i c a l i n s u l a t i o n ,

a n d a v a r i e t y o f m e d i c a l a p p l i c a t io n s [ l ] .

T h i s s t u d y e v a l u a t e d t h e i m p a c t s o f t w o f o r m u l a t i o n c o m p o n e n t s , t in a n d a m i n o - f u n c t i o n a l

s i la n e , o n t h e l o n g - t e r m d u r a b i l i t y o f a s i l i c o n e c o a t i n g ( s e a le r ) m a t e r ia l .

P r e v i o u s s t u d ie s b y D o w C o m i n g i n d i c a te d th e c o a t in g m i g h t c h a lk o v e r t i m e a f te r

a p p l ic a t i o n , a n d t h e r e w e r e s e v e r a l c o m p o n e n t s i n th e f o r m u l a t io n t h a t m a y a f f ec t th e c o a t i n g ' s

d u r a b i l it y . A m o n g t h e m , t i n a n d t h e a m i n o s i l a n e w e r e t h e f o c u s i n t h is s tu d y .

Manuscript received 10 Janu ary 2005; accepted fo r publicat ion 20 Ap ri l 2005; published No vem ber 2005.

Presented a t AST M Symposium on Durabi li ty of B ui lding and Const ruc tion Sealants an d Adhesives on 15-16 June

2005 in Reno, NV.

i E-mail :y.cai@d owcornin g.com.

Copyright9 2005 by ASTM nternational,100 Ban"HarborDrive,PO Box C700, W estConshohockea,PA 19428-2959.

1 6


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C A I O N T I N A N D A M I N O S I L A N E IN S I L IC O N E 7

xperiments

I n th e s t u d y , an e x p e r i m e n t a l d e s i g n [ 2 ] ( D O E ) w a s a p p l i e d . T h e c o n c e n t r a t i o n s o f o r g a n o t i n

c a t a l y s t a n d a m i n o s i l a n e a d h e s i o n p r o m o t e r w e r e c h o s e n a s th e t w o v a r i a b l e s in t h e d e s i g n . E i g h t

s a m p l e s w e r e p r e p a r e d w i t h d i f f e r e n t t i n a n d a m i n o s i l a n e ' s c o n c e n t r a t i o n s i n t h e f o r m u l a t i o n .

T h e s i l i c o n e c o a t i n g s a m p l e s w e r e m a d e u s i n g a l a b o r a t o r y m i x e r . T a b l e 1 l i s ts t h e t in a n d

a m i n o s i l a n e ' s l e v e l s i n th e e i g h t s a m p l e s .

T A B L E

1 - - T i n a n d a m in o si la n e l ev e ls in t he D O E ~ m m p l e s .

S a m p l e I D T i n ( p p m ) A m i n o s i l a n e ~ .p _m )_ .

1 1800 1800

2 1800 1800

3 2 7 0 0 2 7 0 0

4 7 5 0 7 5 0

5 7 5 0 2 7 0 0

6 1800 1800

7 1800 1800

8 2 7 0 0 7 5 0

I n s a m p l e 3 , t h e a m o u n t o f t i n a n d a m i n o s i l a n e w e r e t h e s a m e a s t h e c o a t i n g s t h a t h a d b e e n

d e m o n s t r a t e d t o p e r f o r m w e l l. S o s a m p l e 3 r e p r e s e n t e d t h e n o r m a l c o a t i n g fo r m u l a t i o n , w h i l e

o t h e r s a m p l e s h a d e i t h e r o r b o t h t i n a n d a m i n o s i l a n e l e v e l s a t l o w e r t h a n n o r m a l c o n c e n t r a t i o n s .

A l l s a m p l e s w e r e t e s t e d f o r v i s c o s i t y a n d c u r e r a t e ( u s i n g t a c k f r e e t im e ) . V i s c o s i t y w a s

m e a s u r e d u s i n g a C a r r i m e d R h e o m e t e r ( M o d e l C S L 5 0 0) . T a c k f r e e ti m e w a s d e t e r m i n e d u s i n g

A S T M C 6 7 9 - 0 3 :

Standard Tes t Method fo r Tack-Free T ime o f E las tomer ic Sealants .

T a b l e 2

s u m m a r i z e s t h e v i s c o s i t y a n d c u r e r a t e f o r a l l t h e s a m p l e s .

T A B L E

2 -- S a m p le s initial~opro erties.

S a m p l e I D V i s c o s i t y ( p o i se ) T a c k f r ee t i m e

1 6 2 0 4 4

2 5 8 8 4 4

3 631 28

4 5 8 7 2 4 0

5 732 150

6 6 2 4 4 4

7 615 43

8 525 29

S a m p l e s m a d e w i t h t h e l o w e s t c o n c e n tr a t io n o f t in ( 4 a n d 5 ) n e e d m u c h l o n g e r ti m e t o c u r e.

S a m p l e s 1 , 2 , 6 , a n d 7 , w h i c h h a d a b o u t 33 % l e s s i n t i n a l s o h a d a b i t l o n g e r c u r e t i m e , b u t

w e r e s t il l w i t h i n a n a c c e p t a b l e r a n g e. A m i n o s i l a n e ' s l e v e l d i d n o t s e e m t o i m p a c t c u r e t i m e ,

c o n s i d e r i n g t h a t t h e s a m p l e 8 h a d th e s a m e c u r e t i m e a s t h e n o r m a l s a m p l e 3 . V i s c o s i t y r e s u lt s

a l s o h a d s o m e v a r i a ti o n s , b u t a l l i n a c c e p t a b l e r a n g e . S a m p l e s 5 a n d 8 h a d v i s c o s i t i e s o n t h e

h i g h a n d t h e l o w s i de , r e sp e c t i v e ly , w h i c h c o u l d b e e x p l a i n e d b y t h e l o w l e v e ls o f t in o r

a m i n o s i l a n e .


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A l l s a m p l e s w e r e l e f t o n a p l a s t ic s h e e t a t a m b i e n t t e m p e r a t u r e , 5 0 % h u m i d i t y t o c u re f o r 2 8

d a y s . T h e c u r e d s a m p l e s w e r e t e s t e d f o r t h e m e c h a n i c a l p r o p e r t i e s ( t e n s i l e s t re n g t h a n d

e l o n g a ti o n ) . T h e n t h e y w e r e p u t i n to Q U V [ 3 ] c h a m b e r ( f l u o r e sc e n t U V a n d c o n d e n s a t io n

m e t h o d ) a n d w e r e p e r i o d i c a l l y c h e c k e d f o r c h a l k i n g a n d m e a s u r e d f o r th e m e c h a n i c a l p r o p e rt i es .

T h e Q U V c h a m b e r w a s u s e d a s a n a c c e l e r a te d w e a t h e r i n g t e s te r to r e p r o d u c e t h e d a m a g e c a u s e d

b y s u n l i g h t, ra i n , a n d d e w . A S T M G 1 5 4 -0 4 :

Standa rd Pract ice fo r Operat ing Fluoresc ent Light

Apparatus fo r U V Exposure o f Nonm eta ll ic M ateria ls

d e s c r i b e s t h e b a s i c p r i n c i p l e s a n d

o p e r a t i n g p r o c e d u r e s f o r u s i n g f l u o r e s c e n t U V l i g h t a n d w a t e r a p p a r a t u s . T h e Q U V t e s t s

m a t e r i a l s b y e x p o s i n g t h e m t o a l te r n a ti n g c y c l e s o f U V l i g h t (3 4 0 n m l a m p ) a n d m o i s tu r e a t

c o n t r o l l e d , e l e v a t e d t e m p e r a t u r e s . T h e s p e c i f i c w e a t h e r i n g c y c l e s e m p l o y e d i n t h i s s t u d y

c o n s i s t e d o f 4 h o f U V l i g h t a t 6 0 ~ f o l l o w e d b y 4 h o f c o n d e n s a t i o n a t 5 0 ~ [ 3 ].

I n a f e w d a y s o r w e e k s , t h e Q U V r e p r o d u c e s t h e d a m a g e t h a t o c c u r s o v e r m o n t h s o r y e a r s

o u t d o o r s [ 3 ] . T a b l e 3 s u m m a r i z e s t h e o b s e r v a t i o n s o n t h e c h a l k i n g o f t h e s a m p l e s . T a b l e s 4 a n d

5 s u m m a r i z e t h e t e n s i l e a n d e l o n g a t i o n [ 4] r e s u l ts o f th e s a m p l e s d u r i n g t h e Q U V e x p o s u r e . T h e

t e s t m e t h o d e m p l o y e d f o r d e t e r m i n i n g t e n s i l e s t r e n g t h a n d e l o n g a t i o n w a s A S T M D 4 1 2 -

9 8 a ( 2 0 0 2 ) e l : Standa rd T es t M ethods fo r Vulcanized Ru bbe r and Thermoplas tic Elas tomers-

Tension.

I n F i g s . 1 a n d 2 , t h e t e n s i l e s t r en g t h a n d e l o n g a t i o n d a t a o f t h e s a m p l e s a r e p l o t t e d

v e r su s Q U V e x p o s u r e h o u r s.

T A B L E 3- - C ha l k ~ obs e rv a t ions duri n U V s tu .

Sa m pl e ID Ti m e to ch a lk ~h~. 10 000 h Q U V 17 000 h Q U V ......

1 - 1 0 0 0 0 M i n o r c h a l k C h a l k

2 1 0 0 0 0 - 1 7 0 0 0 N o c h a l k C h a l k

3 N 3 0 0 0 C h a l k C h a l k b a d l y

4 N o c h a l k u p t o 17 0 0 0 N o c h a l k N o c h a l k

5 N o c h a l k u p t o 17 0 0 0 N o c h a l k N o c h a l k

6 - 1 0 0 0 0 M i n o r c h a l k N / A

7 1 0 0 0 0 - 1 7 0 0 0 N o c h a l k M i n o r c h a l k

8 5 0 0 0 - 1 0 0 0 0 M i n o r c h a l k C h a l k b a d l L

S a m p l e

I D

T A B L E

4---Tensile strength tests results durinrmmK_QUV x.j.~re.osure

................................T..en.si~.e.St.reng.th D~. .at .D . ~f fer en t... ..Q ..~ V .E xp o~ ure ~o...ur....s.....(P.S. )...............................

0 h 1000 h 200 0 h 5000 h 10 000 h 17 000 h

1 4 2 4 4 2 7 6 11 4 6 3 4 7 0 5 5 4

2 4 0 6 4 7 4 5 5 6 4 4 5 4 6 0 4 4 1

3 4 2 8 5 3 4 5 9 0 4 4 7 4 7 0 3 6 4

4 4 0 5 5 0 4 6 2 1 4 6 2 4 9 0 5 0 6

5 3 5 6 4 0 7 5 1 8 4 1 5 4 2 0 4 3 3

6 3 8 6 4 6 1 5 5 4 4 2 4 4 7 0 N / A

7 4 1 7 4 7 2 5 8 9 4 4 5 5 0 0 4 51

8 4 1 8 4 6 8 6 1 4 4 3 7 4 4 0 4 61


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CAI ON TIN AND AMINOSILANE IN SILICONE 9

Sample

ID

TABLE 5 E l onga t i o n te s ts r es u lt s du r i nK ~ U V e ~ os ur e .

...................... Elongation Data at Different QUV Exposure Hours (

0 h 1000 h 2000 h 5000 h 10 000 h 17 000 h

1 200 140 167 168 150 87

2 196 153 148 153 145 87

3 176 142 131 130 66 34

4 249 202 197 193 176 128

5 237 197 191 196 165 I18

6 186 151 141 145 140 N/A

7 196 164 158 155 156 96

8 194 126 125 109 105 59

FIG. 1--Tensile

s trength versus Q UV exposu re t ime.

FIG.

2 Elongat ion versus QU V exposure t ime .


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i sc u s si o n s a n d S u m m a r y

S a m p l e 3 s t a rt e d t o s h o w s i g n o f c h a l k i n g a r o u n d 3 0 0 0 h in t h e Q U V c h a m b e r ; its

e l o n g a t i o n v a l u e a l s o d e c r e a s e d s h a r p l y b e t w e e n 5 0 0 0 a n d 1 0 0 0 0 h i n t h e Q U V c h a m b e r .

Sam ples 1 , 2 , 6 , and 7 , wh ich ha d 33 % low er concen t r a t i on o f t in and am inos i l ane , s t a rt ed to

s h o w s i g n s o f c h a lk i n g a r o u n d 1 0 0 0 0 h d u r in g Q U V ; t h e ir e l o n g a t i o n v a l u e d e c r e a s e d s h a r p ly

b e t w e e n 1 0 0 0 0 a n d 1 7 0 0 0 h e x p o s u r e i n Q U V .

I t i s unc l ea r why a l l t he samples had a sha rp i nc rease on t ens i l e s t r eng th a t 2000 h i n QUV

a n d t h e t e n s i l e s t r e n g t h d r o p p e d b a c k a t 5 0 0 0 h . H o w e v e r , t h e e f f e c t d o e s n o t a p p e a r t o b e

re l a t ed t o the t i n o r am inos i l ane conc en t r a t i ons .

B a s e d o n t h e o b s e r v a t io n s o f t h e m a t e r ia l c h a l k i n g p h e n o m e n a , a s w e l l a s t h e m e a s u r e m e n t s

o f t he mate r i a l s ' m echa nica l p rope r t ie s , i t is qu i t e obv iou s t ha t t he conc en t r a t i on of ti n i n t he

f o r m u l a t i o n h a s t h e m o s t p r o n o u n c e d i m p a c t o n t h e l o n g - t e r m d u r a b i l i t y . T h e h i g h e r t h e

conc en t r a t i on o f t he t in i n t he mate r i a l, t he f as t e r t he cha lk ing . W he n cha lk ing occur s , t he

e long a t ion i s r edu ced s ign i f i can t ly .

T h e c o n c e n t r a t i o n o f a m i n o s i l a n e i n t h e p r o d u c t a ls o h a s s o m e i m p a c t s o n d u r a b il it y , b u t n o t

as s ign i f i can t a s t in does . Sam ple 5 , hav in g low ti n l eve l , d id no t cha lk a f t e r 17 000 h i n QU V ,

desp i t e t he f ac t t ha t t he aminos i l ane l eve l was h igh (however , samples wi th l ow t i n l eve l d id no t

c u r e p r o p e r ly ) . S a m p l e 8 , h a v i n g h i g h t in l e ve l , c h a l k e d sl o w e r t h a n sa m p l e 3 b e c a u s e t h e

a m i n o s i l a n e l e v e l w a s l o w e r in s a m p l e 8 . T h e r e f o r e a r e d u c t i o n o f t h e a m i n o s il a n e l e v e l c a n

a l so im prov e the durab i l i ty .

A c o a t i n g m a d e w i th t h e s a m e f o r m u l a t io n a s s a m p l e 1 a n d a r e g u la r c o a ti n g s a m p l e ( as

samp le 3 ) were app l i ed on the f ie ld fo r adhe s ion eva lua tion . The f eedback ind i ca t ed t he re wa s

n o s u b s ta n t ia l d i f fe r e n c e o n t h e a d h e s i o n ; t h e a d h e s i o n p e r f o r m a n c e o f b o t h c o a t i n g s w a s

accep tab l e .

Thi s s tudy sugges t ed t ha t i t i s f eas ib l e t o r educe cur ren t t i n and aminos i l ane amount s by

a b o u t 3 3 % a n d t o i m p r o v e c o a t i n g ' s d u r a b i l i t y b y m o r e t h a n 5 0 % . T h e c h a n g e d o e s n o t

s ign i f i can t ly imp ac t the ma te r i a l ' s p roper t i e s . Bec ause o f s imi l a r fo rm ula t ion / chem is t ry , t hese

c o n c l u s i o n s m a y a l s o a p p l y t o s o m e s i l ic o n e s e a l a n ts a n d a d h e s i v e s .

R e f e r e n c e s

[ 1 Odian , G . , Principles of P olymerization 3 rd ed , Joh n W i ley and Sons , Inc . , N ew Yo rk , 1991 .

[2] Box, G. E . P . , Hunter W. G. , and Hunter , J . S . , Statistics or Experimenters J o h n W i le y a n d

Sons , New York , 1978 .

[ 3] Q - P A N E L L a b P r o d u c ts w e b h o m e p a g e ,

http://www.q-panel.com/html/quv.html

M a y 3 1 ,

2003 .

[4] Fried, J . R. ,

Polymer Science and Technology

Pren t i ce Ha l l , En glew oo d Cl if f s , NJ , 1995.


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