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4. Title and Subtitle. 5. Funding Numbers.Microbial Degradation of Fiber Reinforced Polymer Composites Program ElementNo. 061153N

Project No. 03103

6. Author(s). Task No. 320Little, B. (2nd), R. Ray (3rd), and P. Wagner (4th), and Tucker, W.* 'lst) Accession No. DN094463

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7. Performing Organization Name(s) and Address(es), 8. Performing OrganizationNaval Research Laboratory ELECT iE Report Number.Oceanography Division JUN 2 q1994 9th Intl. Conf. on CompositeStennis Space Center, MS 39529-5004 Ill Materials, Vol. 5, pp. 554-561

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University of Rhode Island Seagrant Foundation Report Number.

Kingston, RI 02881 and .. NRL/PP/7333--93-0007

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Ner',port, RI 02841

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Approved for public release; distribution is unlimited. 94-19932

13. Abstract (Maximum 200 words).

Two fiber reinforced polymer composites were examined for susceptibility to microbial degradation. Composites, resinsand fibers were exposed to sulfur/iron-oxidizing, calcareous-depositing, ammonium-producing, hydrogen-producing andsulfate-reducing bacteria (SRB). Surfaces were uniformly colonized in all cases. Epoxy and vinyl ester neat resins, carbonfibers and epoxy composites were not adversely affected by microbial species. SRB degraded the organic surfactant onglass fibers and preferentially colonized fiber-vinyl ester interfaces. Hydrogen-producing bacteria appeared to disruptbonding between fibers and vinyl ester resin and to penetrate the resin at the interface.

14. Subject Terms. 15. Number of Pages.Biofouling; Corrosion; Biodeterioration; Polymer; Composite; Microorganism; Degradation 8

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COMPOSITES BEHAVIOUR

Proceedings of the Ninth International Conference onComposite Materials (ICCM/9)

Madrid, 12-16 July, 1993

Edited byAntonio Mfravete

Department of Mechanical EngineeringUniversity of Zaragoza

Published byUniversity of Zaragoza.

"Woodhe'd ,Pubijshinig Limited,.' ":'; . .• ', ,'T'

Cover. Full composite radof 'ric,

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NTISDTIC

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UNI0 OF ZARgGOZA Dist ,,50015 zauragan, Spain

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0 1993 UNERSITY OF ZALAGOZA. W()ODl{)H Pi, Bi.SH-G LmITED

ISBN: 1-85573-140-1 (The aet)ISBN: 1.85573-134-7 (Vol. V)Le8l4 deposit: Z-1852-93

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94 6 28 24'1

ICCM/ 9 PROCEEDINGS

Volume I

1. Invited Lectures2. Metal Matrix Composites: Behaviour3. Metal Matrix Composites: Fatigue, Wear and Creep4, Metal Matrix Composites: Fracture5. Meta Matrix Composites; Interface6. Metal Matrix Composites: Processing

VolunW l1

1. Ceramic Matrix Composites: Behaviour2. Ceramic Matrix Compoeites: Analysis.3. Ceramic Matrix Composites: Fracture and Damage4. Ceramic Matrix Composites Processing5. Thermoplastics6. Smart Composites and Smart Manufacturng7. Carbon/Carbon Composites8. Fibres9. Matrix MaterialslO.Interface1I .New Systems12.Intermetallics

Volume III

I. Numerical Modelling2. Micromechanics3. Filament Winding4. Transfer Moulding5. General Processing

6. Chemical Vapour Deposition7. Pultrusion8. Sheet Moulding Compound

volume IV

1. Bonded and Bolted Joints2. Hybrids3. Vibration4. Sandwich Structures5. Thick Laminates6. Repair7. Fabrics8. Optimisation9. Practical Design

Volume V

1. Strength and Failure2. Impact and Dynamic3. Composite Material Systems: Integrated Shynthems, Processing,

Characterization and Design4. Environment5. Fatigue6. Fracture7. Fire Resistance

Volume VI

1. Damage Tolerance2. Viscoelasticity3. Space Applications4. Aeronautic Applications5. General Applications6. Automotive Applications7. Marine Applications8. Reliability9. Buckling1O.CompreesionI 1.Test Methods12.Delamination13.Non Destructive Testing14.Biaxial Testing

TABLE OF CONTENTS

VOLUME V

STRENGTH AND FAILUR ............... ............................... . .. 13

Failre of Carbon Fiber-Reinforced Epoxy Composites under Combined LoadingK.Y. Ki , A. S. C a o .................. ............................. ......................... _ 15

DamaV in Quali-1sotrpic Carbon / Epoxy Com~osite Lamirntes with Circular Holesudronotonic Llnlaxiil LoadingJ. Xiao. C. lBathi . ...... ... . . . .... . ........................ . ................... 23

t. Damage Accumulation and St•ngth of CFRP Laminate. with Ddkrwn Modui, and

I. Kimp'. irs o .7eya ..a. 1. .hu .wa, T. Su... i. .... ............. .. . ..................... ................ 31

Locadized. Damage in Composite Structure.A. P. Christofbroit.............. ..... ..... 39

Response of Lamdmted Composites to Contact LoadsE. Wu, L. Sy ............................ .... ......... 47On Dam!ae Mec~h=Wnsz in Randomly Oriented Short Fiber CompositesF. M eragt• M .1- Bm eSp h . ... ............ ....................... ... .. .................. ........................ . ...... s5

Damig ChacterLzation an Softest Loss of Muti-Dlrectional Composite IAminateswith Matrix CracksA. AsundtY. |. Liu, Y. Du, C. L.Chow ..... .... ........ ..................... .................. ... . ...... 63

Damage Induced Anirotrop in Isotropic CompositesD. Per ux, C. Siqueimt ............................................................................ ................. .............. 7 1Damao Initiation and Development in Chopped Strand Mat CompositesP..E. UburbaW. J. Cantwell, H. H. Kausch;S, J. Youd ... . ............................... 79

Evaluation of Ultimate Stressm in 4-D CompositesV .. o yaoPo . 2q .y..................... .... ............ ................... ....... ....... 8

Prosmeive Failure Analylrt of Liaininated Composites with Trusversa Shoau EffectsC. Huang, A. D. Chslkh Sead Bouh, C. Verche•y ................... ............................. 97

Progressive Failure Analysis for Lamnaited Composite Platos Under Multiple In-planeLoadsI. Shahid, F,-K. Chan&, L. 11. llcewicz _.......... ................................................... 105

Finite Element Analysis of Degradation Processes in Laminated Comnposite StructuresM .H .I. W . Pu s,,J. van den Ei h ff ......................................... .................................. . . 113

Damage Mechanics of Cros-Ply Laminates Resulting trom Transverse Concentrated Loads... :..u ~7' ---- -.... ....... ..... ........................................ :;...... ..... .. .. , ............ 121

Prediction of Failure Modes of Fibrous Composite MaterialsG. A. Abu-Fartakh, Y. A. Abdel-Jawad .................. : ........................................ 129

The Rlenmau Problem foar Wave Propagation in Periodically Layered Ardsotropic

Dynamidc and Scaing Effects in Impact of Composite Structures -

S. R.Swanson . ........... .......... 291

Dynamic, Response ofe a dnated Composite Plate with interface LayersT.H.Ju.S.KUDAfta.J,W.Les .................. ...................... 299

Im Resisance ofLvnazed Composites with Toughened Interfaces

Influence of Low Temperamtpen Energy Absortlon in Laminated. Composites*P. Y. Outta, K. L FamranD.Hut ... .... ..... 311

EnyAsorptlon in Ballstic Perforation of Craphite Epoxy CompositesD. Hu .. ............. 321

Fwnte Elment Modefling of LOWwVeocity impact Damage In Composite LazrdnateA.Mdund *. . -------------...................... ...... ............ 334

Rx~izental Study on ImpAct-Inducod Damage in CFRP L.aminated Composites UsingSA and SEM Techni uH. IKusano, Y. Xaauga, . S. Use C. Miyasaal . ................................................. 342

The Ternerature Dependence of Interlaminar Fracture Toughness and the Correlationwith the Temperature Dependent Impact Behaviour of Composite StructuresClhr.F Amber, F.J. Amdts .........-.............. ~ .........................._ _................. 35D

Damap Testing of Crossply Laminates under Hligh Strain Rates. Effects of intrahsminarShear StressesJ. L. Lataillade, M. Delaut, P. Collombet ............. . ..... ... ... 358

Analysis of the Nont-Penetrating Impact Behaviour of CPRP LaminatesD. Deifowe, R. Vaziri, M. 0, Piersont, A. Poursartip . ......... ............. 366

Anlsso rs AsrigMm t for Automotive Applications

1M. ct Dominan Composite LaminatesP. V. Stra 4i"y M. J. Worswic*. 0. Majeed, C. Poon .......................................... 386

Impact D ama M its Effect on the Oucling Strength of Composite CylindersR. C.Tennyson, S. Krishrakwnar ...........-................~-......................... 394

Dyn amic alure of Bizaterials and CompositesA. J.Roauids,J. Lambros .... ... .... ........................ ................... . ....... 402

Deainination Characteristics of L.aminated Composites Resulting From Instrumented

Numerical and Experimental Imract Damage Evaluation of Laminated Composite PlatesH. V. Lakshminarayans, R. Boukhill, R, Gauvin .. ....-. 422

Transient Analyss of Layered Composite Sub*Wtm to Dynamic Inpiana Impact Loadings 3C.-r.Ma, -CHuang .-..-.-. . ...... ....-.. -.-.. 3

Dynamik Onespos of Crapht ' Epox Composte LamirAtes ubderCompreilion.-P. Pintad1!, Cmdrzj.M P;delCis 017.Bkentlaz ..............,... 3

7

Failure Mechanisms in Ultmhigh Modulus Polyethylene Fiber Reinforced CompodtesH .KC Sin, C. L. Choy ................. .. ................ ......... .... ......... ....................................................... 137

Effects of Fibre Surface Treatment and Test Temperature on Monotonic and FatigueProperties of Carbon Fibre Epoxy Cross Ply LainateY . M atiuhisa, J. I-. King . .................. ....... .. ........... .......... .. ........................................ 145

R-Curves Characterization and Failure Damage of Short Fibre Reinforced PolymerCompo.itesC. Rodr ,ua* FF. J. Sezzunce ............................. ... .............................. ........... ...................... 153

PreEdge anid Size Effect on Failure initiation and Ulturiete Strength of LaminatesConta g a Center HoleG. D. Chu,C. T. Sun .............. ... ... .......... . ................................... ............. . ..... ... 160Edge Finishing Effects on Transverse Cracking of Cross-Ply CFRP LaminatesA. Kitano, K. Yoshioka, K. Noguchl, J. M atc uf ................................................................. 169

Interfacal Strength in PEEK/Carbon CompositeJ. Denault, T. Vu-Khanh ........... ........... . ...... ..................................... I ............ . . ................. 177

Influence of Physical Properties Randomness in Laminated Composites StrengthC. A. Conceigao Ant6rdo, A. V. Soelro, A. Torres Marques ............... ...... ...... 185

On the Decrease in Strength of Carbon Fibre-Epoxy with SizeM .R.Wisnom I...... .............. ... . . ............................... ............... ................. 1933D Fibre Orientation Measurements with the Confocal Laser Scanning MicroscopeA. R. Clarke, C. Archenhold, N. Davidson, N. 1. Williamson ............. ................... 201

Structural Failure in Filament Wound right Circular Cylindrical Shells Subjected toBiaxial External PressureF. Spicola, N. Dubois, W. Tucker,). Butts ..... ......................... . . ............... 209

TOF SIMS Imagng Fractographyof Fbre CompositesF. R. Jon, D. a, P. Deison ................ ................... 217

The Consequatsee of Material Inhomogeneity on the Strain Response of Automated TowPlaced Structures with Stress ConcentrationsD. S. Cairns, L. B. llcewicz, P. J. Mingust ..................................................... . 225

Influence of Embedded Optical Fibers on Tensile Strength and Interlaminar ShearStrength of Composite LamninatesS. Kitade, T. Fulkuda, K. Osaka ............................................................................ 234

The Influence of Matrix Plasticity on the Failure Strain of Transversely LoadedComposite MaterialsJ.M, M. de Kok, H. E. H. Meijer, A. A. J. M Peijs ... ............. . . .............. 242

Modelling Artificial Damage in Carbon Fibre Epoxy Composites .25M .P. C la irke, M , 1. Pavien ........ .............. ......... ........................ ............................. ............................. 2S0

IMPACT AND DYNAMIC ...................... ............... . 259

Hi. Velocitymroact and Penetration of Composite Laminates. Su n, V . t ........... _ _... . ................... ...... ............................................. ........................ .............L........... 2 61

Some High Strain Rate Effects on Composite MaterialsJ. F. NOwL J.K R. Vinson .......................... ....... ....... . ........... 269

Hi h Strain Rate Characterization of Angle-Ply Glass/Epoxy LaminatesG."t.Staeb, A. .ilat .............. .,..,........ .................. .... 278

Pouring A PolYmer into Composite$ in the Veiroca; Direction to Improv, the Impoct

Numerical Analysis and Simplified Model of Tensile Failure of LritdirectIona] FribeReinforced Composite under High Strain Rate

Influencv of Trmnsverse - Shear and Large.- Deformation EffeCts on the Low -Speedlm~rR ofLaminated Composite Plats;

U. AMnr J. KI'tarneafJr. C. B. Prazad ......-- .....-.... . ......... 456

COMPOSMT MATERIAL SY$TSiMSiI NTEGRATED SHYNTH4ESTS, PROCESSING,CHARACTERIZATION AND DESIGN ~ . . . .......................-.... ... 465

Processing of In Situ Composites Based on ThernOPlsIWC Matrices arnd Liquid Crystalline

H. H. Cen, J. P. doSo¶u, D. G.Baird, K.T. TeX J. Morton. ....... ... ............. -- ... 467

Impact Damage Studies in AS4/PEEK and PEKI&/HXIoQOK. T. Tak J. M~orton, J. P'. de Souza, D. C. Baird ......... -............. .... . -.............. 475

Durability and Damage Tolerajce of Piberous Material Systems: 8 iiavior and ModelingK.,Reifanider, D. DifllfioiY. Xu, T. Word .1, .............. ....~......I........,.... 483

Modaling Thermo1 astic Composite Consolidation9

ENVIRONMENT .,..~............... ....... .......... .............- ......................... ..... 499

Thermnal Stabllity ofPEEK Comp~osites in Air: Dynamic Rheological Analysis

Effects of Non-Ficklan Moistumre Diffusion In Polymeric Composites

The Effect of Seawater Exposure on the Fatigue Edge Delamnination Growth of atP. hiu!.C.ornda s. -....... ... ....... .. . ................. ...... . . .... 516

Residual Strengh of Graphite/BMI Compoites after Long Term Cyclical Compression .. 52W. C. Hansen, K Shenoy, E. C. Wolff ............................ .... -....................... 52

Tests of Accelerated Ageing of Composite Materials in ShipbuildingM. Karmm;M. Touratler, P. Pagoraro ............................................................ 532The Crucial Role of Polymer ini Ow Hest Transfer from One Fiber to Another inPolyerCrbon Fiber Composites34

The Machanhsmx of Galvanic Blistering in Carbon Fiber CompositesS. X. Mirlyals. W. C, Tucker, R. Brown, T. 1, Rockett ...... ........ ........... .. ~ ....... 546Jmicrobial Deg~radationt of Fiber Reinforced Polymer CompositesW. C. Tucker;B. J. Ltttk R. 1. Ray, P. A. Wagner ..... -... ............... ........... ....... 554livaluation of ln'llital Damage and Stress Corrosion of CFRPY. FuJI. Z. Maekawa, H. Haimada, T. Kubota, A. Murakami, T. Yoshiki....... . ...... ...... 562

The Mechanism of Sand Erosion of Glass Mat Reinforced PlastirsN. Harold, KC. Tauda, H. Hojo .... - .................................. .......... 569

JExperimental Study of the Variation in Mechanical Characeristics of Orthotropic

Laminfates lmmwsed in Water by a Non Destructive MethodPh~. CuWalg L Lamoine, N. Tsouvallo . ............... ......... .*.*....... ...... *.. . -..... -..... - 577

Suyon the Degradadon Phenomena of SMC in A] kali Condition by AQDustlc EmissionMethodS. Somuyv, T. Morishita .. ...... ...... ...........-..---. 585

~~~¶H~smthuma Aging on the Durability of Class/Epoxy Composite.hui-Ca. " O Atamlyrb and Do. a Cer 4 i nSai Saiue

A. haesmiot, . haer, . .uller, L Vincent ....... -. ...... . -................. 593

Therrmal Spike Rffects on Moisture Absorption by a Bismalelrnide Modified Epoxy/CarbonFibre Compsite . .. .. . ... .. ..-

Silicon-Bansd meinentary Partcle Tracking System: Materials Science and Mechanical

T.W h.bn,1 .Hr~ ...... . ... ~...... .........---- 60*9

Edg Effects in Resin Matrix Composites with Cyclic Environmental Conditions..-elW..a.GVr s -. .............................-. .......... . ....... 617

Thermal Conductivity Measure of Polymer% ýI.hFlash MethodILMartin, A. Jearimalr, I F. Duu..staniti ........ I.............-I-........ ......... .........- 625-

Moisture Absatpton Effects ar Delamination Fracture Mehardsrni of -,rbon FiberPolymerIc Matrix Compoolsie........ ......... 63

Re&Udlng of Glass-Flber-Reir forc@d PlasticsHI.Kelmms . . ............. .............. ,.. .-.-.... 11...... . ... .......... ~ . 642

Parameters lnfueixlrftjtt Thermal Conductivity of a Chopped Cartion Fiber/PolymerComposite --..... . . . . . - . -. 5

Environmental Effects on Carbon Fibre / Epoxy Shear $trengthA. S. Hlicblau, L. Tant, P. Warden ........ .... .............................. . 660

On the Nonlinear Mechanical Behaviour of Some Fibre Composites under Fatigue Loading

The Infuance of the Thermal Treatment on the Fatigue Behaviour of APC-2A. Treub, H. e, C. Mgliereol, G. Marom................ . ............ ..... 677

The fatigue Perfranwce of Gloss Fibre/Epoxy Matrix Filament Wound PipesSR. ILFrost -. .......... ........ ............................ . ...... 69-4

ConstAnt Life Diagrams for Wood Composites atdPolyrner Matrix CompositesM. P.AnsuiIlt.P. Bond, P.W. Bonflcld . ................... ......... . ..............................----- 69A

Cycfic Behaviour of FibreglssEpoxy Comtposite LaminatesP. Ellyin, D. Kujawsid, A. S. chlu ................................. .................. 700

Composite Life Prediction Using a Multiaxisi Fatigue ParameterC. %enC. Glinks, A. Plumtrae...... .......... . ..,...... ........ ......... 70

Behaviour of Cementitious Matrix Compositesi under Dis placement Controlled CyclicLoading,." ..- _'tIA. C.RMagalhees, A. TorrestMarques,1FP.M.PF. Oliveira, P. Sloulcatchoff, P. T. do Castro '..... 715Fatigue Dumae of Composite Laminates under Servic Loading

.J......E.P............ .................... " .723

Role of Matrix Ressin on the Flexural Fatigue Behavior of Unidirectional Pitch BasedCarbon Fiber LaminatesM. Nakads. M. K. McMurray, Norlrntsu Kitade, M. Mobri, Y. Mlyario ..- . -. 731

On the Impact Fat vePerformanco of Interleaved Cross-Ply CF/Ep-L~urninatesY~uan,JTKoVrgP- si ..............-... .. . .... -. . ..-..-.... $

Fatige Strength of Graphbite Epoxy LaminatesH. ondokaH. Wad& ......-... ...-....-- .- ......... .... .......... 4

Damage Analysis of Laminate Under Cyrlic LoadingY.A. Unznis, S. P. Joshi, A. E. Bogdanovib -r ............ 753

Patigm of L.aminated Composites under Complex Cyclic LoadittgJ. Anidmrovs, M. Mikelsona, V. Taznuzo, V. A. Limonov ... ...... ............. 763

FRACTURE .......... ....... .................. . ...... 769

Fractal Approaches In Fracture Analysis of Composites

E valuation of Strain Energy Release Rates of Mixed-Mode Fracture Specimen forLaminated -ompositeC.SHon&J.Y.Rd~nm...........-.........-......................... ........... .... 779

A Study of the 2-D Interactions BetwomnArbitmhrily Orientated Crac~ks and Inclusions

Comparison Between ModelI Interlaminin and lIntriaxlamni Fracture Toughness ofThin-Unidlrectional Graphite (AS4) / Epoxy (1908) Laminates II.1M. Iwamoto, S. ArAki, K. Kurashiki, K. Salto ... .............. -.. ...... . ............... ..... 795

Dynamic Effects and Interfacial Crack PropagationA. .1. Phillipps, W, J. Clegg, T. W. Clyns ............................ ............. . ...... . . -..... 803

Fatigue Damage Growth Characterization of CFRP Composites using InternalDamping Measurements and Acoustic Emission MonitoringL. VellisV, V Kostopoulos, S. A. Paipetis .. ......................... ~......... 8 ..... 11

An Improved Analysis of the Mode I Crack Opening Displacement of CFRP-DCB SpecimensK. Arakawa, K. Takahashi ....... .. ...............-....... . ....... ~...... ... 8..... 19

Correlating Matrix and Composite Fracture Response at Difterent TemperaturesH. Lau, W.E, Rowlands ..........-..................................... ............ .. ... 827

In Situ Observation of Delamination Fracture Test in Graphite/ Epoxy Composite DuringModel11 Loadingj Inside a SEM

Y.Q.Su, . ndersorJ. Tian .... ,.-. ................. ........................ ........834

FEMRd o h Interface Crack in Layered Composite Materials84Il o ,H G a .............. .................. ... . ............... 850

Effect of Ply. Blocking on Intelanilner Fracture in CER1A.Dmport,JI.TumI.R.D.AdIm,M.J.Pavi.T... ...... 5

Characteuization of Fatigue Dalamination Growtht in a Circular Notched CFRP byScanningAcoustio Mirompe and Influences of Water Absorption65

Fleoosil Fatigue &MA Fractumi of Unidrectional Graphite/Epoxy Cornposites at LowTainperotturues

.. ...... . ...... ... . . ............ 8 66

Effects of Water Up-Talke on Intcrlarninar Fracture Properties of Various Carbon Fiber/K........h..... ..... ............ ......... ........ 875

Mechanics of Crack Arrest Wa Short Fiber Reisiforced CompositeS.-W. CatX-L.Xw M. CALH. WangJ. Cal - ---....... -. --- 882

Totaghnea of Carbon FibeftEpoxy Laminates Based on intermediate Modulus Fibers 8J. Vamna, LBerglund ...... 88

Toughness Modellng of mir-Crystalline Potymar and Unidirectional Seml-CryatulllnacornpouZte R ei 9B. Cofawi, 1. Verpoest,, L am ... ......... 9

In-Situ Observation of Deformation and Fracture Process for Fiber Reintforced, Compositesunder SfM

Fracture Criterion lot Notched Carbon Cloth/Epoxy Lanunates

LamDefectonCorrection for Mode U Toughness Measurement of Composite

Prediction of Fire Damage to Composite Aircft StructuresH.L.McMatuz ...... .......... 929

Composite Fire-Resistant PanelsH. Bo~da6J. P. Dorsemaine ~ .. - .~938

Assessment of Firt barap on Composite Materials from Surface Feaurea

Fire Behaviour of Sisal Short Fibers Reinforced Gypsum1. Otalmlz F. Merrdndez.OMvaras, L. de Vilanueva ..... 951

MICROBIAL DEGRADATION OF FIBEl REINFORCED POLYMER COMPOSITES

Naval Undersea Warfare Center DivitsionNeWpot, R1 0214

B.rnds J. Litt* RicharI!. Ray, and $aPvicia A. WagnerN•va.Reerch Ltbormtwy

Stenals Space Center, MS 39529

ABSTRACI

Two fAber reinforced polymer omposites were examiuned for suscepdblltly to microbial degradation.Composites. tesins and fibe were exposed to dfuafu -wr• iung, calcareoua-depositing, ammonlum-producing, hydroe.-prducfIg and sulfate-reducing bacteria (S9I). Surfaces were uniformly colonfzedin all caes. Epoxy and viyl ester nwe resins, carbon fibers and epoxy composites were not adverselyaffected by microbial species. SRB degraded the organic surfactant on glass fibers and prehmatiallycolonized fiber-vinyl ester interfacas Hydrogen-producing bacteria appeared to diswupt bondis betweefibers and vinyl ester resin and to penetrate the rmsin at the interface.

Keywonds: Polymer, composite, mricrorganwar ,wgrato,

INTRODUCTION

M glbaso/polymer and carbon/polyrna composite matahili am used in many aquatic environments.With h atength to weigMt ratios and inproved sfhess for high performance, these matrialsurp"a conventional meots and Alloys for many structural applications. Unfortunately, Uwe attantionhas been paid to evlrontmental deVradation. It was long believed, foe example, that fibergla bouthulls would not otffer corrosion, blofoulin or deterioration found In conventional materials, Howov,it Is now recognized that all engineering materials become colonized by microorganlsms, includingbacteria, with hours aft exposmu in natural waters.' Mcrooranism grow ad produac a viscoelustiolayer or bloffim. The environment at the bloflm/matarsal interface oi radicslly diffent firm the bulkmedium in terms of pH, dissolved oxygen, nd organic and Inorpnic spec" artrnosn%, polymadccomposites m subject to degradation from moisture Intrusion and osmodtc blWise A Although thepoblms of moisture Intrusion and blistering have boon studied and can be eliminated by propermanfa•cotin and Maintenance procedures, repair costso an safety risks wre high.

Polymetic compoeltes are subject to many kinds of envuronmental degradation. Tucker showed thatcazbosi/olymw composites galvanlicaly coupled to metals am degraded by cathodic rtwoons In

, ,.,I,,

se&W~tet. IcesetM l demn Wzta epoxy and nyioo coatiags on steel wets breached by mixedcultures Of marfine kACtetiL Pondrys9 repeated tha p-s5 evaphite fibers wenm attacke by a mixedculWMM of Psezd0*M&_W, aea'ft-Mo and AebwSobwrZC catcoacdlc. commoi soil isolates. Possibleýnehsirims for inirobiall degradationý of polyMero composites inchidaw diret attack of the Main by

* aidds or enzyn"s;blistiting *u to I*s evohitioM enak,1cedecracking d". to calcareu deposits andasevolution sad poymer destbilizatioIn by concentrated clorides and sulfides.

PROCIDURZ

Identity an d Mantenance of Bacterwa Culturt.

A iuu~ur/ron oxidizing bactesium, Thlohec(Ulufrrro=uia. Leathan strain, obtained from Dr. NormanLazarff. State University of New York. Binghamt~on. N a anoand in9. eim 0 cnann

3.0~ ~ ~~ g N1S 4 . C!; 0.5 5 K2MP4, 0'5 £ MgtSO 4.71ýO. 0.01 £ CA(NOý2 dissolved in700 nml distilled water previously acidified to pH 2.5 with H12S04. The sWt solution was stedilzedat 25M' and 150 psi for I!( Minutes. 3W0 Va of an t=o Solution cnt"ainng 44g9 FtSO4'7H 20 InpH 2.5H 2 SO4 was fiwr trilizedandaddedto thesalt solution.

Psued&ordna fluoruictr, a cA1areous-depoiti bacwlur was obtained form ihe America TypeCulture Collection (ATCC #17S71), Roe"&~l. MD). The organism was originally isolated fronPolluted seawater. PS. fluoreacems was maintained in a medium cOOtainin 0.2S5 gCalcium acetatte,

I.4 yukeast 4 exra .0 g glucose.100 ml distilled water, and adjusted to pH 8.0 using NzOHA'

LlactOcoccu' 1actl, sublP. trrctis, ATCC #19435, an amniontum-producing bactarimwn.wa mainta nedin brain heart infusion media.12 Clonridiwur acewbutylcum. ATCC #824, a bacterium previouslyshown to produ1co cpious amounts of bj1droVen ftro fermentato Of sugars WAS maintained ini agro fwthnidur described by Ford et a&L Sulfafte-rducing bactria. isolated as a mixed culture offacultative mic froogaims from a corrosion failure of a carbon stWa was=e piece on a surface

hi,313 were maintained in Postgatc B growthb medium

Exposure Conditions

* ThplHcath coUPOns (2.5 X 2.5 X 0.6 cm) of two fiber reinforced poly=e composis-ag carbon fiber(T-30Q) reifored epXY (NAR4C0.S2OR&r.300, BASF, Snrctsva Materials. Anahem, CA). endsag2a"s (8.2) sed carbon (T-300) einfOrce Vinyl estar (Derakans 411-45, Dow Cbemice' Midland,MD), were exposed to micoubilOSgcal cultures for 161 days. The epoxy was cure in a vaium= bagautoclaved -at., 121-Cr Cure of vinyl esWe rei% was Promoted with 0.3% cobalt naptitenare and0.0AS. dimety1Wanilne catayzed with 2% methyl ethyl katons peroxide, Resins wers poet-curedi at1005C for 8 bours. Carbon fibers, Stlas fibers vinyl ester, and epoxy resins wer exposed for 90) days

* to SRB Yd hy SMe-POducin bacteria. Glass fibers bad been treaed with orgmnfunteonal SumanA4.172 (Union Cizbde Danbiu , C). (M All culture were maintainedi at rown temperu and warepeiodicaly refrehed with 6ew media Triplicate ,,"Woclated controls were maintained under the;amiaexposjrý conditons.

SAznp*a'Were WaIdgl* before and after exposure Moisture uPtafe was calculat .ed after the bitiffim hadbenremoe with'a cotton swab containing acetoe CAd the sample rewelghed.

igurp 3. Light microscope mictographa of glas fibers (a) unexposed. e-xoseo to culture medium.and (c) exposed to SRB in culture medium.

failimte handling. Silanw A-172, a vinyl tris (2-methoxyettoxx ,bin, prornomes adheaion betweenthe vinyl cater resin and glass fibers. MicrobiWldegradatton of the surfatant by SRB was fuinidemonstratod with .SEMBD$S silicon dot maps (Figure 4). Silicon do maps of control fibeen exposedto uninoculatad media showed concntrations of silicon within the core of each fiber'and smallamounts of silicon along the length of each fiber. Similar maps for fibers exposed to SRI showedincreased amounts of sllicon along the length of the fiber, Many microorganisms are known to degradeorganic pol ers.19'° The mixed anarobic culture containing SRI used tn this work has been shownpreviously to degrade marine caulks and traditional polymenrc coangs 1,14A

Hydrogen-producing bacteria appeard to disrupt bonding beriwee fibers "n virnyl eater resin (TilFM 5)."'he orraninms penetrated the rusin and disruption of fibem and rtsLn -a's be due to gas fdnmAdonwithin the eomvposite.

Previous work published for moisture uptake for vinyl ester neat resin and the carbon ViRn)I emaecomposite indicate that the materials should be saturated afer 90 days 1 "Ihe neat resin and.the•.aibonvinyl eater composite amreypically saturated at 0,78 and 2.25% weight gain, respectvely.,In thepresence of blofilms, moisture uptak was typically 0.1 and 0 9% for the neat resin and Cii

- 557

Swt/cc Analyis

Samples, were examined before and after exposure using an environmentui scanning electron micro--scope (ElRccoscan Corporati, Wilmington. MA) coupled with an enrgy-dlpersive x-my analysissysttm (NORAN, Mfiddlewn. WI) (ESEMIES). The ESEM uses a secondary elecpuon dtctor capableof forming high resolution Images at pressure in the ruag of 0.1 to 20 tof, At these pwaiss• c,specie charging is disipued into the gamus anvironment of the specimen chamber, enablingdir:t obacztidon of uncoate, nonconductive specimens, including polymeric composites. If watevapor Is used as the specimen environment we$ samples can be observadL Wet biofilms can be imageddirectly without fixation, dehydration or metal costing, and EDS data can be coUected at the sametime sample morphologyAopography is photogphed. 17.1 Samples were examined for evidence ofdegradation resulting from microbial activity and compared to utinoculatad controls.

RESULTS AND DISCUSSION

In a ll cases, composite, neat resin and fiber surfaces were colonized by all microbial types. Neitherthe epoxy nor the vinyl aster composites were adversely affected by caicarsous-depositing orarnmonuum-producirg bacteria. There was no evidence of attack of resn and fibers remained embeddedwithin both resin. Composites exposed to sulfiarrvoo-oxidizing bacteria (Figure 1) were coveired withcrystalline deposits containing Iron and sulfur in addition to microbial cells. All srfaces exposed •oSRBEwere black due to the deposition of iron sulfides. No damage to the epoxy compositc, epoxy neatMoi,. carbon fibers or vinyl aster neat rmsin could be attributed to the presence and activiti of SRBand hydrogen-producing bacteria.

SRE grew preferen'tially at fiberireuizl interfaces on the vinyl ester composite (Figr 2). Glais fibersexposed to SB lost all rigidity after the 90-day exposure so that the weave patte.rn was no longerevident (Figure 3). Control glass fibers remained rigid and maintained the original weave. pattern(Figure 3). Olasa fibers am routinely treated with an organic surfactant used to size the fibers and to

Figure 1. SulfUr/Iron-oxidizing bacteria withcrystalline deosi on srfadc of fiber reinforced Figure 2- SRB at flWeftik inerae oPCVinylpolymeri composite-ase composite ý k

PI~ EQ dt ap of silicon, foc Slasi fibers (a) exposed to culture medium and~b exposedto SRB in CunmM Urdim. l

reapedveiy., It appears that biofflms may W u ms ýus'u Darner for waWT, rMtazdg Moisture

A-

CONCLUSIONS

Epoxy mein anid csrbon fiber. either individually or in composite, were not degraded by Ulftcdirft.Oxidizinl'3 hydri)gefrproducing, calcarcoiusdepoltitng, or SRB. Bacteria did colonize ruina4ffibers uid -Camrpscites but -did not causew damage SRB preferentially colonized vinyl aster cornpotitasat the 1ibesin riniacrfukd deg&rad earVinyl eamtermain. SRB degrad*Iiiti of the organic surfactanton* glass fibeie Wes demonsarued wlthý ESiWM/S. Hydtrigen-ptodflcifl batei appea to havedisrupd'*'flbest.Yibyl ester remni bo~dng with penetration of the telsIn.

L "

Pigpre S. Hydron-producin e bacteri at disrupted,inteffta bewewe fibers and v•yl ater main.

Ackaowhdgmeanh

Th w work Was suP~crtod by tre University of Rhode Islamd Seagant Foundaton, Kingston, RI 02881a0d by the Offsho TechWmogy Res"r Center, Texa A&M University, Collep Station. TX 77845.Naval Reuearch Labortory Contribution Number N]ULRP/7333-93-O0O7,

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