COMPOSITE TUBES FOR RISER APPLICATION IN DEEP WATER · 2011. 6. 30. · elongation at fracture, for...

$: COMPOSITE TUBES FOR RISER APPLICATION IN DEEP WATER · 2011. 6. 30. · elongation at fracture, for polymeric matrixes used to manufacture composite tubes for riser aplication. Pipes$
16th International Conference on Composite Structures ICCS 16

A. J. M. Ferreira (Editor) FEUP, Porto, 2011

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COMPOSITE TUBES FOR RISER APPLICATION IN DEEP WATER

Ledjane L. Sobrinho*, Verônica M. A. Calado†, Fernando L. Bastian†

* Engenharia de Materiais, Universidade Federal do Ceará (UFC) Campus Cariri

Av. Tenente Raimundo s/n, 63000-000 Juazeiro do Norte, Brazil e-mail: [email protected]

†Escola de Química, Universidade Federal do Rio de Janeiro (UFRJ) Ilha do Fundão, Rio de Janeiro, Brazil.

†Departamento de Engenharia Metalúrgica e de Materiais Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.

e-mail: [email protected]

Key words: Composite tubes, Rubber, Epoxy resin, Filament Winding. Summary. The present work deals with the development of composite pipes for riser

application in deep water. Initially, an epoxy resin system was toughened by rubber addition

(10 wt%) as a way of improving flexibility of future risers. Mechanical and thermal analyses

were carried out for characterizing the polymeric systems. As expected, due to the fact that

the modulus of the CTBN is much lower than that of the epoxy phase, the tensile modulus

decreased with the addition of CTBN, from 3.45 to 2.75 GPa, and the elongation at fracture

increased from 2.96 to 5.24 %. On the other hand, the glass transition temperature (Tg) of the

CTBN-epoxy system changed from 141°C to 136°C. Later, composite tubes were prepared

and mechanically characterized. The influence of matrix toughening and the number of

composite layers on the mechanical behavior of the tubes were determined by hydrostatic and

split-disk tests. In both tests, the results confirm that the matrix plays an important role in

composite fracture processes. In the split-disk tests, the tensile strength and the elongation at

fracture increased with the addition of CTBN, from 731 to 831 MPa and from 2.34 to 3.09 %,

respectively. In the case of hydrostatic tests, the pipes colapse and bursting pressures

increased about 14% and 19%, respectively, with the rubber addition to the polymeric matrix.

At last, it was verified that the strength of the tubes grows linearly with the number of layers.

These results confirm the feasibility of the developed tubes for application as risers in deep

water.



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1 INTRODUCTION

In the aggressive petroleum extraction environment, developing technology for deep water and ultra-deep water oil production, where pressure and temperature conditions are not ideal for pumps and flowlines, has been a crucial matter. One of greatest challenges is to connect the production unit to the sea bottom. Composite materials offer some attractive attributes for the offshore service, such as: high specific strength, high corrosion resistance, high thermal insulation, excellent fatigue performance and specific stiffness [1].

Use of composite materials in deep water riser systems may allow a great decrease in weight, as well as improved fatigue resistance to loads promoted by environmental conditions. With increasing water deep the need to decrease the weight of the risers is evident. In this case, the introduction of lightweight material has been the best economic option indicated for oil industry [2].

In order to utilize the full potential of composite materials, the performance evaluation of neat resins is important, as the resins are responsible for the majority of the degradative process that eventually causes the composite failures [3].

Epoxy resins are considered as one of the most important class of thermosetting polymers and find extensive use in various fields. However, these materials are rather brittle and, for this reason, their toughening has been extensively studied in the last decades [4]. Rubbers are generally well known to affect the mechanical properties of thermoset polymers [4]. The most popular rubbery modifying agent is carboxyl-terminated butadiene-acrylonitrile random copolymer (CTBN) because of its miscibility with the epoxy-hardener mixture during the initial polymerization [5]. The aim, when attempting to toughen brittle polymers, is to increase their toughness without significantly decreasing other properties such as glass transition temperature (Tg), which is a very important parameter since it establishes the service temperature of material.

The main objective of modifying the resin system with toughening agent is to increase elongation at fracture, for polymeric matrixes used to manufacture composite tubes for riser aplication. Pipes can be subjected to very large plastic deformation up to 3% [6] in many situation, such as pipe laying operation (for example, reeling), local buckling or earthquake loading. This work examines the effect of CTBN addition in epoxy resin on its mechanical and thermal properties and on the mechanical properties of tubes manufactured in a pilot plant existent in laboratory by hydrostatic and split-disk tests.

2 EXPERIMENTAL

2.1. Materials

The polymeric system used in this work was a hot curing epoxy system based on Araldite® LY556 epoxy/Aradur 917 hardener/Accelerator DY 070 from Huntsman Company. The Araldite® LY 1556 is a diglycidyl ether of bisphenol-A- based epoxy resin with an epoxide equivalent weight of 5.45eq/kg and viscosity 10000-12000 mPa s at 25ºC. The Aradur 917 is an anhydride hardener and the accelerator DY 070 is an imidazole accelerator with viscosity 50-100 mPa s and 50 mPa s at 25ºC, respectively.

The elastomer used as rubber modifier was CTBN copolymer supplied by Aldrich Chemicals with acrylonitrile content of 18% and molecular weight of 3600 g mol-1, and the



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reinforcing element used was glass fiber type-S2 675 tex, 721B ZenTron, from Owens-Corning Fiberglass.

2.2. Polymeric Specimen Preparation

Samples containing 0 and 10 phr CTBN were prepared, which are termed neat and CTBN-modified resins, respectively. In the case of blend, the epoxy resin was firstly mixed with CTBN, and stirred thoroughly at a temperature of about 60 ºC followed by degassing under vacuum (this procedure allows for the pre-reaction between epoxy resin and CTBN to occur prior to the addition of hardener). Later, the polymeric system was prepared by mixture of resin/CTBN or neat resin with accelerator (2 wt%), followed by addition of the hardener (90 wt%) for at least 5 min. The resultant homogeneous mixture was poured into a steel mold, whose surface was treated with a release agent, and cured into oven for 4h at 80ºC and then post cured for 4h at 120ºC, as indicated by the manufacturer. The specimens’ dimensions followed the ISO 527-2 standard. Specimen geometry and dimensions are shown in Figure 1.

Figure 1: Schematic of the tensile specimens. All dimensions are in millimeters.

2.2.1. Mechanical analysis

Tensile tests of the polymeric samples were made at room temperature using an EMIC testing machine; model DL 10000, with a load cell of 5 kN, extensometer model G-51-12-A, and loading speed of 1.0 mm/min. The extensometer was located at the center of specimens with gage length of 23.6 mm.

The tensile strength, elasticity modulus, strain-to-failure and fracture toughness values were obtained. Fracture toughness was measured from the area under the curve stress vs strain of the tensile tests. The values were taken from an average of six specimens.

2.2.2. Fractography

Fractured surfaces obtained from mechanical tests were examined at different magnification by using JEOL JSM-6460LV scanning electron microscope (SEM) in order to observe the fracture behavior of the specimens, the rubber domains dispersed in the



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matrix, and the interaction of these domains with the epoxy matrix. Specimen surfaces were coated with a thin layer of gold by sputtering to provide a conductive surface.

2.2.3. Differential Scanning Calorimetry

Differential Scanning Calorimeter (DSC) thermograms were obtained using a Perkin-Elmer DSC-7 apparatus. Two scans were made at 40 to 200°C with heating rate of 10 °C/min, followed by a fast cooling (200 to 40 °C) and reheating at the same rate. All tests were conducted in nitrogen atmosphere at 10cc/min.

2.2.4. Dynamic Mechanical Analysis

Dynamic mechanical analyses were made to determine the glass transition temperature of cured resin systems. A DMA 7e instrument from Perkin Elmer was used. Scans were made from 0ºC to 200ºC with heating rate of 3ºC/min and frequency of 1 Hz. The carrier gas was H2 at 60 ml/mim.

2.2.5. Fourier-Transform Infrared (FTIR) Spectroscopy

In order to know the structure of the cured resin, infrared measurements were carried out using a small portion of the cured epoxy system. The specimen was pulverized and the powder was mixed with KBr. The mixture was pressed to form a 15-mm diameter pellet (Carver 4350.L, United States of America). For the liquid sample, CTBN, sodium chloride (NaCl) pellets were used and the material was kept between them. The pellets were then placed into an attachment in the optical compartment of a FTIR spectrophotometer (Spectrum One from Perkin-Elmer). Infra-red (IR) absorbance spectra were recorded in the wavelength range of 4000-500 cm-1 at resolution of 4 cm-1 using 32 scans.

2.3. Manufacturing of Tubes

Tubes were manufactured using a filament winding process, in which the reinforcing fibers are impregnated with the polymeric systems, i.e., neat and CTBN-modified resins, and applied to a 101.6 mm diameter rotating steel mandrel in precise orientation angles. To be consistent with the notation adopted for the polymeric systems, the tubes are called neat and CTBN-modified. A filament-winding machine from Tecservice was used. The angle-ply tubes consisted of eight and sixteen layers with a lamination of [88º2/±55º2/88º2] and [88º4/±55º4/88º4] configuration. Their fiber volume fraction varies between 39% and 41%. Their length was 1800 mm, internal diameter 101.6 mm and thickness 5.6 mm. After 30 minutes of spinning, these wound tubes together with the mandrel were then placed into a temperature controlled oven for the curing operation. After curing, the composite tubes were removed from their mandrels. Figure 2 shows the steps for manufacturing of tubes.



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Mandrel with a release agent Teflon Polyester fabric

Layer at 88º Layer at ±55º Tube in oven

Figure 2: Stages of production tubes.

Initially, to help taking composite tube out, the mandrel surface was treated with a release agent and coated with a layer of teflon sheet. Mandrel then was coated with polyester fabric to improve composite tube. As described above, the tubes were made of internal circumferential layers (88º), followed by layers helical at 55º and external circumferential layers. Finally, after the molding process, the mandrel was put inside an oven and kept turning during the curing process.

2.3.1. Split-Disk Tests

Split-disk test specimens were then produced by cutting of composite tubes. The cutting of specimens and determination of apparent hoop tensile strength were performed according to ASTM D-2290. Specimen geometry and dimensions are shown in Figure 3.The testing machine used was a Shimadzu UHF hydraulic machine with a loading capacity of 1000kN. The loading speed used was of 5mm/min.

Figure 3: Schematic of the split-disk-tests specimens. All dimensions are in millimeters.



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3 RESULTS AND DISCUSSIONS

3.1. Mechanical analysis

Figure 4 presents the stress-strain curves for both polymeric systems considered herein.These results are summarized in Table 1.

Brittle fracture, i.e., absence of yielding, is evidenced for the neat epoxy resin, whereas the CTBN-modified epoxy exhibits a ductile deformation with the appearance of an upper yield stress. It can be observed from Table 1 that CTBN in resin decreased the fracture stress and increased the elongation at fracture. From Figure 3 a yielding is observed.

Resin yσ

(MPa)

Bσ

(MPa)

yε

(%)

Bε

(%)

E

(GPa)

T

(J)

Neat - 76.31 ± 4.39 - 2.96 ± 0.22 3.45 ± 0.72 1.40 ± 0.20

CTBN-

modified 67.87 ± 0.42 66.81 ± 0.40 4.91 ± 0.04 5.24 ± 0.01 2.75 ± 0.04 2.35 ± 0.03

Table 1: Average mechanical properties of the polymeric systems developed.

yσ and yε - Stress and strain at yield, respectively;

Bσ and Bε - Stress and strain at break, respectively.

T – Fracture toughness in Joule (J).

0 2 4 6 80

10

20

30

40

50

60

70

80

Str

ess

(MP

a)

Strain (%)

Neat resin CTBN-modified resin

Figure 4: Stress-strain curves of neat resin and 10% CTBN modified epoxy.



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As expected, the tensile modulus decreased with addition of CTBN, from 3.45 to 2.75 GPa. This might be related to the fact that the modulus of the CTBN is much lower than that of the epoxy phase. The same reason can explain the decrease in the stress at fracture and increase of the strain and toughness as a consequence of CTBN addition. Furthermore, it is well-know that an increase in elongation at break can be an indication of a good adhesion via a chemical reaction between CTBN and epoxy resin, as evidenced by IR spectroscopy.

The increase in both properties strain and toughness is of practical interest as risers often are submitted to large plastic deformations, up to 3%, during ocean operations [6].

3.2. Fractography

Figures 5 and 6 show the SEM micrographs of the fractured surfaces of neat and CTBN-modified resins. The morphology pattern observed for the unmodified formulation shows the presence of three distinct regions characteristic of brittle systems: a) an initial region of fracture characterized by a smooth and flat surface, b) a transition region, where the surface roughness steadily increases and c) a final region of fracture (Figure 5a). These last two regions are characterized by a steady increase in the surface roughness and by the presence of conical marks (indicated for dashed lines in the Figure 5b).

(a) (b)

Figure 5: SEM micrographs of neat resin at magnifications (a) 30x and (b) 1000x.

(a) (b)

Figure 6: SEM micrographs of CTBN-modified resin at magnifications (a) 1000x and (b) 2000x.

a

b

c



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The fractography of the material modified with CTBN presented aspects of the fracture mechanism in which rubber particles were partly fractured, as can be seen in the indicated areas by arrows (Figure 6) It shows the crack developed through the rubber particle and indicates that adhesion between particle and matrix has occurred. In fact, it has been reported that some improvement in the fracture toughness is obtained provided that a phase separation with good interfacial adhesion is achieved [7]. The strong interaction between rubber particles and epoxy matrix leads to efficient stress transfer from matrix to rubber. The rubber particles well interact to the epoxy matrix might promote some localized plastic shear yield leading to the observed increase in toughness [4].

These results are in accordance with those of tensile properties where some yield occurred upon addition of CTBN rubber accompanied by an increase in elongation at break.

3.3. Differential Scanning Calorimetry

The purpose this analysis was to allow the observation of any type of thermal process during heating in the DSC. Exothermic peaks are related to the cure process, i.e., the energy involved in the cross-linking reaction of resin reactive groups [8]. Suitable cure treatment is necessary for producing stable polymeric systems and for avoiding any residual exothermic reactions [9, 10].

As shown Figure 7, neither of samples presented profile characteristic of exothermic reaction, indicating the complete cure of the systems. These results confirm that the cure cycle produced by the manufacturing was enough to ensure the whole cure of both polymeric systems (neat resin and CTBN-modified resin), as there was no heat liberated during runs.

0 50 100 150 200 250-15

-10

-5

0

5

10

End

o __

____

Temperature (oC)

1o scan CTBN-modified resin 2o scan CTBN-modified resin 1o scan Neat resin 2o scan Neat resin

Figure 7: DSC thermograms of specimens: neat resin and CTBN modified resin.



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3.4. Dynamic Mechanical Analysis

The effect of addition of rubber CTBN in epoxy matrix on the glass transition temperature it can be observed in Figure 8.

0 50 100 150 2000,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

136ºC

141ºC

Tan

del

ta

Temperature (ºC)

CTBN-modified resin Neat resin

Figure 8: DMA plots showing the behavior of epoxy resin with and without CTBN.

Addition of CTBN causes a slight decrease in Tg (3.5%). This decrease can be related to the fact that a chemical reaction occurred between the flexible CTBN rubbery phase and the rigid epoxy resin as proved previously with the IR results. Similar results have been reported in [4] and [11].

A small shoulder on curve at approximately 119ºC for the CTBN/epoxy system was observed. Robinette et al. [12] observed an additional peak for the rubber-VTBN system. According to them, it is suspected that this peak represents a transition for a rubber-containing modified system.

3.5. Fourier-Transform Infrared (FTIR) Spectroscopy

FTIR spectra of CTBN and CTBN modified resin have been obtained to verify the occurrence of chemical reaction between epoxy resin and CTBN.

The good adhesion resin/rubber particles observed in the fracture surfaces, which was characterized for the absence of void (absence of coalesced particles), was confirmed for this analysis. In the FTIR spectrums it was verified the occurrence of the reaction between the resin and the CTBN rubber.

A sharp peak at 2239 cm-1 was observed in the spectrum of CTBN (Figure 9-a). This transmittance band which can be ascribed to the nitrile group of CTBN, was not observed in the cured blend system (Figure 9-b). This fact can be considered as a clear indication of the reaction between CTBN and epoxy resin [5, 13-16].



10

4000 3500 3000 2500 2000 1500 1000 5000

10

20

30

40

50

60

NC≡−22

38.9

8

Tra

nsm

ittan

ce (

%)

Wave Number (cm-1)

CTBN

2500 20000

30

60

2238.98

NC ≡−Tra

nsm

ittan

ce (

%)

Wave Number (cm-1)

CTBN

(a)

4000 3500 3000 2500 2000 1500 1000 5000

5

10

15

20

25

30

35

40

45

Tra

nsm

ittan

ce (

%)

Wave Number (cm-1)

Resin System with CTBN

2500 2000

0

20

40

Tra

nsm

ittan

ce (

%)

Wave Number (cm-1)

Resin System with CTBN

(b)

Figure 9: FTIR spectrum of CTBN (a) and CTBN modified resin (b).

3.6. Split-Disk Tests

Split-disk test specimens were then produced by cutting composite tubes according to ASTM D-2290, as shown in Figure 10. In order to verify the effect of addition of rubber CTBN on the hoop tensile properties, split-disk tests were carried out in samples of both composite tubes (CTBN modified and unmodified polymeric matrix). Besides obtaining hoop tensile properties of the specimens, failure types and their locations were also investigated.

The hoop tensile strength versus dislocation curves are shown in Figure 11. Table 2 shows medium values of the hoop tensile strength.

Figure 10: Split-disk test specimens.



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Figura 11: Hoop tensile strength versus dislocation curves for rings of both composite tubes (CTBN modified and unmodified polymeric matrix).

Tube Hoop Tensile Strength

(MPa)

CTBN-modified 709.05 ± 25.23

Neat 572.20 ± 69.93

Table 2 – Medium values of the hoop tensile strength.

As shown in Table 2, the rings of composite tubes with CTBN modified epoxy matrix presented higher values of the hoop tensile strength than tubes with unmodified epoxy matrix. Rubber CTBN acts as plasticizer in epoxy matrix improving the loading and strain distribution to fibers. This feature was observed on photographs of specimens in the failure locations.

Figure 12 shows dominant failure mechanisms observed during the test and their locations on the samples. As seen from the photographs, failure of specimens occurred in the reduced section for all samples.In the samples without CTBN the fracture occurred in blocks of fiber, while in the samples with CTBN occurred uniformly.

For layers having 88º winding angle, fiber-matrix debonding parallel to the fibers was followed by fiber fracture in all of samples of both ring groups (with and without CTBN in polymeric matrix). For ±55º filament winding layers, fiber-matrix debonding and delamination were observed. Similar results were observed by Kaynak and his coworkers [17] which investigated the effect of different winding angle on mechanical performance of specimens under split-disk tests.



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Neat tube CTBN-modified tube

Figure 12: Photographs of specimens after fracture.

3.7. Hydrostatic Tests

All tubes were subjected to internal pressure (burst test) in pure hoop loading (without axial stress) and external pressure (colapse test).

Initially, colapse and bursting tests were carried out on tubes consisting of eight layers (88º2/±55º2/88º2). The colapse and burst pressures versus time curves are presented in Figure 13 and 14, respectively.



13

0 2 4 6 8 10 12 140

1

2

3

4

5

6

Pre

ssur

e (M

Pa)

Time (min)

CTBN-modified tube Neat tube

Figure 13: Representative colapse pressures versus time curves of the tubes with and without CTBN (both composite tubes with eight layers).

0 1 2 3 40

4

8

12

16

20

CTBN-modified tube Neat tube

Pre

ssur

e (M

Pa)

Time (min) Figure 14: Representative burst pressures versus time curves of the tubes with and without CTBN (both

composite tubes with eight layers).

Table 3 (resp. 4) shows mean values for the colapse (resp. bursting) pressures and

times.

Tube Colapse Pressure

MPa (psi)

Time

(min)

Neat 4.76 (690.20) 11.37

CTBN-modified 5.46 (791.70) 13.09

Tabel 3 – Mean values for the colapse pressures and times of the tubes.



14

Tube Burst Pressure

MPa (psi)

Time

(min)

Neat 15.13 (2193.10) 4.03

CTBN-modified 17.98 (2607.80) 4.19

Tabel 4 – Mean values for the bursting pressures and times of the tubes.

It can be observed that CTBN-modified tubes shown higher colapse and bursting pressures and longer fracture times. In these tests, as well as in the split-disk tests, the rubber addition in the polymeric matrix played an important role in the fracture processes. The tubes colapse and bursting pressures increased about 14% and 19%, respectively. More specifically, colapse pressure changed from 4.76 to 5.46 MPa and the bursting pressure attained 17.98 MPa. Colapse and bursting times increased about 15% and 22%, respectively. This may have occurred because toughened resins present higher strength to crack propagation [18 , 19].

In a similar way that the observed in the rings (split-disk test), CTBN rubber acts as a plasticizer in the polymeric matrix improving the loading and strain distribution to fibers. This feature was also observed on photographs of specimens after colapse tests. The tubes with CTBN presented just a small region with delamination (Figure 15a), while the samples without CTBN presented besides a great region with delamination, a larger amount of fibers bending into the tubes interior (Figure 15b). This is probably due to the hardness of crack propagation imposed by the modified matrix. Based on such results, the CTBN-modified tubes provide a good compromise between strength and fracture time.

(a) (b)

Figure 15: Internal regions of the tubes after colapse tests: (a) neat and (b) CTBN-modified.



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The influence of the number of layers on the strength of the selected tubes, i.e., the CTBN-modified ones, was verified by means of the colapse test over a tube with sixteen layers (88º4/±55º4/88º4).

Figure 16 shows the colapse pressure versus time curve for the tube with sixteen (88º4/±55º4/88º4) layers. The results from these tests are summarized in Table 5. To help comparison, Figure 16 also contains the outcomes for the 8-layers tube.

0 10 20 30 40 50 600

5

10

15

20

25

Pre

ssur

e (M

Pa)

Time (min)

88º4/55º

4/88º

4

88º2/55º

2/88º

2

Figura 16: Colapse pressure-time curves of the CTBN-modified tubes with different amount layers.

Tube Colapse Pressure - MPa

(psi)

Eight Layers

[88º2/±55º2/88º2]

5.46

(791.70)

Sixteen Layers

[88º4/±55º4/88º4]

24.50

(3552.50)

Table 5 – Colapse pressures of tubes with eight and sixteen layers.

It was verified that, for the same lamination configuration, the tubes strength grows praticaly linearly with the number of layers. The colapse pressure increased from 5.46 to 24.50 MPa, corresponding to the 8- and 16-layers tubes. In [20], similar tubes were evaluated consisting of ten and fourteen layers, achieving strengths around 7.90 and 17.40 MPa, respectively. Altogether these results demonstrate the dependency between the colapse strength and the number of layers.

The colapse pressure attained by the 16-layers tube corresponds to a water depth of 2500 m, which confirms its feasibility for application in deep water scenarios.



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4 CONCLUSIONS

There was reduction in the values of tensile strength and modulus and increase in the elongation at fracture of modified-CTBN resin which might be attributed to the lowering in cross-linking density of the polymeric network as the rubber occupies the reaction sites. The fractography study reveals that the presence of CTBN particles led the material to fracture in a way akin to ductile materials. SEM analysis showed also the good adherence between the elastomeric phase and the epoxy matrix which was evidenced by IR analysis. The dynamic mechanical thermal analysis of the polymeric systems showed a reduction in the Tg value with rubber addition which may also be attributed to the lowering in cross-linking density.

In the composite tubes, the rubber addition promoted a better fibe/matrix adhesion. In the split-disk tests, the positive effects of the CTBN were observed on hoop tensile strength of rings and fracture features. Hoop tensile strength increased from 572.20 to 709.05 MPa (approximately 20%). Rubber CTBN acted as plasticizer in epoxy matrix improving the loading and strain distribution to fibers. In the hydrostatic tests, the CTBN-modified tubes attained higher values of colapse and bursting pressure and higher time to fracture. The results demonstrate that the tube consisting of sixteen layers presents thecnical feasibility for application in deep water.

REFERENCES

[1] P. Odru, Y. Poirette, Y. S. Saipem, et al., «Composite riser and export line systems for deep offshore applications, 22nd International Conference on Arctic Engineering and Offshore Mechanics, 2003, (1-10). [2] P. Odru, Y. Poirette, Y. Stassen, J. F. Saint-Marcoux and L. Abergel, “Technical and economical of composite riser systems”, Offshore Technology Conference - OTC 14017, Texas, 2002, (1-10). [3] S. B. Lee and J. Rockett, “Interactions of water with unsaturated polyester, vinyl ester and crylic resins”, Polymer, 33, 3691-3697 (1992). [4] N. Chikhi, S. Fellahi, M. Bakar, “Modification of epoxy resin using reactive liquid (ATBN) rubber”, European Polymer Journal, 38, 251-264 (2002). [5] G. Tripathi, D. Srivastava, “Effect of carboxyl-terminated poly(butadiene-co-acrylonitrile) (CTBN) concentration on thermal and mechanical properties of binary blends of diglycidyl ether of bisphenol-A (DGEBA) epoxy resin”, Materials Science & Engineering A, 443, 262-269 (2007). [6] K. R. Jayadevan, E. Østby, C. Thaulow, “Fracture response of pipelines subjected to large plastic deformation under tension”, Pressure Vessels and Piping, 81, 771-783 (2004). [7] J. L. Hedrick, I. Yilgor, G. L. Wilkes, J. E. Mc Grath. “Chemical modification of matrix resin networks with engineering thermoplastics. 1. Phenolic hydroxyl-terminated poly(aryl ether sulfone/epoxy system)”, Polym Bull, 13, 201-208 (1985). [8] G. V. Salmoria, C. H. Ahrens, M. Fredel, V. Soldi, A. T. N. Pires, “Stereolithography somos 7110 resin: mechanical behavior and fractography of parts post-cured by different methods”, Polymer Testing, 24, 157-162 (2005). [9] L. Gautier, B. Mortaigne, V. Bellenger, “Interface damage study of hydrothermally aged glass-fibre-reinforced polyester composites”, Composites Science and Technology 59, 2329-2337 (1999).



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[10] R. Tucker, P. Compston, P. Y. B. Jar, “The effect of post-cure duration on the mode I interlaminar fracture toughness of glass-fibre reinforced vinylester”, Composites: Part A, 32, 129-134 (2001). [11] M. Ochi and S. C. Kim, “Rubber-modified epoxy resin containing high functionality acrylic elastomers”, J Appl Polym Sci, 29, 1381-1391 (1984). [12] E. J. Robinette, S. Ziaee, G. R. Palmese, “Toughening of vinyl ester resin using butadiene-acrylonitrile rubber modifiers”, Polymer, 45, 6143-6154 (2004). [13] R. Thomas, J. Abraham, S. P. Thomas et al., “Influence of carboxylterminated (butadiene-co-acrylonitrile) loading on the mechanical and thermal properties of cures epoxy blends”, Journal of Polymer Science:Part B: Polymer Physics, 42, 2531–2544 (2004). [14] G. Tripathi and D. Srivastava, “Studies on the physico-mechanical and thermal characteristics of blends of DGEBA epoxy, 3,4 epoxy cyclohexylmethyl, 3’, 4’-epoxycylohexane carboxylate and carboxyl terminated butadiene co-acrylonitrile (CTBN)”, Materials Science and Engineering A, 496, 483–493 (2008). [15] P. Huang, S. Zheng, J. Huang, et al., “Miscibility and Mechanical Properties of Epoxy Resin/Polysulfone Blends”, Polymer, 38, n. 22, 5556–5571 (1997). [16] J. L. Hedrick, I. Yilgor, M. Jurek, et al., “Chemical modification of matrix resin networks with engineering thermoplastics: 1. Synthesis, morphology, hysical behavior and toughening mechanisms of poly(arylene ether sulphone) modified epoxy networks”, Polymer, 32, 2020–2032 (1991). [17] C. Kaynak, E. S. Erdiller, L. Parnas and F. Senel, “Use of split-disk tests for the process parameters of filament wound epoxy composite tubes”, Polymer Testing, 24, 648-655 (2005). [18] H. Zhang, L. A. Berglund and M. Ericson, “Rubber-Toughening of glass fiber-epoxy filament wound composites”, Polymer Engineering and Science, 14, 31, 1057–1063 (1991). [19] N. A. Warrior, T. A. Turner, F. Robitaille, et al., “The effect of interlaminar toughening strategies on the energy adbosrption of composite tubes”, Composites Part A: applied science and manufacturing, 35, 431–437 (2004). [20] R. A. F. Silva, Estudo numérico e experimental visando o desenvolvimento de dutos compósitos submarinos pela técnica de enrolamento filamentar. Dissertação de Mestrado, Universidade Federal of Rio de Janeiro, 2008, Rio de Janeiro, Brazil.

ACKNOWLEDGMENTS

The authors acknowledgments the financial assistance of CNPq.

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