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MULTILAYER COMPOSITE PIPE SYSTEM

SHREYAS WANKHEDE

MASTER OF ENGINEERING, MECHANICAL AND INDUSTRIAL ENGINEERING

UNIVERSITY OF TORONTO

AUGUST 14, 2025

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Industry Problem & Project Scope

Multilayer Composite Pipe System

The pipe comprises three primary layers, each designed for a specific performance goal:

2 Tie (Adhesive) Layer�▫ Adhesive layer between the PPS layers�▫ Hypothesis: Fiber reinforcement may improve mechanical & bonding performance�▫ Our work: Investigate impact of CF and PPS fibers on adhesion and modulus

3 Inner Layer�▫ Current solution: PPS, but too expensive�▫ Goal: Replace PPS with cost-effective, fiber-reinforced PERT�▫ Our work: Explore combinations with CF, TF, GF, compatibilizers (PB, NS)

1 Outer Jacket Layer�▫ Requires high thermal and chemical resistance�▫ Current PPS is costly; company is optimizing a new formulation�▫ Our work: Study old vs. new PPS and screen PPS-AX8840 blends

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1.1 Outer Layer: PPS XE5000NA Old vs New

Objective:

Inspect properties for PPS XE5000NA New formulation compared to Old formulation

Materials:

PPS XE5000NA (Polyphenylene Sulfide)

Samples:

PPS XE5000NA Old formulation
PPS XE5000NA New formulation

Methods:

Rheometry @300  °C (viscosity & modulus stability)

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Rheometry: Setup and Procedure

Load Material

Place sufficient PPS pellets on lower plate

Initial Heating (12 min)

Furnace closed, heat to 290 °C

Melt Hold

(4 min)

Maintain at 290 °C for 4+ minutes

Set Gap & Clean

Set 1 mm gap, clean excess around edges

Equilibration (9-10 min)

Heat to 300 °C, stabilize before test

Test Execution (20 min)

Record viscosity & modulus at 300 °C

Anton Paar RheoCompass DMA

Steps:

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Rheometry: Viscosity Old vs New

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Rheometry: Modulus Old vs New

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1.2 Outer Layer: PPS XE5000NA–AX8840 Blends

Objective:

Screen PPS XE5000NA and AX8840 blends for high-temp performance

Materials:

PPS XE5000NA New formulation (Polyphenylene sulfide)
Lotader AX8840 (ethylene–glycidyl methacrylate copolymer) – impact modifier and compatibilizer

Samples:

PPS XE5000NA–AX8840 blends with 11.5%, 17.5%, 20.5%, 23.5% AX8840

Methods:

DMA Temp-Ramp (modulus vs temp): RT – 160 °C (3 °C/min)

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Sample Preparation Procedure

At 300 °C: Compression mold the pellets into ~0.9mm thick sheets

Prepare test sample of dimensions: 30mm x 5mm

Load samples onto clamps, close the furnace

Test method: DMA Temp-Ramp: RT – 160 °C (3 °C/min)

Steps:

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TA DMA Q800

PPS XE5000NA–AX8840 Blends

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Outer Jacket Layer: Conclusions

1.1 PPS XE5000NA Old vs New

New formulation showed better stability at 300 °C within the recorded duration

1.2 PPS XE5000NA–AX8840 Blends

The threshold of AX8840 is around ~19wt%, before which XE5000NA stills retains its properties

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2.1 Reinforced Tie Layer

Objective: Improve PPS adhesion using fiber-reinforced tie layers�Materials:

PPS FX55T1: Polyphenylene Sulfide (thermoplastic outer layer)
Orevac 18722: MAH-grafted PP (used in multilayer films)

Reinforcements:

Carbon Fibers (CF)
Polyphenylene Sulfide (PPSf)

Multilayer Samples:

OV (neat)
OV +3/6 wt% CF
OV +3/6 wt% PPSf

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Bonded region

Unbonded region

PPS

Orevac 18722

Kapton tape

Compression mold PPS FX55T1 films at 300 °C and OV, OV + CF/PPSf films at 230 °C. (dimensions: 8 cm x 8 cm x 0.04 cm)

Assemble the sandwich arrangement. PPS | OV | PPS

Vacuum bag and vacuum for 10 min.

Keep vacuum and compression mold at 300 °C, 0 psi, 5 min.

Keep vacuum and air cool.

Steps:

Multilayer Sample: Preparation Procedure

OV, OV + CF/PPSf: Compounded at 230 °C, 100 rpm for 5mins

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Sample Loading

5mm wide sample clamped in fixture

Heating Phase

Chamber temp ramps up to 95 °C

Temp Stabilization

Hold at 95C for 3 mins

Test Execution

Peel at 1 mm/min extensional speed

Data Collection

Plot Static Force vs. Displacement

Steps:

Anton Paar RheoCompass DMA

F

Multilayer Sample: Peel Test Procedure

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Anton Paar DMA

Peel Test Results comparison (at 95C)

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Anton Paar DMA

Peel Test Results comparison (at RT)

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Anton Paar DMA

Peel Test Results comparison (RT vs 95C)

RT

95C

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Anton Paar DMA

Peel Test: Adhesive to Cohesive transition

25C

Adhesive

40C

Mixed

50C

Cohesive

60C

Cohesive

70C

Cohesive

80C

Cohesive

95C

Cohesive

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Peel Test: Adhesive to Cohesive Theory (RT vs 95C)

Temperature-Dependent Failure Behaviour:

Citations: Zhao & Ramani; Teixeira de Freitas; Mohammed et al; Kendall

At RT: Orevac is under tensile residual stress; low chain mobility limits interfacial healing → adhesive failure.

At 95 °C: Orevac softens, stress relaxes, chain mobility improves → stronger interface, energy dissipation → cohesive failure.

Mechanism:

Condition	Orevac State	Stress State	Chain Mobility	Result
RT (~25 °C)	Ductile but tense	High tensile stress	Low	Adhesive failure
95 °C	Soft/rubbery	Stress relaxed	Moderate	Cohesive failure

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Thermal Mechanical Analysis: OV-x, PPS

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Thermal Mechanical Analysis: OV-x, PPS

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Reinforced Tie Layer: Conclusions

Observation:

Peel strength increases from ~15.28 N at RT to ~31.1 N at 95 °C for neat Orevac.
Fiber-reinforced Orevac shows lower strength at both temperatures, despite cohesive failure at 95 °C.

Proposed Explanation:

At RT: High tensile residual stress due to CTE mismatch + stiff polymer chains → adhesive failure.
At 95 °C: OV softens, residual stress relaxes, chain mobility increases → cohesive failure, more energy absorption.

CTE Insights (TMA):

Neat Orevac has high CTE → stores more stress during cooling.
OV–3PPSf has lower CTE → less stress buildup, but fibers restrict chain motion → lower peel strength.

Key Takeaway:

Temperature-dependent peel strength is driven by the relaxation of thermal residual stress and mobility of the polymer chains — both of which are suppressed in fiber-reinforced systems.

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3.1 Reinforced PERT: Tension & Torsion Tests

Composite Preparation

Compounding: at 220 °C, 100 rpm for 5mins

Sample Preparation

Injection Molding

Melting in cylinder at 220 °C for 4mins

Injected into mold at 80 °C

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Storage Modulus in Tension

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Storage Modulus in Torsion

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Loss Factor in Tension

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Loss Factor in Torsion

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Modulus Summary: Tension & Torsion Tests

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Loss factor Summary: Tension & Torsion Tests

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3.2 Reinforced PERT: Orientation Study

IM PERT

IM PERT 15TF

IM PERT 15CF

CM PERT

Extruded PERT

CM PERT 15CF

CM PERT 15TF

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Storage Modulus in Tension for Reinforced PERT

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Storage Modulus in Torsion for Reinforced PERT

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Loss factor in Tension for Reinforced PERT

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Loss factor in Torsion for Reinforced PERT

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IM

CM

EX

IM

CM

IM

CM

IM

CM

EX

IM

CM

IM

CM

IM

CM

EX

IM

CM

IM

CM

Orientation Study: Results

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3.3 Reinforced PERT: Compatibilizer Effects

PERT – 18CF – 20% Polybond

PERT – 18CF – 10% Polybond

PERT – 18CF –10% Nova Sclair

PERT – 18CF – 10% Polybond + 10% Nova Sclair

Injection Molded Samples

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Tensile test for Different Compatibilizer

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Tensile test for Different Compatibilizer: Results

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Reinforced PERT-Compatibilizer Effects: Conclusions

Summary of Findings:

Stiffest Composite: 10% Nova Sclair (2437 MPa)
Strongest Composite: 10% Polybond (55.5 MPa)
No synergistic benefit from combining Nova Sclair and Polybond

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3.3 Reinforced PERT: Temp Ramp Study

Neat PERT

Injection Mold Samples

PPS FX55T1

PERT 10PB 18CF

PERT 10PB 15TF

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Temp Ramp Study: Tensile Storage Modulus

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Temp Ramp Study: Tensile Loss factor

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Temp Ramp Study: Conclusions

Thermal Performance Summary:

PPS FX55T1: Best modulus retention
PERT 18CF: High stiffness but declines with temperature
PERT 15TF: Balanced performance with moderate stability
Neat PERT: Lowest modulus least suitable elevated temperatures

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3.3 Reinforced PERT: Progressive Damage Study

Stress Controlled Cyclic Tensile Test

Each test begins at 1 MPa tensile stress. (initialization)

In each cycle, the stress is increased in 5 MPa steps (5, 10, 15 … up to 60 MPa)

After each cycle, the sample is unloaded back to 5N

At the end of each cycle, strain is measured, and storage modulus is calculated

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Stress Controlled Progressive Damage Test

Injection Mold Samples

PERT

PPS FX55T1

PERT

10PB-15TF

PERT

10PB-20GF

PERT

10PB-15CF

PERT 10PB 3volTF 7volCF

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Stress Controlled Progressive Damage Test

Extension (mm) vs Time (sec)

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Stress Controlled Progressive Damage Test

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Stress Controlled Progressive Damage Test

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Stress Controlled Progressive Damage Test

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3.4 Reinforced PERT: Progressive Damage Study

Strain Controlled Cyclic Tensile Test

Test begins at 1% strain

In each cycle, the strain is increased in steps of 1% (1, 2, 3 … up to 12%)

After each cycle, the sample is unloaded back to 0.3% - 5N

At the end of each cycle, strain is measured, and storage modulus is calculated

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Strain Controlled Progressive Damage Test

Injection Mold Samples

PERT

PPS FX55T1

PERT

10PB-15TF

PERT

10PB-20GF

PERT

10PB-15CF

PERT 10PB 18CF

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Strain Controlled Progressive Damage Test

Extension (mm) vs Time (sec)

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Strain Controlled Progressive Damage Test

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Strain Controlled Progressive Damage Test

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Strain Controlled Progressive Damage Test

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Progressive Damage Tensile Test: Conclusions

Stress Controlled Cyclic Tensile Test

Strain Controlled Cyclic Tensile Test

PERT-20GF: Least amount of Residual Strain

PERT-15TF: Best Modulus Retention

PERT-15CF: Least amount of Residual Strain

PERT-15TF: Best Modulus Retention

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Final Comments and Future Scope

2 Tie (Adhesive) Layer�▫ None of the compositions able to surpass the adhesion strength of Neat Orevac�▫ Change additives from fibers to CNT or GNP?

3 Inner Layer�▫ Few of the composites outperform PPS in some properties but lack stability in other areas

▫ Maybe switching PERT with Nova Sclair?

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Thank you very much!

PRESENTED BY SHREYAS WANKHEDE