Production of Kevlar Panels Using High Pressure Resin Transfer ... · 2021. 4. 3. · Production of Kevlar Panels Using High Pressure Resin Transfer Molding (HP-RTM) and Liquid Compression

Production of Kevlar Panels Using High Pressure

Resin Transfer Molding (HP-RTM) and Liquid

Compression Molding (LCM) Process and Their

Performance

K. Chang, D. Buzzelli, G. Meirson,

O.R Tutunea-Fatan

Fraunhofer Project Centre for

Composites Research

FPC @ Western

A joint venture between:

Western University, London, Ontario, Canada

And

Fraunhofer Gesellschaft, Munich, Germany;

Institute for Chemical Technology (ICT), Pfinztal, Germany

Contact: [email protected]

www.eng.uwo.ca/fraunhofer

Kevlar®

Aramid fibers

Meta-Aramid Para-Aramid

(Kevlar®)

Wet spinning

Semi-crystalline fiber

with molecular chain oriented along the fiber axis

Dry jet wet

spinning

Fully extended liquid

crystal chain along the axis

Can withstand stress

during fire exposure and high temperatures

Incredibly stronghttps://www.dupont.com/fabrics-fibers-and-nonwovens/kevlar-for-aerospace.html

Why Kevlar®?

Extremely strong yet lightweight and

durable, Kevlar® provides the perfect

balance of form and function—allowing you

to redefine performance and explore new

possibilities for a better tomorrow. Whether it’s used for protection, consumer products

or transportation, Kevlar® keeps you at the

forefront of innovation.

Kevlar has a unique combination of high

strength, high modulus, toughness and

thermal stability

https://www.dupont.com/fabrics-fibers-and-nonwovens/kevlar-for-aerospace.html

Kevlar® Fiber properties

Kevlar 49 E-glass Carbon

Modulus [GPa] 112 72 220

Specific tensile strength

[106 cm]

21.25 13.79 17.6

Elongation at break % 1.4 4.8 2.4

Kevlar® fabric:

Woven 175 gsm

HP-RTM LCM

• ~5 minute cycle time

• 3D geometry

• Thick parts

• ~3 minute cycle time

• 2.5D geometry

• Thickness us to ~2.5m

LCM

Research objectives

▪ Explore the process of Kevlar® molding through HP-RTM

▪ Explore the process of Kevlar® molding through LCM

▪ Explore the properties of Kevlar® composites made through HP-RTM and LCM

▪ Explore the properties of hybrid Kevlar®/carbon properties

Composite Manufacturing

RTM Rimstar Thermo 8/4/8 with 2 Mixing Heads

• Self-cleaning mixing head

design

• Separate mixing heads

for epoxy and

polyurethane systems• Internal mold release

system can be used for

third injection component

• Precision dosing between

0.05 - 2.0 g/s• Mixing pressures between

60 and 180 bar

• Resin flow rates: 20 - 120

g/s

• Active pressure/flow monitoring

Composite Manufacturing

• Parallel motion control system

• Maximum closing force of 25,000 kN

(using full parallel motion control force)

• Minimum closing force of 250 kN

• Rapid motion up to 800mm/s ram speed• Precision closing speeds up to 80mm/s

at low force and 20mm/s at high force

Dieffenbacher CompressPlus DCP-U 2500

Manufacturing conditions

• Hexion’s epoxy system Epikote

6150/Epikure 6150

• Mold temperature set to 120◦C

• 5 min curing time

• 1500 kN press force during injection • 4500 kN press force during cure

Kevlar® molding

▪ Kevlar® turned out extremely easy to mold with very wide operational envelop

Kevlar® molding

▪ Since Kevlar is from family on polyamides effect of dehydration was investigated

Water vapors leaving the fabric

Test Dried As is

Compression strength

[MPa]

99.32 97.48

Tension strength [MPa] 440.41 428.75

Flexure strength [MPa] 398.73 391.25

Impact 204.15 201.16

Test Dried As is

Compression modulus

[GPa]

20.05 20.10

Tension modulus [GPa] 26.10 23.86

Flexure modulus [GPa] 21.74 21.43

Sample specification:

2 mm thick panels

50% volume fraction

8 layers of Kevlar®

LCM vs. HP-RTM

Test HP-RTM LCM

Compression

strength

[MPa]

99.01 99.32

Tension

strength

[MPa]

512.50 440.41

Flexure

strength

[MPa]

392.13 398.73

Impact 149.79 204.15

Sample specification:

2 mm thick panels

50% volume fraction

8 layers of Kevlar®

Dried samples

HP-RTM thick vs. thin panels

Test Thick* Thin*

Compression

strength [MPa]

146.86 103.09

Tension strength

[MPa]

514.41 434.21

Flexure strength

[MPa]

407.97 40.32

Impact 141.18 188.46

Test Thick* Thin*

Compression

modulus [GPa]

21.47 22.53

Tension

modulus [GPa]

28.25 28.06

Flexure

modulus [GPa]

25.10 21.53

Sample specification:

Thin*: 2 mm, 50% vol, 8 layers

Thick*: 4 mm, 50% vol, 16 layers

*Fabric was treated with plasma

Kevlar® vs. Carbon composite

Test Kevlar® Carbon

Impact [kJ/m2] 149.79 (188.46 with

plasma)

188.35

Flexure strength

[MPa]

392.13 939.88

Flexure [GPa] 21.21 49.00

Sample specification:

Kevlar®:

50% volume, 8 layers

2 mm thickness

Carbon:

50% volume, 6 layers

2 mm thickness

Hybrid composite

Test Kevlar® (8K) Carbon

(6C)

2C/3K/2C K/6C 3C/K/3C

Impact [kJ/m2] 149.79(188.46P) 188.35 201 228.40 221.11

Flexure strength

[MPa]

392.13 939.88 1059.19 886.34(KT)

1052.21 (KT)

1104.42

Flexure [GPa] 21.21 49.00 59.39 52.00 61.41

52.2% vol 56% vol 56% vol

Summary

▪ Kevlar® was extremely easy to mold

▪ Kevlar has good compatibility with epoxy resin

▪ Adding Kevlar® to carbon in small amounts provides a lot of added value in

terms of properties

▪ In some cases Plasma has provided significant increase in properties

Acknowledgments

▪ We would like to thank DuPont for funding the project

▪ We would like to thank NSERC for funding the project

▪ We would like to thank Hexion for donating the epoxy resin for the project

▪ We would like to thank Plasmatreat for proving the plasma equipment for the

project