HIGH TEMPERATURE POLYIMIDE MATRIX COMPOSITES · 3 Polyimide resin as high temperature matrix Epoxy...

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HIGH TEMPERATURE POLYIMIDE MATRIX COMPOSITES

Tsuyoshi Ozaki, Composites Research and DevelopmentKoji Moriuchi and Shinichi Sakane, IST Corporation

Satoshi Uehara and Takashi Yokoyama, Super Resin Inc.

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Fiber reinforced plastic matrix composites

Very attractive materials

＊ Light-weight structures

＊ Especially for aerospace applications

Some of the aerospace parts such as engine componentsrequire high heat resistance of more than 200 ℃.

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Polyimide resin as high temperature matrix

Epoxy

Bismaleimide5250-4, 5270-1 Less than 230 ℃

SKYBONDⓇⓇ 700, 703, 705

PMR-15 More than 300 ℃

Very attractive matrix for high temperature composites

High heat resistance

Polyimide

Less than 200 ℃

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Major disadvantage of polyimide matrix resin

＊ The difficulty in polyimide curing process

＊ Imidization and curing happened simultaneously.⇒ High voids of more than 3 %⇒ Derade the mechanical and thermal performance

SolventSolvent

ImpregnationImpregnation LaminationLaminationHeatHeat

DryingDrying CuringCuring

HeatHeat

WaterWaterSolventSolvent

ImpregnationImpregnation LaminationLaminationHeatHeat

DryingDrying CuringCuring

HeatHeat

WaterWater(Imidization)

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IST’ｓ SKYBONDⓇⓇ 8000 and SKYBONDⓇⓇ 800

IST has developed new polyimide resins to solve the problem.2 solutions are proposed.

（１） SKYBONDⓇⓇ 8000 for RTM (Resin Transfer Molding)

Citraconic endcapped imide oligomer

（２） SKYBONDⓇⓇ 800 for two stage autoclave process

Citraconic endcapped amic acid oligomer

N NR’ RR

OO

n

O O

N N

O OO O

N NR’ RR

OO

n

O O

N N

OO OOO O

N NR’ RR

O

O

O

OOH

OOHO

n

O O

OHN N

HON NR’ RR

O

O

O

OOH

OOHO

n

O O

OHN N

HO

SKYBONDⓇⓇ 8000 for RTM

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Resin Transfer Molding (SKYBONDⓇⓇ 8000)

SKYBONDⓇⓇ 8000 (Citraconic endcapped imide oligomer )

(1) Solvent free (imidized powder)

(3) Can be cured at >300 C

without volatiles

(2) Low melt viscosity (of less than 1.0 Pa･s)

N NR’ RR

OO

n

O O

N N

O OO O

m

N NR’ RR

OO

n

O O

N N

OO OOO O

m

N NR’ RR

OO

n

O O

N N

O OO O

N NR’ RR

OO

n

O O

N N

OO OOO O

0 100 200 300 400

1E+1

1E+2

1E+3

1E+41E+5

1E+6

Temperature (℃)

Visc

osity

(P)

0 100 200 300 400

1E+1

1E+2

1E+3

1E+41E+5

1E+6

Temperature (℃)0 100 200 300 400

1E+1

1E+2

1E+3

1E+41E+5

1E+6

0 100 200 300 400

1E+1

1E+2

1E+3

1E+41E+5

1E+6

0 100 200 300 400

1E+1

1E+2

1E+3

1E+41E+5

1E+6

Temperature (℃)

Visc

osity

(P)

Temperature Scan with 10℃/minFig.1

1.0 Pa･s

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SKYBONDⓇⓇ 8000 molding & cure condition

Carbon Fabric 1) G30(0/90)n

Volume Fraction 48-50 %Injection Temp. 240 ℃Cure Temp. 335 ℃

200

250

300

350

0 100 200 300 400

335 ℃ x 4 h cure

Ramp Step 1 C/min

Injection & Hold Step

Time (min)

Tem

p. (℃

)

Table 1. Molding condition

Fig.1 Cure cycle

1) Desized at 400 C for 1hr

1.40 (0.29)48.5 (0.45)50.1 (0.38)40.7 (0.39)1.50 (0.00)Ave. (Std. Dev.)1.648.849.741.01.503

1.648.050.440.31.502

1.148.850.240.81.51Sample1

Voids (%)Resin Volume (%)Vf (%)Resin (wt%)Density (g/cc)

1.40 (0.29)48.5 (0.45)50.1 (0.38)40.7 (0.39)1.50 (0.00)Ave. (Std. Dev.)1.648.849.741.01.503

1.648.050.440.31.502

1.148.850.240.81.51Sample1

Voids (%)Resin Volume (%)Vf (%)Resin (wt%)Density (g/cc)

Fig.4 Microscopy of Cross Section

Fig.3 Ultrasonic C-scan-Poor

Good

Small amount of voidscompared with conventional polyimide composites

ASTM D3171

Table 2. Summary of the Acid Digestion

Void content of SKYBONDⓇⓇ 8000 RTM FRP

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Calculated void content by digestion method

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Flexural Strength of SKYBONDⓇⓇ 8000 FRP

0

20

40

60

80

100

120

StressModulus

Ret

entio

n R

ate

(%)

23℃ 180℃ 200℃ 220℃ 230℃ 240℃ 250℃

Stress 856.4 MPaModulus 48.1 MPa

n = 5 error bar = σ

Test Temp. (℃)

0

20

40

60

80

100

120

StressModulus

Ret

entio

n R

ate

(%)

23℃ 180℃ 200℃ 220℃ 230℃ 240℃ 250℃

Stress 856.4 MPaModulus 48.1 GPa

n = 5 error bar = σ

Fig.5 Flexural strength of SKYBONDⓇⓇ 8000Test Temp. (℃)

> 60 %

Only a small reduction

Good retention

SKYBONDⓇⓇ 800 for two stage autoclave process

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Two stage cure autoclave process

ConventionalImidization stage and curing stage would overlap.

Imidization stage Curing stage1st 1st -- StageStage 2nd 2nd -- StageStage

Cure laminatesCure laminatesRemove volatiles Remove volatiles (solvent/water)(solvent/water)

Two stage cure for autoclave process

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SKYBONDⓇⓇ 800 for two stage autoclave process

SkybondⓇⓇ 800 (Citraconic endcapped amic acid oligomer)

N NR’ RR

O

O

O

OOH

OOHO

n

O O

OHN N

HON NR’ RR

O

O

O

OOH

OOHO

n

O O

OHN N

HO

150 ℃ to 220 ℃

1st :Imidization stage

Imidization was completely

separated from curing stage

Laminates can be cured

without influence of water

N NR’ RR

OO

n

O O

N N

O OO O

N NR’ RR

OO

n

O O

N N

OO OOO O

N NR’ RR

OO

n

O O

N N

O OO O

m

N NR’ RR

OO

n

O O

N N

OO OOO O

m

> 300 ℃

2nd : Curing stage

Very unique resin for molding of composite laminates

having such a ‘two-stage’ cure cycle.

with NMP solvent

DSC (Differential scanning calorimetric analysis) of SKYBONDⓇⓇ 800

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Fig.6 DSC thermograms of SKYBONDⓇⓇ 800 powder after it is dried

Metho d: imidizationdt 1 .0 0 s 30 .0 -40 0 .0°C 3 .00 °C/minSynchro nizatio n enabled

Sa mple: SK8 00 PAA powder.., 9 .0 4 00 mg

Co ntent 12 .0 8e+0 3 % no rma lized -12 0 .76 J g^-1Onset 13 4 .17 °CPea k 16 2 .63 °CLeft L imit 11 0 .34 °CRig ht L imit 23 2 .81 °C

m W

0

5

10

m in

°C50 100 150 200 250 300 350

0 20 40 60 80 100

^ e x o

S T A R e S W 9 . 2 0L a b : M E T T L E R

ImidizationCrosslink

Endothermic

220 ℃335 ℃165 ℃

Temperature

Hea

t flo

w

Exothermic

Imidization ratio of SKYBONDⓇⓇ 800

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Table 3　　 Imidization ratio of SKYBONDⓇ 800

Conditions 1)Ratio 2)

1376 cm-1

/1500 cm-1

Imidizationratio(%)

150 ℃ -1 hr 0.740 0

150 ℃ -1 hr, 220 ℃ -30 min 1.000 71

150 ℃ -1 hr, 220℃ -1 hr 1.036 81

150 ℃ -1 hr, 220℃ -2 hrs 1.080 93

150 ℃ -1 hr, 220 ℃ -1 hr and 335 ℃ -4hr 1.106 100

1) Atmospheric pressure

2) 1376 cm-1: C-N streching of imide group

2) 1500 cm-1: C-N streching of para-benzene group

Tg of SKYBONDⓇⓇ 800 neat resin

16Fig.7 DMA of SKYBONDⓇⓇ 800 neat resin

2 stage cured film

296 ℃

Tensile properties of SKYBONDⓇⓇ 800 neat resin

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Table 4　Tensile properties of SKYBONDⓇ 800 neat resin

Properties 23 ℃ 250 ℃ Measurement

Tensile strength 96 MPa 52 MPa ASTM D638

Tensile modulus 2.6 GPa 1.5 GPa ASTM D638

Elongation 5.6% 4.8% ASTM D638

Help to make the composite tougher than other brittle resin matrix like BMI.

About 5% elongation

SKYBONDⓇⓇ 800 FRP with two stage cure process

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0

100

200

300

400

500

600

0 2 4 6 8 10 12

Time (hrs)

Tem

pera

ture

(℃

)

-12

-8

-4

0

4

8

12

Pre

ssur

e (k

gf/c

m2 )

Pressure : 10 kgf/cm2

2nd : 335 ℃4hrs

1st : 220 ℃1hr

Two stage cure cycle (full autoclave)

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Full vacuum

Fig.8 Cure cycle

SKYBONDⓇⓇ 800 FRP and void content

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Fig.9 SKYBONDⓇⓇ 800 GFRP and CFRP

Fig.10 Cross section of GFRP

Fig.11 Cross section of CFRP

Void content

(Digestion method)

< 0.5 %

GFRP KS1581,(0°45°‐45°90°)/s

Carbon fabric was desized at 400 ℃ for 1 hrCFRP G30, (0°60°‐60°)/s

Very low void content compared with conventional polyimide FRP

Void content

(Combustion method)

< 0.5 %

Tg of SKYBONDⓇⓇ 800 FRP

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T e m p C e l4 0 0 .03 0 0 .02 0 0 .01 0 0 .00 .0

E' P

a

1 .0 E + 0 7

1 .0 E + 1 11 .0 E + 1 1

tanD

1 .0 0 0 0

0 .9 0 0 0

0 .8 0 0 0

0 .7 0 0 0

0 .6 0 0 0

0 .5 0 0 0

0 .4 0 0 0

0 .3 0 0 0

0 .2 0 0 0

0 .1 0 0 0

0 .0 0 0 0

E" P

a

1 .0 E + 0 6

1 .0 E + 1 21 .0 E + 1 2

2 9 1 .6C e l1 .2 E + 1 0P a

3 1 3 .8C e l0 .2 3 1 8

3 0 5 .4 C e l1 .2 E + 0 9P a

Fig.12 DMA of SKYBONDⓇⓇ 800 FRP Carbon fabric was desized at 400 ℃ for 1 hr

292 ℃

Short beam shear strength of SKYBONDⓇⓇ 800 FRP

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Table 5　SBS strength of SKYBONDⓇ FRP

23 ℃ 200 ℃ Measurement

SBS strength 50 MPa 40 MPa ASTM D2344

Carbon fabric was desized.

Good bonding between resin and fiber

Free standing cure with SKYBONDⓇⓇ 800

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Free standing cure

SKYBONDⓇⓇ 800 advantageImdization stage and curing stage of are completely separated.

＊ Free standing cureThe out-of-mold cure

＊ AdvantagesLess expensive toolsEpoxy-like autoclave cureDoes not require high temperature autoclave

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Full autoclave Free standing cure1st stage in an autoclave in an autoclave2nd stage in an autoclave in an oven

Free standing cure of SKYBONDⓇⓇ 800800

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Table 6　Free standing cure condition and Tg of SKYBONDⓇ 800 FRP

1st stage(Autoclave)

2nd stage(Free standing)

Tg

220 ℃ -6 hrs 300 ℃ -8 hrs 280 ℃

Carbon fabric was desized.

Fig.13 Cross section of free standing cured FRP

Carbon fabric G30, (0°60°‐60°)/s

Void content

(Digestion method)

< 0.5 %

SBS of free standing cured SKYBOND ⓇⓇ FRP 800

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Free standing Full autoclave Measurement

SBS strength 40 MPa 50 MPa ASTM D2344

at 23 ℃

Table 7　Comparison of SBS strength of FRP between free standing cured and full autocalve molded

Good in spite of low pressurecompared with full autoclave process.

Summary

(1) Polyimide composite laminates with very low void content have been successfully fabricated both in the RTM process and the autoclave process.

(2) SKYBONDⓇⓇ 8000 composite laminates cured in RTM process have very good retention of mechanical and thermal properties at elevated temperature.

(3) SKYBONDⓇⓇ 800 resin ｆor autoclave also exhibits excellent thermal stability. In addition, this resin provides the unique feature of “two stage” cure, which leads to vapour free cure in the second stage of the molding.

(4) Due to two stage process, SKYBONDⓇⓇ 800 enables fabricating polyimide composite laminates with “free standing cure”.

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Acknowledgement

This work was partially supported by grant from JST (Japan Science and Technology Agency).

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