The purpose of this paper is to identify and develop arc-track resistant insulation materials that can operate reliably at 300 C. In the first phase, high performance polymers are evaluated based on structure, thermal stability and electrical properties. Next, the polymers are ranked according to performance and experimental characterization. Then, experimental evaluations in wire configuration are conducted. And selection is made based on performance and commerical potential

Dorogy, W.

Farrell, B.

Jayaraj, K.

Landrau, N.

English

NASA Technical Reports Server

i
: I
: N96-17096
i EVALUATION OF HIGH TEMPERATURE POLYMERS
._ K. Jayaraj, W. Dorogy, B. Farrell, and N. Landrau _,
Foster-Miller, Inc. J/ _ -,_'
Waltham, Massachusetts
G& o
High Temperature ,7- l)
Aerospace Insulation
• Goal
- Identify and develop arc-track resistant insulation
materials that can operate reliably at 300°C
• Phase I SBIR program, July 1991 to January 1992
• Monitored by Mr. Caorge Slenski, and Mr. Eddie White
of USAF Wright Laboratory/Materials Directorate
• Phase II program: Ociober 1992 to September 1995
• Contract monitor: Mr. John Nairus
Foster-Miller Approach to Developa 300°CRated,
Arc-TrackResistantAerospaceInsulation
Large Classes of High Performance Polymers
Evaluation Basedon
Pha_e I • Structure
' Program Thermal Stability
t • FJectrlcalProperties: 6 Msterials
II • ExperimentalCharacterization
• Rank According to Performance
2 l_derlals
I"'_._ ,,--'_'_b • Experlmentel Evalustlons in
i n-w- B Wlm Configurstfon
• Selection BaNd on Performance
and Commercialization Potential
One MaterialSystem for Consideration to Include in QPL ,_
211
1986109911-207
https://ntrs.nasa.gov/search.jsp?R=19960009930 2020-06-16T05:47:23+00:00Z
kAdvantages and Disadvantages of Key Structural Feat.ms
Structural I
, Features Advartagas Disadvantages
n
b;luorlne content For low dkdectric constant, low loss Aliphstic fluoropolymors, such as Tefzol, hove_poor
factor, high volume resistivity, unflonn m4_chenicelpropedles st _igh temporMuras. ]o
eisctrlcel properties over a wide range of overcome this limitation, must incorporate other
temperatures, resistance to erc-tranking features
i
Liquid crystalline Solvent resistance, high thermal stability, Liquid crystldlinepolymers are difficult to process, need •
and possible improved mlstance to to incorporate additional fcethm, e.g., polylmide Iarc-trocklng
Polylmlde High themml stability, abrasion Poor reslstlmce to aro-trasking. Improvedthrough i
rsslsten:e, and good proceesablUty introduction of additional futures, e.g., fin,urinated ]groups, c.-ystmllinltyAromatic High thermal stability Highly awommtlcpolymers yield conducting char uponi pyrolysis
, I
Rigidity/ RIgMlty Increases thermal and mechanical High rigid polymers can be Intractable, difficult tostiffness ce_bii.lty, _tnd reduces susceptibility to process, and low elongation to break. Some degrees of
SOlVents flexibility desired
,,: Cross-linking X-linking significantly increases thermal X.linking greatly reduces flexibility, reduces elongation
stabHy..This processis widely used in to break, and embrlttles
the deVelopment of 371"C-rated
; composites
m
._ Carbon High carbon to hydrogen ratio Inorsusas High carbon to hydrogen radiomay cause the formation •
/hydrogen ratio thermal capability of polymers of conductive char and susceptibility to arc-tracking l
HE
212
!
1986109911-208
DetailedProgramPlan
Performance Goals for
Selected Materials
• Arc-track resistance
- >180 sec using ASTM D495
- Concern: 0.125 in. thick samples
- Develop alternate test for thin films
• Lifetime > 15,000 hr at 300°C
• Cost comparable to Kapton
• Amenable to manufacture into aerospace wire
I configurations on current equipment with little
or no modificetion
213
1986109911-209
Initial Set of Materials
6F-PBO-PI Hoechst Celanese/Foster-Miller
, i
6F-PBO thermoplastic Dsychem Laboralorles, Dayton, OH
benzoxazole polymer
3F-PBO-PE Virginia Polytm:hnic institute
., Low-char Polylmlde Dupont
6FOA (20%) PMDA (80%)-4BDAF Virginia Polytechnic Institute
36FDA-FDA United Technologies, Hartford, CT
Xydar blends AMOCO/Foster-Miller
MechanizedFilm Casting Setup
214
]
1986109911-210
Verification of Procedures
• Polyamic acid of Kapton was cast into films,
cured and tested to verifyprocedures
• Arc tracking results agreewith publisheddata
• Film cashing, thermal treatmentand test
., proceduresvalidated
Arc Track Resistance Tester
• Test methodASTMD495
• Apparatus
215
1986109911-211
Arc Track Resistance-
Critical Parameters
• Film thickness
- Test method requires 125 roll
Our tests indicate5 roll thickness is sufficient
• Pressure of electrodes on films
• Angle of electrodes
• Volatile content of films
• Heat generation during testing
• Surface cleanliness
I
Arc TrackingResistance- RibbonTest
A High-Voltage, Low-Current Test was Developed by
Sigma Labs which Highly Differentiates Test Films!
t
ArcTmcldng Test Setup
Stare StN_ ElJct_x_
• Steelelectrodes,2 in. long
_0., T_ coveredwithlaye_ of film
a. ,r _ • Distancearctracksin3 rain
at 7.5KVis noted
• Smallerdistancethat arc
trackseqdalsbetterarc
,,c_,,_ trackingresistam;e
T_ o" kere Fltat t.ayl-s
216
i
1986109911-212
Initial Evaluation
• Arc-track testing Indicated that these
materials may not meet program goals
• A new set of polymers were Included
In the evaluation
New Materials
6FDA-I"FMB - High1"9,highfluorine content (31%)
LaRC-CPI - Highly crystalline rnated-I
Aorimide - Arylene ether phosphene oxide
t
i . Expected to form a non-conductive char
Slioxane Copolylmldes - "in aitu" silicon dioxide formation
DuPont fluorinated polyimide - High fluorinecontent (43%)
Polylmkle-clayhytxtds, proprietarypolymer
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1986109911-213
, Candidate Arc-Track Resistant Polymer
, Electrical Properties
ii |l
D-495 Ribbon Didectric Dissip'n Dielectric
Arc Track Arc Track Constant Factor Strength
Polymer Resistance Resistance (KV/mil)
(seconds) (inches)
,m
Kapton HN200 120-180 0.75 3.40 0.002 6100
Upilex 180-240 3.50 0.001 5100
PBO 180-240 1.6 3.48 0.011 6000
6FDA/PMDA/4BDAF 60-120 0.69 3.25 0.003 6740
(30 rains, 400°C)
6F-PBO-PI 60-120 3.22 0.006 5400
(30 rains, 420°C)
6F-PBO-PE < 60 1 2.66 0.007 5570
(20 rains, 400°C)
i i |l ill
ProprietaryI-ITPolymer 180-300 2.92 0.006 7000
36FDA/m-PDA < 60 3.12 0.003 7200
(40 rains, 400°C)
LARC CPI < 60
u
TRW Partially 3.1 0.001 6000
Fluorinated
Polyimides
PerFluoro(Ethylme 180-240 2.1 .0001 4050
ethoxyethylene)
i u
3F-PBG-PE < 60 4.04 0.014
(20 mins, 400°C)
DuPont < 60 4.83 0.013
_" Low Char
Polyimide
. (15 mins, 400°C)
i
DuPont < 60 2
Fluorinated Polyimide
6FDA/TFMB < 60 3.12 0.005
AORIMIDE < 60
52% Siloxane Copolyimide < 60 2.72 0.003
, ,,,,,
Polyimide 8e Clay Hybrid < 60 6200
I
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1986109911-214
a_ m _ •CandidateAr,. T=ack ResistantPoi,mer
Thermomechanical Prope:lies
|. ii i i rr all iq ,m
Tg Th ¢rmogravimetric Coeffidmt Of
Polymer (°C) Analysis Thermal Expansion
(°C @ 5% wt. loss in air) (ppm/°C)
Kapton HN200 360-4!0 527 20
Upilcx > 500 590 0.8 (20-1o0°C)
i-
PBO None
i i =
6FDA/PMDA/4BDAF 279 439 44 (< 0°C)
(30 rains, 400°C) 64 t>I00°C)
|
6F-PBO-PI 40 (-100->200°C)
(30 rains, 420°C)
6F-PBO-PE 290 501 35 (< 0°C)
(20 rains, 400°C) 55 (>100°C)
in
ProprietaryHT Polymer None 0
36FDA/m-PDA 325 34 (-100->200°C)
(40 rains, 400°C)
LARC CPI 258
i
TRW Partially -
Fluorinated
Polyimidts
PexFluoro(Etbyl:ae - 466 130 ,'-100 -> 200° ,
ethoxyethylene)
lie •
. 3F-PBO-PE 299 -
(20 rains, 400°C)
=
" DuPont 230 -
Low Char ,
Polyimide
(15 rains, 400°C)
DuPoat
Flrorimaed Polyimide
ii
6FDA/'rFMB 335
AORIMIDE
52% Siloxane Copolyimide
ill J
Polyimide 8% Clay Hybrid 363 478 16(-100 -> -50°C)
20(100 -> 2500C)
|
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1986109911-215
ICandidateArc-TrackResistantPolymer
Physical and Chemical Properties
P
Polymer _mk Stress % Sa'ain at Break Modulus
(i_i) tKSl)
Kapton 20VHN 28.9 43 320
Upilex
PBO -140 2.5 7.5
6FDA/FMDA/4BDAF 12.7 6.7 280
(30 mias, 400°C)
6F-PBO-PI 13.3 4.6 350
(30 rains, 420°C)
6F-PBO-PE 13.3 7.7 276
(20 mira, 400°C)
lItl
Proprietary HT Polymer 38.1 6 1680
36FDA/m-PDA 16.4 4.4 370
(40 mins, 400°C)
i
LARCCPI 60 -
H
TRW Pmially
Fluorinated
Polyimid_
w m,
PerFlucrt_Ethylme
ethoxyethyleue)
3F-PBO-PE
- (20mills,400°C)
i
DuPont
LowChar
Polyimide
(15mins, 400°C)
ii iJ
' DuPont -
FluorinatedPolyimide
iii
6FDA/TFMB
AORIMIDE
ii
52%SiloxaneCopolyimide ,_
Polyimide8%Clay Hybrid
i
220
1986109911-216
Summary _,
I
• Most candidate materials failed due to a
conductivechar
• Fluorinecontent is not solely responsible for
arc-track resistance
• Materials believed to generate non-conductive
char failed
• Highly crystallinematerials also failed
" - Film quality appearsto Impact arc-track resistance
• Proprietarymaterial,upilex and perfluoro (ethylene
ethoxyethylene)are better than Kapton
• 6FDA/PMDA/4BDAFis comparable to Kapton
in arc-track resistance
221
1986109911-217


Evaluation of high temperature polymers

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