HYDROLYTIC AGING CHARACTERISTICS FOR VARIOUS POLYIMIDE FILMS USED

HYDROLYTIC AGING CHARACTERISTICS FOR VARIOUS POLYIMIDE FILMS USED IN AIRCRAFT WIRE SYSTEMS JUNE 2002 AWIGG MEETING PRESENTED BY: PHIL LACOURT DUPONT HIGH PERFORMANCE MATERIALS

ACKNOWLEDGEMENTS • DAVID LEE, ED TAYLOR, ROBERT ERNST • JIM HEACOCK, RICK COOPER, TOM COOPER, JEFF WALISA

ITEMS TO BE COVERED • PURPOSE FOR WORK • MATERIALS TESTED • METHODS USED TO AGE AND ANALYZE MATERIALS • MATERIAL AGING CONDITIONS • DATA OBTAINED • CONCLUSIONS • RECOMMENDATIONS

PURPOSE FOR WORK • US NAVY (NAVAIR) EXPERIENCED PERFORMANCE ISSUES WITH WIRE INSULATED WITH POLYIMIDE MATERIAL (MILW-81381) – – – • US NAVY IS PARTICIPATING IN THE DOD SPI WIRE PROGRAM – – – • F-18 E/F AIRCRAFT WITH WIRE INSULATED WITH POLYIMIDE CONTAINING MATERIAL (MIL-DTL-22759/80 -92) ARE BEING DELIVERED TO THE US NAVY PART OF SINGLE PROCESS INITIATIVE PROGRAM AT BOEING OASIS® “T’ TYPE FILMS ARE INCLUDED IN THE PRIMARY WIRE INSULATION FOR THESE AIRCRAFT US NAVY CONCERNED ABOUT EXCESSIVE MAINTAINENCE COST AND “OUT OF SERVICE” AIRCRAFT ASSOCIATED WITH THE AGING OF THE NEW WIRE – • PREMATURE AGING OF INSULATION (HYDROLYSIS) HIGHER LEVEL OF OUT OF SERVICE AIRCRAFT, UNBUDGETED REPAIR COSTS, ETC. US NAVY CAUTIOUS ON WHERE POLYIMIDE CONTAINING WIRES ARE USED PRIMARY CONCERN IS HYDROLYSIS OF THE POLYIMIDE US NAVY-DUPONT AGREED TO JOINTLY FUND WORK TO BETTER UNDERSTAND THE HYDROLYSIS BEHAVIOR OF OASIS® “T” INSULATION MATERIALS

MATERIALS TESTED • DUPONT KAPTON® 100 HN – ONE OF THE POLYIMIDE BASE FILMS USED TO INSULATE MIL-W-81381 TYPE WIRE (CONTROL SAMPLE) • DUPONT OASIS® 100 T – BASE MATERIAL USED IN THE ‘MEDIUM WEIGHT’ INSULATION DESIGNS DESCRIBED IN SPECIFICATION MIL-DTL-22759/80 -92 • DUPONT OASIS® 65 T – BASE MATERIAL USED IN THE ‘LIGHT-WEIGHT’ INSULATION DESIGNS DESCRIBED IN SPECIFICATION 22759/80 -92

METHOD USED TO AGE POLYIMIDE SAMPLES SEMI-SEALED CONTAINER MULTIPLE SAMPLES OF ALL THREE TEST MATERIALS SUSPENDED IN “VAPOR” REGION SATURATED SALT SOLUTION (FOR RH < 100%) CONTAINER WITH POLYIMIDE FILM SAMPLES PLACED IN OVEN AT DESIRED TEST TEMPERATURE - SAMPLES ARE REMOVED PERIODICALLY FOR ANALYSIS

METHOD USED TO ANALYZE AGED FILM SAMPLES • TENSILE TESTING – ASTM D-882 – ELONGATION TO BREAK • DIELECTRIC STRENGTH TESTING – ASTM D-149 – DIELECTRIC BREAKDOWN VOLTAGE • INHERENT VISCOSITY TESTING – DUPONT INTERNAL METHOD – RELATIVE FLOW RATE CALCULATE INHERENT VISCOSITY

INHERENT VISCOSITY PROCEDURE AND CALCULATION [n] INHERENT = {Ln (t/to)}/c WHERE C IS THE SOLUTION CONCENTRATION IN grams/dl SOLVENT SAMPLE (CONC H 2 SO 4) (KAPTON® HN) VISCOMETER =t = to

MIL-W-81381 SPECIFICATION FOR PI/FP FILMS

CONCLUSIONS • • • THE HYDROLYTIC AGING DATA FROM THIS TEST AGREES WITH RESULTS FROM PREVIOUS TESTING (HN DATA) THE HYDROLYTIC AGING CHARACTERISTICS OF “T” FILM ARE SIGNIFICANTLY DIFFERENT THAN THE HYDROLYTIC AGING CHARACTERISTICS OF “HN” FILM THE HYDROLYTIC AGING PROPERTIES OF “T” FILM ARE SIGNIFICANTLY IMPROVED OVER THE PROPERTIES OF “HN” FILM. – ELONGATION TO BREAK – DIELECTRIC STRENGTH THE AGING MECHINISM AT HIGH PRESSURE CONDITIONS (PARR BOMB) APPEARS TO BE DIFFERENT THAN THE AGING MECHINISM AT ATMOSPHERIC PRESSURE AND THIS DOES NOT SEEM TO BE AN APPROPRIATE WAY TO MEASURE THE DETERIORATION CHARACTERISTICS OF ‘T’ OR ‘HN’ FILM. THE AGING DATA ON FILM APPEARS TO SUPPORT THE “ON-WIRE” TESTING DATA SEEN IN THE QUALIFICATION TO THE “ 22759” SPECIFICATON. – • LIFEHYD ‘T’ >> LIFEHYD ‘HN’ ORIGINAL OBJECTIVE OF THE PROGRAM, DEVELOP A MATHEMATICAL RELATIONSHIP BETWEEN INHERENT VISCOSITY OF ‘T’ AND THE PROPERTIES OF ‘T’, COULD TAKE YEARS TO ESTABLISH

RECOMMENDATIONS • WORK SHOULD BE EXTENDED TO ‘ON-WIRE’ STUDIES – – • • WIRE STRESS HUMIDITY LEVEL TEMPERATURE LEVEL WIRE DESIGN THE US NAVY SHOULD CONTINUE TO REQUIRE HYDROLYTIC STABLITY TESTING AS A REQUIREMENT FOR ‘ 22759’ QUALIFICATION (AND REQUALIFICATION) THE US NAVY SHOULD INVESTIGATE INCREASING THE HYDROLYTIC STABILITY PERFORMANCE REQUIREMENTS TO MATCH THE CAPABILITIES OF INDUSTRY TO ASSURE CERTAIN CONSISTENT PERFORMANCE LEVELS.

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