Effect of EB iririrradiationir radiation on the physicochemical characteristics of polyimide film for aerospace material

Joon-Pyo Jeun Korea Atomic Energy Research Institute Phil-Hyun Kang*, Young-Chang Nho Content

• Historical background of Polyimide

• Radiation process (EB curing)

• Effect of EB radiation on Polyimide film Map of Plastics

High High PI Super Engineering Plastics PEEK PAI LCP PEI PES Heat resistance Price PPS PSF PAR

PA POM PC Engineering Plastics PBT PET m-PPO Low PE PP ABS PS Low PMMA Commodity Plastics Crystalline Amorphous Development of Polyimides (PI) Coatings Composites 1990 ~ Adhesives Film, 1984 Nissan JSR Molding 1982 Hitachi 1972 UBE (PI coatings (Upilex for LCD and 1970 GEGEGE Upimol) semiconductor) (PEI) TRW Injection 1962 (PMR-15) Dynamit Amoco moldable PI 1962 Nobel (PAI) NASA (PEsI) (PI3N) DuPont Kapton Vespel Pyralin Characteristics of PI

• Structure of typical polyimide: Kapton O O

N N O

O O n • Advantages – Excellent high temperature mechanical performance – Very high tensile and compressive strength – Outstanding bearing and wear properties – Very high purity – Good chemical resistance

• Disadvantages – Difficult to fabricate and require venting of volatiles – Hydroscopic and subject to attacks by alkaline – Comparatively high cost Typical ApplicationApplicationssssof PI (1)

Fields Applications Electronic •Flexible printed circuit board (FPCB) •Tape automated bonding (TAB) •Bar code label •Spiral tubes FPCB (((www.desow.com/Upfiles) •Masking tapes Electric •Electric motor and generator insulation •Flat cable and wire insulation •Magnet wire and capacitor insulation • Flexible flat cable Magnetic Wire Magnetic and pressure sensitive (www.indiamart.com/chainelectronics ) (www.madewww.made----inininin----china.comchina.com ) tapes and tube Typical ApplicationApplicationssssof PI (2)

Automotive •Diaphragms •Alternator heat insulator pads

• Speaker Sensor and switches (((www.autotoys.com ) •Seals and gasket •Spark plug boot •Speaker part •Disposal pin carrier Switching system Check ball •3 Radiator plug (((www.solvayadvancedpolymers.com ) (((www.plalution.com/4.html ) Composite •Vacuum bags in fabrication of advanced resin matrix composite •Traction belts on computer printers • Heating elements and insulator Traction belt Dielectric substrate (((www.serpent.com ) (((http://(http://http://www.fraivillig.comwww.fraivillig.com ) Typical ApplicationApplicationssssof PI (3)

Aerospace •Wire and cable insulation •Motors/alternators (insulation) •Smoke hoods •Composite bagging film

•Cockpit sun shade Cockpit sun shade Acoustic insulation (((www.bizbuzzmedia.com(www.bizbuzzmedia.com ) (((www.ferret.com.au(www.ferret.com.au ) •Multilayer thermal blankets (satellite) www.algor.com/news_pub/cust_app/srs/srstech.aspwww.algor.com/news_pub/cust_app/srs/srstech.asp •Speakers (airports) and acoustic insulation •Antenna system (satellite)

Satellite antenna system Chemical structures (commercially available)

• AURUM (MITSUI) • UPILEX-S (UBE) O O O O

N N O O N N

O O n O O n

• ULTEM (GE) • KAPTON (DuPont)

O O O O

N CH3 N N N O O C O O O n CH3 O O n

• UPILEX-R (UBE) • KEVLAR (DuPont)

O O O O H H N N O C C N N

n O O n What is Radiation ?

• A form of energy that is emitted from a source and travels in the form of waves or particles through a medium, eg air or a vacuum.

NonNon----IonizingIonizing radiation : microwaves, IR, radio frequencies Ionizing radiation : α, β, neutron, electron, gamma, X-ray, UV

---The electromagnetic spectrum Non-ionizing radiation Ionizing radiation

Radio frequencies Heat Visible Gamma Microwaves light X-rays

Infra red Ultraviolet Electron Beam Process

• Electron beam process creates useful changes in material properties and performance, such as polymer crosslinking and chain scissioning.

• Electron beam process is also widely used for medical device sterilization, cosmetics sterilization, and pharmaceutical sterilization. Electron Beam Curing Process

• Nonthermal, nonautoclave curing method that uses high-energy electrons to initiate polymerization and cross linking reactions. Comparison of radiation and thermal curing

Factor EB UV Thermal Energy consumption O △△△ X Running costs △△△ O X Commercial Space requirements △△△ O X Speed O △△△ X Chemical resistance O △△△ X Damage to sensitive △△△ O X Technical substrate Adhesion to different O △△△ X substrate Fire hazard O O X Health & Environmentally Safety O O △△△ hazardous materials

O : Advantage △△△ : Intermediate X : Disadvantage Experimental

• Materials – Polyimide film (Kapton HN, 5mil, DuPont)

• Irradiation – Electron beam – Nitrogen atmosphere – Energy of 1.14 MeV, 4 mA 4 – Total radiation dose : 0.2~3.8 x 10 kGy Characterization

• Dynamic Mechanical • Thermogravimetric Analyzer (DMA) analysis (TGA) – Storage/loss modulus – Decomposition temp. – Tan delta – Residue

17.25

• Tensile properties • Electrical properties – Tensile strength – Dielectric constant – Young ’s modulus – Conductivity – LCR meter 17.25 Typical DMA curves of PI

βββ222 relaxation Glass relaxation 4000 0.060 100 3500 0.055 90 0.050 (MPa) Loss modulus 3000 0.045 80 2500 0.040 70

2000 Tan delta 0.035 60 0.030 1500 50 0.025

Storagemodulus (MPa) 1000 0.020 40

500 0.015 30

0 100 200 300 400 500 Temperature(o C) Tan delta curves of PI

0.060

0.055 Control 1.5 x 10 4 kGy 0.050

0.045

0.040

0.035 Tan delta delta Tan 0.030

0.025

0.020

0.015

100 200 300 400 Temperature (oC) Relaxation temperature

150 450 βββ relaxation 2 Glass relaxation 140 440 Temperature Temperature ) C o

( 130 430

120 420 ( o C ) Temperature 110 410

100 400 0.0 0.5 x 10 4 1.0 x 10 4 1.5 x 10 4 Radiation dose (kGy ) Values of tan delta (Glass relaxation)

0.056

0.054

0.052

Tan delta Tan 0.050

0.048

0.046

4 4 0.0 0.5 X 10 4 1.0 X 10 1.5 X 10 Radiation dose (kGy ) Mechanical Properties

20 320 ) 2 280

15 Modulus 240

200

10 ( kgf/mm 160

120 2

5 ) Tensile strength (kgf/mm strength Tensile 80 0 0 0.5 x 10 4 1.0 x 10 4 1.5 x 10 4 Radiation dose (kGy) Thermal stability

Radiation Td T5 T10 Residue dose 100 (oC) a (oC) b (oC) c (%) (x10 -4 kGy) 90

0 571.42 563.58 583.50 61.41 80

Control

Weight (%) Weight 70 0.4 571.17 562.42 583.04 60.79 0.4 X 10 4 kGy 1.0 X 10 4 kGy 60 1.0 571.25 560.08 582.10 59.80 1.5 X 10 4 kGy 200 300 400 500 600 700 800 1.5 570.67 557.89 580.82 58.10 Temperature (oC)

a Thermal decompositiono temperature (on-set) from TGA measurement, scan rate: 10 C/min, N 2 protection b Temperature at 5% weight loss from TGA measurement c Temperature at 10% weight loss from TGA measurement Electric properties

3.4 10 -5 )

-1 -7 3.2 10 cm

-1 -9 Ω Ω Ω Ω 10 (

3.0 -11

10 Control 10 -13 8,000 kGy 2.8 15,000 kGy -15 25,000 kGy Dielectric constant Dielectric control 8,000 kGy 15,000 kGy 10 33,000 kGy

25,000 kGy 33,000 kGy 38,000 kGy Conductivity 38,000 kGy 2.6 10 -17 -2 0 2 4 6 8 -2 0 2 4 6 8 log f log f Summary

• Polyimide films show extensive radiation resistivity • Irradiation leads to decrease in the β2 relaxation temperature and the thermal decomposition temperature • The tensile strength decrease insignificantly and Young ’s modulus tends to increase slightly with dose • A significant change of the dielectric constant is observed after electron beam irradiation • Polyimide is sufficiently endurable to survive the high energy irradiation and temperature fluctuations present in space environments

Brownian movement (motion)

• Brownian motion is the random movement of particles suspended in a liquid or gas or the mathematical model used to describe such random movements, often called a particle theory. • The mathematical model of Brownian motion has several real-world applications. An often quoted example is stock market fluctuations. Another example is the evolution of physical characteristics in the fossil record LRC meter

Cylindrical instrument

Stainless steel

PI film Terminology

• Glass transition temperature – When an amorphous polymer is heated, the temperature at which it changes from a glass to the rubbery form is called the glass transition – SSSegmentalSegmental motion occurring

• Secondary beta relaxation – The rotation or oscillation of functional groups occur