electron beam curing of polymers - crosslinking, scission, degradation, and graft polymerization...

Download ELECTRON BEAM CURING OF POLYMERS -    CROSSLINKING, SCISSION, DEGRADATION, AND GRAFT POLYMERIZATION ..... Crosslinking and Scission ..... Related Effects of Crosslinking

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  • CONTENTS

    1 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . 1

    2 SUMMARY .........................

    Market and Producers ................... Equipment ........................

    Economics ........................ Technical ........................

    3 INDUSTRY STATUS .....................

    Markets ......................... Equipment Suppliers ...................

    Wire and Cable ...................... Shrink Tubing ...................... ShrinkFilm .......................

    Coatings ......................... Textiles ......................... Speciality Applications .................

    Future Developments ...................

    4 FUNDAMENTALS OF ELECTRON CURING OF POLYMERS .......

    Basic Characteristics of High Energy Radiation ......

    Radiation Units and Definitions .............

    Ionization ........................ Basic Techniques of Ionization and Excitation ......

    XRays ......................... GammaRays ....................... Accelerated Electrons .................

    Penetration ....................... Linear Energy Transfer (LET) ...............

    Radiation Chemical Yields (,,Gw Value) ..........

    Dosimetry ........................ Basic Chemical Effects .................. Free Radical Reactions ..................

    5 CROSSLINKING, SCISSION, DEGRADATION, AND GRAFT POLYMERIZATION .....................

    Crosslinking and Scission ................ Related Effects of Crosslinking and Scission ...... Crosslinking Theory ..................

    Degradation ....................... Graft Polymerization ...................

    3

    3 6

    10 12

    17

    17 20 24 25 25 26 27 27 28

    31

    33 35 38

    40 43 44 47 51 54 56 62 65

    69

    72 78 82 83 86

    Vii

  • 6 ACCELERATED ELECTRON BEAM EQUIPMENT ............ 95

    Insulating Core Transformer ................ 95 Dynamitron ........................ 109 Curtain and Planar Beam Accelerators ........... 117 Resonant Transformer ................... 126 Van de Graaff Electrostatic Accelerator .......... 130 Traveling Wave Linear Accelerators ............ 134 Other Very High Voltage Accelerators ........... 137 Radiation Protection and Shielding for Electron

    Accelerators ....................... 139 Summary of Industrial Electron Beam Accelerators ..... 151

    7 INDUSTRIAL APPLICATIONS OF ELECTRON BEAM RADIATION .... 159

    Raychem Corporation .................... 167

    W. R. Grace and Company, Cryovac Division ......... 175

    Ford Motor Company--Electrocure@ Process ......... 182

    Deering Milliken Company ................. 185

    Western Electric/Bell Laboratories ............ 192

    Radiation Vulcanization of Rubber ............. 200

    Surface Coatings and Adhesives .............. 203

    8 ECONOMICS OF ELECTRON BEAM CURING OF POLYMERS ....... 233

    Electron Beam Accelerator Sizing ............. 234

    Accelerator Processing and Capital Costs ......... 234

    Electron Beam Versus Thermal Curing ............ 243

    Synthetic Rubber Sheet Vulcanization--EB Versus Rotocure@ .................... 243

    Polyethylene Tubing--EB Crosslinking .......... 245

    Flocking Adhesives--EB Versus Thermal Curing ...... 248

    Polyethylene Insulation on Cable--EB Versus Continuous Vulcanization ................ 250

    Comparative Economics of EB, Thermal, and Ultraviolet Systems ................... 257

    CITEDREFERENCES........................ 261

    PATENTREFERENCES BYCOMPANY. . . . . . . . . . . . . . . . . . 281

    viii

  • ILLUSTRATIONS

    2.1

    2.2

    2.3

    4.1

    4.2

    4.3

    4.4

    4.5

    4.6

    4.7

    4.8

    4.9

    5.1

    5.2

    5.3

    6.1

    6.2

    6.3

    6.4

    6.5

    6.6

    6.7

    6.8

    Schematic Outlines of Industrial Polymer Irradiation Processes .................

    Comparison of Scanned Electron Beam Accelerator and Linear or Planar Electron Curtain

    Accelerator ......................

    Schematic Mechanism for Crosslinking ..........

    Electromagnetic Spectrum of Radiation .........

    Basic Techniques for Radiation Processing of Polymers ......................

    Typical X Ray Spectrum .................

    Distribution of Ions and Excited Molecules in the Track of a Fast Electron .............

    Dose-Depth Curve in Water for Electrons ........

    Average Linear Energy Transfer (LET) for Electrons inWater .......................

    Approximate Values of Linear Energy Transfer and Ion Density in Water ...............

    Applications of Radiation Dosimetry ..........

    Pathways in Radiation Chemistry ............

    Mechanism of Crosslinking and Endlinking ........

    Polyethylene Crosslinking ...............

    Crosslink and Endlink Networks .............

    Typical Electron Processing Systems ..........

    Insulating Core Transformer ..............

    Schematic Diagram of a Three-Phase ICT Power Supply ...................

    Voltage-Stabilizing Circuit for an ICT Power Supply ...................

    Electron Accelerator and Section of Tube ........

    Electron Beam Scanner .................

    Irradiation of Cable by Three Accelerators . . l l l l .

    High Energy Integral ICT Electron Accelerator .....

    5

    8

    14

    287

    41

    42

    46

    48

    52

    53

    58

    68

    73

    75

    77

    97

    98

    99

    100

    102

    103

    105

    106

    iX

  • 6.9 Electron Penetration Curves . . . . . . . . . . . . . . . 107

    6.10

    6.11

    6.12

    6.13

    6.14

    6.15

    6.16

    6.17

    6.18

    6.19

    6.20

    6.21

    6.22

    6.23

    6.24

    6.25

    6.26

    6.27

    6.28

    6.29

    6.30

    6.31

    Basic Dynamitron Schematic ............... 112

    Typical System Arrangements for Dynamitron III ..... 114

    Curtain Electron Beam Processor Schematic ........ 118

    Electrocurtain@Accelerator ............... 119

    Product Handling Configurations, Electrocurtain@ .... 121

    Broad Beam Electron Gun ................. 122

    Comparison of Planar Electron Beam Gun with SweptBeam ....................... 123

    Cold Cathode Broad Beam Electron Gun Pulsed-Plasma Emission of Electrons .......... 125

    Resonant Transformer and Electron Accelerator ...... 128

    Principal Circuit Elements of Resonant Transformer ...................... 129

    Van de Graaff 2 MeV Electron Accelerator ........ 131

    Operating Principle of a Van de Graaff Electron Accelerator .................. 133

    Linear Accelerator with RF Power Feedback ........ 136

    In-Line Electron Radiation Processing System ...... 144

    Energy Range for Various Absorbers ........... 145

    Electron Range Versus Energy for Several Absorbers ....................... 146

    Attenuation in Lead of X Rays Produced by Potentials of 250 to 400 Kilovolts ........... 147

    Attenuation in Lead of X Rays Produced by Potentials of 500 to 2,000 Kilovolts Constant Potential ................... 148

    Attenuation of Electron Energy in Concrete ....... 149

    Direct and Indirect Type Accelerators .......... 153

    Toroidal Electron Beam Accelerator System ........ 156

    Magnetically Turned Electrons .............. 157

    X

  • 7.1

    7.2

    7.3

    7.4

    7.5

    7.6

    7.7

    7.8

    7.9

    7.10

    Schematic of Memory Effect of Irradiated

    Polymer . . . . . . . . . . . . . . . . . . . . . . . . 160

    Schematic of Process for Making Expanded

    Shrinkable Polyethylene Tubing . . . . . . . . . . . . 173

    Methods of Producing Film Having Improved Shrink Energy . . . . . . . . . . . . . . . . . . . . . 180

    Application of Electrocure@ Process on Automotive Instrument Panels . . . . . . . . . . . . . 184

    Two Types of Composite Plastic-Textile Wire Insulation for Which a Single Material, Irradiated Polyvinyl Chloride, Will Be Substituted . . . . . . . . . . . . . . . . . . . . . . 193

    "Figure 8" and Double-Side Irradiation of Conductor . . . . . . . . . . . . . . . . . . . . . 195

    Four-Side and Three-Side Irradiation ofCable . . . . . . . . . . . . . . . . . , . . . . . 196

    Comparison of Floor Space Requirements for Conventional Curing and Radiation Curing . . . . . . . 202

    Schematic Layout of Radiation Cure on Sheet Rubber . . . . . . . . . . . . . . . . . . . . . 204

    Bixby International Corporation Electrocurtair# FlockLine . . . . . . . . . . . . . . . . . . . . . . 208

    8.1 Electron Beam Penetration Capability . . . . . . . . . . 235

    8.2 Processing Cost Rates Versus

    8.3

    8.4

    8.5

    8.6

    8.7

    8.8

    Electron Beam Power . . . . . . . . . . . . , . . . . . 240

    Capital Costs Versus Electron Beam Power . . . . . . . . . . . . . . . . . . 241

    Capital Cost Versus Power and Time . . . . . . . . . . . 242

    Thermal Efficiency of Electron Beam Cure Versus Thermal Cure . . . . . . . . . . . . . . . . . . 244

    Schematic of an Electron Beam Irradiation System for Insulated Electrical Cable . . . . . . . . . . . . 254

    Schematic of Catenary Continuous Vulcanizing System for Insulated Electrical Cable . . . . . . . . . . . . 255

    Power Consumption--Thermal, UV, and Electron Beamcuring...................... 259

    ILLUSTRATIONS

    xi

  • TABLES

    2.1 Major Electron Beam Processing Applications . . . . . . 3

    2.2 Major Suppliers of Electron Beam Equipment . .

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