Crosslinking and Scission in Polymers

MOLECULAR WEIGHr CHANGES AND NE1WORK FORMATION BY SCISSION AND CROSSUNKING A. Charlesby 1 Introduction Main Chain Scission of Polymers _ 1 Crosslinking _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . _ . 4 5 Random Crosslinking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Enhanced Crosslinking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Other Forms of Crosslinking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Combined Crosslinking and Scission _ _ . . . 11 Antioxidants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Fillers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . 12 Crosslinking of Polymers in Solution . . . . . . 12 References _. 13 HIGH ENERGY RADIATION-AND UV UGHr-INDUCED CROSSLINKING AND CHAIN SCISSION w. Schnabel Introduction 15 Importance of Radiation-Induced Crosslinking and Main-Chain Scission in Linear Polymers _ 15 TYPes of Radiation and Radiation Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Absorption of Radiation . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 General Aspects Concerning XL and CS in Linear Polymers _ . _ . _ . _ 22 Random and Specific Site Attacks . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . 22 Detection of XL and CS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Simultaneous XL and CS Mechanisms 25 Ion Beam-Induced Radiation Effects In Linear Polymers _ .

Zusammenfassung
Proceedings of the NATO Advanced Study Institute on Advanced Methods of Determination of Crosslinking and Scission in Polymers and Their Effects on Mechanical Properties, Kemer-Antalya, Turkey, September 4-16, 1988

Inhalt
Molecular Weight Changes and Network Formation by Scission and Crosslinking.- Main Chain Scission of Polymers.- Crosslinking.- Random Crosslinking.- Enhanced Crosslinking.- Other Forms of Crosslinking.- Combined Crosslinking and Scission.- Antioxidants.- Fillers.- Crosslinking of Polymers in Solution.- References.- High Energy Radiation-and UV Light-Induced Crosslinking and Chain Scission.- Importance of Radiation-Induced Crosslinking and Main-Chain Scission in Linear Polymers.- Types of Radiation and Radiation Sources.- Absorption of Radiation.- General Aspects Concerning XL and CS in Linear Polymers.- Random and Specific Site Attacks.- Detection of XL and CS.- Simultaneous XL and CS Mechanisms.- Ion Beam-Induced Radiation Effects in Linear Polymers.- X-Ray-Induced Radiation Effects in Linear Polymers.- References.- Main-Chain Scission of Linear Polymers as Studied by Pulse Radiolysis and Flash Photolysis.- Studies on the Dynamics of Macromolecules in Solution.- Studies Concerning Intramolecular Interactions.- Studies Concerning Preferential Solvation.- Studies Concerning the Dynamics of Polynucleotides.- Detachment of DNA Double Strands.- Lifetime of Salt Bridges.- Concluding Remarks.- References.- Carbon 13 NMR of Gamma-Irradiated Polyethylenes.- Carbon 13 NMR of Polyethylene.- Severe Melt Processing of Polyethylene.- Irradiation of Polyethylene-Solution NMR.- Carbon 13 NMR of n-Hexatriacontane.- Carbon 13 NMR Spectra of NBS 1475 before and after 60Co Gamma Irradiation.- Carbon 13 NMR Spectra of Marlex 6003 before and after 60Co Gamma Irradiation.- Irradiation of Polyethylene-NMR of the Solid State.- Summary.- Acknowledgements.- References.- The Use of Pulsed NMR to Determine Network Formation by Crosslinking and Entanglement.- References.- Methods for Studying the Effects of High-Energy Irradiation on the Mechanical and Electric Properties of Polymers.- Mechanical Properties.- Modulus and Compliance.- Ultimate Mechanical Properties.- Recovery.- Electrical Properties.- Multiple Transitions and Molecular Mobilities.- Physical Ageing.- Experimental Technique and Examples.- Time-Domain Techniques.- Frequency-Domain Methods.- Temperature-Domain Methods.- Thermally Stimulated Electrical Current-Fluctuations.- Conclusions.- References.- Thermally Stimulated Discharge and Dielectric Measurements of Cure in Resins and Gelled Materials.- Influence of Gelation of Polar Media.- Interfacial Regions in Copolymer Systems.- Phase Separation Processes.- Conclusion.- Recommended Reading.- Ultrasonic and Viscoelastic Studies of Chain Entanglement in Polymer Solutions.- Dynamic Properties of Isolated Polymer Chains in Solution.- Ultrasonic Relaxation Measurements on Polymer Solutions.- Viscoelastic Processes.- Ultrasonic Studies of Entangled Polymer Systems.- Phase Separation in SBS Solutions.- Ultrasonic Studies of Network Formation in Rigid Networks.- Recommended Reading.- Specific Papers.- Determination of Cross-Link Density in Amorphous Networks by Stress-Strain-Swelling Experiments.- Molecular Constitution of a Network.- Macroscopic Deformation.- Microscopic Deformation.- The Elastic Free Energy of the Single Chain and the Network.- The Affine Network Model.- The Phantom Network Model.- Stress-Strain Relations for the Phantom and Affine Network Models in Simple Tension.- The Constrained Junction Theory of Networks.- Determination of the Degree of Cross-Linking by Equilibrium Swelling Measurements.- Numerical Example of Cross-Link Density Calculation.- Deviations From Ideal Ne…