Radiation Chemistry

Abstract

The article contains sections titled: 1. Radiation‐Induced Polymerization 1.1. Introduction 1.2. Mechanisms 1.2.1. Initiation Processes 1.2.2. Free‐Radical Polymerization 1.2.3. Cationic Polymerization 1.2.4. Characterization Methods 1.3. UV and Visible‐Light Curing 1.3.1. Photoinitiators 1.3.2. Monomers and Oligomers 1.3.3. Additives 1.3.4. Typical Formulations 1.3.5. Equipment 1.3.6. Applications 1.3.7. Health, Safety, and Environment 1.4. High‐Energy‐Particle‐Induced Photopolymerization 1.4.1. Equipment and Definitions 1.4.2. Electron‐Beam Processes 1.4.3. Health, Safety, and Environment 1.5. Conclusion and Outlook 2. Irradiation of Foods and Feeds 2.1. Introduction 2.2. Capabilities of Food and Feed Irradiation 2.2.1. Prolongation of Shelf Life 2.2.2. Quarantine Measures 2.2.3. Control of Pathogenic Organisms 2.3. History 2.4. Effects of Food Irradiation 2.4.1. Induced Radioactivity 2.4.2. Chemical and Sensory Changes 2.4.3. Changes in Nutritive Value 2.4.4. Effects on Microorganisms 2.4.5. Toxicological Consequences 2.5. Regulations on the Irradiation of Foods and Feeds 2.5.1. The European Community 2.5.2. Federal Republic of Germany 2.5.3. Other Countries 2.5.4. International Organizations 2.5.5. Consumers 2.6. Industrial Irradiation of Foods and Feeds 2.6.1. Irradiation Plants 2.6.2. Costs 2.6.3. Present Level of Use 2.7. Inspection of Irradiated Foods

Radical induced cationic frontal polymerization as a versatile tool for epoxy curing and composite production

“…For wavelengths over 400 nm, very common PIs are bis (acetylphosphinoxides) (BAPOs). Nevertheless, BAPO would be no choice for this particular application, because it was already shown by Allonas et al that the formed 2,4,6‐trimethylbenzoyl radicals cannot directly react with diaryl iodonium initiators. Further the shielding effect of the BAPO molecule in the relevant absorbing region of the PAG prevents the cleavage of the cationic photoinitiator .…”

“…The penetration depth of light is directly dependent of the wavelength. Therefore shortwave UV‐irradiation as it is usually applied for cationic photoinitiation has its limitation, since typical PAGs like iodonium salts show absorption only below 350 nm . Sensitizing is a very common technique in which a molecule (the sensitizer) is added to a formulation that contains a photoinitiator which does not absorb in the spectral region the irradiation source provides.…”

The Chemistry and Physics of Bayfol® HX Film Holographic Photopolymer

“…Due to the limited power of highly coherent lasers, holographic recording costs are heavily influenced by the overall efficiency of the photonic steps. This overall efficiency is determined by the molecular absorption coefficient of the sensitizer dyes at the recording wavelength λ, the quantum yield with which the reactive species are formed and react, the reactivity of generated photo products, and the possibility of the bleaching of the sensitizer dyes during the photo-polymerization [ 13 , 29 , 30 , 31 , 32 ]. The photo-polymerization efficiency thus depends on the nature of photo-initiators.…”

Novel Dual‐Cure Initiating System for Cationic Polymerization of Epoxides

“…Photopolymerization becomes nowadays a quite smart technology allowing the “Cure‐On‐Demand” of monomers and oligomers in many different industrial domains . However, the decrease of the penetration of light with increasing thickness represents a serious drawback for thick pigmented coatings and fiber‐reinforced composites.…”