Shear properties radiation effects

Three groups of phenomena affect the frequency-dependence of ultrasonic wave propagation classical processes, relaxation, and scattering, of which scattering is likely to dominate in foodstuffs due to their particulate nature. The two classical thermal processes are radiation and conduction of heat away from regions of the material, which are locally compressed due to the passage of a wave they can lead to attenuation but the effect is negligible in liquid materials (Herzfield and Litovitz, 1959 Bhatia, 1967). The third classical process is due to shear and bulk viscosity effects. Attenuation in water approximates to a dependence on the square of the frequency and because of this it is common to express the attenuation in more complex liquids as a()/o or a(f)jf2 in order to detect, or differentiate from, water-like properties. 

The mechanical properties, fiacture stress, fiacture strain, yield stress, and modulus, were measured (67) for doses up to 100 Mrads. Fracture strain was found to increase with dosage but shear yield strength decreased. Decreases averaging roughly 50% were noted for the other properties. Therefore, it is evident that the -radiation produces a predominance of chain scission over crosslinking in the epoxy. It was concluded that irradiation does not have much effect on the graphite fibers but that it degrades mechanical properties of the epoxy matrix. 

Laminating adhesives The cross linking achieved by radiant energy enhances the temperature, solvent and shear resistance of hot-melt adhesives with limited effect on critical adhesion properties such as tack and peel. Hot-melt adhesives, especially block copolymers, are also easily cured by EB and UV radiation. These hot-melt adhesives are used as laminating adhesives. 

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