Irradiation surface energy

With the increase in irradiation dose, however, there is an optimum value of the surface energy at 10 Mrad irradiation. In order to explain these results, the grafting levels calculated from the IR spectra [30] are... 

UV irradiation on a polymer surface produces chemical modification as well as wettability and bondability improvement. It causes chain scission and oxidation on polymer surfaces. -iven in the presence of an inert gas [45]. Carbonyls are found to be introduced onto polyethylenes on UV irradiation. Sivram et al. [46] have used photochemical treatments for surface modification of polymers. They have generated surfaces of vaying surface energies by simple organic reactions. 

FIGURE 31.6 Change of the surface energy parameters of control and modihed ethylene-propylene-diene monomers (EPDMs) with irradiation dose. (From Sen Majumder, P. and Bhowmick, A.K., Radial. Phys. Chem., 53, 63, 1998. With permission.)... 

Bhowmick and co-workers [168] investigated the bulk and surface modification of ethylene propylene diene monomer (EPDM) rubber and fluoro-elastomer by electron beam irradiation. The structure of the modified elastomers was analysed with the help of IR spectroscopy and XPS. The gel content, surface energy, friction coefficient and dynamic mechanical properties of bulk modified fluoro-elastomers and the surface-modified EPDMs were also measured. The resultant properties of the modified EPDM were correlated with the structural alterations. 

It was suggested that greater efficiency of orientation of the crystallites was produced during sliding under irradiation because of enhanced removal of pollutants such as water vapour, which affect the surface energy distribution. This explanation is not entirely satisfactory for two reasons. The first is that the effect takes place... 

In contrast, the roughness of the (100) face of l(S)-2 decreased on irradiation and the surface ultimately became flat (Figure 27.2g-i). The experimental results provide the visual evidence that the molecules on the (100) surface moved inside or outside the crystal leading to a decrease in the surface energy to a minimum,... 

Electron spectroscopy for chemical analysis (ESCA) is used for characterizing polymer surfaces and is also known as X-ray photoelectron spectroscopy (XPS). This method is based on the observation that electrons are emitted by atoms under X-ray irradiation. The energy of the emitted electrons yields the binding energy of the electron to the particular atom. ... 

Polyamide, polyurea, polyhydrazide and polyurethane materials having modified surfaces, which are antimicrobial, are prepared using selective UV photon irradiation, high energy electron irradiation or low energy eleetron irradiation. 

The C/SiC test panel was irradiated with the flash of light momentarily. After the flash, the surface radiates energy much like reflection of light. The irradiated surface also conducts heat into the sub-surface. With time, we first get the IR image of the surface and subsequently the images of the internal sample at deeper thickness as the heat is conducted. 

Heterogeneous photocatalysis steps were reviewed by Cunningham and Hodnett, (1981), Jacoby etal., (1996) and Yue( 1993) among others. These steps include the mass transfer of substrate from the bulk of the fluid to the catalyst surface, the transport of the reactants within the catalyst particle and the adsorption of substrates on the active catalytic surface. Once the Ti02 is irradiated, photon energy is absorbed, followed by the generation of electron-hole pairs, the formation of radicals, the surface reaction, radical recombination and finally the desoiption and mass transfer of products from the particle surface into the bulk of the fluid. 

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