Temperature effects photochemical degradation

Temperature will affect the degradation rate of different organic pollutants. Weir et al. (1987) reported that benzene and hydrogen peroxide are insensitive to temperature because photochemically induced reactions often have low activation energies. Koubek (1975) stated that temperature has little effect on the oxidation of refractory organics however, Sundstrom et al. (1986) observed that the decomposition rates of some halogenated aliphatics increased with temperature. 

Sande (98) reported that temperature is not expected to affect the absorption of photons as such, and no additional energy is needed for the reaction to take place. However, the temperature will affect subsequent chemical degradative reactions in the usual manner as described by the Arrhenius equation. If a secondary thermal reaction is involved, a temperature effect on the overall reaction quantum yield would be expected. A change in the viscosity of the liquid as a result of increase of room temperature can influence the rate of photochemical degradation. 

What is more important in respect to a loss of flavin compounds from various sources is the possibility of photochemical degradation. It is quite clear that the light intensity is the rate-determining factor for riboflavin loss, whereas increased temperature has only little effect. March et al. studied the effect of light... 

Photochemical degradation may cause changes in the monomer imit (by oxidation reactions), the macromolecular chain (through crossUnking or chain scission reactions), and even on the macroscopic scale [7, 25]. Thermal-oxidative degradation, hydrolysis and microbial attack are simultaneously promoted by the presence of the other associated factors (oxygen and ozone, temperature and freeze-thaw cycles, environmental moisture and microorganisms) and contribute to the overall effect [26-29]. 

The SMP based syntactic foam may be used in various lightweight composite stmctures. Most of the time, the structures may be used outdoors with uncontrolled environmental attacks. The most obvious environmental attacks include ultraviolet (UV) radiation, moisture, temperature, and combinations of these single factors, such as hydrothermal attacks. Polymers are extremely sensitive to these environmental attacks due to the photophysical and photochemical effects. Often, the combination of UV radiation with oxidative and hydrolytic factors leads to more severe degradation than that from a single factor. The damage may range from mere surface discoloration to extensive loss of mechanical properties. 

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