Degradable effects of uv light

The drawbacks of cellular materials include limited temperature of appHcations, poor flammabiUty characteristics without the addition of fire retardants, possible health ha2ards, uncertain dimensional stabiUty, thermal aging and degradation, friabiUty, and embrittlement due to the effects of uv light (3,6,15). 

Akhland MS, Schuchmann HP, von Sonntag C. Degradation of the polysaccharide alginic acid a comparison of the effects of UV light and ozone. Environ Sci Technol 1990 24 379-383. 

This paper describes the effects of UV light, the most significant aspect of outdoor weathering, on a variety of Degradable Plastics and also discusses the extent of biodegradability of the photodegraded samples. 

The most adeqnate laboratory tool to stndy the effect of UV light on plastic and composite materials is a weathering box, or an environmental chamber, weatherom-eter, among others. None of them matches precisely the spectrum of natural UV light however, they provide all four major components of oxidative degradation of materials at conditions of natnral exposnre UV light, heat, water, and oxygen. 

It has teen known for some time that a water soln of TNT, upon exposure to sunlight or artificial sources of UV light, undergoes a chemical conversion into products which impart a pink or reddish coloration to the water. This fact suggested that TNT is to some measure vulnerable to the action of UV light and could be degraded by it. This report describes studies to determine the effectiveness of UV light on the decompn of TNT under various conditions... 

Ultraviolet radiation can cause colour change and degradation of physical properties, especially in polyolefins, ABS, PVC, PC, and PU. Stabilizers to protect plastics compounds against the effect of UV light (especially sunlight) act to prevent oxidation from that source. To counteract this, UV additives offer three... 

The absorption of UV light by plastics results in discolouration, embrittlement and a marked fall-off in such physical properties as tensile strength, elongation at break and impact resistance. It is therefore obviously necessary to protect polymers from the degradative effects of UV radiation, particularly in the case of those plastics designed for outdoor service or certain severe indoor applications, such as wall coverings or guards for fluorescent tubes. As it is not usually practical to shield the plastics material from the source of radiation, protection is usually afforded by the inclusion of suitable additives in the polymer. 

While the plastics processor is normally concerned with inhibiting the degradative effects of UV radiation on the physical properties of his product, there are certain instances where incident UV light may be turned to advantage. This occurs when optical brightening agents are incorporated in a plastics composition to enhance the apparent brightness of white or pastel shades. 

The effects of UV irradiation to enhance the degradation of aged Pu(IV) polymer in HClOi. Depolymerization under dark conditions for each experiment is shown by a data point directly above the last light sample point (4). 

Effect of UV Radiation on Sodium Pentachlorophenate. Sodium pentachlorophenate is quickly degraded in the presence of ultraviolet light as well as daylight, as shown in Table III. The degradation is almost complete after 16 hours exposure to the General Electric R.S. sunlamp. Three and one-half days of rainy and overcast skies account for the somewhat lower degradation observed in the sample exposed to daylight. 

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