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Dyes and pigments are used in polymer materials to provide colour, however they can also effect the rate of photo-oxidation. Many absorb UV rays and in so doing protect the polymer, however absorption can cause the dyes to enter an excited state where they may attack the polymer or transfer energy to O 2 to form damaging singlet oxygen .
Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition. Polymers and particularly plastics are subject to degradation at all stages of their product life cycle , including during their initial processing, use, disposal into the environment and recycling. [ 1 ]
The degradation rate of many organic compounds is limited by their bioavailability, which is the rate at which a substance is absorbed into a system or made available at the site of physiological activity, [11] as compounds must be released into solution before organisms can degrade them. The rate of biodegradation can be measured in a number ...
Polymer-based membranes have shown reduced fouling and self-cleaning properties in both blended and coated TiO 2 membranes. Photocatalyst-coated membranes show the most promise, as the increased surface exposure of the photocatalyst increases its organic degradation activity.
To determine whether a polymer will undergo surface or bulk erosion, the degradation rate of the polymer in water (how fast the polymer reacts to water) and the rate of diffusion of water penetrating through the material must be considered. If the degradation process is faster than the diffusion process, surface erosion will occur since the ...
That is, the polymer is unstable in a water based environment. This is the prevailing mechanism for the polymers degradation. This occurs in two stages. 1. Water penetrates the bulk of the device, attacking the chemical bonds in the amorphous phase and converting long polymer chains into shorter water-soluble fragments.
The onset of thermal degradation dictates the maximum temperature at which a polymer can be used. It is an important limitation in how the polymer is manufactured and processed. For instance, polymers become less viscous at higher temperatures which makes injection moulding easier and faster, but thermal degradation places a ceiling temperature ...
Comparison of the changes in physical properties of the plastic both with and without potential biodegradable additives throughout the degradation process can provide insight into the efficacy of the additive. If the degradation is significantly affected with the addition of the additive, it could indicate that biodegradation is improved. [14]