Degradation susceptibility

Microbial degradation susceptible to attack by yeasts, fungi, bacteria very susceptible in aerobic conditions... 

Once the polycyclics are released from the combustion system, presumably adsorbed on soot or fly ash, they are then exposed to potential atmospheric degredation. A simple way in which to note the relative degradation susceptibility of the various PAH is to compare the GCMS data of the PAH coming from a combustion system (see Figure 1) with the PAH profile of atmospheric particulates... 

UV, heat, oxidation degradation susceptibility Limited plasticizer resistance... 

Gi is defined as radiation chemical yield which represents the number of radiolysis events caused by the absorption of 100 eV of radiation energy. expresses the degradation susceptibility of the polymer during radiation and can be calculated by Equation 31.18 ... 

Liu, C., Xin, Y., Tian, X. Chu, P. K. (2007) Degradation susceptibility of surgical magnesium alloy in artificial biological fluid containing albumin. J Mater Res, 22, 1806-814. 

Azobisnittiles are efficient sources of free radicals for vinyl polymerizations and chain reactions, eg, chlorinations (see Initiators). These compounds decompose in a variety of solvents at nearly first-order rates to give free radicals with no evidence of induced chain decomposition. They can be used in bulk, solution, and suspension polymerizations, and because no oxygenated residues are produced, they are suitable for use in pigmented or dyed systems that may be susceptible to oxidative degradation. 

A very low output voltage from the load cell, commonly 1 ]lV per displayed division, makes the signal susceptible to noise and degradation (particularly over long distances)... 

The signal is less susceptible to noise and degradation this factor is particularly important where long cable mns are necessary... 

Like most other engineering thermoplastics, acetal resins are susceptible to photooxidation by oxidative radical chain reactions. Carbon—hydrogen bonds in the methylene groups are principal sites for initial attack. Photooxidative degradation is typically first manifested as chalking on the surfaces of parts. 

Geotextiles may be woven, nonwoven, or knitted. AH types, woven, nonwoven, or knitted, are susceptible to degradation owing to the effects of ultraviolet light and water. Thus stabilizing agents are added to the base polymeric material to lessen the effects of exposure to ultraviolet light and water. 

Thermal, Thermooxidative, and Photooxidative Degradation. Polymers of a-olefins have at least one tertiary C-H bond in each monomer unit of polymer chains. As a result, these polymers are susceptible to both thermal and thermooxidative degradation. Reactivity in degradation reactions is especially significant in the case of polyolefins with branched alkyl side groups. For example, thermal decomposition of... 

Like P—O—C linkages, P—O—P linkages are susceptible to hydrolytic degradation. Scrambling or interchange usually occurs for phosphoms oxyesters at temperatures and acidities lower than those required for the carbon esters but greater than those for the sulfur esters. 

Plasticizer molecules can undergo thermal degradation at high temperatures. Esters based on the more branched alcohol isomers are more susceptible to such degradation. This can, however, be offset by the incorporation of an antioxidant, and plasticizer esters for cable appHcations frequently contain a small amount of an antioxidant such as bisphenol A. 

Molecular Weight. Measurement of intrinsic viscosity in water is the most commonly used method to determine the molecular weight of poly(ethylene oxide) resins. However, there are several problems associated with these measurements (86,87). The dissolved polymer is susceptible to oxidative and shear degradation, which is accelerated by filtration or dialysis. If the solution is purified by centrifiigation, precipitation of the highest molecular weight polymers can occur and the presence of residual catalyst by-products, which remain as dispersed, insoluble soHds, further compHcates purification. 

PTMEG is a polymeric ether susceptible to both thermal and oxidative degradation. It usually contains 300—1000 ppm of an antioxidant such as 2,6-di-/ f2 -butyl-4-hydroxytoluene (BHT) to prevent oxidation under normal storage and handling conditions. Thermal decomposition in an inert atmosphere starts at 210—220°C (410—430°E) with the formation of highly flammable THE. In the presence of acidic impurities, the decomposition temperature can be significantly reduced contact with acids should therefore be avoided, and storage temperatures have to be controlled to prevent decomposition to THF (261). 

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