Critical degradation agent

Usually, there is more than one degradation agent present, giving a more complicated situation. For the purposes of life prediction it is desirable, wherever possible, to identify the critical degradation agent for the particular application or the particular objective. 

Regardless of the validity of the extrapolation procedure, the intrinsic experimental uncertainty of the measurements will be magnified as the degree of extrapolation increases. In addition, the difficulties associated with knowing the critical degradation agents and the critical properties for the application have been discussed earlier. 

The purpose of the trial also affects the choice of degradation agents and the parameters used to monitor degradation. For comparison and quality control purposes, single agents are most frequently used. For prediction purposes multiple agents are more likely to be representative of service, but at the same time they make extrapolation rules more complicated. The parameters measured in trials to predict lifetime must be those critical to service, but in many instances of comparison or quality checks the choice of parameter can be heavily influenced by experimental convenience. 

Using these relationships the change in the property for longer times and lower levels of the degrading agent can be predicted. Clearly, the success of the process is critically dependent... 

The degradation agents used are not the ones critical to service performance. 

The concentrate derived from ultrafiltration is usually a thick colourless gel containing about 4-8% solids. This must contain an antimicrobial agent to inhibit microbial growth and biological degradation. The type of antimicrobial agent used depends on the particular application for the exopolysaccharide. For example, the nature of file antimicrobial agent is less critical for industrial applications, such as enhanced oil recovery, than for use in cosmetics. 

For many applications it is not possible to put a component into service to test its durability. Similarly, in product testing one cannot always simulate full service conditions in one test or things become too complicated - for example, time-dependent loading plus abrasion plus environmental ageing. Car tyres have a complicated pattern of cornering, sports surfaces are subject to the actions of different sports and pipes in the North Sea have almost unpredictable wave motions superimposed. No simulation test will reproduce service conditions perfectly, therefore, in accordance with Section 4.13, the test has to be restricted to the critical agents of degradation. 

Tpo maximize the utility of crosslinked cycloaliphatic epoxy resins in some of the more critical application areas, improved toughness is required. Such improvements can often be made through modification with various flexibilizing agents, but as a rule this improvement is accompanied by a severe degradation of the strength and heat distortion temperature of the cured system. 

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