Degradation testing protocol

DEGRADATION TESTING PROTOCOL INCLUDING GOAL DEGRADATION PRODUCT... 

Presents degradation testing protocols important for durability and failure mode studies of PEM fuel cells... 

This overview is an attempt to briefly cover the history and recent developments In environmentally degradable commodity and specialty polymers and plastics. Degradation pathways are mentioned, polymer types, including blends, are reported and the limitations of current testing protocols raised. The chapter concludes with generalizations on structural requirements for degradable polymers. 

Stress testing is used to help identify degradation pathways under the influence of accelerated heat, light, and RH conditions in the presence or absence of air or oxygen. Such stability testing protocols represent an important aspect of a pharmaceutical ingredient process validation program. 

The use of biocides in plastics is commonplace. They are added to protect the plastic itself from degradation by microbes or alternatively to provide an external antimicrobial hygienic surface. The choice of suitable test method and the appropriate biocide can be difficult, as the different ways in which biocides work will affect how they perform under certain test protocols. 

Having documentation and uniform protocols is important to obtain the most value from test beds and operational deployments. A continually evolving operational deployment such as the Pentagon could provide valuable real-world experience and data comparable to those obtained in test beds if all tests are well documented and standardized. For operational facilities or test facilities, establishment of uniform testing protocols to test effectiveness and validate protection systems would make their results useful to others. For example, information on degradation, maintenance, and operational and life-cycle costs (real... 

Current evaluation methods are time consuming, and are application specific. A common test protocol that would identify a degradation mechanism in a relatively short time does not exist. This also will require research and development to relate such parameters as temperature to time. 

Yet another method used to reflect endurance is to calculate an endurance-related work ratio. Many isokinetic testing devices, such as the one shown in Figure 76.3b, will calculate work (integrate force or torque over displacement). In this case, the total amount of work performed in the first five repetitions is compared with the total amount of work performed in the last five repetitions of a series of repetitions (usually 25 or more). Work degradation reflects endurance and is reported as percentage. An additional limitation of using these endurance ratios is that work cannot be determined in isometric test protocols. Mechanically there is no movement, and no work is being performed. 

Table 7 Typical Testing Protocol for Accelerated Degradation Studies.

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