Subject thermal ageing

If natural mbber compounds are subjected to thermal aging plus fatigue, the conventional systems perform no better than EV systems. The compromise obtained by usiag semi-EV systems iavolves the balance between heat aging and flex life. 

Exposure can result thereafter in increased thermally-induced changes. In order to evaluate this aspect of the potential harm that exposure to light represents, the exposed sheets were subjected to thermal aging at 90°C and 50% RH and the changes in HAS matter and DP measured. Thus, not only were the immediate changes that took place during exposure monitored but the effect of exposure upon subsequent thermally-induced deterioration were determined as well. This is basically the same technique of investigation used by Launer and Wilson in 1943.(2)... 

Figure 12 shows results of a thermal-aging experiment. Sheets of Whatman No. 42 filter paper were first exposed to near-UV radiation (BLB fluorescent black lights), after which they were subjected to oven... 

Blends of PPE with SBS, and an antioxidant/ metal deactivator (di-octylamine) were developed [Richards and Kelly, 1992 1994 Richards and Pickett, 1995]. Subjected to recycling at temperatures T = 250-350°C (or to thermal aging at T = 50-200°C), the blends maintained excellent retention of impact strength. Similarly, recyclable blends were prepared in two steps (1) PPE was capped with salicyhc acid ester, then blended with... 

When elastomers are subjected for extended periods of time at elevated temperatures to a compressive load while being permitted to distort, they will not recover to their original dimensions when the load is removed. Measuring the compression set of compressed elastomers during thermal aging is a very useful and realistic means of evaluating materials for gasket applications. 

FIGURE 25.15 (a) Discharge profiles of LIB cells subjected to thermal aging at 60 °C for 0-8 weeks, (b) Discharge profiles of LIB cells subjected to thermal aging at 70 °C for 0-8 weeks. 

It was shown in [25] that in the thermal aging of massive rubber objects (for example, tire treads), only the outer surface of the tread and the boundary layer of rubber adjoining it are subjected to the influence of oxygen. The authors convincingly showed on extensive experimental ma-... 

Drift due to high power is usually due to internal resistor heating. It is different from thermal aging in that the heat is generated at the point-to-point metal contacts within the resistor film. When a resistor is subjected to heat from an external source, the whole body is heated to the test temperature. Under power, local heating can result in a much higher temperature. Because lower value resistors have more metal and, therefore, many more contacts, low-value resistors tend to drift less than higher value resistors under similar loads. 

Fig. 6.8 Schematic illustration of Ciofer22APU plate/SACN sealant/ASC joined SRU subjected to dual atmosphere thermal ageing test (Smeacetto and coworkers 2011)...

Taking the foregoing concerns into account this chapter discusses in detail the key metallurgical aspects including as-solidified microstructure, thermal stability characteristics, effects of elemental additions, and thermal aging, etc. as they relate to the Sn-Ag, Sn-Cu and their ternary alloys (Sn Ag Cu) into account. These alloy systems are the subject of much attention as solder replacement candidates for solders of the Pb-Sn system, particularly eutectic Sn-Pb. In addition, the chapter discusses the major mechanical properties of interest for electronic packaging applications as a consequence of their metallurgical characteristics. 

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