Aging at elevated temperature

Aging at elevated temperatures typically involves exposing test specimens or products at different temperatures for different extended time periods. Tests are performed at room or the respective testing temperatures for whatever mechanical, physical, or electrical property is of interest. These tests of aging 

Note Adding certain fillers and reinforcements can raise decomposition temperatures. 

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Fig. 8. Tensile strength of Parylene C on aging at elevated temperature. To convert Pa to psi, multiply by 0.145 x 10. ...

Changes observed in the composition of the rubber/brass interphase correlated well with results of adhesion tests carried out on brass-plated steel wires embedded in blocks of rubber [46]. The force required to pull the wires out of the blocks decreased steadily as vulcanization temperature increased. This effect was especially pronounced when the specimens were aged at elevated temperature and humidity for several days before the wires were pulled out of the rubber blocks. 

Essentially the same process can be used for the preparation of monodispersed particles of internally mixed composition. To do so, solutions containing two or more different metal salts are aged at elevated temperatures in the presence of urea. 

Materials. A number of papermaking pulp samples, including bleached and unbleached, sulfite and sulfate, hardwood and softwood, and semichemical varieties, were analyzed thermogravimetrically. Some of these pulps, artificially aged at elevated temperatures and humidity, were also included. A list of the pulps and the codes assigned to them for easier reference are given in Table I. 

The formation of non-redispersible sediment in a pesticide flowable formulation is often the primary cause of product failure during inventory/sheIf storage. In order to develop and maintain a quality pesticide flowable formulation, a formulator needs evaluation techniques which will enable him to quickly determine the relative stability performance of a sample in a non-subjective manner. Accurate sample characterization and early prediction of shelf life is also highly desirable. Many methods for flowable sample evaluation, such as sediment probing, are subjective and destructive to the integrity of the sample. Often, samples have to be aged at elevated temperatures to obtain measurable differences in stability performance within reasonable time constraints. The purpose of this paper is to describe equipment and methodology which can be utilized to measure the relative... 

The submitters have observed that aging at elevated temperature for long periods (>8 hr) will lead to a 3-5% decrease in yield. Over-heating the solids on the walls of the flask may discolor the product. 

Often, accelerated aging tests are conducted with samples drawn from a production lot. These tests look at aging at elevated temperatures over short periods of time, using the Arrhenius relationship to allow trading temperature for time. 

Adhesives that are used to bond dissimilar materials must produce sufficient shear strength and tensile pull strength and maintain this strength for the life expectancy of the part and under the environmental conditions that the part will encounter. A reduction in bond strength generally occurs on aging at elevated temperatures and under moist conditions, but the reduced strength may still be sufficient for the intended application. 

Results from room temperature and elevated temperature lap shear testing of the elastomer-modified LARC-13/titanium bonds are presented in Table 1. After 500 hr at elevated temperature, all four adhesive formulations were reduced in strength compared to LARC-13 control specimen. However, it should be noted that the silicon-containing adhesives showed improved strengths at 260 C after aging at elevated temperature. Such behavior is probably due to additional cross-linking. 

Kerlau M., Kostecki R. Interfacial Impedance Study of Li-Ion Composite Cathodes during Aging at Elevated Temperatures, J. Electrochem. Soc. 2006, 153, A1644-A1648. 

In Vitro Ageing—ageing in an artificial extracellular fluid for long time-periods at body temperature, 37°C. Ageing at elevated temperatures, for short intervals, in artificial extracellular fluids. 

Slip agents such as saturated and unsaturated fatty acid amides can overcome film surface friction. These agents migrate to the film surface dining processing and upon aging at elevated temperatures (see Release Agents). 

On aging, either natural aging at room temperature or artificial aging at elevated temperature, a great number of small particles AljCu are precipitated. These precipitations will be obstacles for dislocation movements and sUp in the crystal planes. These phenomena increase the yield and tensile strength. The alloy has been hardened. 

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