Physical aging determination methods

Geyh, M. A. and H. Schleicher (1990), Absolute Age Determination Physical and Chemical Dating Methods and Their Application, Springer, New York. 

Demortier G (1991) Review of the recent applications of high energy microprobes in art and archaeology. Nucl Instrum Meth B, Beam interaction with materials and atoms 54 334-345. Geyh MA, Schleicher H (1990) Absolute Age Determination, Physical and Chemical Dating Methods and their Application. Springer, Berlin. 

ARCHAOMETRY. Application of chemical and physical analytical methods to archaeology, Among those used are microanalyhcal methods, spectroscopic analysis, X-ray, and other types of nondestructive tests. For age determination 14 C measurement (chemical dating) is one of the most valuable techniques. 

There are two TGA techniques to determine the degradation temperature of a plastic. The first is called the isothermal method and is based on setting the sample on a temperature that is between 50 and 150C above its melting temperature and letting the instrument measure the weight loss with time. This is one technique used to determine physical aging of a sample under extreme conditions. A typical decomposition curve is shown in Fig. 6. 

The effects of physical aging on the pure-gas permeation properties of PMP were determined with nitrogen by both the constant pressure/variable volume method (15 psia permeate pressure) and the constant volume/variable pressure method (0 psia permeate pressure). The experiments were carried out at 25°C the feed pressure was 50 psig. 

Combination of the above methods is useful to analyze change of catalyst structure and activity of PAFC electrode in the course of operation. Such an aging study helps to determine the various modes of catalyst decay. Maoka et al. (1996), reported various physical and electrochemical methods to determine PAFC cathode catalyst deactivation over time. 

---