Physical ageing Terms Links

Note 2 Physical aging, crystallization, physical cross-linking, and post-polymerization reactions are sometimes referred to as curing . Use of the term curing in these cases is discouraged. 

There are no known long-term psychological effects from creatine supplementation. However, at least one study has linked the use of performance-enhancing supplements to an increased incidence of health risk behaviors. The 2001 study, which surveyed approximately 500 men and women between the ages of 17 and 35, found that study participants who took ergogenic nutritional supplements such as creatine were more likely to get drunk, drink and drive, and become involved in physical confrontations. However, since the research was limited by the fact that it involved a very specific population (subjects were new recruits entering military service), further study is needed to determine if ergogenic aids such as creatine are directly linked to an increase in these behaviors. 

Understanding the link between microstructure in PDMS foams and the mechanical performance is crucially important for the development of ageing trends that allow long term qualification. The plots in Figure 13 show force decay curves for a series of siloxane foam samples with varying closed cell contents. The trend demonstrates the time dependent nature of the measurement of physical properties. This creates an additional source of variation and if possible then it should be eradicated by the production of 100% open cell structures. 

Put very simply, copal is young version of amber. There is no definite age at which copal turns into amber, as the process is continuous firom the moment the resin appears on the tree and begins to solidify. In physical terms, when the resin is sufficiently cross-linked and polymerised it becomes amber (see Chapter 13, Plastics ). In other words, the resin has dried out and hardened. This process takes thousands if not millions of years, and not all copal becomes amber as much of it disintegrates with time. Furthermore, as the process is such a long one it is not possible for us to follow it or to replicate it in a laboratory, so there is still much that is speculation. We know, however, that there are some instances of copal that have begun to look like, and take on, the properties of amber. 

---