Shelf life thermally activated

With respect to organic compounds, those that are precursors to pharmaceuticals have attracted increasing interest from the viewpoint of their thermal properties, and TA techniques are used frequently in quality control procedures for such compounds. A wide variety of common and less common pharmaceuticals have also been investigated using a variety of thermal methods - mainly BSC and mainly in the context of purity determination. There is also potential for using TA techniques to identify pharmaceutical activity and for shelf-life determinations. 

Polylactides (PLA) may have many potential applications for an important set of products but some of their properties should be improved to obtain similar performance to petroleum-based commodities. One of the most important current applications of PLA is food packaging, in particular for short-shelf-life products with common applications such as rigid containers, drinking cups, over-wrap and lamination films. PLA production and consumption are expected to increase therefore research into the variation of PLA mechanical and barrier properties is currently very active. The control of barrier properties in PLA films is possible by modification of the polymer network through the formation of intramolecular and inter-molecular covalent crosslinking, for example by applying thermal treatment, or by modifying the chemical composition. Another method is to incorporate fillers, in particular layered nanoclays, and this will be the subject of this chapter. 

Frying is defined as a process of cooking and drying through contact with hot oil. It is intended to make food more palatable and tasteful, but at the same time makes food safer and provides a preservative effect that results from thermal destruction of microorganisms and enzymes, and a reduction in water activity at the surface or throughout the food. The shelf life of fried products is mostly determined by the moisture content after frying. Products that retain a moist... 

From environmental temperatures between —40 and +70 °C thermal batteries may be activated and used indiscriminately. Their extremely good storability in the frozen state at normal temperatures makes them especially suitable for military applications in weapons and equipment whose system shelf-life in total is often shorter than that of the integrated batteries. Because of their compactness thermal batteries are particularly resistant against shock, vibration, acceleration, and spin. 

The shelf life of an unactivated thermal battery is typically 10 to 25 years, depending upon design. Once activated and discharged, though, they are not reusable or rechargeable. 

The lifetime or shelf life of a polymer can be estimated from the kinetic data. Ozawa [3] observed that the activation energy of a thermal event could be determined from a series of thermogravimetric runs performed at different heating rates [4-8]. As the heating rate increased, the thermogravimetric changes occurred at higher temperatures. The measurement of lifetime is discussed in more detail in Section 2.2.8. 

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