Overview

As pointed out earlier, fluoroplastics offer a variety of unique properties, in particular, a good to outstanding chemical resistance, and stability at elevated temperatures. Because of that, they have been used increasingly in applications where most hydrocarbon-based materials would fail, such as chemical processing, motor vehicle engines, nuclear reactors, in the manufacture of semiconductors, and space applications. On the other hand, they exhibit some deficiencies when compared with most engineering thermoplastics. Typically, they have poorer mechanical properties, higher permeability values for gases and often a considerably higher cost. Some of the specific shortcomings of commercial fluoroplastics are shown in Table 5. Knowing the advantages and disadvantages of individual materials and understanding how structure affects properties and performance is very important for proper selection of processing technology and for the suitability for specific practical applications. As pointed out earlier, the advantageous properties of fluorocarbon polymers are the result of the very strong bond between carbon and fluorine, the shielding of the carbon backbone by fluorine atoms and of the fact that they are fully saturated macromolecules [a.3]. The following sections will cover the correlation between structure and some of the fundamental properties of the most common commercial fluoroplastics.