Temperature dependence polymer weathering

Outdoor weathering is undoubtedly the most valuable test of practical polymer stability because of the extreme complexity of the natural conditions. Indeed, though photodegradation is initiated by light, ambient temperature, humidity, rainfall and atmospheric contaminants all have an influence on the course of the degradation, and the interrelationship of these factors is not yet fully understood. Several chemical reactions, the relative importance of which are dependent on the weathering conditions, usually contribute to the failure of the sample. 

All polymers are affected by the environment in which they arc used or stored, although the rate and degree of change is dependent on the polymer and indeed the partieular grade or formulation. The most common environment is that termed weathering exposure to light, ambient temperature, precipitation, and possibly atmospheric contaminants,... 

Polyvinylindene fluoride. Polyvinylindene fluoride (PVDF) is crystalline with a melting point near 170°C. The structure of PVDF is shown in Fig. 1.10. PVDF has good chemical and weather resistance, along with good resistance to distortion and creep at low and high temperatures. Although the chemical resistance is good, the polymer can be affected by very polar solvents, primary amines, and concentrated acids. PVDF has limited use as an insulator because the dielectric properties are frequency dependent. The polymer is important because of its relatively... 

Alloys are combinations of polymers that are mechanically blended. They do not depend on chemical bonds, but do often require special compatibilizers (explained below). Plastic alloys are usually designed to retain the best characteristics of each constituent. Most often, property improvements are in such areas as impact strength, weather resistance, improved low-temperature performance, and flame retardation (see Figs. 2-6 to 2-9 and Tables 2-10 to 2-12). 

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