Polymers -insulating coating Degradation

Insulating coatings have been of particular interest in corrosion protection. A large number of papers deal with the characterization of polymer layers and their degradation [25-27]. An electrode with a perfectly insulating coating shows... 

Protective Coatings. Some flame retardants function by forming a protective Hquid or char barrier. These minimize transpiration of polymer degradation products to the flame front and/or act as an insulating layer to reduce the heat transfer from the flame to the polymer. Phosphoms compounds that decompose to give phosphoric acid and intumescent systems are examples of this category (see Flame retardants, phosphorus flame retardants). 

Although elimination reactions are clearly degradation, leading to color and char formation, they can have advantages. Conjugated sequences and ladder structures confer thermal stability on the polymers, forming stable chars. This is the basis of the preparation of carbon fibers by pyrolysis of polyacrylonitrile. It is also one reason for the use of plasticized PVC in electrical insulation in a fire, the char acts as a protective coating and maintains the electrical insulation properties of the cable. 

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