DETERIORATION OF ORGANIC POLYMERS 



1089 



bond in peroxides or by the dissociation of a relatively more stable bond 

 such as — C — C — or — C— H. Needless to say, the ease with which such 

 cracking occurs is influenced by chemical structure. These free radicals, 

 which may be produced in very minute amount, react with oxygen to form 



Fig. 10— (1) Cellulose acetate exposed six months at Murray Hill, N, J. 



(2) Nylon test panels exposed 5 months at Yuma, Arizona. 



(3) Clear Polyethylene sheet exposed 3 years at Murray Hill, N. J. 



(4) Clear polyethylene coated wire exposed 3 years at Murray Hill, N. J. 



peroxidic radicals. This is illustrated by the following chemical equation in 

 which the radical is represented by the letter R and the fact that it is "free" 

 or reactive is indicated by the dot. 



R- + O, 



R— O— O 



