ABSTRACT
Degradation of a polymer may occur during synthesis or in the fabrication process. For example, high-speed stirring, turbulent flow, and ultrasonic irradiation of polymer solutions can cause changes in polymer structure. The predominant response is a decrease in molecular weight, because recombination of radicals is not favored in solution. Similarly, when a melt is masticated at high shear rates, a great deal of mechanical energy is dissipated in the system. Recombination of radicals can take place, as well as some other reactions depending on circumstances.
