Mechanism of damage of transparent polymer materials due to multiple exposure to laser radiation pulses

Removal of absorbing microinclusions from polymethylmethacrylate (PMMA) increased considerably its ability to withstand multiple exposure to laser radiation pulses. Introduction of carbon black microparticles of 25 nm size into PMMA facilitated its damage by laser radiation. It was concluded that the processes of carbonization, resulting from local thermolysis of a polymer in the vicinity of absorbing microinclusions, played the dominant role in the damage caused by multiple exposure to laser radiation. The results of tests on methylmethacrylate and styrene copolymers were in agreement with this hypothesis.