Mechanism of laser damage to polymer materials

Numerical estimates are obtained of stresses which appear in polymethylmethacrylate (PMMA) as a result of heating of microinclusions. The results of model experiments on pulsed electrical heating of microscopic wires in PMMA agree with these estimates and they demonstrate that the cracking of this polymer does not occur at least up to inclusion temperatures 2×10³°C. An analysis is made of the gaseous products of laser pyrolysis of PMMA. The results obtained are in good agreement with the thermochemical model of laser damage to polymers.