Formation of ultrafine microaggregates in laser ablation of polymers

Abstract

Experimental results on polymer laser ablation are considered using the regularities of gas dynamics and flow of viscous fluids. It is shown that a significant role in the ablation of polymers is played by destructive and thermochemical processes of modification of the molecular structure during irradiation, leading in some cases to a reduction and in others to an increase in the viscosity of the melt. The intensity of the laser irradiation, optical properties, and physicochemical state of the surface layer of the polymer determine the nature and quantitative parameters of the formation and the shape of the microaggregates in the ablation flow. The emphasis is placed on polytetrafluorethylene (PTFE), the capabilities of which in terms of formation of a microaggregate fraction can be raised to high values, which makes it possible to use laser ablation (LA) for production of fiber-porous PTFE with unique properties. Fiber-porous PTFE is used in the manufacture of high performance filters that can operate in corrosive environments and under high temperatures.