A study of photothermal laser ablation of various polymers on microsecond time scales

Abstract

To analyze the photothermal ablation of polymers, we designed a temperature measurement setup based on spectral pyrometry. The setup allows to acquire 2D temperature distributions with 1 μm size and 1 μs time resolution and therefore the determination of the center temperature of a laser heating process. Finite element simulations were used to verify and understand the heat conversion and heat flow in the process. With this setup, the photothermal ablation of polystyrene, poly(α-methylstyrene), a polyimide and a triazene polymer was investigated. The thermal stability, the glass transition temperature Tg and the viscosity above Tg were governing the ablation process. Thermal decomposition for the applied laser pulse of about 10 μs started at temperatures similar to the start of decomposition in thermogravimetry. Furthermore, for polystyrene and poly(α-methylstyrene), both with a Tg in the range between room and decomposition temperature, ablation already occurred at temperatures well below the decomposition temperature, only at 30–40 K above Tg. The mechanism was photomechanical, i.e. a stress due to the thermal expansion of the polymer was responsible for ablation. Low molecular weight polymers showed differences in photomechanical ablation, corresponding to their lower Tg and lower viscosity above the glass transition. However, the difference in ablated volume was only significant at higher temperatures in the temperature regime for thermal decomposition at quasi-equilibrium time scales.

Resonant polymer ablation using a compact 3.44 μm fiber laser

“…The creation of rims around the grooves during ablation follows the same behavior as the bump formation. It is usually attributed to expulsion and resolidication of material or to unfinished ablation, as shown by Kappes et al (2014). In our case, since the main mechanism of ablation is vaporization, it cannot produce large rims by expulsion and redeposition of the material.…”

Fabrication of UV Laser-Induced Porous Graphene Patterns with Nanospheres and Their Optical and Electrical Characteristics

“…The thickness of the 3D carbon network increased from the laser speed of 60 mm/s, but the thickness of the total thickness of patterns decreased (as shown in Table 4 ). It is because of photothermal ablation based on heat-induced melting [ 35 ].…”

Effect of biaxial‐simultaneous stretching conditions on OTR and CO2 permeation of CO2 laser perforated poly(lactic acid) film

“…. There are several studies in the literature addressing a study of lasers interacting with polymer materials . However, only a few works reported the production of a breathable packaging film by laser .…”

“…[13][14][15][16][24][25][26][27][28] There are several studies in the literature addressing a study of lasers interacting with polymer materials. 12,[29][30][31] However, only a few works reported the production of a breathable packaging film by laser. [12][13][14][15][16] Studies on the relationship between the high-order structure of films and laser perforation behavior have rarely been reported.…”