Thermal diffusivity in femtosecond-laser-structured micro-volumes of polymers

Thermal diffusivity of laser micro-structured regions in plastics was determined using a temperature wave method with a lateral resolution reduced to similar to 10 mu m using an array of micro-sensors. A high volume fraction (> 25%) of laser modified phase was recorded by tightly focused femtosecond-laser pulses inside films of poly-methylmethacrylate, non-oriented polyethylene, polystyrene, and polyimide-Kapton. Changes in thermal diffusivity inside the laser-structured volumes of the order of a few percent were reliably determined with the miniaturized sensors. The origin of the change of thermal properties in plastics is discussed.