Micro-scale thermal diffusivity measurements of banded spherulites of poly-(l-lactic acid) using a thermo-electric micro sensor

We have succeeded in developing a thermo-electric micro sensor designed with a three-dimensional electric wiring to measure the thermal diffusivity in micro scale. Temperature wave in the area of 12.5 μm in diameter is observed as a periodical change of thermo electromotive force. The phase shift of temperature wave is measured by means of a lock-in method and the thermal diffusivity of polymer film is determined with a standard deviation less than 2%. The micro-scale distribution of thermal diffusivity in the banded structures of spherulites of poly-l-lactic acid (PLLA) is demonstrated.

► We have newly designed a thermoelectric micro-sensor for TWA method.
► This sensor enables us to measure thermal diffusivity in micro scale.
► The repeatability of the measurement is less than 2%.
► The micro-scale distribution of thermal diffusivity in PLLA spherulites is mapped.
► In banded PLLA spherulites, thermal diffusivity showed periodic and drastic change.