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.