Effect of PLA stereocomplex crystallization on the thermal conductivity of its composites with graphene nanoplatelets

As the amount of e-waste generated globally increases, there is a growing interest in biodegradable polymer composites for electronic devices. However, the use of the materials available today is limited due to their insufficient properties, such as thermal conductivity and stability in elevated temperatures. In this study, we promoted stereocomplex formation in composites based on an equimolar blend of L-PLA and D-PLA, filled with graphene nanoplatelets to enhance the thermal conductivity of the materials. Using Raman spectroscopy, differential scanning calorimetry, and dynamic mechanical analysis, we demonstrated how such processing affects matrix composition and phase transitions. Although the graphene nanoplatelets did not favor the crystallization of stereocomplex, the wide-angle X-ray scattering experiment showed that its content in the composites increased to about 35%. As a result, their room temperature thermal conductivity rose by even 17% and further increased with the ambient temperature rise. The results were supplemented by directional measurements to determine the influence of morphological anisotropy.