The effect of nanofiller geometry and compounding method on polylactic acid nanocomposite films

Abstract

The effect of the compounding method and of the nanofiller geometry on the thermo-mechanical properties and electrical behavior of polylactic acid (PLA) nanocomposite films was investigated. The films were fabricated using two methods: (i) melt compounding followed by melt fiber spinning or (ii) solution compounding followed by electrospinning. Both the melt and electrospun fibers were then compression molded. In the case of melt compounding, both exfoliated graphite nanoplatelets (GNP) and carbon nanotubes (CNT) were used as reinforcement, whereas only CNT were used in the case of solution compounding. The microstructure was examined using scanning electron microscopy and the crystallization behavior, thermo-mechanical behavior, and electrical response of the PLA composite films were investigated as a function of nanofiller content, geometry, and compounding method. It was concluded that the GNP/PLA films had the highest percolation at greater than 3wt% of GNP, while the CNT/PLA films had the lowest at less than 1wt% of CNT. In addition, the solution method and electrospun fibers resulted in a higher conductance compared to the CNT/PLA films of the same CNT content made by melt compounding due to a more heterogeneous distribution and dispersion of CNT throughout the matrix that facilitated the formation of interconnected conductive networks.