Preparation and characterization of micro-graphite filled poly(lactic acid) composites: Part 2 - Crystallinity and electrical properties

Abstract

Micro-graphite was incorporated into poly(lactic acid) via solution blending in chlorof orm with varying concentrations: 0, 5, 10, and 15%wt. Before being poured in the glass mold, the adding micro-graphite is accompanied by stirring at 650 rpm and 60°"C (for 1 hour) to homogenize the dispersion of micro-graphite into the PLA solution. This report is discussing the characterization results of the prepared micro-composites, i.e., crystallinity and electrical properties. The crystallinity was analyzed using X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). Both surface and bulk crystallinity were demonstrating a considerable dependence with the micro-graphite loading. The onset temperature of the melting point has a slight shift about 2-4°C. However, the melting point of neat PLA and micro-composites is not significantly changed. The electrical property was carried by Keithley 2602A SYSTEM SourceMeter to measure their resistivity. In the voltage range of 0-1 volt, the presence of micro-graphite starts to have an impact at 15%wt load. Resistivity decreases become 1,686*104 Q.mm from out of the device measurement range. The ATR-FTIR (Attenuated Total Reflection-FTIR) spectra show that the residue of chlorof orm solvent is not detected in the dry prepared samples. It means the solvent can be predicted totally evaporated from the sample.