Abstract:

In this paper， PLA/PDLA/CNTs composites with low over diffusion and high conductivity were prepared by using a solution adsorption⁃melting method. The PDLA component in the composites plays a good role of volume repulsion in promoting the dispersion of CNTs and enhancing the crystalline properties of PLA， thus effectively regulating the conductive network structure of the composites. The conductivity of the composites showed an increasing trend at first and then tended to decrease with an increasing in the PDLA content. The composite containing 0.2 wt% PDLA and 0.6 wt% CNTs obtained an increase in electrical conductivity from 10^-6 to 10^-4 S/m， which were improved by two orders of magnitude. Its conductive percolation value was reduced to 0.45 wt% compared to the PLA/CNTs composite （0.58 wt%）. In addition， the introduction of CNTs and PDLA effectively improved the crystallization properties and complex viscosity of the compo⁃sites. The onset crystallization temperature and the maximum peak crystallization temperature of the composite with 0.5 wt% PDLA and 0.6 wt% CNTs increased by 30.6 ℃ and 20.8 ℃， respectively， compared to those of pure PLA. The mechanical investigation indicated that the tensile strength of the composites was further improved as a result of the synergistic effect of CNTs and PDLA. Therefore， the conductive network structure could be effectively regulated through incorporating PDLA into the PLA/CNTs composites， along with an improvement in the mechanical properties of the composites. This work provides a new method for improving the comprehensive performance of conductive composites.

Key words: poly（lactic acid）, crystallization performance, electrical conductivity, mechanical property