Fabrication of PLA/CB composites with excellent electrical conductivity and stiffness-ductility balance based on coupling extensional stress with thermal field

A newfound scalable strategy of annealing stretching-thermal treatment is proposed to tune electrical con-ductivity and stiffness-ductility balance of polylactide/carbon black (PLA/CB) conductive composites. The extensional stress-induced orientation and crystallization lead to a significant increase in tensile strength (from 69.3 MPa to 102.0 MPa) and elongation at break (from 9.8 % to 48.7 %). Further thermal treatment effectively reconstructs the conductive network destroyed by the strong extensional stress, causing a sharp increase in electrical conductivity to 5.75 S/m, which is surprisingly similar to 10(9) higher than that of neat PLA (5.61 x 10(-9) S/m). Besides, the ductility (44.3 %) and strength (97.8 MPa) are well preserved after thermal treatment, attributed to the preservation of oriented amorphous phase and the perfection of oriented crystals, respectively. Moreover, the heat resistance is also improved after thermal treatment. This work could provide significant guidance for facile and efficient fabrication of high-performance bio-based conductive polymer composites.

Automated summary

A new scalable strategy of annealing stretching-thermal treatment is proposed to tune the electrical conductivity and stiffness-ductility balance of polylactide/carbon black conductive composites. The strategy involves extensional stress-induced alignment and crystallization to increase tensile strength and elongation at break, and subsequent thermal treatment to rebuild the conductive network and enhance electrical conductivity. The ductility, strength, and heat resistance of the composites are well-preserved after the treatment. This work provides significant guidance for the fabrication of high-performance bio-based conductive polymer composites.