Preparation and Properties of Ultrathin Flexible Expanded Graphite Film via Adding Natural Rubber

Abstract

Expanded graphite (EG) films exhibit potential use in a wide field including thermal management, conductive applications, and electromagnetic interference (EMI) shielding. However, their poor tensile strength and brittleness are crucial deficiencies for commercial applications. To address these defects, in our work, natural rubber (NR) is employed to improve EG films for better mechanical strength and flexibility. The origin of the strengthening effect of EG films by the addition of natural rubber mainly arises from the formation of a simulate shell structure. Compared to the neat EG films, the addition of merely 2 wt% NR can give rise to superior ductility. Further, the loading of 10 wt% NR realizes a significant mechanical enhancement of the EG/NR films, i.e., 2.4 and 11.4 times increase in tensile strength and elongation at break, respectively. Besides, EG/NR films containing 10 wt% NR can still sustain excellent thermal and electric conductivities of 173 W·n−1·K−1 and 75 S·cm−1, respectively. Furthermore, a very high EMI of 41.4 dB is achieved as the film thickness reaches 50 μm. Thus, the lightweight EG/NR films with comprehensive performance as well as their virtue of green and simple large-scale preparation endow them with the possibility of designing next-generation flexible electronics.