The mechanical properties of flexible graphite sheets made by exfoliated graphite flakes have been investigated in term of the density changes and the flake size variation. The fracture toughness of flexible graphite sheets has been characterized using the concept of essential fracture work (w(e)). The experimental results indicate that both tensile strength and the fracture toughness monotonically increase, but the sheet flexibility decreases with the density of flexible graphite sheets and the size of pristine graphite flakes. A compromise combination of compression and recovery can be achieved in the density range of 1.0-1.4 g cm(-3). The flake size has little effects on both compression and recovery. A micro-disc model has been developed based on friction between the interlocked micro-discs in which air is encapsulated. This model interprets the effects of the density and flake size on certain mechanical properties of the flexible graphite sheets. (C) 1998 Elsevier Science Ltd. Aii rights reserved. References: 4
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