Shape-memory, Low-transitional Temperature and Directionally Preferred Electrically Conductive Graphite Nanoplatelets (GNP)/Epoxy Nanocomposites as Strain Sensors

Along broad applications of shape-memory polymers (SMPs), SMPs need to be electrically conductive, too, so that they could be employed in electronic circuits acting as electrical sensors upon receiving external stimuli. Studies show even though a majority of SMP based materials consists of nonconductive polymers exhibiting shape-memory effects, the polymeric alloying systems lead to serious limitations when they are to be employed as sensors. This work represents the fabrication of a new class of thermosetting based nanocomposite films exhibiting electrical conductivity and shape-memory behavior upon low-temperature heating cycle whilst the conductivity varies through the direction of films being the greatest along the fabrication direction. To fabricate the conductive sheets, graphite nanoplatelets (GNP) as the conductive filler were mixed with epoxy resin on a calendering device to control the thickness, dispersion of fillers and curing condition of the resin/GNP compound forming onto the heating rolls. The fabricated films exhibited preferred conductivity through longitudinal and transverse directions whilst representing shape-memory behavior upon heating-cooling-heating cycles. The conductive nature of the nanocomposite SMPs suggested their applications as resistance strain sensors. A single cantilever test further demonstrated the blocked force values a s a measure of the recover ability of the fabricated SMPs at the ۱۵ wt% of GNPs.

Keywords:

Shape-memory polymer (SMP) , Epoxy nanocomposite , Electrical conductivity , Calendering.