Thermoreversibly Cross-Linked EPM Rubber Nanocomposites with Carbon Nanotubes

• Main Authors: Lorenzo Massimo Polgar, Francesco Criscitiello, Machiel van Essen, Rodrigo Araya-Hermosilla, Nicola Migliore, Mattia Lenti, Patrizio Raffa, Francesco Picchioni, Andrea Pucci
• Format: Article
• Language: English
• Published: MDPI AG 2018-01-01
• Series: Nanomaterials
• Subjects: strain sensor; rubber nanocomposite; thermoreversible cross-linking; Joule effect; crack-healing
• Online Access: http://www.mdpi.com/2079-4991/8/2/58

Conductive rubber nanocomposites were prepared by dispersing conductive nanotubes (CNT) in thermoreversibly cross-linked ethylene propylene rubbers grafted with furan groups (EPM-g-furan) rubbers. Their features were studied with a strong focus on conductive and mechanical properties relevant for strain-sensor applications. The Diels-Alder chemistry used for thermoreversible cross-linking allows for the preparation of fully recyclable, homogeneous, and conductive nanocomposites. CNT modified with compatible furan groups provided nanocomposites with a relatively large tensile strength and small elongation at break. High and low sensitivity deformation experiments of nanocomposites with 5 wt % CNT (at the percolation threshold) displayed an initially linear sensitivity to deformation. Notably, only fresh samples displayed a linear response of their electrical resistivity to deformations as the resistance variation collapsed already after one cycle of elongation. Notwithstanding this mediocre performance as a strain sensor, the advantages of using thermoreversible chemistry in a conductive rubber nanocomposite were highlighted by demonstrating crack-healing by welding due to the joule effect on the surface and the bulk of the material. This will open up new technological opportunities for the design of novel strain-sensors based on recyclable rubbers.