Gold functionalized graphene oxide (GOAu) nanoparticles were reinforced in acrylonitrilebutadiene rubbers (NBR) via solution and melt mixing methods. The synthesized NBR-GOAu nanocomposites have shown significant improvements in their rate of curing, mechanical strength, thermal stability and electrical properties. The homogeneous dispersion of GOAu nanoparticles in NBR has been considered responsible for the enhanced thermal conductivity, thermal stability, and mechanical properties of NBR nanocomposites. In addition, the NBR-GOAu nanocomposites were able to show a decreasing trend in their dielectric constant (ε´) and electrical resistance on straining within a range of 10–70%. The decreasing trend in ε´ is attributed to the decrease in electrode and interfacial polarization on straining the nanocomposites. The decreasing trend in electrical resistance in the nanocomposites is likely due to the attachment of Au nanoparticles to the surface of GO sheets which act as electrical interconnects. The Au nanoparticles have been proposed to function as ball rollers in-between GO nanosheets to improve their sliding on each other and to improve contacts with neighboring GO nanosheets, especially on straining the nanocomposites. The NBR-GOAu nanocomposites have exhibited piezoelectric gauge factor (GFε´) of ~0.5, and piezo-resistive gauge factor (GFR) of ~0.9 which clearly indicated that GOAu reinforced NBR nanocomposites are potentially useful in fabrication of structural, high temperature responsive, and stretchable strain-sensitive sensors.

Abstract
 1. Introduction
 2. Experimental
  2.1. Materials
  2.2. Synthesis of GOAu nanoparticles
  2.3. Preparation of NBR-GOAu nanocomposites
  2.4. Characterization
   2.4.1. Scanning electron microscopy
   2.4.2. Ultraviolet spectroscopy
   2.4.3. X-ray diffraction (XRD)
   2.4.4. X-ray photoelectron spectroscopy (XPS)
   2.4.5. Raman spectroscopy
   2.4.6. Cure property
   2.4.7. Crosslinking density
   2.4.8. Tensile property
   2.4.9. Thermal analysis (DSC and TGA)
   2.4.10. Dielectric spectroscopy
 3. Results and Discussion
  3.1. Characterization of GOAu nanoparticles
  3.2. Morphology and dispersion of GOAunanoparticles in NBR matrix
  3.3. Cure properties
  3.4. Mechanical properties
  3.5. Thermal degradation behavior
  3.6. Effect of strain on electrical resistance
  3.7. Dielectric properties
  3.8. Gauge factor
 4. Conclusions
 Conflict of Interest
 Acknowledgements
 References

• Bismark Mensah(BK21 Plus Haptic Polymer Composite Research Team, Department of Polymer-Nano Science and Technology, Chonbuk National University)
• Dinesh Kumar(Biomaterials Lab, Department of Bionano System Engineering, Chonbuk National University)
• Gi-Bbeum Lee(BK21 Plus Haptic Polymer Composite Research Team, Department of Polymer-Nano Science and Technology, Chonbuk National University)
• Joohye Won(BK21 Plus Haptic Polymer Composite Research Team, Department of Polymer-Nano Science and Technology, Chonbuk National University)
• Kailash Chandra Gupta(Polymer Research Laboratory, Department of Chemistry, Indian Institute of Technology Roorkee)
• Changwoon Nah(BK21 Plus Haptic Polymer Composite Research Team, Department of Polymer-Nano Science and Technology, Chonbuk National University) Corresponding Author