Clay/carbon nanotube hybrid mixture to reduce the electrical percolation threshold of polymer nanocomposites

Insights and Perspectives on Graphene-PVDF Based Nanocomposite Materials for Harvesting Mechanical Energy

Multiscale modelling and simulations, based on molecular dynamics (MD) and object-oriented finite element method (OOFEM), are two important simulation tools to predict property enhancement of polym...

Graphene-reinforced thermoplastic polyurethane nanocomposites: A simulation and experimental study:

In this study, the role of polymer matrix molecular structure and drastically different processing method on the conduction behavior of carbon-filled polymer composites was investigated. The electrical conductivity and percolation parameters of poly-dimethylsiloxane (PDMS elastomer) filled with carbon nanofibers (CNFs) and carbon nanotubes (CNTs) via solution mixing were first determined. Using the power law model the percolation threshold (φc) for CNF was 0.83 wt% and the critical exponent (t) was 2.86. This t value depends on the filler dimensionality and the intrinsic conducting property of the composite system; however, the conduction behavior was found to be independent on filler dimensionality at nano-scale beyond the percolation threshold. These results were applied to a much different polymer composite system of nylon-6 thermoplastic filled with CNTs prepared by extrusion method to predict its percolation behavior. The predicted φc of the nylon composite was in good agreement with our experimental value as φc-CNT,prediction = 3.02 wt% and φc-CNT,experiment = 2.96 wt%.

Electrical property validation of percolation modeling in different polymer structures of carbon-based nanocomposites

Acrylonitrile-butadiene-styrene (ABS) terpolymer was loaded with expandable graphite (EG) at four different concentrations of 5%, 10%, 15% and 20% using micro-compounder followed by injection molding process. Mechanical, thermomechanical, thermal, flame retardancy, melt flow and morphological characterizations of composites were done by tensile, hardness and impact tests, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), melt flow index (MFI) test and scanning electron microscopy (SEM), respectively. According to test results, tensile strength and storage modulus of ABS were improved with the increase in EG content. Storage modulus and glass transition temperature of ABS yielded enhancement with the inclusion of EG. However, percent elongation and impact strength values showed decreasing trend with EG additions. ABS/EG composites gave higher fire performance relative to ABS including enhancement in LOI and reduction in heat release rate. MFI test revealed that incorporation of EG with the lowest amount displayed no dramatic change for MFI value of neat ABS. EG flakes exhibited well-dispersion and exfoliated structure for all of the filling ratios as the SEM microimages of composites were examined. 15% and 20% EG containing ABS composites were remarked as the most suitable candidates among prepared composites.

Evaluation of flammability, thermal stability and mechanical behavior of expandable graphite-reinforced acrylonitrile–butadiene–styrene terpolymer

Polyphenylene sulfide (PPS)-expanded graphite (ExGr) conducting nanocomposites have been prepared by powder mixing and in situ polymerization routes after sonicating ExGr particles in acetone. Synt...

Polyphenylene sulfide- expanded graphite nanocomposites: Processing route dependent electrical percolation

Powder-mixed polypropylene (PP)–graphite binary composites exhibit an electrical percolation threshold at 10 wt% graphite signifying insulator-semiconductor transition. Three conducting fillers such as carbon black (CB), sonicated expanded graphite (s-ExGr), and carbon nanofiber (CNF) are mixed with PP-7 wt% graphite binary composites. The electrical percolation threshold has been found to have inverse relation to the aspect ratio of second conducting fillers in hybrid composites. The aspect ratio of second conducting fillers varies in the order CB < ExGr < CNF. The electrical percolation threshold is found to vary for the hybrid composites as 2.2 wt% for CB addition, 0.75 wt% for ExGr addition, and 0.2 wt% for CNF addition in the PP-7 wt% graphite binary composites. When the aspect ratio of second conducting fillers increases, they reduce the barrier for the charge transport. The second conducting fillers occupy the interspace of graphite and alternating current studies show that the effective dielectric...

SD Deshpande

Papers

Polyphenylene sulfide- expanded graphite nanocomposites: Processing route dependent electrical percolation

Polypropylene-based conducting nanocomposites: Effect of aspect ratio of second conducting filler on the electrical percolation