Browsing by Subject "Conductive"

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Conductive nickel nanostrand-reinforced polymer nanocomposites
(2013-05) Lu, Chunhong; Krifa, Mourad
Conductive and flexible nanocomposites can have wide applications in textiles, including wearable sensors, antenna, electrodes, etc. The objective of this research is to develop electrically conductive fibers and films that are flexible and deformable for use in textile structures able to accommodate the drape and movement of the human body. To achieve this objective, we evaluate the electrical properties of PEDOT:PSS/nickel nanostrand as well as nylon 6/nickel nanostrand nanocomposites. Nickel nanostrands (NiNS) were first used to reinforce an intrinsically conductive polymer, Poly(3,4-ethylenedioxythiophene) (PEDOT:PSS), in order to fabricate nanocomposite films with high electrical conductivity. The electrical properties of the films were evaluated by the Van der Pauw method. The addition of 10 wt% nanostrands in PDOT:PSS provided a two order of magnitude improvement in electrical conductivity. In addition to PDOT:PSS, nylon 6/NiNS nanocomposite fibers were produced using electrospinning and exhibited diameters in the sub-micron range. The NiNS-reinforced fibers had electrical conductivity that exceeded the ESD range, which offers the potential for use in protective textile applications.
Highly conductive, nanoparticulate thick films processed at low processing temperatures
(2012-08) Nahar, Manuj, 1985-; Kovar, Desiderio; Ferreira, Paulo J.; Becker, Michael F.; Keto, John W.; Bourell, David L.
Applications such as device interconnects require thick, patterned films that are currently produced by screen printing pastes consisting of metallic particles and subsequently sintering the films. For Ag films, achieving adequate electrical conductivity requires sintering temperatures in excess of 700˚C. New applications require highly conductive films that can be processed at lower processing temperatures. Although sintering temperatures have been reduced by utilizing finer nanoparticles (NPs) in place of conventional micron-size particles (MPs), realization of theoretically achievable sintering kinetics is yet to be achieved. The major factors that inhibit NP sintering are 1) the presence of organic molecules on the NP surfaces, 2) the dominance of the non-densifying surface diffusion over grain boundary or lattice diffusion 3) agglomeration of NPs, and 4) low initial density of the NPs. Here, we report a film fabrication technique that is capable of eliminating these deleterious factors and produces near fully dense Ag films that exhibit an order of magnitude higher conductivity when compared to other film fabrication techniques at processing temperatures of 150 – 250 °C. The observed results establish the benefits of NP diffusion kinetics to be far more profound when the deleterious factors to sintering are eliminated. The sintering behavior exhibits two distinct temperature regimes – one above 150 ᵒC where grain boundary diffusion-dominated densification is dominant and one below 100 ᵒC where surface diffusion-dominated coarsening is dominant. An analytical model is developed by fitting the experimental data to the existing models of simultaneous densification and grain growth, and combining this model with existing models of the dependence of conductivity on grain boundary scattering and pore scattering. The combined model successfully describes the evolution of density, grain size and conductivity of nanoparticulate films as a function of annealing treatment, with reasonable accuracy. The model was also used to evaluate the effect of initial NP size and initial relative density of films on the final sintered properties and conductivity of films.
Study on selective laser sintering components with electrically conductive channels
(2001) Gibson, F.P.Y. Ting I; Cheung, W.L.
Electrically conductive channe ls were created using conductive carbon cement (CCC) by a simple non-contact continuous deposition method on sintered DuraFormTM Polyamide parts. The deposition system consisted of a drive circuit, a Micro Inert Solenoid Valve (MIV), a nozzle head and two liquid material reservoirs. Effect of CCC/solvent ratio, speed of deposition head and sintering condition of the Polyamide base material on the electrical properties of the conductive channels were investigated. The paper will then go on to discuss how these results relate to potential applications of Selective Laser Sintering (SLS) components with electrical property.