Enhanced electrical properties

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Jiang, L. and Gao, L., Carbon nanotubes-metal nitride composites a new class of nanocomposites with enhanced electrical properties , J. Mater. Chem., 2005, 15(2), 260-266. 

N. Gopal Sahoo, Y.C. Jung, HJT. So, and J.W. Cho, Polypyrrole coated carbon nanotubes Synthesis, characterization, and enhanced electrical properties, Synth. Met., 157,374—379 (2007). 

The addition of rigid particles into the polyolefin matrix can result in a number of desirable effects on the composite including increased stiffness, improved flame retardancy, and enhanced electrical properties. 

Based on the above analysis and interpretation, we can tentatively propose the morphological criteria for enhanced electrical properties (i) semiconducting phase in composite should be morphologically continuous (ii) in order to supply enough tv o-phase interfacial area, the phase separation of SP/IP composite should be on the nanometer scale. These criteria can be used to conduct the further optimization of SP/IP composite for electronic application. 

Materials with Enhanced Electrical Properties. The resin and the reinforcement determine the D], and tan 5 of a composite material. Standard FR-4, made up of epoxy resin and woven glass, has a Dt in the range of 4.0 to 4.4 and a tan 8 of 0.02. This may be reduced somewhat by replacing some or all of the epoxy resin with PPO, cyanate ester, or PTFE. Further reductions require replacing the glass reinforcement, which contributes a Dt of 6.0 to the effective D of the system. 

The calcined clays are considerably harder than their hydrated counterparts but they impart better electrical properties to both thermosetting compounds and thermoplastics. Clay is also of particular use in fibre-filled epoxides, where its plate-like structure and viscosity increasing properties prevent fibres blooming or appearing at the moulded surface. Calcined clay is used to increase volume resistivity in the formulation of electrical laminate type compounds. A hydrophobic surface treated version of calcined clay is available for applications where enhanced electrical properties are required even under humid conditions. 

Commercial fluoropolymers are based on TFE, vinylidene fluoride, and, to a lesser extent, CTFE. Examples of other comonomers include perfluoro-methyl vinyl ether, perfluoroethyl vinyl ether, PPVE, HFP, CTFE, and perfluorobutyl ethylene. The general consequences of the substitution of fluorine for hydrogen in a polymer include increased chemical and solvent resistance, enhanced electrical properties such as lower dielectric constant, lower coefficient of friction, higher melting point, increased photostability and thermal stability, improved flame resistance and weakened mechanical properties. The ultimate, most useful and sought-after properties are achieved in perfluorinated polymers. 

A number of useful cross-linkable or thermosetting plastics are available. When cross-linked, these materials tend to be stiff, but with poor impact strength and low elongation. Normally reinforcing fillers have to be incorporated into the polymers to produce strong, useful materials, known as composites. Selected fillers can be also used to enhance electrical properties, such as volume resistivity, or to reduce the cost of the compounded polymers. Cross-linked polymers used in large volumes include ... 

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