Elastomeric electronics

Oraby, W., and Walsh, W. K., "Elastomeric Electron Beam Cured Coatings Structure-Property Relationships. Part I. Oligomer Structure," J. Appl. Polym. Sci., in press. 

Fabrication of Single-Layer Passive Elastomeric Electronics... 

To achieve low stress embedding material, low modulus material such as siUcones (elastomers or gels) and polyurethanes are usually used. Soft-domain elastomeric particles are usually incorporated into the hard (high modulus) materials such as epoxies and polyimides to reduce the stress of embedding materials. With the addition of the perfect particle size, distribution, and loading of soft domain particles, low stress epoxy mol ding compounds have been developed as excellent embedding materials for electronic appHcations. 

Similar types of lamellar morphologies were observed for triblock copolymers of diphenylsiloxane and dimethylsiloxane having 40 wt% polydiphenylsiloxane, using electron microscopy, 47-148>. The lamellae thickness was approximately equal to the chain length of the rigid polydiphenylsiloxane blocks. These copolymers showed elastomeric properties comparable to those of conventional silica-reinforced, chemically crosslinked silicone rubbers. Tensile tests yielded an initial modulus of 0.5-1 MPa, tensile strength of 6-7 MPa and ultimate elongation between 400 and 800 %. 

Chattopadhyay S., Chaki T.K., and Bhowmick A.K., New thermoplastic elastomers from poly(ethyle-neoctene) (engage), poly(ethylene-vinyl acetate) and low-density polyethylene by electron beam technology structural characterization and mechanical properties. Rubber Chem. TechnoL, 74, 815, 2001. Roy Choudhury N. and Dutta N.K., Thermoplastic elastomeric natural rubber-polypropylene blends with reference to interaction between the components. Advances in Polymer Blends and Alloys Technology, Vol. 5 (K. Finlayson, ed.), Technomic Publishers, Pensylvania, 1994, 161. 

Anonymous, New silicone modified TPE combines best of both worlds, Elastomerics, 120, 28, 1988. Hill B., Industry s integration of environmental product design, IEEE International Symposium on Electronics and the Environment, Virginia, IEEE, 1993. 

Chattopadhyay, S., Chaki, T.K., Bhowmick, A.K., Gao, G.J.P., and Bandyopadhyay, S., Structural characterization of electron-beam crosslinked thermoplastic elastomeric films from blends of polyethylene and ethylene-vinyl acetate copolymers, J. Appl. Polym. Sci., 81, 1936, 2001. 

Sun, Y. Kumar, V. Adesida, I. Rogers, J. A. 2006. Buckled and wavy ribbons of GaAs for high-performance electronics on elastomeric substrates. Adv. Mater. 18 2857-2862. 

To assess the effect of elastomer degradation on composite performance, additional composites were fabricated with the same 121°C cure epoxy without any addition of the elastomer (211. The expansion behavior of the modified epoxy composite was similar to the toughened material. For electron doses less than 10 rads the CTE of the toughened and untoughened composites were essentially the same which suggests that the epoxy matrix and not the elastomeric component controls the thermal expansion behavior. 

Many published results on electronic transport properties of organic materials, where metal contacts are usually made by evaporation of metals, do not describe the quality of the organic/metal interface, and some exotic observed features may perhaps be ascribed to extrinsic effects such as metal diffusion. The relatively simple contact lamination technique may become an alternative, since it provides a means for establishing electrical contacts without the potential disruption of the organic material associated with metal evaporation. The method consists in bringing the organic layer into mechanical contact with an elastomeric element coated with a thin metal film, which can also be patterned. The contacts are robust and reversible... 

Furthermore, another advantage of nanofillers is not only to reinforce the rubber matrix but also to impart a number of other properties such as barrier properties, flammability resistance, electrical/electronic and membrane properties, and polymer blend compatibility. In spite of tremendous research activities in the field of polymer nanocomposites during the last two decades, elastomeric nanocomposites... 

The last contribution in the prevailing volume deals with the application of a relatively new class of materials based on the addition of (electron-beam) activated polytetrafhioroethylene (PTFE) powder in rubber matrixes for preparing PTFE-based elastomeric composites. Besides other properties, the remarkably lower friction coefficient of PTFE enables its utilization for tribological applications. However, PTFE in rubbers has not been fully explored mainly due to its inherent chemical inertness and incompatibility. The present work signifies the electron modification of PTFE powder to improve its compatibility with rubber matrixes, the state of the art regarding its application in rubbers, and the preparation of PTFE-based elastomeric composites for several tribological applications. 

A family of elastomeric foams has been developed by Rand 129) for use as stress relief coatings on electronic components in encapsulated electronic assemblies. Polysulfide, silicone and polyurethane elastomers blended with glass and phenolic microspheres have been used to formulate syntactic foams (Fig. 10) These foams are used to minimize the stress caused by differential thermal expansion between the component and the encapsulant. 

The materials obtained are extremely stable,43 because the electron pair of the phosphine structure has been donated to an oxygen atom. A final series of chains of this type are the poly(phosphorylamides). An example, the poly(phosphoryldimethylamide) chain, is shown in 6.48. These polymers have interesting elastomeric properties, but presumably are hydrolytically sensitive.42... 

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