Epoxy-silicone compositions

Fig. 7,2. Fracture toughness, R, of Kevlar 49-epoxy matrix composites (a) under varying strain rates in three-point bending and (b) at different temperatures under impact loading (O) uncoated fibers (0)41%, (Q) 63% and ( ) 100% Estapol coated fibers (A) silicone vacuum fluid (SVF) coated fibers. After Mai...

Fig. 7.4. Fracture toughness (O) and flexural strength ( ) of silicone rubber coated carbon fiber-epoxy matrix composites as a function of coating thickness. After Hancox and Wells (1977).

Although a majority of these composite thermistors are based upon carbon black as the conductive filler, it is difficult to control in terms of particle size, distribution, and morphology. One alternative is to use transition metal oxides such as TiO, VO2, and V2O3 as the filler. An advantage of using a ceramic material is that it is possible to easily control critical parameters such as particle size and shape. Typical polymer matrix materials include poly(methyl methacrylate) PMMA, epoxy, silicone elastomer, polyurethane, polycarbonate, and polystyrene. 

Rigid composites are obtained by mixing graphite powder with a non-conducting polymeric matrix into a soft paste that becomes rigid after a curing step [52,53]. They could be classified according to the nature of the binder or the polymeric matrix into epoxy composites, methacrylate composites or silicone composites. 

Fig. 24. Time dependence of conversion p (p — open marks, p — full marks) of the system epoxy silicone oligomer — PBTPh (composition 100 7.5) at curing temperatures (°C) of 140 (IX160 (2), 180 (3), 193 (4), 200 (5), 220 (6) [106,127]...

Polymeric substrate materials in use include highly filled phenolic and epoxy resins for rigid printed circuit boards, polyimides and polyesters for circuit substrates as well as for more general applications, special foamed poly(tetrafluoroethylene) polymers and copolymers, foamed composite materials of the latter, special epoxy fiberglass composites, and polyimide support layers for TAB. In addition, epoxies and silicone polymers are used increasingly in applications as encapsulants, as humidity and environmental barriers within packages, and as packaging materials themselves. 

Ali Raza, M., Westwood, A., Stirhng, C., Brydson, R., Hondow, N., 2012. Effect of nanosized carbon black on the morphology, transport, and mechanical properties of rubbery epoxy and silicone composites. Journal of Applied Polymer Science 126 (2), 641-652. 

A part, consisting of a carbon fiber composite tube, was initially adhered to the inside of a short titanium coupling by a silica-filled epoxy. The bond failed and a fluorinated mold release was believed to be the cause of the failure and was the purpose for this investigation. A sample of the epoxy (Sample A) and the part (Sample B) were submitted for X-ray photoelectron spectroscopy (XPS) to analyze for the presence of both fluorine and silicon. 

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