Silicon filled polyethylene

The First plastic sabots were made of glass-fiber filled diallylphthalate sheathed in nylon and they included metal reinforcements whenever it was felt necessary to redistribute the stresses. The nylon sheath was necessitated by the abrasive nature of glass-filled materials. Nylon also is used for rotating bands on projectiles and on metal sabots. Other plastics used for the structural portions of sabots include poly propylenes, polycarbonates, celluloses, epoxies and phenolics. Polyethylene, neoprene, and silicone rubbers are used for seals and obturators... 

Adsorption of Hg nuclides on silicon detectors, as in the successful experiment with Hs04, proved experimentally not feasible, since Hg was adsorbed on quartz surfaces only at temperatures of -150 °C and below. However, Hg adsorbed quantitatively on Au, Pt, and Pd surfaces at room temperature. As little as 1 cm2 of Au or Pd surface was sufficient to adsorb Hg atoms nearly quantitatively from a stream of 1 1/min He. Therefore, detector chambers containing a pair of Au or Pd coated PIPS detectors were constructed. Eight detector chambers (6 Au and 2 Pd) were connected in series by Teflon tubing. The detector chambers were positioned inside an assembly of 84 3He filled neutron detectors (in a polyethylen moderator) in order to simultaneously detect neutrons accompanying spontaneous fission events, see Figure 27. 

In general, plastics are superior to elastomers in radiation resistance but are inferior to metals and ceramics. The materials that will respond satisfactorily in the range of 1010 and 1011 erg per gram are glass and asbestos-filled phenolics, certain epoxies, polyurethane, polystyrene, mineral-filled polyesters, silicone, and furane. The next group of plastics in order of radiation resistance includes polyethylene, melamine, urea formaldehyde, unfilled phenolic, and silicone resins. Those materials that have poor radiation resistance include methyl methacrylate, unfilled polyesters, cellulosics, polyamides, and fluorocarbons. 

Figure 5.9 Supercritical fluid assisted processing of filled polymer compositions. Blend of 50% by volmne silicon nitride/polyethylene extruded at 180 °C...

Several workers have proposed new combinations of materials in an attempt to overcome wear. Studies involving polyimides, polyamide-imides, and poly-tetrafluoroethylene-filled polyoxymethylene demonstrated that although wear characteristics were good in dry conditions, the presence of lubricants (blood plasma, water) decreased the wear resistance. Results obtained with reinforcing materials such as carbon fibre and with an aluminium oxide ceramic ball used in conjunction with a polyethylene socket have been presented, Examples of other types of reconstructive surgery involving hard tissue replacement are the use of poly(methyl methacrylate) in chest wall reconstruction and repair of depressed skull fractures, the repair of major crano-orbital defects with the aid of a polyurethane-coated poly(ethylene terephthalate) mesh, and the use of silicone rubber in total finger joint and carpal bone replacement. 

Takala M, Ranta H, Nevalainen P, Pakonen P, Pelto J, Karttunen M, Virtanen S, Koivu V, Pettersson M, Sonerud B, Kannus K (2010) Dielectric properties and partial discharge endurance of polypropylene-silica nanocomposite. IEEE Trans Diel Electr Insul 17 1259-1267 Tanaka T, Kozako M, Fuse N, Ohki Y (2005) Proposal of a multi-core model for polymer nanocomposite dielectrics. IEEE Trans Diel Electr Insul 12 669-681 Vaughan AS, Swingler SG, Zhang Y (2006) Polyethylene nanodielectrics the influence of nanoclays on structure formation and dielectric breakdown. Trans lEE Jpn 126 1057-1063 Venkatesulu B, Thomas MJ (2010) Erosion resistance of alumina-filled silicone rubber nanocomposites. IEEE Trans Diel Electr fiisul 17 615-624 Weibull W (1951) A statistical distribution function of wide applicability. J Appl Mech Trans ASME 18 293-297... 

Dey, T.K. andTripathi, M. (2010) Thermal properties of silicon powder filled high-density polyethylene composites. ThermodurrUca Acta, 502, 35-42. 

Fig. 12. Effect of temperature and frequency on electric strength of (a) mica-filled phenolic resin (b) glass-silicone Ifiminate (c) polytetrafluoroethylene and (d) polyethylene.

---