Updated October 22, 2004
Acrylics - Plexiglas, Perspex - A generally useful material that is easily machined, although it has an annoying tendency to chip or shatter.
Delrin - Acetal Copolymer - Easily machinable, stronger than nylon. Black delrin is black because of they use carbon black as a filler. Obviously, this alters its electrical properties significantly.
Nylon - in virgin grades, a good insulator. It doesn't cold flow like Teflon.
Phenolic - Phenolic type "GPO3" is very tracking resistant. It is a red to pink polyester phenolic that is used in all kinds of HV electrical stuff. McMaster sells it somewhere but I can't find it at the moment... Polypropylene will burn up bad, but it is very resistant to failing in the first place that may indeed fix the problem ;-)) G-10 is nice for low voltage stuff but GPO3 is best of HV.
Polycarbonate - Lexan - Somewhat more expensive than acrylic, but it is much stronger although a bit softer. It doesn't shatter like acrylics do, which is why it is used for bulletproof windows.
Polychloroprene, aka, Neoprene, has a dielectric constant of 6.6 at 1kHz, 6.3 at 1MHz and 4.2 at 1GHz (p. 13-15), these numbers can vary with density, purity and degree of crystallinity, et. al. It has a dielectric strength kV/mm of 15.7 - 27.6 (p. 15-37, Handbook of Chemistry and Physics, 83rd 2002-2003 Ed.)
Polyethylene - Good dielectric properties, terrible mechanical ones. Sheets of low or high density polyethylene are used in making capacitors, insulating panels, and so forth. The higher density grades (e.g. UHMW - ultra high molecular weight) are useful as bearing surfaces at a substantially lower cost than teflon.
PTFE - Teflon - a great insulator and it has a really low coefficient of friction. It does cold flow, so it shouldn't be used where it is under static load.
PVC - a good insulator when virgin grade. It is soft, and gets even softer at a fairly low temperature, so don't use it for structural purposes. PVC pipe makes handy non-structural standoff insulators, and so forth.
Structural Fiberglass/Polyester composite- Extren - Structural fiberglass is an incredibly useful material. It is available in pretty much the same shapes as aluminum and steel (e.g. Angle, I-beam, square and round tubes, etc.). It can be used much like aluminum, in terms of density, strength, and cost. It is about twice as flexible as aluminum, and is noticeably weaker across the member (i.e. in shear), however, for construction of structures that have to take significant loads (i.e. cap banks, Marx generators, etc.) its insulating properties are a godsend.
KF Polymer Film has a dielectric strength of 10kV per mm, and a diel. constant of 9.8 at 60hZ. Here's a link to a data sheet on this in roll form for cap. construction: www.surplussales.com/rf/rfteflon-mylar_sht.html John.
KF-film is a trade name for capacitor dielectric that is made from PVDF-polyvinylidene fluoride. I have the dielectric constant just need to know the puncture voltage. This stuff is in a roll 773mm width and 1km in length. Have 3 rolls. Original poster: Rod and Pattu rstapivic@cfl.rr.com.
Starboard - July 3, 2004. Original poster: mck@ezy.net. Hello all, Every once in a while I work with a Marine material called Starboard that works nice for primary supports, etc. Its somewhat obscure (it comes in 60"by 90" sheets) but if anyone lives near a boat repair place they might be able to check and see if they have any leftover scraps. The stuff planes, drills, and cuts very nice. http://www.kingstarboard.com/newmain.htm Bill Mck.
Tesla List Comments Regarding Plastics
I've used both UHMW poly and black Delrin. They both seem to work even at power levels of 15 kVA. Dr. R.
June 20, 2004. Yes......UV does damage plastics. The white PVC plastic around my spark gap quickly turns yellow and LDPE becomes brittle, so your question about Lexan is valid. even teflon gets crumbly on the surface in time. I have not tested lexan . I suspect it acts like other plastics. Robert H.