Phenolic looks like wood but is made by impregnating paper, canvas, linen, or woven glass with thermoset resin. There are different types or grades depending on what reinforcing material is used. You may see it in some older switch gear - it is primarily used as an electrical insulator but has good mechanical properties and it is machinable. It's a fair thermal insulator as well and can withstand temps up to 250~280F.
Check with a local plastics supply house. For more info see:
www.usplastic.com
I plan to use pieces of phenolic as insulating structural members between the therm die body and outer housing, filling the cavity with ceramic insulation. I may also cap my therm die sim with a plate of phenolic, which will provide a rigid, insulated deck for mounting waterblocks and heatsinks.
Hopefully I will be able to devote more time to projects this winter as the weather closes in.
Vacuum sounds interesting but sorta over-kill to me for dealing with secondary losses. I would think the challenges of sealing and insulating around the exposed die surface would negate any slight advantages. Even with vacuum you still need some kind of structural support, which might conduct far greater losses than what you would save using vacuum vs. a more conventional insulation???
Anyway, sounds interesting and good luck...
