Ever wonder why those 180°C temperatures?
Don't claim this is the answer, but maybe.
Wiki says PET's Vicat B (softening point) temperature is 170°C.
(FWIW: Wiki says the melting point is 260°C.)
(And the "Glass" point is 75°C - a limiting factor in EESU testing to 85°C?)
Wiki on Vicat B:
Vicat softening point or Vicat hardness is the determination of the softening point for materials such as polycarbonate, which have no definite melting point. It is taken as the temperature at which the specimen is penetrated to a depth of 1 mm by a flat-ended needle with a 1 sq. mm circular or square cross-section. For the Vicat A test, a load of 9.81 N is used. For the Vicat B test, the load is 49.05 N.
Standards to determine Vicat softening point include:
ASTM D 1525
The 180°C temperature important mostly for PET reasons (as well as other reasons)?
Also note, PET has amorphous and semi-crystaline states.
Possibly PET getting "poled", too?
Last edited Mon, 08 Jun 2009, 12:21am by nekote
Go DW Go - *economical* mass production