Specific heat (Cp) for liquid epoxy?

[RPstress]

Does anyone have a data source for the specific heat (aka Cp, units J/kelvin/cc, etc.; any units welcome) of epoxy while it's liquid?

The ever unreliable Internet has given me values from 1.1 to 1.9 J/K/cc for the solid stuff, and I found this paper at
lib.physcon.ru/download/p1261.pdf
However, that's about it.

(We're trying to estimate times/temperatures for heating up an RTM resin from 100 deg C to 165 deg C.)

At this stage even approximate values would help; however, there seems to be very little out there.

 

[Compositepro]

Most are in the range of 0.4 to 0.5 cal./gram. For your purpose use 0.5 to be conservative. Interestingly most metals are around 0.1 cal./gram. Resins also have very low thermal conductivity. The ratio of thermal conductitivity divided by heat capacity is known as thermal diffusivity and tells you how fast heat will travel through a material by conduction. Resins have very low thermal diffusivity.

Natural or forced convection (mixing while heating) is usually the main mode of heat transfer in resins because diffusivity is so poor.

Equipment that is designed to quickly melt resins will contact the resin with a heated surface and then wipe the melted film away from the surface so that more resin can be exposed to the heat transfer surface. Rotating heated rolls with a small gap between the rolls is one example.

Heated follower plates that lower into cans of resin are used on some RTM equipment. Raptor Resins makes BMI (bismaleimide)RTM and VARTM resins that is supplied in cans and they have instructions on the best way to melt resins. You can request a copy by writing to:
support(at)raptorresins.com (of course change at to @).

 

[GTwigg]

A good PhD thesis which I often reference for the hard to find thermal properties is: "AN INTEGRATED MODEL OF THE DEVELOPMENT OF PROCESS-INDUCED
DEFORMATION IN AUTOCLAVE PROCESSING OF COMPOSITE STRUCTURES", ANDREW A. JOHNSTON, UBC, 1997.

His experiements yielded the following:
CPr = 2790 J/kgK - 3.80 J/kgK°C * T (°C) for T > Tg

 

[RPstress]

Many thanks both. That's given us a bit of confidence that we're in the right ballpark.