THERMODYNAMIC FUNCTIONS OF THERMOSETTING POLYMERS
Abstract
The increase in entropy ( S) and in enthalpy ( H) of a number of amorphous thermosetting polymers have been calculated from specific heat (Cp) data over the temperature range 298 degrees K (25 degrees C) to 433 degrees K (160 degrees C). The polymers studied included epoxies, a polyester, a polyamide-epoxide copolymer, and diallyl phthalate. At the glass or second order transition temperature (Tg), the plots of entropy vs. temperature exhibit small changes in slope. The enthalpy vs. temperature plots are slightly curved and are characteristic of amorphous solids. Plotting the slope of the entropy curve Cp/T) vs. temperature offers a sensitive way of locating the glass transition temperature, but is little better than the Cp curve for locating Tg when applied to thermosetting polymers. These data may be useful to those engaged in deciding whether the glass transition is a relaxation process or a thermodynamic transition. The entropy and enthalpy data are discussed in relation to the overall structure of the polymers. (Author-PL).
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 07, 1960
- Accession Number
- AD0248281
Entities
People
- M.c. Petree
- R.w. Warfield
Organizations
- Naval Ordnance Laboratory