Bryan Bilyeu (a), Witold Brostow (*,a) and Kevin P. Menard (b)

(a) Laboratory of Advanced Polymers and Optimized Materials (LAPOM), Department of Materials Science, University of North Texas, Denton, TX, 76203-5310, USA; and Department of Physics, University of North Texas, Denton, TX 76203, USA; brostow@unt.edu
(b) Perkin Elmer Instruments, 761 Main Ave. F71, Norwalk, CT 06987

ABSTRACT

Prepregs of a mixture of the tetrafunctional epoxy tetraglycidyl 4,4-diaminodiphenyl methane (TGDDM) and the tetrafunctional amine 4,4'-diaminodiphenylsulfone (DDS) were characterized with temperature-modulated DSC (TMDSC) as well as dynamic mechanical analysis (DMA). The baseline shift of the glass transition was separated from the curing exotherm by using temperature-modulated and step scan DSC temperature scans. Likewise, the baseline shift in heat capacity due to vitrification was isolated using TMDSC isotherms. Using the TMDSC glass transition temperature, degree of conversion and vitrification results, combined with the gelation data generated from DMA, a time-temperature-transformation (TTT) diagram was constructed, providing information necessary for optimization of industrial processing of the epoxy prepreg. Thus, effects of storage, preprocessing, and postprocessing on the overall curing process are taken into account.