Development of a PVT Apparatus for Thermosetting Resin and Its Application to an Epoxy Resin

A bellows type PVT apparatus was developed to obtain PVT data of thermosetting resin during cure. The apparatus uses a stainless capsule and FEP (fluorinated ethylene propylene) film in its sample cell to realize easy handling of liquid resin and measurement without any anisotropic strain. The temperature controlling system of the apparatus almost eliminates overshooting and hunting, which might cause troublesome noise for measurement of reactive systems such as thermosetting resins. With this apparatus the specific volume of an epoxy resin during cure was studied. The resin system is diglycidyl ether of bisphenol-A mixed with diethyltoluenediamine. The cure cycle is a two-step cure of 353-453K. In the cure cycle in which resin is kept at 353K for 15h, an increase in specific volume by postcuring was observed. By comparing with DSC measurements, a proportional relationship between cure shrinkag and heat generation during isothermal cure, and correspondence between the volume-temperature relationship and enthalpy-temperature relationship of resin in physically aged glass state were observed.