| Abstract: | A series of epoxy resins derived from diglycidyl ethers of bisphenol A with differing initial linear molecular chain lengths have been studied during and after curing with the diamines MDA (4,4′-methylene dianiline) and DDS (4,4′-diamino diphenyl sulfone). The properties that were measured during curing were the volume, the fictive temperature Tf, the gel fraction, the viscosity, and the equilibrium compliance. Graphs of Tf as a function the time of curing tc obtained at four curing temperatures between 40 and 100°C have been reduced to a common curve. After curing, creep compliance curves J(t) were determined which characterize the viscoelastic response from the glassy compliance level to a rubbery equilibrium compliance level. The change in properties that occurs during the time-dependent spontaneous densification below the glass temperature Tg was monitored with repeated measurements of J(t). Time-scale shift factors as a function of volume contraction obtained during this physical aging below Tg were reduced to a common curve. |
