Temperature-dependent elastic moduli of epoxies measured by DMA and their correlations to mechanical testing data

Abstract

Measurements of temperature-dependant elastic moduli of two cured epoxy systems and two silica–epoxy nanocomposites were conducted using dynamic mechanical analysis (DMA) methods with different loading fixtures. Comparisons of the results were made with those obtained from tests with different loading modes and from mechanical testing results under various temperatures. Discrepancies were found between the temperature-dependant elastic moduli measured by DMA with different loading modes and varying test conditions, such as machine compliance, drive amplitude, loading frequency and contact stresses, although the specimen-to-specimen deviations were relatively small between specimens tested with the same fixture and similar test parameters. However, the elastic moduli obtained from DMA measurements can be used to represent the temperature dependence of elastic modulus once corrections are made based on the static mechanical testing data obtained at ambient temperature. Although there were discrepancies in magnitude between the original temperature-dependant elastic moduli determined by DMA and those measured by mechanical tests, very good agreement was found for the two epoxy systems and two silica–epoxy nanocomposites after the DMA data were shifted.