Thermomechanical properties of advanced epoxy composites

Advanced epoxy¿fibre composites provide high performance in their time-temperaturemechanical properties. A selection of thermomechanical techniques was applied using static, dynamic and modulated force, and modulated temperature to reveal creep, storage and loss modulus, reversing and non-reversing properties. Cure, ageing, thermal expansion, creep, recovery, elasticity, damping, thermal transitions, thermal activation and isotropic properties are distinguished and compared by combining technique from the one instrument family. Emphasis is placed upon modulated temperature thermomechanometry (mT-TM) under constant stress to determine reversing and non-reversing deformations. Multi-frequency measurements were made with either a series of discrete frequencies with a step temperature program, or a complex synthetic frequency with a linear temperature program, followed by Fourier deconvolution of the individual frequencies. The epoxy¿fibre composites may exhibit residual cure and thermal aging. They exhibit a glass transition temperature with Arrhenius activation and WLF frequency(time)¿temperature¿superposition leading to plateau, transition and terminal viscoelastic regions.