Measuring and understanding cure-dependent viscoelastic properties of epoxy resin: A review

The experimental determination of cure-dependent viscoelastic properties is of utmost importance for processing and use of epoxy (EP) resin-based materials and structures. Although this complex topic is frequently addressed in literature and in practice, no standards and few general guidelines for this task are available. Hence, a comprehensive review on rheological experiments and dynamic-mechanical analysis (DMA) including their preparation, conduction and evaluation was conducted. According to the results of our literature research, operators are well advised to rely on holistic test protocols that take care of the strong interaction between the curing process, the realistic device capabilities and the viscoelastic phenomena to be measured. We show that erroneous data or misinterpretations may occur if inappropriate measurement setups are employed. Methods for the prevention of both material- and device-related disturbances are suggested. Finally, remaining experimental challenges and future trends in the context of cure-dependent viscoelastic properties of EP are pointed out.