Guidelines for performing storage modulus measurements using the TA Instruments DMA 2980 three-point bend mode

An experimental study of the effects of oscillation amplitude on the elastic storage modulus, E′, for a rigid thermoplastic measured using three point-bending is presented. The results are part of a wider investigation on the operating conditions needed to improve repeatability and reproducibility of E′ measurements for the recently commercialized TA Instruments 2980 Dynamic Mechanical Analyzer. It has been found that sample alignment is required to achieve reliable E′ values. Based on experiments performed on polycarbonate at 1 Hz using a span-to-thickness ratio of 11, 17 and 33, respectively, the optimum amplitude for obtaining the lowest standard deviation under ambient conditions is found to be about 100 μm. It is also found that a span-to-thickness ratio of