Abstract

In this study, fly ash/polyurea (FA/PU) composites of various fly ash volume fractions were fabricated. The time-domain stress relaxation behaviors of pure polyurea and the FA/PU composites were measured by dynamic mechanical analysis (DMA) in tension mode at various temperatures. Both temperature and volume fraction of fly ash can affect the segmental motion of polyurea as well as the interaction between fly ash hollow spheres and polyurea matrix, which constitutes the intrinsic mechanism of stress relaxation. Master curves of relaxation modulus were constructed and compared for PU and FA/PU composites. A model was proposed to relate the relaxation modulus and volume fraction of fillers based on three-parameter fractional derivative model and Mori-Tanaka model. The numerical predictions obtained from the model are found to be in good agreement with the experimental results.

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