Effect of a filler on the long‐term mechanical behavior of an epoxy matrix/mineral particle composite

Abstract An analysis is provided for the continuous relaxation and retardation spectra of epoxy matrix composites filled with different amounts with marble micro‐particles. The particle size distribution is characterized by the diameter sampling medium d₅₀ = 13 μm and the sampling quantile d₉₇ = 80 μm. The concentration of this filler was 10, 29 and 44.5 vol%. The creep compliance and the relaxation modulus were determined from experimental results. Alfrey's method is used to define the continuous spectra from these long‐term (10³ days) creep and stress relaxation data. A polynomial approximation is applied to the analytical form of the results. The influence of the filler fraction on the spectra's distribution and on the equilibrium values of relaxation moduli and creep compliances is discussed. The application of discrete relaxation and retardation spectra and the mutual transition between them are demonstrated using a Laplace transform.