The mechanical properties of latex paint films containing different volume fractions of TiO2, CaCO3 and kaolin were measured in uniaxial tension over a broad range of temperatures and crosshead speeds. Young’s modulus results in the glassy region are first compared with several micromechanics theories for particle-filled composites containing elastic phases. It was found that the Mori-Tanaka theory [1, 2] slightly under-predicted the modulus enhancement, while the Lielens approach [3, 4] provided very accurate results. A nonlinear viscoelastic material model involving a Prony series and the neo-Hookean hyperelastic function was used to represent the tensile data up to relatively small strains (3-4%). Using the experimental data, the material model was calibrated and the parameters of the model were determined. The derived parameters were then used to re-construct time dependent shear modulus plots which were compared with the approximations given by Clements and Mas [5, 6] for the viscoelastic Mori-Tanaka theory in the time-domain. It was found that the experimentally observed modulus enhancement was much stronger than the predicted values in the rubbery region. This is attributed to the small particle size, the high level of constraint posed on the latex matrix at the particle interface or possibly the formation of a particle network.
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