engleski

Mathematical Modelling of the Composite Mechanical Behaviour

The additions of inorganic fillers to the polymer matrix affect the basic mechanical properties of the particulate-filled polymer composites. The tensile properties of the filled polymer composites are more difficult to predict because they depend strongly on the local polymer-filler interactions at the interface, as well as on the other factors. The poly(vinyl acetate) (PVAc) matrix filled with various fillers, such as calcite (CaCO3), silica and kaolin, used in adhesive compositions, were supposed as composites and investigated in the form of films. Several models have been proposed to quantify the influence of fillers on the interface interactions with the matrix. The effects on the composite interface of the filler particle size, chemical structure and filler surface pre-treatment, were also examined. Theoretical and/or empirical equations based on the ultimate tensile properties fitted more or less well with the experimental results of the relative stress dependence on the icreased filler volume fraction. The results showed that all factors which influenced the composite failure, that is matrix behaviour, critical influence of the filler, and interactions at the interface between the matrix and the filler, should be taken into account. The originally proposed equation, that described the dependence of the composite relative elongation to the matrix, on filler volume fraction, did not fit well with the experiments. In this paper other existing mathematical models were checked and extended to the relative elongation-filler volume fraction dependence to achieve a better fit with the experiments. The effects of various filler characteristics, including filler surface pre-treatment, may be followed through the interaction coefficients calculated from the appropriate model equations. The discussion of the model applicability, provides a quantitative view of the degree of interaction at the interface, between the PVAc matrix with various fillers. Considering the calculated interaction coefficients, several conclusions were drawn about the best model fitting in with the experiment and the physical meanings of the calculated coefficients. The predictions of the optimised adhesion between the PVAc matrix and the filler were made.

Adhesion between matrix and filler; filled composites; interaction coefficients; models of composite mechanical behaviour

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