Tensile properties of calcium carbonate-reinforced poly(vinyl acetate)

In certain applications, a reinforced composite is used as an adhesive layer. In this study, the bulk mechanical behaviour of composite films based on a poly(vinyl acetate) (PVAc) matrix and various calcium carbonate (CaCO3) fillers was investigated. The interactions depend on the morphology and chemical structure of the filler and the polymer matrix. The polar natures of both PVAc and CaCO3 have a strong influence because of acid-base interactions. The tensile properties of PVAc/CaCO3 composites showed an increase in strength at break with increased filler concentration. The interactions can be modified by surface pretreatment of CaCO3 with stearic acid, which lowers the surface interaction and changes the degree of filler dispersion in the PVAc matrix. Micrographs confirmed the tendency of small CaCO3 particles to agglomerate and as a consequence, discontinuity of the composite film is observed. An effective surface treatment reduced the particle agglomeration tendency, which improved the film elongation at break. Quantitative determination of interactions was made by using various theoretical and empirical models which describe the composite mechanical behaviour dependence on the filler volume fraction.