Effect of calcium carbonate particle size and surface pretreatment on polyurethane composite Part I: interface and mechanical properties

摘要

In the present paper, the changes at interface between calcium carbonate (CaCO3) and polyurethane (PU) matrix in correlation to the mechanical and morphological properties were investigated. The effect of the untreated CaCO3 microfillers versus nanofillers and/or selected silane pretreatment of nanofiller surface were followed. Correlation between the calculated adhesion parameters i.e. interfacial free energy, thermodynamic reversible work of adhesion and coefficient of wetting, based on the measured surface free energies of pure components using the contact angle method, and composite properties was made. The lower surface free energy of the micro CaCO3 filler than the surface energy of the unmodified and silane modified nanofillers resulted in lower work of adhesion for PU/micro CaCO3 than for the PUano CaCO3 composites. These results implied weaker interactions in PU/micro CaCO3 than in the PUano CaCO3 composites followed by the lower tensile strength and failure at the interface.