Silica-Polyester Nanocomposites Prepared by Polycondensation In Situ: Synthesis and Mechanical Properties

New multiblock polymer-matrix nanocomposites were prepared by the in situ polycondensation. Polymers containing 30% hard segments of poly (butylene terephthalate) (PBT) and 70% soft segments built up from dimerized fatty acid (DLA), were modified with silica nanopowder. The nanocomposite materials were prepared by polycondensation in situ with the use of two different catalysts. Two types of nanosilica (Evonic Aerosil R 972 hydrophobic, and Aerosil 130 - hydrophilic) in amount of 0.1, 0.2 and 0.3 wt. % were used. Physical and mechanical properties were examined. The results indicate a strong influence of transesterification stoichiometry and type of catalyst on physical and mechanical properties. The amount of nanofiller and its character (hydrophilic or hydrophobic) showed also an influence on mechanical properties of synthesized nanocomposites indicating the best mechanical properties for nanocomposite containing 0.1wt% hydrophobic silica nanopowder (over 70% increase in elongation and 30% increase in tensile strength).