Nanoparticle surface polarity influence on the flow behavior of polymer matrix composites

The influence of three different nanosized titanias with opposite surface polarity and different particle morphology, dispersed in an unsaturated polyester matrix, on the resulting composite flow behavior was investigated systematically. In addition the maximum filler load was estimated by use of established empirical models. It is known from composites containing microsized particles that a surface polarity conversion from a hydrophilic to a more hydrophobic character allows higher solid loads due to a pronounced viscosity reduction. In this work it was derived from viscosity measurements that a large hydrophobic nanoparticle surface area caused a pronounced attractive interaction between the filler and the polymer matrix reducing the maximum accessible filler load in contrast to a similar hydrophilic nanoparticle. For comparison a highly agglomerated hydrophilic nanosized titanium dioxide with very large specific surface area was investigated also, the large agglomerates with particle sizes in the micrometer range allowed higher solid loads in contrast to the both “real” nanosized titania. POLYM. COMPOS., 34:1425–1432, 2013. © 2013 Society of Plastics Engineers