The relationship between nanosilica dispersion degree and the tensile properties of polyurethane nanocomposites

LEONEL MATIAS CHIACCHIARELLI; I. PURI; D. PUGLIA; J. M. KENNY; L. TORRE

COLLOID AND POLYMER SCIENCE

SPRINGER

Lugar: Berlin; Año: 2013 vol. 291 p. 2745 - 2753

0303-402X

The tensile properties and structure of silica based Polyurethane (PU) nanocomposites were parametrically studied as a function of silica type and weight concentration, Polyol OH number and mixing methods. The variation of the silica functionalization groups (from silanols to silazanes) had a relevant effect on dispersion. An elevated inter-particle distance of the silica agglomerates improved substantially the tensile strength (up to +87%) and strain to failure (up to +115%) with respect to the neat PU matrix. Polyol?s with different OH numbers dramatically modify the silica dispersion degree by the modification of the stability of the colloidal dispersion. An increase of its value deteriorated dispersion and the tensile properties of the nanocomposites. The effect of three dispersion methods (ultrasonic dispersion, high shear mixing and tip sonication) has shown to have a relative effect on the reduction of agglomerate size and the interparticle distance. High power sonication methods were more effective in reducing agglomerate size in contrast to shear methods. Classical theories of colloidal dispersion (DLVO) have been able to explain the correlation between the silica aggregation state and the final tensile properties of the nanocomposite.