Surface modification of silica with a hydrophilic polymer and its influence on reinforcement of natural rubber latex

Abstract

: Surface modification of precipitated silica particles
was carried out in both aqueous and non aqueous media
separately with a polyacrylic based hydrophilic polymer
synthesized in the laboratory. FTIR spectroscopy and thermo
gravimetric analysis of the modified and unmodified silica
particles were performed to confirm successful surface
modification. Colloidal stability of the aqueous dispersions
of the unmodified/modified silica particles were observed
at different pH levels. The dispersions at neutral pH were
incorporated in different proportions to un-compounded
and compounded natural rubber latex (NRL) separately
and thin latex films were produced from them by casting.
Dispersability of silica particles within the rubber matrix was
examined through microstructure studies of films cast from
unmodified/modified silica incorporated un-compounded
NRL. The influence of surface modification upon the
reinforcement of NRL was investigated through tensile and tear
strength properties of vulcanized NRL cast films containing
modified silica. The uniform dispersion of silica particles
and the improved mechanical properties envisaged better
compatibility of modified silica particles with NRL by means
of interfacial interactions. A significant improvement in the
mechanical properties was observed in the films produced with
5 – 7 phr of modified silica.