Abstract:
A fast growing interest in applying nanomaterials in various fields has been observed
in recent years. Nano-silica is one of the widely used nanomaterials in adhesives,
fiber optic strands, sealants, surface coatings, defoamers, cosmetics, food additives,
cement-based building materials and rubber composites. As an agricultural country,
Sri Lanka produces tones of paddy husk annually. The benefit of using paddy husk
has been identified in many applications. Paddy husk is burnt to generate energy
resulting paddy husk ash (PHA). PHA is rich in silica (-60 %) and can be an
economically viable raw material for the production of nano-silica through chemical
method as a value added product. Also Sri Lanka has highly pure vein quartz (~98%)
which can be converted in to nano-silica. In this research, nano-silica was prepared
by precipitation method from both PHA and vein quartz and characterized by various
analytical techniques. Scanning electron micrographs showed that nano-silica
particles from both resources were in the agglomerated form (primary particle size
50-70 nm). The particle shape was found to be spherical. X-ray diffractograms
showed a strong broad peak at 22 ° (2G) indicating that the obtained products from
both starting materials were amorphous and also the Infrared spectra data supports
the presence of hydrogen bonded silinol groups and siloxane groups in silica. Silica
nanoparticles were surface modified by oleic acid and characterized using TGA and
FT-IR techniques.
Reinforcing ability of the synthesized nano-silica from PHA (NS) in natural rubber
composites (NRNS) was investigated. Cure characteristics and mechanical properties
of the NRNS nanocomposites were compared with that of commercial grade silica
(PS) reinforced natural rubber composites (NRPS) and it was found that NS has
lower reinforcing ability compared to that of PS.
