Big potential for nanoparticles in buildings

 

Due to their
potential fire hazard, polymer-based building materials, other than paints, are
traditionally not commonplace on a building site. If researchers at the CSIR
have it their way, that is bound to change through the inclusion of clay
nanoparticles.

“The
addition of a relatively small amount of clay significantly improves the
mechanical and material properties of polymers,” says Professor Suprakas Sinha
Ray, chief researcher, polymer nanocomposites and leader of the CSIR-hosted
National Centre for Nanostructured Materials (NCNSM), one of the Department of
Science and Technology’s nanotech innovation centres.

“The comparison with pure
polymer materials or conventional filler-filled composite materials is quite
remarkable.” The “relatively small amount” that Sinha Ray is referring to is
exactly that. Researchers at the NCNSM have shown that the inclusion of just 2%
(in weight) of clay dramatically changed the inherent properties of composites –
including paints and coatings. Among others, the paint and coatings become both
UV and fire resistant, and it flows better or, as the scientists say, has
“improved rheological behaviour”. “The nano centre is currently negotiating the
transfer of the technology to a paint producer,” he says. Professor Suprakas
Sinha Ray and Manfred Scriba from the National Centre of Nanostructured
Materials

Small addition, major impact

According to Sinha Ray, researchers worldwide
are giving a great deal of attention to the addition of nanoclay particles into
polymer matrices to produce composite materials.

He explains: “This is because
the nanoclay particles improve the properties of those materials. For instance,
nanoclays can act as flame-retardant fillers by moving to the surface of the
polymer, forming a coating that acts as a heat shield.

In addition, as shown by
research at the NCNSM, chemically modified nanoclays may act as a binder 
between otherwise un-mixable polymers.”

Manfred Scriba, a senior researcher at
the NCNSM, comments on another way that nanoclays may impact on the building
industry. “By manipulating the surface
chemistry of nanoclay particles to facilitate proper dispersion and binding, we
are able to convert plastic waste into advanced composite materials for housing
components such as extruded window and door frames, and possibly even whole wall
panels. The particles also act as a fire retardant. Furthermore, by including
biomass such as wood or bamboo flour into the composite material, building costs
as well as the carbon footprint may be reduced.”

The commonly-used clays for the
preparation of nanocomposites belong to the same general family of 2:1 layered
or phyllosilicates. These layers are about one nanometre thick. “The secret,”
says Sinha Ray, “lies in the modification of the surface of these nano-layers or
nanoplatelets so that the nano-properties come to the fore when incorporated in
the paint or the plastic.”

Upscaling for industry

The NCSNM recently acquired a
piece of equipment that will greatly assist scientists’ efforts in developing
nanomaterials for industry use. This equipment, called a batch extruder, can
produce 30 kg of composite per hour. “This will allow us to upscale
laboratory-produced nanocomposites by producing small batches that can be tested
in extruders and injection moulding processes in industry,” explains Scriba. The
first product to follow this route will be bamboo and wood plastic composites
intended for housing components. – Petro Lowies