JEC COMPOSITES MAGAZINE - Issue #122 - July 2018 - 61

Conductive glass fibre products using single-wall carbon nanotubes

Fig. 4: SEM
micrographs
of singlewall carbon
nanotubes and
carbon black

Fig. 3: Expected improvement of mechanical
properties through TUBALL
nanotubes

SWCNTs can prevent or redirect crack development due to their record-breaking strength. This nanotube property reinforces the polymer
matrix and enhances its crack resistance.
OCSiAl, with its unique technology for mass SWCNT production, is
the first company to make their application technologically feasible and
economically viable in a wide range of industries. The company has
been selling TUBALL™ nanotubes since 2014 and has developed nanotubes-based concentrates. Their unique TUBALL™ MATRIX concentrates can increase the effectiveness of nanotube applications, making it
considerably easier to work with nanotubes and preserve the formulation and technology for producing the composite materials. Depending
on the type of cloth, binder, composite moulding method, nanotube
introduction method, and concentration of nanotubes, several properties can be expected to improve: interlaminar shear strength, fracture
toughness, bending strength, tensile creep, fatigue strength under cyclic
tension, damage resistance and compression after impact.
Most of these properties are primarily dependent on the polymer matrix and the adhesion between the matrix and the composite fibres. The
properties can be controlled by reinforcing the polymer matrix with nanotubes.
Anti-static properties in glass fibre composites
SWCNTs are widely used as a conductive additive to impart anti-static and ESD properties to composite materials. Due to their high
length-to-diameter ratio (> 2,500), nanotubes can create a three-dimensional conductive network even at ultra-low concentrations, which
in turn makes it possible to preserve the colour of the material, to avoid
the degradation of physical and mechanical characteristics, and even to
achieve reinforcement of the material. The conductive network creates
uniform and permanent volume and surface resistivity without any dangerous "blind spots", which are typical of most widespread additives.
Depending on the specifications, TUBALL nanotubes can impart conductive properties in the range of 109-103 Ω to the most widespread
thermoset-based systems: epoxy, vinyl ester, polyester, polyurethane,
acrylic, melamine and phenolic.
In late 2016, the European Pipe Factory (all the names of the partners
are covered by NDA) started mass production of the world's first an-

ti-static glass fibre pipes with SWCNTs. To impart anti-static properties
to composite pipes, manufacturers traditionally apply anti-static paint
over glass fibre pipes, which cause several technological and operational
problems. Adding TUBALL nanotubes to the resin enables the plant to
impart volume and uniform conductivity to glass fibre, which is critical
for lowering the risks of accidents at explosion-prone production facilities, such as in the coal industry. In addition, adding nanotubes resulted
in a 15% increase in the strength of anti-static pipes, which in turn allowed an increase in the maximum operating pressure.
In 2017, another European company, a waste treatment system manufacturer, successfully tested OCSiAl's SWCNTs and started mass production of anti-static glass fibre tanks for oil waste storage and transportation and for oily wastewater treatment and pumping.
By adding just 0.2 % TUBALL™ MATRIX concentrate to the polyester resin, the company was able to manufacture glass fibre tanks with a
uniform resistivity of 105 Ω*cm. Nanotubes enabled the manufacturer
to improve its products in accordance with safety requirements for oil
waste storage, while streamlining the tank production process.
Glass fibre reinforcement with nanotubes
SWCNTs are increasingly often used as a reinforcing additive in various
types of composite materials. Depending on the type of resin, production method and several other parameters, they can significantly improve the characteristics that affect the polymer matrix properties and
its adhesion to the fibre. As a result, the material's bending strength, interlaminar shear strength, damage resistance, impact resistance, as well as
several other key characteristics, are enhanced.
Improved fatigue strength and increased creep resistance in composite products are one of the most promising applications of SWCNTs.
Nanotube applications are determined by their ability to improve the
technical and performance features of composite materials. For example, PolyCompozite LLC, one of the largest manufacturers of composite
materials in Russia, is planning to market composite rebar reinforced
with TUBALL SWCNTs.
Metal corrosion, which eventually leads to the destruction of reinforced
concrete bearing structures, is one of the key drawbacks of steel rebar.
Composite rebar made up of glass, basalt, carbon or aramid fibres imN°122 July 2018

/ jec composites magazine

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Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #122 - July 2018
