From clay to strong and lightweight composite materials

(Nanowerk News) Scientists from 4 Asian universities, namely Sri Ramakrishna Engineering College, Universiti Teknologi Malaysia, Saveetha Institute of Medical and Technical Sciences, and Newcastle University in Singapore have reported a novel way to produce reinforced resin composite materials using clay particles with the potential to lower carbon emission compared to conventional carbon particles (Polymer Composites, "Montmorillonite nano-clay/unsaturated polyester composites").
The team, led by Dr. Umar Abdul Hanan (Universiti Teknologi Malaysia (UTM)), has successfully developed a method that uses montmorillonite (clay) particles to reinforce resin composites. 
Unsaturated polyester (UP) resin is a low cost thermoset with excellent processing ability and mechanical properties that finds applications in fiber-reinforced polymer (FRP) materials. It also crosslinks readily in the presence of a catalyst such ketone peroxide, forming an even stronger and stiffer resin.
Unfortunately, this also leads to lower fracture toughness. Several methods to enhance the toughness of the cross-linked resin have been proposed; one such method involved blending with nano-fillers made from rubber but this reduces the strength and stiffness of the resin.
Here, for the first time, the team has demonstrated that nano-clay composite made from unsaturated polyester (UP) blended with montmorillonite (MMT) nanoparticles of high compressive strength, stiffness and toughness could be achieved by optimising the filler content.
The blending process was straight-forward, involving a simple mechanical stirring and ultrasonic agitation process, followed by the degassing process in the vacuum gas chamber to remove air bubbles, and crosslinking the UP using methyl ethyl ketone peroxide. The optimisation process involved characterising the composite (pre- and post fracture) under a transmission electron microscope to quantify the dispersion of the MMT in the UP matrix.
This study demonstrated that the optimum weight fraction of MMT needed to maximise the compressive properties was around 0.60 wt%. In other words, about 99.4 wt% of the bulk comprised the UP; when applied in the environment, essentially the bulk appearance, and environmental influence on the composite material properties
The feasibility of this approach can open up the applicability of the load carrying capacity of the UP-MMT composites for greater load carrying structural applications. 
Source: Newcastle University in Singapore
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