right). Both polypropylene and high- density polyethylene matrices with the carbon nanotube fillers out perform aluminum in specific energy absorption, making them candidates for applications in industries like automotive. Photo Credit: University of Glasgow Polypropylene (PP) and high-density polyethylene (HDPE) are two widely used polymers that are low cost, widely available, easy to process, reusable, resistant to solvents and have other benefits, but, as a team of researchers led by engineers at the University of Glasgow (Glasgow, U.K.) point out, the materials have an “unsatisfying impact behavior [low impact strength and penetration resistance]” — which they have addressed by developing a plate-lattice cellular metamaterial that uses multiwall carbon nanotubes (MWCNTs) in the polymer matrix.