Rain Noe (AKA hipstomp) at Core77 ran a few articles last week that featured a rather interesting flavor of composite materials. What sounds like a contradiction in terms, polypropylene composites combine the ballistic properties we typically associate with traditional glass-fiber composites with the low density, high impact and abrasion resistance of polypropylene. Hipstomp’s first example is Tegris, a polypropylene thermoplastic composite developed by textile and chemical giant Milliken for use in lifesaving armor, NASCAR race cars and protective gear for NFL players. Baggage manufacturer Tumi is now using this material in their new Tegra-Lite collection, starting with a pair of carry-ons (above).
A few days after his initial post, Hipstomp was turned on to Pure, the same type of material manufactured by Dutch textiles manufacturer The Royal Lankhorst Euronete Group. In both products, this material starts with co-extruded tapes that consist of a highly oriented, high strength and high modulus polypropylene core and a specially formulated skin on both sides for welding the tapes together in a compaction process using a hot-press or continuous belt press. This tape can be used as-is or woven into fabric or sheets or laminated onto structural panels like foam or honeycomb substrates from which you can construct a wide range of products. But it’s this ability to mold this material by compressing and heating it so that it bonds to itself that I find so interesting.
Pure has a very nice illustration of this process:
One of the key advantages to considering this type of composite is that in addition to being strong and lightweight, these materials are 100% polypropylene (the inner PP fiber core and the outer layer of PP that is heat fused) and therefore can be fully recycled. This is in sharp contrast to traditional composites using a thermoset polyester resin to lock glass or carbon fibers together and can’t be re-melted or separated. They refer to this as a “mono-material concept” since heating the material to melt temperature results in just polypropylene resin.
Of course there will be times when you don’t want your composites to soften or melt under high-heat situations, but this new technology provides new opportunities for designers who think they need a composite, but are looking for a more sustainable solution.