composites | Materials
plant and was ramped up in the summer of last year with the commissioning of an industrial-scale facility. the carbon fibres are recovered from production
waste, including dry carbon fibre scraps and prepreg offcuts, as well as end-of-life parts. the sorted waste undergoes pyrolysis and refining steps prior to chopping or milling of the recovered fibres. the chopped fibres have lengths from 3 to 100 mm while the milled grades have a length of 120 microns. According to carbonXt, the resulting fibres have an excellent surface finish that increases adhesion levels with thermoplastics, including PA6 and Pc.
Above: Sabic’s carbon-fibre- filled Ultem PEI is being tested as a replace- ment for
aluminium in aircraft table arms
while most of the interest is in aerospace, defence
and energy applications, rtP expects to see a growing demand from automakers pushing for lighter weight, particularly as the cost of carbon fibres comes down. Sabic Innovative Plastics has also been working with
carbon fibres, creating new carbon-fibre-filled grades of its Ultem Pei resin. the new high-performance compound is designed to replace heavier die-cast and machined aluminium parts in aircraft interiors. the company is working with injection moulding company Vaupell to validate the material. it has produced prototype aircraft tray table arms that are 50% lighter and up to 40% stronger than die-cast aluminium versions. other potential applications include armrests, footrests and galley items. two specialty compounds have been developed: lnP
thermocomp ec006PXQ contains 30% by weight chopped carbon fibre, while ec008PXQ contains 40%. Both are about 50% lighter than aluminium, have tensile strength greater than that of die-cast aluminium (7075-o) and their strength-to-weight ratio is compara- ble to machined aluminium (7075-t6). the tray arms made with the materials exhibited
Far right:
Teijin’s high- performance aramid fibres now come in black as well as yellow
30
outstanding load-bearing capacity as high as 213 lb (97 kg), says the resin maker. results showed that tray arms made with the 40% carbon fibre-filled material provide better stiffness and lower deflection with good load-bearing capacity; tray arms made with the 30% carbon fibre-filled material provide even greater load- bearing capacity but with some compromise in stiffness and deflection. the weight savings were 46% and 44% respectively and cost savings of up to 77% can be realised compared to aluminium, according to Sabic. A relatively new source of chopped carbon fibres is
CarboNXT in Germany. it provides 100% recycled materials sourced from its sister company, cFK Valley Stade recycling – both are subsidiaries of the Karl Meyer Group. Production started in 2008 using a pilot-scale
injection world | january/February 2012
www.injectionworld.com
Aramid turns black Until now it’s usually been easy to distinguish between carbon and aramid fibres, with one being very black and the other a distinct shade of golden yellow. However, Teijin Aramid has just started production of what it claims to be the first all-black high-performance aramid fibre. called twaron Black, the new grade was launched last month. the company’s manufacturing process has been
adjusted to inject the fibre with a black dye during the process, which ensures that the threads become completely black. Mechanical properties are said to be the same as the traditional yellow fibres. teijin Aramid ceo Gert Frederiks says: “with twaron Black, it is possible to combine the special characteristics of the aramid fibre with a beautiful look. Black aramid fibres have already been produced in the world, but they do not have the same characteristics (modulus) as the standard twaron aramid fibre.” the new development was driven by customer
requests from the sailing and sports industries. Aramid fibres are frequently used in combination with carbon fibre in sporting goods. “For example, you often see the golden-yellow of aramid in sails on a professional yacht or the underside of a canoe,” explains Frederiks,
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