High-flow PBT aimed at cars

GE Plastics has developed a family of high-flow polybutylene terephthalate (PBT) materials.
Its Valox super sigh flow resins, available as glass- and mineral-filled grades, should help moulders – particularly in the automotive industry – make thinner parts with greater detail using lower injection pressures.

GE claims that the material’s flow – the ease with which it fills an injection moulding tool – is twice that of standard PBT grades. It has achieved this by adding a proprietary additive to the PBT.
There is a growing trend towards making thinner and lighter parts. One option is to combine multiple functions into a single component, which saves space and allows car makers to pack in extra features.
“Although these challenges appear unrelated, they are all about enhancing vehicle appeal by meeting the demands of today’s consumers for greater fuel efficiency and added features,” said Vikram Gopal, global crystalline programme manager at GE Plastics.
GE believes the material could be used for parts such as power distribution boxes, high pin density connectors and HVAC vanes – whose significant length and thinness can challenge other materials.
The fact that the materials can be processed at lower pressure could also lead to savings – by using smaller machines and less energy.

Rubber recycled without pollution
By applying large amounts of converging ultrasonic waves in a barrel reactor, it is possible to devulcanize rubber crumb from old tyres in such a way as to produce negligible amounts of pollution.
According to Tom Faust, managing director or Redwood Renewables in Northern California: “It comes out like hot buttered popcorn – sticky, tacky rubber that can be remoulded.”
He claims that it comes at an energy cost of only 2 cents per pound and is produced as a minimum, Class C industry grade with characteristics that are about two-thirds of those of virgin material.
Tests have shown that it can be used to form up to 25% of new tyres without loss of performance, but it can also be made into new products. Redwood Renewables turns it into building products, particularly roofing tiles, which visually resemble slates.
“We get golf ball-sized hailstones in the Mid West, which just bounce off our tiles,” he says. “But it can be used in many other applications, such as railroad crossings.”
The company also has a scheme to incorporate the tiles in roofs that include integrated solar photovoltaic cells.
The process thus takes a material that presently has a negative value – which cannot now be buried under the European Union Landfill Directive, and cannot be burned in the EU after 2008 – and uses it as a feedstock to make products with a good potential sale value.
The process is patented. Redwood Renewables is now in commercial production in California and is looking to set up production in the UK.

PA46 sits well with rubber
DSM Engineering Plastics says that its Stanyl polyamide 4,6 (PA46) is increasingly replacing metal in assemblies that incorporate rubber – such as automotive strut mounts, anti-vibration and energy-absorbing components and exhaust hangers.
“Replacement of metal with thermoplastics began decades ago,” said Paul Habets, application developments manager Stanyl. “But, there are significant challenges when selecting the right material for applications with rubber components.”
Manufacturing requires high heat for vulcanisation, and many rubber-to-metal components require high stiffness and strength – which Stanyl has shown it can match for the rigid element in many cases.
It can handle continuous use temperatures of 200°C with peaks of up to 250°C, as well as good chemical resistance – particularly to grease, gasoline and oil.

Tom Shelley

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