Rubber, too, competes for the car

Press, 22 January 1979, Page 14

Rubber, too, competes for the car

From the “Economist,” London

Producers of natural rubber are also getting into the automobile act. On tyres, naturally, and on engine mountings. But also, they now hope, in less traditional uses like lightweight body panels. The key is the recent development of a thermoplastic (i.e. readily mouldable) natural rubber by scientists at the British laboratories of the Malaysian Rubber Producers’ Research Association (M.R.P.R.A.). The objective was to produce a substance which could be processed as easily and as quickly (i.e. by injection moulding) as a thermoplastic like P.V.C., but retained the bounce-back capability of ordinary natural rubber.

The market is clearly there. Sales of synthetic thermoplastic rubbers are already running at roughly 100,000 tonnes a year and are expected at least to double within the next three years — primarily for use in soft front and rear end components of motorcars. The M.R.P.R.A. boffins have been chasing various ideas for hitching natural rubber to this bandwaggon for some years. Now one of them looks like paying off.

In effect, the natural rubber men have pinched a page (and an ingredient) from the book of their synthetic competitors. They have come up with a blend of natural rubber and a crystallisable polyolefin (e.g. polyethylene), plus a dash of peroxide cross-

linking agent. After extensive testing, they think they have a winner. The thermoplastic natural rubber performs well in conventional injection moulding machinery. With the addition of carbon black, it can be painted electrostically. It withstands repeated recycling. and wears well. Its ability to bend and recover without damage after impact is retained over the range of temperatures (-30 degrees C to 70 degrees C) specified for car panels.

Nor is the automobile market the only one being eyed. One' of the bull points of the thermoplastic natural rubber blend is that its precise physical properties (the balance of stiffness to flexibility) can be varied by changing the blend. So the range of potential applications could also include footwear and cable coverings. Above all, it is simple to produce. That means users could make their own requirements, cut out proprietary producers of synthetic thermoplastic rubbers material costs. Not bad. The M.R.P.R.A. researchers still hope to come up with a more elegant direct route to a thermoplastic natural rubber — grafting a polymer to the backbone of the natural rubber molecule. But that is for tomorrow, by which time a lot more rubber production may be needed, to satisfy all the new markets.