Duprene

Captain Christopher Columbus peered through the South American underbrush and was astonished to see a pair of natives bouncing a rubber ball. Three centuries later Poet Percy Bysshe Shelley could make his erasures with a new-fangled device called a rubber. Two generations after that a Mr. Farris was collecting rubber seeds from Brazil to plant in Ceylon, East India and Polynesia, and Chemist Greville Williams had just discovered that rubber and isoprene were polymers. Then a Frenchman and an American made the plant almost indispensable and the War set half a dozen, nations to work trying to find a way to produce rubber within their boundaries. Thomas Edison boiled up native U. S. weeds, found goldenrod promising. And last week was written a new chapter in rubber's polysyllabic history.

Three enthusiastic young chemists of E. I. du Pont de Nemours & Co. arose and addressed the Rubber Division of the American Chemical Society at Akron to describe the following experiment: By catalytic polymerization of acetylene they had produced mono-vinylacetylene. This they had treated with hydrogen chloride to obtain chloroprene. Polymerization of the chloroprene had resulted in a sub stance similar to the product obtained by vulcanizing rubber with sulphur. Stopping the polymerization at an intermediate point gave them -- Rubber. In short, they had produced synthetic rubber from acet ylene (product of coal and limestone), salt and water. While the rubber chem ists cheered, the three young du Ponters -- W. H. Carothers, F. B. Downing, Ira Williams -- generously gave most of the credit to a 53-year-old Catholic priest, Rev. Julius Arthur Nieuwland, C.S.C., of Notre Dame University. Father Nieuwland, born a Belgian, at tended Notre Dame and later settled down in South Bend to a life of avowed poverty and chemical research. In 1906 he passed some acetylene into a copper salt mixture and obtained therefrom a strange and terrific stench.

Father Nieuwland, holding his nose, decided that if he could separate the derivative responsible for the stench, he might have something interesting. Fifteen years later he succeeded: By use of a more highly concentrated mixture he produced a liquid which he called divinylacetylene. Father Nieuwland shook his head, decided it might be good for drying oil or possibly sheep dip.

Far from discouraged, he lectured on his experiments. One day a scout for the du Pont Co. heard him, immediately enlisted his aid. Du Pont was seeking a means of producing synthetic rubber, thought Father Nieuwiand might be on the right track. Two years later Father Nieuwland's divinylacetylene was treated with a vulcanizing agent and there was produced a material somewhat resembling rubber. It bounced.

Experiments continued at the du Pont Co.'s Jackson Laboratories and in Father Nieuwland's laboratory at Notre Dame. The chemists gave up working on divinylacetylene and concentrated on the more homely mono-vinylacetylene. They treated it with hydrogen chloride and first thing they knew they had a fine pot of chloroprene. Chloroprene differs from rubber's polymer, isoprene, only in that a chlorine atom replaces the methyl group, so after that the going was fairly easy. They had only to polymerize the chloroprene to the right point, and all of them were experienced polymerizers. When they finished they put a piece of their rubber into a bottle of kerosene, left it 72 hr. When it came out it was still rubber, retained more than half its original strength. (A piece of real rubber immersed 72 hr. in kerosene comes out act- ing like a piece of chewing gum.)

The enthusiastic du Pont Co. immediately christened their product Duprene, ordered a plant built at Deepwater, N. J. to manufacture rt commercially. Since it needs only acetylene, salt and water, it will not be expensive to make. Duprene looks like natural rubber, shows the same molecular makeup in xray, but is denser, more resistant to water absorption, to attacks by ozone, oxygen and other chemicals, to swelling by gasoline & kerosene. It is vulcanized by heat alone, without sulphur. At high temperatures it hardens slowly. Its powers of resistance are expected to give it many commercial uses now denied to rubber, but so far it has not been produced in a form sufficiently pliable for use in automobile tires. Du Pont officials believed that in spite of the present low price of rubber (about 5^ per Ib.) Duprene would have enough uses to warrant its production on a large scale, could be developed to replace natural rubber entirely in case the U. S. supply were shut off. In addition to Duprene, an artificial latex (mother liquid of rubber) was also produced from chloroprene which can impregnate porous materials that real latex cannot penetrate.

Last week dour Father Nieuwiand, undisturbed by publicity, paused in his work only long enough to say that he would give all the money he gets from the discovery to the Congregation of the Holy Cross. Then he went back to his laboratory, the door of which he opens with a foot pedal because his arms are usually full of retorts, bottles and discoveries.

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