Polyesters & Polyamides
With the preliminary problems associated with the
commercialization of neoprene solved,
Carothers’ group turned its attention to synthetic fibres,
specifically to find a replacement for silk which was in short
supply because of trade and political problems between the USA
and Japan.
Carothers had postulated some years earlier that if an acid and
alcohol could condense with the elimination of water to produce
an ester, it should be possible to make a giant molecule
(polymer) by linking di-ols to di-acids. This was soon achieved
by one of his team, Julian Hill, to give an early polyester but
the physical properties were too poor for commercialisation and
Carothers turned his attentions to polyamides, replacing the
di-ols with di-amines. In 1934 the first successful fibres were
made.
Carothers’ team was working with over 100 different materials
and he identified them by two numbers, indicating the number of
carbon atoms in the di-acid and di-amine. In February 1935 he
polymerised adipic acid (C6) and hexamethylene diamine (C6) to
give specimen 66 which had good physical properties when it was
drawn into a fibre. The material was christened Fiber 66 and, in
September 1938 re-christened Nylon66.
Carothers’ immediate superior decided to target just one market
with this new product and in May 1940 nylon stockings hit the
hosiery stores nationwide. At just over one dollar a pair, five
million pairs were sold on the first day. When the US entered
the Second World War and arrived in the UK, a few pairs of
nylons could buy anything! By that time however, production of
nylon had been directed towards the war effort, particularly
parachute canopies, rot-proof cords and life rafts and the
ladies had to wait a few more years to have an unlimited supply
of seamless or fully fashioned nylon stockings.
Today nylon is ubiquitous, being used as threads, sheets or
blocks from which a vast range of products can be created
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