Page 48 - FOUNDATIONS FOR LIFE; EXPLORING GOD’S UNIVERSE

Science Y5 – God’s Amazing Matters – lesson 7

RUBBER

From Wikipedia, the free encyclopaedia (adapted)

Latex being collected from a tapped rubber tree

Rubber is an elastic substance that naturally occurs as a milky
solution, or latex, in the sap of some plants. It can also be
synthesized (made up from other materials).

Explanation

The major commercial source of natural latex used to create rubber is
the Para rubber tree. This is largely because it responds to wounding
by producing more latex. Henry Wickham gathered thousands of
seeds from Brazil in 1876 and they were germinated in Kew Gardens, England. The seedlings were
sent to Colombo, Indonesia, Singapore and British Malaya. Malaya was later to become the biggest
producer of rubber. Liberia is another rubber-producing country.

Other plants containing latex include figs, euphorbias, and the common dandelion. Although these
have not been major sources of rubber, Germany attempted to use such sources during World War
II when it was cut off from rubber supplies. These attempts were later supplanted by the
development of synthetic rubber.

Collection

A woman in Sri Lanka in the process of harvesting rubber.

In places like Kerala, where coconuts are in abundance, the shell of half
a coconut is used as the collection container for the latex. The shells are
attached to the tree via a short sharp stick and the latex drips down into
it overnight. This usually produces latex up to a level of half to three
quarters of the shell. The latex from multiple trees is then poured into
flat pans, and this is mixed with formic acid, which serves as a coagulant
(something which causes thickening). After a few hours, the very wet
sheets of rubber are wrung out by putting them through a press before
they are sent onto factories where further processing is done.

History

Rubber is believed to have been named by Joseph Priestley, who discovered in 1770 that dried latex
rubbed out pencil marks.

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