Rubber Trees: Latex

Question:

Does rubber really come from trees?

Answer:

The sap-like liquid from “rubber” trees is actually latex, but it is commonly called rubber. The name “rubber” originated around the  end of the 18th century when European scientists started to look at the properties of latex.  The British scientist Joseph Priestley called latex rubber because he observed its ability to rub out pencil marks. This name is still being used today.

rubber tree bands

The cute photo shows how the Pará rubber tree (Hevea brasiliensis) is cut so that latex drips out. But the photographer has skipped a few stages in production by showing rubber bands falling from the spout. Instead, about 1 cup of  white thick latex would drip out of the cut during the day. New cuts would have to be made to collect more latex.

Question:

Who discovered rubber trees?

Answer?

The discovery of rubber trees  is generally attributed to Christopher Columbus, who observed the inhabitants of Haiti using the sap  to make playballs.  Europeans later discovered that rubber could be extracted from many different kinds of trees and shrubs, mostly native to the tropics.

Question:

What were some of the first uses of latex (rubber)?

Answer:
By the start of the 19th century rubber was an expensive curiosity with no serious uses. Thomas Hancock devised methods for mechanically working rubber so it could be shaped, and he built England’s first rubber factory in 1820. In 1823, Charles McIntosh  devised a practical method of waterproofing fabric with rubber. The molecules of natural rubber, however, contains virtually no crosslinks, so it becomes soft and sticky when hot and stiff when cold. The original rain gear made by MacIntosh was very sticky in hot weather and stiff and brittle in cold weather.

scientist1Question:

What did Charles Goodyear do to latex so it was more temperature resistant?

Answer:

1839 Charles Goodyear, an American inventor (1800-1860) vulcanized rubber, which is done by heating latex with  with sulfur. This changes it so that it is not sticky when hot or brittle when cold.

Challenge:

 1. Where is latex found inside of rubber trees?

2. Why are the cuts in the bark of rubber trees slanted? Why do the cuts only go half-way around the tree?

3. Why are cuts  in rubber trees are made at night?