Balloons

Balloons

Introduction

Not just a lot of hot air! Most children have played with balloons, but few have thought about the chemical and physical concepts involved in balloon production and use. In the activities that follow, students explore balloon properties and their use in demonstrating various scientific concepts.

Objectives

• Explain how balloons are inflated.

• Describe the basic properties of balloons.

Background

A balloon can be defined as an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons are made from materials such as rubber, latex, polychloroprene, metalized plastic or a nylon fabric.

Long before there was something as stretchy as rubber, balloons existed. In the pre-rubber era, balloons came from animal bladders. A pig's bladder was inflated by Galileo in an experiment to measure the weight of air. Inflated animal bladders were used in play by Indian and Inuit children. Most of the bladders were from sea animals.

The Aztecs are thought to be the very first people in history to make 'balloon animals' out of the bowels of cats to be presented to the gods as a sacrifice. The bowels were carefully cleaned, turned inside out, and sewn with a special vegetable thread whose main property was that it stuck to itself when left to dry in the sun, and this produced an almost airtight seal. The bowels were then twisted and air was blown into them after each twist.

The first rubber balloons were made by Professor Michael Faraday in 1824 for use in his experiments with hydrogen, at the Royal Institution of Great Britain in London. Faraday made his balloons by cutting two round sheets of raw rubber, called caoutchouc (French word for rubber), laying them one on top of the other and pressing their edges together. The tacky rubber welded automatically, and the inside of the balloon was rubbed with flour to prevent the opposing surfaces joining together.

Toy balloons were introduced by rubber manufacturer Thomas Hancock the following year (1825) in the form of a do-it-yourself kit consisting of a bottle of rubber solution and a condensing syringe.

Vulcanized toy balloons, which were unaffected by changes in temperature, were first manufactured by J.G. Ingram of London in 1847 and can be regarded as the prototype of modern toy balloons.

In 1931, the Tillotson Rubber Company achieved another milestone in balloon technology: they created the first modern latex balloon made from the sap of a rubber tree. Before that, the balloon-making process was difficult and dangerous due to the use of solvent-dissolved rubber, similar to rubber cement. This new balloon, shaped like a cat's head with pointed ears and a whisker-printed face, was also possibly the world's first novelty-shaped and printed balloon.

The natural rubber latex used today comes from the sap of the rubber tree, Hevea Brasiliensis, which grows in Malaysia. This sap looks like milk and is exported in large ocean tanker ships. Once removed from the tree, the sap is called latex. To make this suitable for balloon production, curing agents, accelerators, oil, color, and water must be added. Next, the modified latex is put into an open tank, and the balloon mold, which is in the shape of a balloon, is dipped.

A video on how balloons are made is available in the resources section.

A safety note: Some people are violently allergic to latex, particularly people who work in health care, people with spina bifida, and those who have had multiple surgeries.

Entire Lesson

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Other Resources

Science World Resources | Full Lesson | Air
Science World at TELUS World of Science | School Workshop | Chemistry