Mylar balloons

Explain why helium-filled, Mylar-foil balloons can float freely for several weeks, but latex balloons for less than 24 hours. 

Foil balloons are derived from the effort of National Aeronautics and Space Administration (NASA) Space Command with the concept and technology to metalizate plastic sheeting. While the balloons are often referred to as Mylar or silver Mylars, they are not made from Mylar, a trade name for certain polyester film. They should be simply referred to as foil balloons. They are made from nylon film coated on one side with PE and metallized on the other. The nylon film gives the balloon some strength and the PE gives it some flexibility and helps retard the release of the held gas. 

Chemically, Dacron and Mylar are polymers made from a ring structure called dimethyl terephthalate and ethylene glycol (HO-CH2CH2-OH). The polymer unit is called polyethylene terephthalate, or PET. Dacron fiber is used in tires and fabrics, and is even used to repair blood vessels. Mylar is used in magnetic recording tape. In the 1960s, it was used in huge balloons that were sent into orbit around Earth. Plastic soda containers are made of PET. 

Because no vacuum system can be truly leak-free, it is important to determine whether or not you have a leak of consequence. In other words, does any system leak actively affect your work For example, a common rubber balloon holds water better than it holds air, and it holds air better than it holds helium. If your needs are to contain water, a standard rubber balloon is sufficient. Similarly, if you want to contain helium for a limited time, again a rubber balloon is sufficient. However, if you want a helium balloon to stay up for several days, then a rubber balloon is insufficient and you must spend the money for a Mylar balloon, which can contain helium much better than a rubber balloon. 

Dacron fiber is used to make fabric and tire cord, and Mylar film is used to make magnetic recording tape. Mylar film is strong, flexible, and resistant to ultraviolet degradation. Aluminized Mylar was used to make the Echo satellites, huge balloons that were put into orbit around the Earth as giant reflectors in the early 1960s. Polyethylene terephthalate) is also blow-molded to make plastic soft-drink bottles that are sold by the billions each year. 

Polyester can be formed into a film called Mylar. These films, coated with aluminum foil, are used to make balloons that remain inflated for long periods. They are also used as the base for recording tapes and photographic film. 

Herman Poole s expression was inscrutable as he gazed at all the commotion. Silver Mylar blimps dive-bombed the long tables, and everywhere computer screens flickered. A robot hand crawled by, chased by a Mylar balloon shaped like a man. A man in a synth suit danced, and his motions made music. Amidst all this noise, color, and space, Herman felt small and lost. I m like this place, he thought, a dismembered part of me here, part of me there. My life is many small compartments, most of them unhappy. 

Cold packs (for large ingestions, Mylar balloons Wall board... 

Mylar balloons add zest to a party and because they are PETE can be recycled. 

When you buy a Mylar balloon in the winter months in colder places, the shopkeeper will often... 

Because Mylar film has very tiny pores, it is used for balloons that can be inflated with helium the helium atoms diffuse only slowly through the pores of the film. 

The same polyester can be fabricated into a particularly strong film called Mylar. Mylar polyester film is used for the long-term protection of artwork and historical documents because of its transparency, strength, and inertness. Mylar is popular for its use in the manufacture of balloons for festive occasions. Mylar was also used to cover the 94-foot wingspan of the Gossamer Albatross, a human-powered aircraft used to fly the English Channel in 1979. Only two pounds of the polyester was needed to cover the entire wingspan, and the polyamide Kevlar was the material used for construction of the rudder of this aircraft In the United States, production of polyester fibers exceeds 3 billion pounds per year. 

A mylar balloon (left) and rubber balloon freshly filled with helium. 

Helium-filled party balloons are made of Mylar, a polyester film made from 1,2-ethanediol (ethylene glycol) as one of the reactants. 

You may have seen Charles s Law in action when a latex rubber or Mylar foil balloon was subjected to a temperature change. A rubber balloon left in a hot car will expand significantly. Either balloon will shrink when brought from a warm home or store to the cold outdoors on a winter day. 

A mylar balloon is filled with helium gas to a pressure of 107 kPa when the temperature is 22°C. If the temperature changes to 45"C, what will be the pressure of the heUum in the balloon ... 

Polyesters may be formed by the reaction of a diol with a dicarboxylic acid or a dicarboxylate ester. In some older organic textbooks, you will find this referred to as a condensation polymer (because it is formed by a condensation reaction), but the polymer community frowns on this nomenclature. One such polymer is polyethylene terephthalate (PET) (Figure 21.18). Much of this is used in fibers for clothing and home furnishings. As a thin film. Mylar is used for survival blankets and balloons, as well as thermal and electrical insulation, food and drink packaging, cine films, and musical and electronic equipment. The reaction involved is a transesterification (Figure 21.19). 

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