The physical and chemical properties needed in a balloon material are: (1) chemical stability, (2) low permeability, (3) high tensile strength, (4) low brittle temperature, (5) high tear resistance, (6) high transparency to heat radiation and (7) light weight.
In Table 1 the properties of 7 plastics and 2 coated materials are given. From this data polyethylene and saran appear to be the most suitable films.
Table 1
Fabric
Low Temperature Properties
Permeability
Tensile Strength
Tear Resistance
Ease of Fabrication
Stability to Ultraviolet
Polyethylene
Good
Medium
Low
Good
Good
Good
Saran
Fair
Low
High
Poor
Fair
Fair
Nylon
Good
Low
High
Low
Good
Good
Vinylite
Very poor
Medium
Medium
Good
Good
Good
Teflon
Believed good
Low
High
Good
Cannot be fabricated
Good
Ethocellulose
Good
Very high
Low
Fair
Good
Good
Pliofilm
Poor
High
Poor
Fair
Good
Poor
Nylon or silk fabric coated with:
Neoprene
Fair
Low
High
Fair
Fair
Fair
Butyl rubber
Good
Low
High
Fair
Fair
Good
Having decided upon the proper fabric to be used, an effort was made to interest a number of companies in the fabrication and production of balloons. The first supplier of balloons made of polyethylene was Harold A. Smith, Inc., Mamaroneck, New York. In these balloons, 4 and 8 mil sheets were heat sealed to form a spherical cell open at the bottom. Load attachment tabs were set into the fabric and loading lines ran from these tabs to a load ring. This method of supporting the load proved to be unsatisfactory.
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