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Release No. 96-035
For Release: May 8, 1996

STS-77 Gas Permeable Polymer Materials (GPPM) Experiment

What Is The GPPM Experiment?

The GPPM experiment uses the microgravity of space to produce plastics that are more uniform and permeable than those produced on Earth. The GPPM experiment is being carried out by the NASA Langley Research Center in collaboration with Paragon Vision Sciences Inc. of Mesa, Arizona.

What Are Permeable Plastics?

Plastics are made up of very large molecules called polymers. Some polymers allow one or more types of gases to pass through them. These polymers, and the plastics they create, are called gas permeable. When used in extended wear contact lenses, gas permeable plastics provide increased durability over soft lenses as well as decreased health risks and easier maintenance. Permeable plastics are ideal for the manufacture of extended wear contact lenses because they allow more oxygen to reach the cornea, which is essential to prevent swelling of the eye.

Why Fly GPPM Aboard The Space Shuttle?

Gravity may affect many properties of a polymer as it is formed. The GPPM experiment, which flew aboard STS-57 in 1993 and on STS-63 in 1995, showed that plastics made in the microgravity environment of the space shuttle are more uniform and permeable than those made on Earth. Making polymers in microgravity has also helped scientists better understand how polymers are formed.

What Are Some Applications Of The GPPM Products?

Commercial applications of uniform, permeable plastics include membranes for dialysis machines and monitoring blood gases, controls for fermentation and other manufacturing processes, the commercial production of pure gases, and highly sensitive sensors that can monitor indoor air quality to detect dangerous gases such as carbon monoxide.

How Does The GPPM Experiment Work?

Twenty-eight polymer materials are placed inside each of two sealed aluminum Polymerization Modules. Each Polymerization Module is installed in a Commercial Refrigerator/Incubator Module (CRIM), a small refrigerator and oven in a single unit that can maintain temperatures over a range of four to 40 degrees Celsius for indefinite periods. Identical samples are placed in a CRIM that will remain on Earth during the STS-77 mission. The samples made in the microgravity environment of space will be compared to those made in gravity on Earth.

What Will Be Done With The STS-77 GPPM Plastics?

If the GPPM experiment can produce far superior plastics once again, Paragon Vision Sciences Inc. will apply for approval from the U.S. Food and Drug Administration to test the contact lens materials on humans as soon as analysis of the plastics is complete. If FDA approval is received, Paragon could be ready to market extended wear contact lenses made with plastics produced commercially in space as early as the year 2000.

For more information on the GPPM experiment, contact the NASA Langley Research Center Office of Public Affairs at (804) 864-6123.

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