Keeping the Fizz In
     YOUR AVERAGE SODA LASTS 6-12 WEEKS SITTING ON THE SHELF.  OVER THAT TIME
THE PLASTIC BOTTLE LET'S CARBONATION SEEP OUT SO THAT WHEN YOU OPEN THE SODA
INSTEAD OF FIZZ 

(SFX: opening soda fizz, pouring it out) 

YOU GET FLAT 

(SFX: opening, no fizz sound, "oh yuck!").  

IT HAPPENS BECAUSE THE BOTTLE  LETS CARBON DIOXIDE SNEAK OUT BETWEEN ITS
MOLECULES.  BUT IF THE PLASTIC HAD A TIGHTER FRAMEWORK OF MOLECULES IT WOULD
BE SO STIFF THAT IT COULDN'T EASILY BE MOLDED INTO BOTTLE SHAPES.  THE SOLUTION? 

     Freeman: "liquid crystals"
     
     CHEMICAL ENGINEER BENNY FREEMAN AT NORTH CAROLINA STATE UNIVERSITY IS
TAKING THE STUFF YOU'RE USED TO SEEING IN A DIGITAL WATCH AND TURNING IT INTO
SODA BOTTLES.

     Freeman:  "Liquid crystal is a state of matter that exists between that of a liquid
where molecules are oreinted randomly and a crystal where the molecules are lined up
perfectly. "

     THAT MEANS THAT WHEN THEY'RE HEATED THE LIQUID CRYSTALS ARE SOFT ENOUGH
TO BE EASILY MOLDED, BUT WHEN THEY COOL DOWN AND SOLIDIFY THE MOLECULES ARE
SO TIGHTLY  ORDERED THAT THEY KEEP THE CARBON DIOXIDE IN THE SODA. 

     Freeman: "Liquid crystals since they are 100 times less permeable than
conventional materials would increase shelf life by those kidn of factors. "

     ONE OF THE MAIN PROBLEMS NOW, IS THAT LIQUID CRYSTALS ARE MUCH MORE
EXPENSIVE THAN PLAIN OLD PLASTIC.  FREEMAN IS TRYING TO LOWER THAT COST BY
IDENTIFYING JUST WHAT PART OF THESE SUPER MOLECULES MAKES THEM SUCH GOOD
BARRIERS--THEN HE HOPES TO MAKE A CHEAPER VERSION.