Giant Inflatables Hovering Over a Crowd… What Could Go Wrong?

Did you have your fill of Thanksgiving food last week?  How about your fill of parades?  As someone involved in polymers and plastics analysis, I found the many iconic, giant balloons at the Macy’s Thanksgiving Day Parade to be fascinating.

There were over 25 of those giant balloons floating above the crowds throughout the parade route.  Some of the character balloons were as high as a 6-story building.  The iconic, giant balloons require up to 90 people to handle one of the oversized inflatables making sure it does not go off course. That is a lot of material to hold!

One of the most important components of the balloon is plastic.  At one time, the balloons were made of rubber, but now it is plastics, more specifically polyurethane, that make these floating characters possible.

The production of polyurethanes (PU) starts with polyols — the chemical compounds containing multiple hydroxyl groups. Polyols are based on alkene oxides, generally ethylene oxide (EO) and propylene oxide (PO). The EO content of polyols dictates the characteristics of the final polyurethane products. Nuclear Magnetic Resonance (NMR) spectroscopy is an inherently quantitative technique, and due to the abundance of protons in the repeating structures of polyols, combined with the dispersion of signals, proton NMR spectroscopy is ideally suited for rapid characterization of EO content.  Benchtop NMR has been proven to be able to determine EO content in polyols.

As you can guess, the hydroxyl value is a critical parameter routinely measured by polyol manufacturers to determine the quality of their product. Users of these polyol products often depend on the manufacturer’s certification of quality to confirm the appropriateness of the material for their own manufacturing processes. As we wrote in a previous article about FT-NIR and Polyurethane Analysis:

The physical properties of polyurethane are controlled by a variety of factors during the manufacturing process, including the molecular nature of the polyol starting material. Therefore, determining the hydroxyl value of the polyol reactants is a crucial step to ensure the polyurethane products exhibit the desired physical and chemical properties.

Getting the polymer composite correct is critical to the health of the balloon.  These balloons have to be flexible, but tough enough to withstand the elements during the parade and any sharp objects they may encounter.  As a precaution, the iconic parade balloons are created with different chambers so if one section tears, the other segments will remain intact. The ‘skins’ must be able to get rolled up and packed down for transportation, and then ‘thumped’ during skin stress testing to check inflation.  In fact, when inflated, those iconic balloons can contain 14,000 ft³ of helium, making the balloon weigh 400 pounds.  The balloons are hand painted while inflated, so the paint will not crack. 

Polyol manufacturers often use the measurement of the hydroxyl value as a critical in-process test to indicate the completeness of a polymerization reaction. Use of a material with inappropriate properties is usually very costly as it leads to the manufacture of products that are not within specifications, wasting production time and materials.

Monitoring the polymerization reaction is important, therefore, Fourier transform near-infrared (FT-NIR) spectroscopy is part of the manufacturing process for the balloon material.  FT-NIR is commonly used to determine the hydroxyl value of various materials, per ASTM D6342-12.3, Standard Practice for Polyurethane Raw Materials: Determining Hydroxyl Number of Polyols by Near Infrared (NIR) Spectroscopy.  An FT-NIR instrument can analyze any sample type and provide robust and reliable data collection for at-line, online and in-line analysis – helping to ensure a quality product.

On rare occasions, Thanksgiving Day Parade balloons have failed because of environmental or human factors.  One article cites an occasion when a balloon collapsed due to strong winds, another time a balloon was so drenched from the rain it had to be carried, and more recently, several balloons caused injuries when they careened into street lamps. 

There are some worrisome situations that just cannot be avoided when there are mammoth-sized floating models hovering over the heads of onlookers near New York’s Central Park, but the integrity of the materials used for important products should never be one of them.