Re: COVID-19 and GPSL

stan siems

Another important factor to consider is the variation in temperature between the day and night, since many materials are known to act differently in different temperatures. For    this study one concern is that the temperature might drop down below the glass transition temperature (Tg) of the natural latex used to create the balloons. Going below the  Tg   would cause a definite change in the behavior of the material; materials above their Tg still retain elasticity, whereas those cooled below their  Tg become glassy and brittle.22This may cause the balloon to burst more quickly, especially considering the pressure and changes of volume the balloon experiences in its ascent. The Tg value of natural rubber latex is73Celsius.23Since an average day flight will see temperatures of below40Celsius in the upper troposphere should night temperatures drop to the range of65Celsius, it is possible that the natural latex rubber of the weather balloon will experience temperatures that would cause it to undergo glass transition

On 3/22/2020 3:29 PM, Joe WB9SBD wrote:

Some evidence, But not totally also.

I wonder how must is lost when the latex is NOT stressed?

Like stretched ONLY to 50% elongation.

We have tension tested many many samples of latex, and it is amazing on how linear the force is when a piece is being stretched. From barely stretched to right at the end like 99% of it's stretchability  the forces only change like 10%

But that last bit it the force to pull it any further skyrockets! ten times or more the rest of the force, and the amount it continues to stretch is like nothing.

You can even easily feel this by hand. Take a scrap of a balloon and cut say a 1" wide strip from it. Now start to pull,  the force is more or less the same then it like hit a brick wall where it does not want to let you stretch any more then finally breaks.

Hence the flight that lasted two or three days that went from California to Morocco.


On 3/22/2020 3:16 PM, stan siems wrote:

Here is your answer
by DC Handke - ‎2019
May 1, 2019 - al (2013) examined the degradation of latex films in different environments. The degradation rate was most strongly linked to treatments with the most solar radiation, causing the fastest rate of breakdown. Photo-oxidation was the primary pathway for this degradation. This occurred in response to UV light from the sun.

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