Name: Tom
Status: Other
Age: 50s
Location: N/A
Country: N/A
Date: N/A
Question:
I need to know the rate of change of size of a piece of
acrylic relative to the % of humidity. Is there a scale for this
similar to that for the coeficient of thermal expansion?? For
example:
Thermal
expansion can be expressed in inches per inch per degree F. Is there a
similar coeficient for % humidity?
Replies:
When you say "acrylic" you have to be careful because acrylics are a whole
CLASS OF hundreds of related chemical compounds [copolymers]. Methyl
methacrylate p-MMA has the commercial name "Plexiglas" and its coefficient
of expansion with humidity is virtually zero. Acrylic acid,
hydryoxyethylacrylate, or hydroxyethylmethacrylate are very hydrophylic and
have enormous coefficients of expansion with relative humidity.
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