How to Calculate the Absorption Coefficient of a Polymer

The absorption coefficient (also sometimes called the extinction coefficient) of a polymer is a measure of how much light a given polymer will absorb and prevent from passing through. If you're starting from scratch, ascertaining the absorption coefficient of a polymer in practice is quite difficult due to the number of variables which you must be able to measure. Calculating the coefficient is based on an experiment where scientists shine a light through the polymer that is either in a liquefied, dissolved or a gaseous state. From there if you know the values for the light's intensity both before and after it passes through the polymer, the concentration of the fluid polymer and the length of distance the light has traveled through the polymer, then you can use Beer-Lambert's Law to calculate the polymer's molar absorption coefficient.

Things You'll Need

• Scientific calculator

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Instructions

1. • 1

     Divide the value of the light's initial intensity by its intensity after leaving the polymer.

   • 2

     Take the common logarithm (the button on your calculator that says "log") of that number, if your polymer is in the form of a liquid,. If the polymer was in gaseous form, instead take the natural log ("ln" on your calculator) of the intensity ratio..

   • 3

     Multiply your answer by -1. This is your absorption value -- not to be confused with the absorption coefficient, which you are going to be ultimately calculating.

   • 4

     Multiply the value for the polymer's concentration by the length of the polymer through which the light shone.

   • 5

     Divide your absorption value by the product of concentration and length that you just calculated. This is your molar absorption coefficient.