Analysis of Part per Million Water Content in Polymers

摘要

All polymers contain some small amount of water. This water is absorbed by the polymer pelletsfrom the ambient relative humidity. This water content may be detrimental to the polymer propertiesafter melt extrusion. Excess water can cause large, easily-observable bubbles or small voids that givethe polymer a cloudy appearance. A thermogravimetric analyzer (TGA) can be used in this application,if it has a large dynamic range. The dynamic range of a TGA is the ratio of the maximum weight thebalance can measure divided by the smallest mass it can measure, usually expressed in orders ofmagnitude. With a large dynamic range, you can use large samples (improved average results) andmeasure small weight losses (resolution down to ppm levels of water).This paper will demonstrate how polycarbonate, stored at different relative humidities, willabsorb different amounts of water. This technique will also be used to compare the moisture absorptionability of different polymers.