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In many plastic resins, such as polyamides and polycarbonates, moisture content is an important factor for processing, product appearance and product properties. If plastic pellets are too moist, processing problems during injection molding can occur. There may also be a loss in quality of the final product, evidenced by splaying, formation of flash and impaired mechanical properties such as reduced impact and tensile strength. Many plastics are susceptible to absorbing moisture during transportation and storage, which is why the control and monitoring of moisture content is crucial to ensure high quality end products.

The HX204 moisture analyzer offers the best measurement performance for samples with low moisture content (<1% MC) such as plastic pellets and resins, e.g. polyamides, ABS and polycarbonates. Thanks to the hanging weighing pan, which separates heating and weighing elements, and the high-performance weighing cell, low moisture contents can be measured with a high degree of accuracy. The HX204 moisture analyzer offers the option of a resolution as fine as 0.1 mg. This is important because the rounding error of the last digit is the dominant cause of error whenever the second last digit (% MC) is of significance. Therefore, this high resolution of 0.001% MC (or 10 ppm) is required for plastic pellets, which often have a moisture content below 0.1% MC.

Samples with very low moisture content (< 1% MC), such as plastic pellets and resins, require superior measurement performance and 0.1 mg readability to deliver reliable, repeatable moisture content results (0.001% MC). The HX204 moisture analyzer not only has the necessary readability, it also offers special settings, such as pre-heating to minimize possible weighing errors and the function to delay the switch-off criterion, which serves to allow extra time to heat plastic samples in order to provide an accurate measurement of the moisture content in the plastic or resin. Furthermore, ASTM standard D6980-12 “Standard Test Method for Determination of Moisture in Plastics by Loss in Weight” only recognizes the use of moisture analyzers with 0.1 mg resolution, such as the HX204 moisture analyzer.

The HX204 moisture analyzer can determine the moisture content of various plastics and resins, such as ABS (Acrylonitride butadiene styrene), PC (Polycarbonate) various types of PA (Polyamide), PET (Polyethylene terephtalate), reinforced polymers and many others. The temperature from a drying oven method or from Karl Fischer Titration can be taken as a starting point, but should be adjusted depending on the plastic type and color. For moisture content determination of plastics containing plasticizers special care need to be taken as the plasticizer might evaporate and will therefore be recorded as moisture content.

Learn more about moisture content determination in plastic pellets here:

• How to measure moisture content in plastic pellets?