Correct drying of plastic granules – how to reduce moisture


Just how important is drying of plastic granules – really?

Well, more important than you might think. In fact, faulty drying is known to be the biggest source of material related problems. You might feel, that when using non-hygroscopic materials, such as polyethylene and polystyrene there would be no real need to consider vigorous drying. But the fact is, that moisture frequently is attracted to the surface of these materials.
One typical example of this problem arises, when such materials havebeen stored outside the processing area, at different temperatures prior to use. Or is the summertime, when differences in temperature and air humidity can result in the same dew-point related problems.

The tolerances are very small
Just a fraction of a percent too much moisture content is detrimental to the end result, on the other hand reducing moisture in plastic significantly improves overall quality. Typically, causing polymer breakdown from hydrolysis or oxidation. And causing discoloration by way of splay marks or small bubbles.

In most cases, drying of non-hygroscopic materials, such as polyethylene and polystyrene can be carried out quite cost effectively using Hot Air Drying. But more elaborate and complex drying methodsare considered when using hygroscopic materials such as nylon, ABS, polycarbonate, cellulose and polymethacrylate. Extra caution is required when using type-6 nylon, as this material can absorb up to 9.5% of its weight in moisture.

To learn more about the different drying method applications, send for the whitepaper on “How to choose the right drying system” below. And find out more about how to overcome the issue of moisture related problems in the most cost effective manner.



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