Plastic can accumulate water in several ways. Three types of moisture are relavant: surface moisture, capillary moisture and molecular moisture. Most materials have hygroscopic properties (ABS, PC, PA, PET) and water can penetrate within them, both in granulate form and as plates or fittings. From the material processing technological point of view, moisture is the most dangerous where processing at higher temperatures is conducted – thus in virtually every type of plastic technology. In our materials science laboratory, water content is determined using a weighing-drying method based on in-house procedure BOSMAL/I-7-49/05.

 

For those materials absorbency (absorbability) can also be determined. Strongly absorbent materials including polar groups, for example: cellulose, phenolic polymers, aminoplastics, polyamides. Water absorbency expressed in weight percentage is called weight absorbency and is defined as the ratio of the mass of water absorbed by the sample to the mass of the dry sample. Polymer materials’ absorbency (absorbability) tests are conducted in the laboratory using climatic chambers according to the norm PN-EN ISO 62:2008 p. 6.3, 6.4, 6.6 Equipment. The laboratory possesses a number of dryers, vacuum dryers and analytic scales.