What is ISO 15512 – Water content in plastics about?
Water content is an important parameter for processing materials and is expected to remain below the level specified in the appropriate material standard. Increased moisture content in plastic can cause variations in material behaviour under load; for instance, it can increase ductility and reduce stiffness and strength. Over time, this introduces changes in the material's properties and could potentially result in substandard products.
ISO 15512 specifies methods for the determination of the water content of plastics in the form of powder, granules, and finished articles. These methods do not test for water absorption (kinetics and equilibrium) of plastics as measured by ISO 62. Method A described in ISO 15512 is suitable for the determination of water content as low as 0,1 % with an accuracy of 0,1 %. Method B and Method C are suitable for the determination of water content as low as 0,01 % with an accuracy of 0,01 %. Method D is suitable for the determination of water content as low as 0,01 % with an accuracy of 0,01 %. Method E is suitable for the determination of water content as low as 0,001 % with an accuracy of 0,001 %.
Method D described in ISO 15512 is suitable for polyamide (PA), polycarbonate (PC), polypropylene (PP), polyethylene (PE), epoxy resin, polyethylene terephthalate (PET), polyester, polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polylactide (PLA), polyamidimid (PAI), it is especially not recommended for samples which can release NH3. Methods A, B, C and E are generally suitable for all types of plastic and moisture level.
Who is ISO 15512 – Water content in plastics for?
ISO 15512 on water content in plastics is useful for:
- Manufacturers of plastic products
- Suppliers of plastic raw materials
- Testing laboratories
- Quality control personnel
- Product development teams
Why should you use ISO 15512 – Water content in plastics?
Determining the water content in plastics is an important step to ensure finished-goods quality. ISO 15512 discusses six alternative methods:
Method A is an extraction method using anhydrous methanol followed by a Karl Fischer titration of the extracted water. It can be used for all plastics and is applicable to granules smaller than 4 mm × 4 mm × 3 mm. The method can also be used for, e.g. prepolymer materials in the form of a powder that are insoluble in methanol.
Method B1 is a vaporization method using a tube oven. The water contained in the test portion is vaporized and carried to the titration cell by a dry air or nitrogen carrier gas, followed by a Karl Fischer titration or a coulometric determination by means of a moisture sensor of the collected water. It can be used for all plastics and is applicable to granules smaller than 4 mm × 4 mm × 3 mm.
Method B2 is a vaporization method using a heated sample vial. The water contained in the test portion is vaporized and carried to the titration cell by a dry air or nitrogen carrier gas, followed by a Karl Fischer titration of the collected water. It can be used for all plastics and is applicable to granules smaller than 4 mm × 4 mm × 3 mm.
Method C is a manometric method. The water content is determined from the increase in pressure, which results when the water is evaporated under a vacuum.
Method D is a thermocoulometric method using a diphosphorus pentoxide (P2O5) cell for the detection of the vaporized water. The water contained in the test portion is vaporized and carried to the sensor cell by a dry air or nitrogen carrier gas, followed by a coulometric determination of the collected water.
Method E is a calcium hydride based method. The water content of a sample evaporates due to a combination of vacuum and heating. The evaporated water reacts with calcium hydride to molecular hydrogen and calcium hydroxide. The hydrogen causes an increase of pressure in the vacuum that is proportional to the evaporated water. ISO 15512 guidelines help you to ensure that the plastic products you manufacture are durable and long-lasting.
