Resin Handling and Storage

This section discusses the fabrication of PTFE, known asfine powder or coagulated dispersion powder, into shapes and articles. The most common fabricated commercial forms include rods, tapes, wire insulation, tubing, sheeting, and other profiles. Tube diameters range from a fraction of a millimeter to almost a meter with wall thicknesses of 100 pm to a few millimeters. Rods up to 5 cm diameter can be produced and calendared, prior to sintering, to produce tapes. Unsintered tapes are broadly applied as 

Fine powder PTFE is susceptible to shear damage, particularly above its transition point (19°C). Handling and transportation of the containers could easily subject the powder to sufficient shear rate to spoil it if the resin temperature is above its transition point. The phenomenon caWedfibrillation (Fig. 5.26) occurs when particles rub against each other, in which fibrils are pulled out of the surface of PTFE particles. Uncontrolled fibrillation must be prevented to insure good quality production from the powder. Premature fibrillation leads to the formation of lumps which cannot be broken up easily. 

To ensure that the resin does not fibrillate, it should be eooled below its transition temperature prior to handling and transportation. A t5 ieal eom-mercial eontainer (20-30 kg) should be eooled 24-48 hours to 15°Cl l to assure temperature uniformity throughout the eontainer. In practice, drums of resin are stored and transported at 5°C. Specially designed shallow eylindrieal drums are used to minimize lump formation, eompaction, and shearing of the resin. 

Individual partieles of PTFE form agglomerates which are roundish and average several hundred microns in size. 

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Resin manufacturers usually provide health and safety information through Material Safety Data Sheets (MSDS) that discuss resin handling and storage, toxicity, combustibility, disposal, labeling, and FDA status. 

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