Particle size distribution of polytetrafluoroethylene (PTFE) powder
The plastic polytetrafluoroethylene (PTFE), also known under the trade name Teflon®, is a semi-crystalline polymer that is extremely nonpolar and, therefore, anti-adhesive and barely wettable. Excellent gliding properties, its large temperature application range, electrical insulating properties and resistance to weather, UV radiation and chemical influences make it a versatile material. In addition to the use as a non-stick coating in household items such as frying pans, baking tins or irons, PTFE is also used in the chemical plant as a lining material for pipelines, containers or compensators.
PTFE is also used in sealing technology, as a sliding material in bearing and in components subjected to friction, for insulation in high-frequency and high-voltage engineering or as a climate-regulating membrane in textiles. Due to the high service life, the smooth surface and good biocompatibility, medical applications as implants are also popular, e.g. as vascular prostheses. The rather moderate wear resistance can be countered by compounding with fillers such as graphite or bronze powders. Similarly, the properties in terms of application and further processing can be specifically optimised by further mixing and conditioning. Used as a compounding additive, the properties of other materials can be modified by PTFE.
PTFE is composed of fluorine and carbon and is polymerised from tetrafluoroethylene (TFE) under pressure. The polymerisation process can run as emulsion or suspension polymerisation. The polymer itself is linear. Different molecular and particle sizes arise depending on the reaction and conditions. The emulsion polymerisation forms PTFE as a fine powder from the aqueous phase with particles of around 400 microns to 600 microns in size. Irregularly shaped, granular PTFE grains of approximately 300 microns to 3,000 microns are formed in suspension polymerisation. Over the course of further processing, the raw material is ground to the desired fineness of around 10 microns to 100 microns or agglomerated for better pourability and dosing depending on the application area and the shaping process, and is then a powder with particle sizes in the range of 100 microns to 700 microns and grain size distribution that is as small as possible.
Particle size distribution of PTFE powder
The particle size analysis of PTFE is a challenging task given the particular characteristics. As PTFE is difficult to wet and can therefore only be dispersed with great difficulty when wet, this is where the particular strengths of the RODOS dry dispersion come into play. The particle separation for the dry laser diffraction analysis is reliable and reproducible thanks to an efficient energy input with the help of compressed air and a dispersion in the aerosol free jet.
- Particle size distribution of PTFE determines its processability
- Qualities mainly differ via the particle size
- Quick and reproducible particle size analysis
- Reliable dispersion of highly agglomerated PTFE powder
- High energy input and unimpeded product flow in the aerosol open jet with dry dispersion
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- Quick, reliable RODOS dry dispersion without extensive sample preparation
- High dispersion pressure for complete particle separation, also in the coarse range and specific disruption of agglomerates
- Unhindered product flow without re-agglomeration thanks to straight dispersing section and open measuring zone
- Measurement of well dispersed primary particles in the aerosol open jet, even with large sample sizes
- High reproducibility of the measurement results
- Avoiding sample preparation and organic dispersing, as with the wet measurement
- Efficient quality control thanks to quick measurements and high sample throughput
- Reliable, comparable measurement results through complete dispersion
- Optimum production management through timely measurements
- Reduction of faulty production
- Gain in efficiency and savings of dispersing liquids through measurement of PTFE powder in dry state