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PTFE Standard Compound

The more common compounded PTFE grades are filled with glass fibre, bronze, graphite, carbon.
The values from the associated chart are obtained by the analysis of both the moulding and extrusion process. The first column on the left sums-up the basic data of virgin PTFE G400, in order to compare with the values of the different compounds.
“G” COMPOUNDS AVAILABLE - FILLERS AND THEIR FUNCTIONS
In addition to virgin PTFE G400 products, GUARNIFLON® offers a wide range of compounded products as well.
Among these compounds, processed directly in Guarniflon® compounding unit starting from selected polymers and special high-purity fillers, end users are enabled to find the right answer to their technical requirements.
To make their selection easier, the following tables resume:
  • the correlation among single fillers, properties and common uses
  • properties of standard and special compounds among those most commonly marketed
The following table shows the way each filler affects physical and mechanical properties.
Combinations of two or more fillers (not considered in the table) allow a large number of compounds.
Thus the resulting combined properties offer a variety of applications.
FillerPropertyMost common applications
GlassEnhanced wear resistance.
Enhanced chemical resistance (except for alkali and hydrofluoric acid).
Valve seats, seals, bearings, requested to resist sliding and chemicals. Suitable for bearings working at low PV values.
GraphiteExtremely low coefficient of friction. Fairly good compressive strength. Good wear resistance.Bearings for high speed on fairly hard surface.
CarbonGood thermal conductivity. Good resistance to deformation.Valve seats. Bearings for high speed and when fast dissipation of electric charges is needed. Elastic bands for unlubricated compressors.
Molibdenum disulphideEnhanced non-stick properties. Low static coefficient of friction. Fairly good resistance to deformation.Guide bands. Details needing good resistivity.
BronzeEnhanced compressive strength. Good wear resistance and high thermal conductivity.Anti-extrusion rings. Unlubricated bearings for high speed on not hard surface.
Guarniflon® can offer an extremely wide range of skived tapes, sheets, extruded and moulded rods and tubes, in compounded PTFE from G series. Dimensions and relevant tolerances are included in the Dimensional Brochure. Tapes, sheets and finished products can be supplied etched.
PropertyTest methodUnitVirginG Standard Compounds
G400G403 15% GLASS FIBERG405 25% GLASS FIBERG412 15% GRAPHITEG415 25% SOFT CARBONG453 25% CARBOGRAPHITEG458 60% BRONZE 2% CARBON
Moulded
Specific gravityASTM D792g/cm32.14 - 2.182.19 - 2.222.20 - 2.262.10 - 2.152.05 - 2.112.05 - 2.113.75 - 3.93
Coefficient of linear thermal expansion 25-100¡CASTM D69610-5 (mm/mm)/¡C12 - 1311 - 137.5 - 118 - 109 - 1210 - 127 - 8
Hardness Shore DASTM D2240Punti≥51≥60≥70≥ 55≥ 60≥ 64≥ 62
Tensile strengthISO 527N/mm2≥24≥17≥17≥18≥15≥14≥15
Elongation at breakISO 527%≥250≥250≥230≥200≥150≥90≥100
Compressive strength at 1% deformationASTM D695N/mm24 - 56 - 78 - 96.5 - 7.57 - 97 - 910 - 11
Deformation under load (24 h 13.7 N/mm2 23¡CASTM D621%≤17≤14≤10≤10≤6.5≤7≤6
Permanent deformation (as above after 24 h relaxation)ASTM D621%≤9≤7≤6.5≤6≤4≤5≤2.5
Kinetic coefficient of frictionASTM D1894/0.030.120.130.070.130.110.13
Wear factor at PV 100ASTM D37022.90010 - 2010 - 156020 - 3016 - 2010
Extruded
Specific gravityASTM D792g/cm32.14 - 2.182.18 - 2.212.18 - 2.262.09 - 2.142.04 - 2.102.04 - 2.103.80 - 3.88
Hardness Shore DASTM D2240Punti≥40≥ 60≥60≥ 55≥ 60≥ 64≥ 65
Tensile strengthISO 527N/mm2≥20≥15≥13≥ 14≥15≥12≥13
Elongation at breakISO 527%≥ 200≥200≥180≥150≥50≥50≥80
PROPERTIES FOR DESIGNING
Fillers blended with PTFE allow to improve some basic physical properties of virgin polymers.
The advantages are the following:
  • enhanced compressive strength
  • enhanced thermal conductivity
  • reduced thermal expansion
  • reduced wear factor
MECHANICAL PROPERTIES
When talking about the material mechanical properties, tensile strength and elongation at break are usually the topics before others. However, these two properties, though the most common ones, do not always carefully reflect the behavior of the material itself in some applications, while compressive properties are actually the most important ones. We’d highlight compressive strength at a set deformation, deformation under constant load and permanent deformation at a set temperature.