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PTFE Special Compound

Special compounds compliment the series of standard “G” compounds.
Guarniflon® special compounds are gaining more and more market share due to the increasing demand for solution to high tech industrial applications.

The associated table illustrates the properties of some special “G” compounds by Guarniflon®. They represent only a small number of the compounds available among the range of solutions Guarniflon® is able to suggest.
Some of Guarniflon® compounds include fillers like PEEK, PPS, polyimide, LCP, molybdenum disulphide, etc.
SPECIAL COMPOUNDS AVAILABLE
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 virgin PTFE as well as compounded from G series.
Dimensions and relevant tolerances are included in the Dimensional Brochure. Tapes, sheets and finished products can be supplied etched.
MAIN PROPERTIES | MOULDED
ProprietàMetodo di provaUnità di misuraCompound G Special
G416
40% BRONZE
2% CARBON
G418
15% GLASS FIBER
5% MOS2
G420
50% STEEL
G427
40% BRONZE
5% MOS2
G436
3% MOS2
G455
35% CARBOGRAPHITE
G456
25% HARD CARBON
STAMPATI
Peso specificoASTM D792g/cm32.98 - 3.162.20 - 2.303.25 - 3.353.15 - 3.252.18 - 2.241.90 - 2.002.05 - 2.11
Coefficiente di dilatazione termica lineare 25-100 °CASTM D69610-5 (mm/mm)/°C8 - 119 - 1210 - 129 - 1211 - 126.5 - 108 - 11
Durezza Shore DASTM D2240Punti≥ 58≥ 55≥ 65≥ 60≥ 50≥ 65≥ 62
Resistenza a trazioneISO 527 v=50mm/minN/mm2≥ 20≥ 18≥ 17≥ 20≥ 23≥ 8≥ 12
Allungamento a rotturaISO 527 v=50mm/min%≥ 220≥ 230≥ 180≥ 200≥ 230≥ 40≥ 70
Resistenza a compressione all'1% di deformazioneASTM D695N/mm28-108-910 - 10.56.5 - 85.5 - 6.512 - 13.57 - 11
Deformazione sotto carico (24 h 13.7 N/mm2 23°CASTM D621%≤ 8≤ 8≤ 6.5≤ 7.5≤ 14≤ 6≤ 5.5
Deformazione permanente (come sopra dopo 24 hdi recupero)ASTM D621%≤ 5≤ 4≤ 3≤ 3.5≤ 6≤ 1.5≤ 1.9
Coefficiente d'attrito dinamicoASTM D1894/0.130.080.130.130.080.120.12
Fattore di usura a PV 100ASTM D37029 - 1310 - 2020 - 3010 - 153.00020 - 3012 - 18
PROPERTIES OF IMPORTANCE FOR DESIGNING
Fillers mixed with PTFE allow to improve some basic physical properties of virgin polymer.
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.