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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.

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“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.

Filler	Property	Most common applications
Glass	Enhanced 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.
Graphite	Extremely low coefficient of friction. Fairly good compressive strength. Good wear resistance.	Bearings for high speed on fairly hard surface.
Carbon	Good 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 disulphide	Enhanced non-stick properties. Low static coefficient of friction. Fairly good resistance to deformation.	Guide bands. Details needing good resistivity.
Bronze	Enhanced 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.

MAIN PROPERTIES | MOULDED

Property	u.m.	Method	G Special Compounds
Property	u.m.	Method	G400	G403	G405	G412	G415	G453	G458
Density	g/cm2	ASTM D792	2,14-2,18	2,19-2,22	2,23-2,25	2,10-2,15	2,05-2,11	2,05-2,11	3,80-3,90
Coefficient of linear thermal expansion		ASTM D696	12-13	11-13	7,5-11	12-13	12-13	10-12	8-9
Hardness Shore D	Punti	ASTM D2240	≥58	60-65	62-67	55-60	60-65	62-67	65-70
Tensile strength	N/mm2	ASTM D4894 ASTM D4745	≥24	17-24	14-21	15-20	15-20	14-18	17-23
Elongation at break	%	ASTM D4894 ASTM D4745	≥250	250-300	230-270	170-250	150-200	70-120	100-160
Compressive strengtat 1% deformation	N/mm2	ASTM D695	14-17	10-14	7-10	8-10,5	4,5-6,5	5-6	5-6
Deformation under load	%	ASTM D621	7-9	6-7	4-6,5	4-6	2,5-4	2,5-4	1,5-2,5
Permanent deformation (as above, after 24-h relaxation)	%	ASTM D621	7-9	6-7	4-6,5	4-6	2,5-4	2,5-4	1,5-2,5
Kinetic coefficient of friction	/	ASTM D1894	0,06	0,12	0,13	0,07	0,13	0,11	0,13
Wear factor at PV 100		ASTM D3702	2,900	10-20	10-15	60	20-30	16-20	10

MAIN PROPERTIES | EXTRUDED

Property

u.m.

Method

G Special Compounds

G400

G403

G405

G412

G415

G453

G458

Density

g/cm2

ASTM D792

2,14-2,18

2,18-2,21

2,22-2,14

2,09-2,14

2,04-2,10

3,80-3,88

Hardness Shore D

Punti

ASTM D2240

51-60

60-65

62-67

55-60

60-65

62-67

65-70

Tensile strength

N/mm2

ASTM D4894

≥20

≥15

≥13

≥14

≥12

≥13

Permanent deformation (as above, after 24-h relaxation)

ASTM D4745

≥200

≥180

≥70

≥100

≥200

1,5-2,5

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.

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