State of the Art Polyamide 66 (PA66) is an engineering thermoplast that is widely used in mechanical engineering, particularly in tribologically stressed components such as plain bearings, gear wheels and sleeves. Glass fibres (GF) are primarily used as reinforcing materials to improve mechanical and thermal properties. They increase the modulus of elasticity, strength, impact resistance and thermal conductivity [1, 2]. The coefficient of friction can be influenced by the correct selection and alignment of the fibres. The type, quantity, shape and orientation of the fibres in the PA66 matrix as well as the application parameters are decisive factors here [3-5]. Studies show that the coefficient of friction is impacted by the fibre content. Fibre breakage leads to an increased accumulation of glass fibre fragments in the contact area. These fragments affect the adhesive friction between the contact partners, as there is increased frictional contact between the glass fibre and metal. However, as the fibre content increases, the wear on the polymer matrix can also increase due to abrasive effects. Broken fibre fragments act like abrasive particles, tearing further glass fibres out of the matrix [3, 4, 6]. Solid lubricants such as PTFE, MoS 2 and graphite are used to optimise tribological properties [1, 2]. PTFE is used in many applications as a friction modifier. Due to its low polar surface energy, it offers excellent sliding properties and is considered a particularly effective solid lubricant [2]. Many studies have investigated the influence of PTFE-lubricated PA66GF compounds in this regard. Demici et al. conducted a study in which they investigated the tribological properties of PTFE-lubricated PA66GF compounds while varying the sliding speed, bearing pressure and temperature. They show that the combined addition of glass fibres and PTFE significantly improves tribological behaviour. Increased bearing pressure reduces the coefficient of friction, but at the same time leads to a rise in temperature at the sliding contact. Due to their high thermal conductivity, glass fibres can efficiently dissipate heat at this point, but they also have an abrasive effect on the opposing surface. PTFE compensates for this disadvantage by forming a transfer film that reduces the coefficient of friction [7, 8]. Previous studies have shown that the quality, homogeneity and adhesion of PTFE-based transfer films have a significant influence on tribological performance [9]. However, PTFE is a PFAS compound and is increasingly subject to regulatory pressure due to its environmental persistence. Specialist authorities in several EU countries have submitted a dossier to the EU discussing a partial or complete ban on substances containing PFAS. Science and Research 5 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 Alternatives to PTFE as Solid Lubricant in Glas Fiber Reinforced PA66: A Comparative Study Matthias Graf, Timo Knöner* submitted: 22.09.2025 accepted: 21.05.2026 (peer review) Presented at the GfT Conference 2025 This study investigates the tribological behavior of PA66-GF30 compounds, modified with various friction-reduction additives, under standardized test conditions using ball-on-disc and sliding bushing experiments. The results show that PTFE-containing materials deliver low and stable friction coefficients as well as low wear rates. As expected, this is particularly evident when compared with a comparable compound without solid lubricant. Adding of MoS 2 achieves friction and wear values comparable to PTFE only at higher concentrations. Graphite as an additive, however, exhibits unstable friction behavior and low wear resistance under non-humid conditions. Overall, the study demonstrates that PTFE is tribologically superior to the alternatives examined, while MoS 2 , when used in appropriate dosage, may represent a promising alternative—especially in view of future regulatory requirements for PFAS-free materials. Keywords PA66GF30, PTFE, PFAS, MoS 2 , Graphite, Glass fiber, Polyamide, Solid lubricant Abstract * Prof. Dr.-Ing. Matthias Graf M. Eng. Timo Knöner Hochschule Emden/ Leer Constantiaplatz 4, 26723 Emden conductive particles, which limits its use in electronicssensitive environments [15]. Thermoplasting processing companies that currently use PTFE-containing compounds are often seeking substitutes due to growing environmental regulations. However, a 1: 1 replacement with no impact on tribological behaviour is not to be expected; rather, the choice of solid lubricant will depend on the specific application. Materials and Samples The seven materials used in this study include an unmodified PA66-GF30 and six tribologically modified variants with incorporated additives such as PTFE, MoS 2 and graphite. The materials were purchased as finished compounds from various manufacturers. Selected properties are listed in Table 1 according to the manufacturers’ data sheets. From an economic point of view, purchasing the unlubricated material is typically the most cost-effective option. The addition of solid lubricants can significantly increase the price of the material - even to more than five times the price of the unlubricated material. Sliding discs (outer diameter: 23 mm, thickness: 2 mm) and sliding bushings (outer diameter: 12 mm, inner diameter: 10 mm, width: 12 mm) were manufactured by injection moulding as test specimens; see Figure 1 for examples. The sliding discs were not reworked, while the inner surfaces of the sliding bushings were reamed with an H7 reamer in accordance with DIN ISO 7148-2 and deburred and chamfered on the front side [16]. Science and Research 6 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 A statement from the European Chemicals Agency (ECHA) is expected in 2026 [10]. This brings the industrial application of alternative additives for PA66GF30 compounds into focus. MoS 2 and graphite are considered promising alternatives. Both have a lamellar hexagonal layer lattice with an anisotropic structure. The crystallographic structure of MoS 2 consists of alternating chalcogenide layers, each comprising two layers of sulphur and one layer of molybdenum disulphide molecules in between. There is a strong covalent bond between the atoms of molybdenum disulphide and sulphur. Weak van der Waals forces between the sulphur layers of neighbouring chalcogenide layers promote the sliding of the layers even with very small relative movements. MoS 2 has particularly low friction coefficients in a vacuum and in a dry environment [11, 12]. The crystallographic structure of graphite consists of layers of embedded carbon atoms. The van der Waals forces acting between the layers are greater than in MoS 2 . Graphite relies on the incorporation of water molecules to develop its good lubricating properties. These reduce the van der Waals forces and improve the sliding properties [11]. In combination with glass fibres, both additives show reduced friction and wear values, with the effect of MoS 2 having been researched more extensively [13-15]. With graphite, interactions with other additives can occur or can agglomerate, which can have a negative impact on mechanical properties. Under high mechanical stress graphite can lead to increased abrasion of electrically Table 1: Mechanical properties of the materials investigated, according to manufacturer’s datasheets. The friction modifier content of GF32-MoX-E is unspecified. ! ! "#$! "#$! "%$! "%$! "&$! "&$! Figure 1: Test geometries: Sliding discs (left) and sliding bushings (right) made of, for example, (a) GF30-A, (b) GF30- G5-S and (c) GF30-PTFE15-A Test methodology and test procedure Before conducting the tribological tests, the sliding discs and sliding bushings were each conditioned for at least 24 hours under ambient conditions in the test laboratory [16]. The sample surfaces and the counter surfaces of the test equipment were then cleaned with isopropanol. The tribological tests on the sliding discs were carried out on a ball-on-disc tribometer (TBR 3 , Anton Paar) in dry running mode; see Table 2 for parameters. Five test specimens of each of the seven materials were tested using both test methods (7 x 5 x 2 = 70 tests). The tribological tests on the sliding bushings were carried out on a test bench designed for the geometry of these sliding bushings, see Figure 2. The test bench is based on test method C2 in accordance with DIN ISO 7148-2 [16]. The sliding bushings are placed in a pendulum device and supported on one side by a motor-driven shaft. The test load is applied using a defined test weight. Friction is measured by recording the horizontal deflection of the pendulum arm using a contactless laser sensor. The coefficient of friction is then calculated from this deflection. The test conditions are based on the DIN ISO 7148-2 standard [16]. A turned steel shaft (R z = 4.5 µm) made of V2A stainless steel serves as the counter body. The tests were carried out at a PV-value (product of specific surface pressure and sliding speed) of 0.03 MPa·m/ s. The load between the shaft and the sliding bushing was adjusted so that a specific surface pressure according to load level F2 in accordance with the above-mentioned standard was achieved, see Table 2. Results and Discussion Friction: Ball-on-Disc The friction behaviour observed during the ball-on-disc tests is shown in Figure 3. Five individual ball-on-disc tests were carried out for each material, and the resulting friction coefficient curves were averaged arithmetically. The superimposition of these averaged curves shows that all materials tested exhibit characteristic friction behaviour in ball-on-disc contact over the sliding distance. For the discussion of the results, the sliding distances from 0-200 m are referred to below as the “running-in Science and Research 7 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 ! ! ! "#$#%&'$#()('' ! "#$#%&'*+(,#%&(' "# $ %&! '(! )% $ )! $ )#(&#*&! +,- ./ 011! 2345! 678! 7 , 9! 43: ; / <! 23=5! >'#&! 3? ! 8! @: A: ! 8! .#BA! C%*)DE#(! F*% $$ G*%! 3H@! .I#! JK L =: ? ? ! .I#M! / ! I*'N%O)%&! *%P%*%(O%! F*% $$ G*%! ! / ! ? A<1! .I#! , QE&E(R! $ F%%&! ! ? A3! ST $ ! ? A3! ST $ ! , QE&E(R! &E $ )#(O%! 3? ? ? ! S! 3? ? ? ! S! - *#OU! &E#S%)%*! 3: ! SS! / ! V'G()%*! W '&X! Y ! 3? ! SS! "#QQ! J3? ? V*=M! Y ! 3? ! SS! ,Z #P)! J [ < + M! - %SF%*#)G*%! <3\<@! ]V! ! CGSE&E)X! H<\=H! ^ ! Table 2: Test parameters for sliding discs and sliding bushings 3H Y Figure 2: Test bench used for testing the sliding bushings #$%&%'( ) *+,-%'( ) %' ) .-/ ) 0/ '&+$+1 ) &%2%3/ 45,/ 6 ) ,/ ',76 ) 1/ 5,+6/ , ) 0/ '&+$+1 ) &/ 8 $/ 3.%7' ! embedded in the matrix and are only exposed as the test progresses. At the same time, wear will increase the nominal contact area, while the nominal peak stress will decrease. The unmodified reference material (GF30-A) exhibits a significant increase in the coefficient of friction to a maximum at the beginning of the “running-in phase”. In this phase, unlubricated ploughing wear will lead to an Science and Research 8 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 phase”, while sliding distances between 800 -1000 m are referred to as the “test phase”. During the “running-in phase”, all materials exhibit similarly low coefficients of friction, which increase with increasing sliding distance. In the “test phase”, the materials can be divided into two friction coefficient ranges: µ > 0.15 and µ < 0.10. It must be assumed that at the start of the test, the glass fibres are still practically completely Figure 3: Friction coefficient curves averaged over five individual ball-on-disc tests Figure 4: Friction coefficients and standard deviations obtained from the ball-on-disc tests increased coefficient of friction. A slight reduction in the coefficient of friction can be observed as the sliding distance increases. Exposed glass fibres in frictional contact will contribute to reducing friction, as discussed in [3]. The use of additives such as MoS 2 , graphite and PTFE significantly influences the tribological properties. Even 1 % MoS 2 (GF30-Mo1-A) slows down the “running-in phase” behaviour, although the basic progression is maintained. Increasing the MoS 2 content to 2 % (GF30- Mo2-A) delays this behaviour even further, with the initial friction coefficients and those in the test phase remaining unchanged in the three variants discussed. MoS 2 therefore leads to significantly slower “runningin phase” behaviour and thus to a stabilisation of the initially low friction coefficients. However, when glass fibres are significantly exposed, the influence of MoS 2 disappears. This trend, albeit even more delayed, is also evident in the material lubricated with an unknown MoS 2 content (GF32-MoX-E): over long sliding distances, the coefficient of friction remains constantly low at approximately µ = 0.05 and slightly undercuts samples with PTFE. With GF32-MoX-E, too, an increase in the coefficient of friction can be seen as the sliding distance progresses. With a graphite content of 5 % (GF30-G5-S), the curves contain two plateaus (not shown), which are reflected in a step-like progression in the coefficient of friction averaged over five samples (Figure 3). In the “running-in phase”, the values are approximately µ = 0.05, but the coefficient of friction increases significantly with increasing sliding distance. In addition, fluctuations occur that indicate larger wear particles in the sliding contact. The use of graphite, in this case in a low-humidity environment, also leads to a delay in the “running-in phase” behaviour and a stabilisation of the initially low coefficient of friction, but not to a reduction in the coefficient of friction over long friction distances. A low coefficient of friction even over long friction distances was observed in the samples lubricated with 15 % PTFE from two different manufacturers (GF30- PTFE15-A and GF30-PTFE15-S). It is known from the literature [1, 2] that a stable PTFE transfer film forms after just a few metres of friction contact and remains intact over the entire sliding distance. Both materials exhibit the most stable coefficients of friction of all the materials tested. Under the test conditions used here, the other solid lubricants (MoS 2 and graphite) only achieve such low coefficients of friction during the “running-in phase”, but not over long sliding distances. For further analysis, the arithmetic mean value was calculated for each material across the “running-in phase” (0-200 m) and the “test phase” (800-1000 m), as shown in Figure 4. The standard deviations were calculated from the five averaged friction coefficients of a material and are shown as error bars. The two PTFE-containing samples (GF30-PTFE15-A and GF30-PTFE15-S) exhibit a consistently low standard deviation in both phases, which indicates uniform transfer film formation. While GF30-Mo2-A and GF32-MoX-E exhibit a low standard deviation in the “running-in phase”, increased fluctuation is evident in the “test phase” - an indication of stable “running-in phase” behaviour, but less stable behaviour towards the end of the sliding distance examined here. This effect can already be observed in the “running-in phase” for materials with less or no lubrication (GF30-A, GF30-Mo1-A, GF30-G5-S), where larger standard deviations occur. Friction: Bushings Similar to the investigations of the sliding discs, an average friction coefficient curve was also created for the sliding bushings from five individual measurements per material, see Figure 5, and the scatter was also evaluated, Figure 6. The measurement data were acquired with a sampling rate of 250 Hz. Frequencies associated with the rotational speed and the natural frequency of the mass pendulum were removed from the measurement series using band-stop filters with frequency ranges of 0.7- 0.9 Hz and 3.0 -3.2 Hz. When comparing the two tests, it must be taken into account that the sliding bushings have a significantly larger friction surface area. With an engagement ratio of 1.0, the sliding bushings have significantly less opportunity to remove wear particles and heat from the friction contact than in the ballon-disc test. Such altered tribological conditions may also affect the formation, stability and quality of PTFEbased transfer films, which are known to strongly influence friction and wear behaviour [9]. However, characteristic differences in the friction coefficient curve of the individual materials are also evident here. At the start of the sliding section, the friction coefficients of all materials are lower, but increase as the section progresses. GF30-Mo1-A exhibits the highest friction coefficients in the “running-in phase”, followed by a decline and slight fluctuations. Increased fluctuations occur from approximately 600 m onwards. GF30-PTFE15-A, GF30-PTFE15-S and GF30-Mo2-A exhibit the lowest coefficients of friction during the “running-in phase”. GF30-PTFE15-S in particular shows a constant coefficient of friction curve with very low fluctuations after the “running-in phase”. In contrast, the coefficient of friction increases almost linearly for GF30-PTFE15-A, which indicates uneven transfer film formation across the sliding surface of the bushings. GF30-Mo2-A exhibits similar behaviour to GF30- PTFE15-S: during the “running-in phase”, the coefficient of friction is slightly higher than that of PTFE, but approaches it as the process continues and remains stab- Science and Research 9 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 Friction coefficients comparable to those of the two PTFE-filled samples are achieved with 5 % graphite (GF30-G5-S) or 2 % MoS 2 (GF30-Mo2-A), at approximately µ = 0.49. However, the graphite-filled samples exhibit markedly stronger temporal fluctuations in friction compared to PTFE and MoS 2 . The remaining materials (GF30-A, GF32-MoX-E, GF30-Mo1-A) show friction coefficients of about µ = 0.57, which are higher than those of the PTFE-lubricated materials. Science and Research 10 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 le. Significant fluctuations in friction coefficients are evident in GF30-G5-S with 5 % graphite. While a relatively constant friction coefficient is still observed during the “running-in phase”, the fluctuation increases significantly with increasing sliding distance. This indicates an unstable lubricating film in the contact area. In the “test phase”, the materials can be divided into two groups: Figure 5: Friction coefficient curves of the slide bushing materials examined Figure 6: Friction coefficients and standard deviations of examined sliding bushings For further analysis, the arithmetic mean was calculated for each material over the “running-in phase” (0-200 m) and the “test phase” (800 -1000 m), as shown in Figure 4. The standard deviations were calculated from the five averaged friction values of each material and are shown as error bars. A larger error bar thus indicates greater scatter between the five samples of each material, but not greater temporal fluctuation. In particular, the differences in standard deviation between the “runningin phase” (0 -200 m) and the test phase (800 -1000 m) remain at an almost unchanged level. A reduction of the standard deviations between the five samples compared to the PTFE case is achieved only with graphite lubrication, which, however, exhibited fluctuations over time. Particularly large standard deviations are also found in the samples with a low or unknown MoS 2 content (GF30-Mo1-A, GF32-MoX-E). Wear: Ball-on-Disc The wear of the sliding discs was determined based on the penetration depths recorded by the tribometer and is shown in Figure 7 as a wear curve. The data was evaluated in the same way as the friction coefficients. Five individual measurements were carried out for each material variant. The penetration-depth data were recorded with a sampling rate of 250 Hz. High-frequency fluctuations were eliminated using a moving average with a window size of 15,555 data points in order to emphasize the long-term quantitative wear trend and to suppress local transient effects inherent to tribological measurements. Subsequently, the individual measurements were combined into a wear curve for each material by arithmetic averaging of the penetration depths. In the “running-in phase” (0-200 m), all materials exhibit varying degrees of penetration depth. While GF30-A and GF30-PTFE15-A show hardly any penetration in the first 50 m, GF30-G5-S in particular exhibits a steep increase in penetration depth during this phase. As the sliding distance increases, the penetration depth continues to rise for all materials, which is due to plastic deformation, the smoothing of roughness peaks and the formation of a track groove. After approx. 50 m, the wear progression stabilises. Over the entire sliding distance, GF30-A exhibits the lowest penetration depth and GF30-G5-S the highest. To assess the progress of wear after “running-in phase”, the slope of the compensation curve between 200 and 1000 m of sliding distance is determined (wear rate). The materials can be divided into three groups. The highest wear rate of 20.1 µm/ km is found in graphite (GF30-G5-S) - significantly higher than the wear rate of the unlubricated material GF30-A. The middle group, with wear rates of 9.5-10.2 µm/ km, consists of the unlubricated material GF30-A and the variant with low MoS 2 content (GF30-Mo1-A). A higher MoS 2 content (GF30- Mo2-A) or PTFE (GF30-PTFE15-A/ S) deliver the lowest wear rate of 7.4-3.8 µm/ km in the present study. A high MoS 2 content even enables lower wear rates than with PTFE. A visual inspection of the friction marks after the test reveals easily recognisable abrasion particles in the unlu- Science and Research 11 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 Figure 7: Wear curves of examined sliding disc materials (dashed line: compensation levels 200 - 1000 m sliding distance) Acknowledgment This study was financially supported by the BMFTR (Bundesministerium für Forschung, Technologie und Raumfahrt, Federal Ministry of Research, Technology and Space): “DATIPilot - Sprint - PANTHER: PFAS - Alternativen in neuen Thermoplasten in Reibanwendungen”, Founding Code: 03DPS1188. References [1] G. Erhard, Konstruieren mit Kunststoffen, 4. Aufl. München: Hanser, 2008. [2] H. Czichos und K.-H. Habig, Tribologie-Handbuch. Wiesbaden: Springer Fachmedien Wiesbaden, 2020. [3] S. Kukureka, C. Hooke, M. Rao, P. Liao und Y. Chen, “The effect of fibre reinforcement on the friction and wear of polyamide 66 under dry rolling-sliding contact,” Tribology International, 1999, Volume 32, Issue 2, S. 107- 116. doi: 10.1016/ S0301-679X(99)00017-1. [4] R. Autay, S. Missaoui, J. Mars und F. Dammak, “Mechanical and tribological study of short glass fiber-reinforced PA 66,” Polymers and Polymer Composites, 2019, Volume 27, Issue 9, S. 587- 596. doi: 10.1177/ 0967391119853956. [5] G. Srinath und R. Gnanamoorthy, “Effect of Short Fibre Reinforcement on the Friction and Wear Behaviour of Nylon 66,” Appl Compos Mater, 2005, Volume 12, Issue 6, S. 369 - 383. doi: 10.1007/ s10443-005-5824-6. [6] T. Kunishima et al., “Tribological behavior of glass fiber reinforced-PA66 in contact with carbon steel under high contact pressure, sliding and grease lubricated conditions,” Wear, 2020, Volume 456-457, S. 203383. doi: 10.1016/ j.wear.2020.203383. [7] Mihaly Kozma, “Effect of Incorporated Lubrication on the Tribological Properties of Polyamides,” The Annals of University “Dunărea De Jos” of Galaţi Fascicle VIII, 2005. [8] M. T. Demirci und H. Düzcükoğlu, “Wear behaviors of Polytetrafluoroethylene and glass fiber reinforced Polyamide 66 journal bearings,” Materials & Design, 2014, Volume 57, S. 560 - 567. doi: 10.1016/ j.matdes.2014.01.013. [9] A. Keller, M. Enger, S. Trubnykov und J. Molter, “Quality of PTFE containing transfer films and their impact on tri- Science and Research 12 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007 bricated and graphite-lubricated material, see Figure 8, which are not visible in the samples with PTFE and MoS 2 . Nevertheless, the wear curves of these materials lie between those of GF30-A and GF30-G5-S, so a similar amount of wear volume must occur. The assumption is that the abrasion particles of differently lubricated materials have different agglomeration behaviour. Conclusion The tribological tests carried out show clear differences in the friction and wear behaviour of the materials examined. Additives such as PTFE, MoS 2 and graphite have a significant influence on the tribological properties of glass fibre reinforced PA66 materials. Above all, materials containing PTFE (GF30-PTFE15-A/ S) exhibit consistently low and stable coefficients of friction and comparatively low wear rates due to the formation of a uniform transfer film. The additive MoS 2 reduces the wear rate compared to the unlubricated case, in some cases even lower than the PTFE-containing variants, and significantly improves the friction behaviour with increasing proportion. However, in terms of the coefficient of friction, MoS 2 only leads to comparable values to PTFE at the beginning of the tests. When glass fibres are extensively involved in the friction contact, MoS 2 can no longer play to its strengths. In the case of graphite, the coefficient of friction shows no advantage over the unlubricated case in terms of friction and wear behaviour over long distances. The tests were carried out at normal room humidity; it is expected that graphite can demonstrate its strengths in the presence of increased water molecules. These results are consistent across two test situations (ball-on-disk and sliding bushings). Differences in behaviour between sliding discs and bushings can be explained by different geometries and loads. Overall, materials containing PTFE deliver the best results, while PA66GF30 with higher MoS 2 content materials are a promising alternative, as long as glass fibres do not come into contact with friction on a large scale. Graphite is not an alternative in dry environments. ) ) H: #.! J#.UC&6: =! H: #.! U.#&N! Figure 8: Agglomeration of abrasion particles from the examined sliding disc materials GF30-A (left) and GF30-G5-S (right) bological performance - Über die Güte von PTFE-basierten Transferfilmen und deren Einfluss auf tribologische Leistungsfähigkeit,” Tribologie und Schmierungstechnik, 2020, Volume 67, Issue Nr. 4, S. 5-14. [10] ECHA. “All news - ECHA announces timeline for PFAS restriction evaluation.” Zugriff am: 15. September 2025. [Online.] Verfügbar: https: / / echa.europa.eu/ de/ -/ echa-announces-timeline-for-pfas-restriction-evaluation [11] H. Birkhofer und T. Kümmerle, Feststoffgeschmierte Wälzlager. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. [12] R. Kumar, S. K. Mishra und S. Jayapalan, “Effect of Molybdenum Disulfide (MoS 2) Reinforcement on the Structural, Thermal, Mechanical, and Tribological Analysis of Novel Polyamide 6,6 ( PA 6,6) Composites,” J of Applied Polymer Sci, 2025, Volume 142, Issue 26, e57081. doi: 10.1002/ app.57081. [13] A. Horovistiz, S. Laranjeira und J. P. Davim, “Influence of sliding velocity on the tribological behavior of PA66GF30 and PA66 + MoS 2 : an analysis of morphology of sliding surface by digital image processing,” Polym. Bull., 2018, Volume 75, Issue 11, S. 5113-5131. doi: 10.1007/ s00289-018-2314-1. [14] H. Sun et al., “Graphite fluoride and fluorographene as a new class of solid lubricant additives for high-performance polyamide 66 composites with excellent mechanical and tribological properties,” Polymer International, 2020, Volume 69, Issue 5, S. 457-466. doi: 10.1002/ pi.5975. [15] E. Basavaraj, B. Ramaraj und Siddaramaiah, “A study on mechanical, thermal, and wear characteristics of nylon 66/ molybdenum disulfide composites reinforced with glass fibers,” Polymer Composites, 2012, Volume 33, Issue 9, S. 1570-1577. doi: 10.1002/ pc.22293. [16] DIN ISO 7148-2, Gleitlager - Prüfung des tribologischen Verhaltens von Gleitlagerwerkstoffen - Teil 2: Prüfung von polymeren Gleitlagerwerkstoffen (ISO_7148- 2: 2012), Berlin. [17] ASTM G99, Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus, ASTM International, 2017. Science and Research 13 Tribologie + Schmierungstechnik · volume 73 · issue 2/ 2026 DOI 10.24053/ TuS-73-0007