Lehvoss LUVOCOM 3F PPS CF 9938 BK is a black polyphenylene sulfide compound containing carbon fiber reinforcement and formulated within the LUVOCOM 3F range for additive manufacturing by material extrusion. The grade is supplied for fused filament fabrication and direct pellet extrusion rather than powder-bed fusion or injection molding. The material designation identifies a semi-crystalline PPS matrix, carbon fiber filler, and a black colorant package. The 9938 series is intended for high-temperature extrusion where dimensional stability, chemical resistance, and reduced warp are required. Because product-specific datasheet values for this exact compound are not always fully published in open literature, representative data for carbon fiber reinforced PPS compounds are used here only as orientation and do not replace the supplier certificate of analysis or lot-specific test report.

The base PPS polymer provides a continuous service temperature above 200 °C in non-oxidizing environments and inherent resistance to a range of solvents, fuels, and process chemicals. The carbon fiber reinforcement reduces the coefficient of linear thermal expansion and bulk shrinkage compared with unfilled PPS, but increases melt viscosity and abrasive wear on extrusion hardware. For fused filament fabrication, the material requires an all-metal hot end capable of sustained operation at 315 °C to 345 °C and a heated build chamber. Published processing guidance for PPS-based compounds indicates that chamber temperatures below 80 °C can increase interlayer stress and delamination in large cross-sections. The use of a hardened steel, ruby, or silicon carbide nozzle is required because carbon fiber accelerates brass nozzle wear.

What drying and extrusion parameters prevent porosity and warpage in the CF 9938 BK grade?

Predrying is a prerequisite for filament production and printing. PPS has low equilibrium moisture absorption, but surface moisture and absorbed water can generate voids at extrusion temperatures. The compound should be dried in a desiccant dryer to a residual moisture level at or below 0.02 wt%. Typical drying conditions for PPS compounds are 100 °C to 120 °C for 4 h to 8 h, depending on ambient relative humidity and pellet storage history. At relative humidity above 60%, drying time should be extended or the hopper should be blanketed with dry nitrogen. Moisture above 0.02 wt% can produce nozzle steam, surface splay, and reduced interlayer adhesion.

Filament production from LUVOCOM 3F PPS CF 9938 BK typically uses single-screw extruders with L/D ratios from 20:1 to 30:1 and compression ratios from 2.5:1 to 3.5:1. Barrel temperature profiles should rise from approximately 300 °C at the feed throat to 330 °C to 340 °C at the metering section, with die temperature held near 330 °C. Melt temperature should not exceed 360 °C for prolonged residence times because PPS can undergo chain extension, gel formation, and nozzle blockage. A melt pump may be required to stabilize filament diameter when using higher carbon fiber content. Filament diameter tolerance for reliable FFF feed should be maintained within ±0.05 mm.

The carbon fiber filler reduces melt extensibility and increases the minimum bend radius before filament fracture. Filament handling paths should avoid sharp turns and use PTFE or ceramic guides. In direct pellet extrusion, screw and barrel alloys should be hardened or bimetallic because carbon fiber causes progressive wear. Feeder stability is critical because filler and matrix can segregate in the pellet hopper. Low-cost volumetric screw feeders may produce inconsistent fiber concentration if the pellet bulk density varies. A gravimetric feeder with gentle agitation is preferable for maintaining composition uniformity.

Interlayer adhesion in PPS is controlled by melt temperature, chamber temperature, and deposition speed. If the chamber temperature is below 80 °C, the previously deposited layer can crystallize before the next layer is applied, producing weak fusion at the interface. Deposition speeds from 20 mm/s to 50 mm/s are often used for small parts, but the speed should be reduced when layer thickness exceeds 0.20 mm to allow thermal transfer. Print cooling fans must be disabled or heavily restricted because forced convection creates excessive undercooling. For parts thicker than 10 mm, annealing after printing may be required to reduce residual stress. Published data for the specific annealing cycle of this grade is limited; typical PPS annealing profiles involve slow heating to 180 °C to 200 °C and controlled cooling below 1 °C/min to avoid cracking.

Carbon fiber loading and dimensional stability under thermal load

The addition of carbon fiber to a PPS matrix alters the property profile in three measurable directions. First, tensile and flexural modulus increase. Representative carbon fiber reinforced PPS compounds tested according to ISO 527-2 and ISO 178 often show flexural modulus values from 8 GPa to 12 GPa, whereas unfilled PPS typically lies near 3.5 GPa to 4 GPa. Second, elongation at break falls sharply, usually below 2%, so the material is not suitable for snap-fit designs relying on high strain. Third, the coefficient of linear thermal expansion decreases, reducing warpage and improving printability on large flat geometries. Unfilled PPS can exhibit CLTE values above 50 µm/(m·K) in the flow direction, while carbon fiber reinforced grades frequently show values between 20 µm/(m·K) and 30 µm/(m·K). These values are orientation-dependent in additive manufacturing because fiber alignment follows the deposited road direction.

Heat deflection temperature under load is determined according to ISO 75-2 method A at 1.8 MPa or ASTM D648. Carbon fiber reinforced PPS grades often retain structural stiffness above 250 °C at the stated stress. However, HDT is not a continuous use limit. The continuous use temperature is influenced by oxygen exposure, load duration, and chemical environment. PPS is susceptible to oxidative degradation at elevated temperatures, particularly above 180 °C in long-term air service. The carbon fiber does not remove this limitation. For non-oxidizing conditions, PPS can operate at higher temperatures than in air. Designers should use UL 746B relative thermal index data when available for the exact compound to establish long-term electrical or mechanical service limits.

Density of carbon fiber reinforced PPS typically falls between 1.35 g/cm³ and 1.45 g/cm³ when measured by ISO 1183. The black colorant and carbon fiber produce a low-gloss black surface. The material has low moisture uptake after printing, but it is not recommended for continuous immersion in hot strong oxidizing acids, concentrated nitric acid, or sodium hypochlorite. PPS has excellent resistance to many non-oxidizing acids, bases, hydrocarbons, and automotive fluids, but specific chemical exposure should be validated by ISO 175 immersion testing at the service temperature. Stress cracking may occur under combined mechanical load and chemical exposure even when unstressed chemical resistance is acceptable.

Unlike unfilled PPS, the carbon fiber grade has a higher thermal conductivity, which reduces internal hot spots during printing but also accelerates cooling after deposition. The increased thermal conductivity can be beneficial for dimensional accuracy in thick sections, but it also means that the deposited road loses heat more quickly. A heated chamber is therefore more important for this grade than for unfilled PPS. In addition, the anisotropic thermal conductivity is higher along the fiber direction than across the layer interface. This anisotropy can lead to nonuniform warpage if the raster pattern is not balanced across the part cross-section. Alternating raster angles between ±45° and 0°/90° layers reduces directional warpage in flat parts.

When PPS CF 9938 BK replaces unfilled PPS or PEEK in functional manifolds and housings

LUVOCOM 3F PPS CF 9938 BK is used where unfilled PPS produces unacceptable warpage or insufficient stiffness. In additive manufacturing, unfilled PPS is difficult to print because high crystallization shrinkage causes corner lifting and interlayer cracks. The carbon fiber in the 9938 grade mitigates these effects by reducing shrinkage and increasing the effective viscosity of the deposited road. The same fiber content also reduces creep under sustained mechanical load, which is relevant for fluid manifolds, pump housings, and brackets exposed to elevated temperature. Compared with glass fiber reinforced PPS, carbon fiber provides higher specific stiffness and improved wear resistance, but at higher filler cost and with greater melt viscosity. The higher melt viscosity can reduce flow through small nozzles and increase extruder torque.

Compared with PEEK carbon fiber grades, PPS carbon fiber has a lower continuous service temperature in air and lower impact toughness. PEEK carbon fiber materials can often sustain service temperatures above 240 °C in air, while PPS is typically limited below 200 °C for long-term oxidative exposure. However, PPS offers better resistance to some hot acidic environments and processes at lower melt temperatures. The processing window for PPS carbon fiber is broader than for PEEK carbon fiber, and the raw material cost is generally lower. PPS also has inherent flame retardance without halogen additives, and many PPS compounds achieve UL 94 V-0 at thicknesses down to 0.75 mm. Product-specific UL 94 certification for this grade should be confirmed from the Lehvoss data sheet or third-party test report.

Electrical connector bodies and sensor housings are potential applications because PPS provides dielectric stability and chemical resistance at soldering temperatures. In material extrusion, the carbon fiber reinforcement lowers surface resistivity compared with unfilled PPS, which may reduce electrostatic charge accumulation but may also limit use in high-voltage insulation where volume resistivity is critical. The exact surface resistivity depends on print orientation, fiber loading, and moisture content. Parts requiring consistent electrical insulation should be tested according to IEC 62631-3-2 or ASTM D257 under the intended temperature and humidity conditions.

The use of carbon fiber reinforced PPS in low-volume production requires attention to support removal and post-processing. The material is hard and abrasive, so conventional high-speed steel cutting tools wear rapidly. Carbide or diamond-coated tools should be used for any machining operation. Drilling, tapping, and milling should be performed at low speeds with adequate ventilation because carbon fiber dust and PPS fumes pose occupational exposure concerns. Fused filament parts have anisotropic properties, so threaded inserts are preferred over direct tapping when a load-bearing thread is required. Heat-staked brass or stainless steel inserts provide more consistent pull-out strength than printed threads in fiber-filled PPS.

Dimensional verification should include measurement of both as-printed and annealed parts because internal stress relaxation can change critical dimensions. The amount of change depends on layer height, raster direction, and chamber temperature during printing. Parts printed with lower chamber temperatures and unmelted core regions show greater dimensional shift after annealing. A controlled annealing cycle near 180 °C to 200 °C may increase crystallinity and improve creep resistance, but it can also increase distortion if the part is not supported on a flat, heat-stable fixture. For tight-tolerance features, a trial annealing study should be performed before production use.

Regulatory documentation for this product should include RoHS 2011/65/EU compliance confirmation and REACH EC 1907/2006 SVHC status. These statements are packaging-lot and region-dependent and must be obtained from the supplier. Food contact and medical use are not automatically supported by the base PPS chemistry. If the part is intended for potable water or food contact, migration testing under the relevant national regulation is required. The carbon fiber filler and black colorant may contain constituents that are not approved for direct food contact. No FDA 21 CFR clearance should be assumed for this specific grade.

The selection of this material should be supported by printed test coupons from the intended production machine rather than injection-molded data alone. Additive manufacturing introduces layer interfaces that are not present in injection-molded specimens. Tensile strength perpendicular to the build plane is typically lower than in-plane strength. For carbon fiber filled PPS, the in-plane tensile strength can range from 60 MPa to 90 MPa depending on raster strategy, while interlayer tensile strength may be only 30% to 60% of the in-plane value. Test coupons must be conditioned according to ISO 291 or the relevant ASTM conditioning standard before mechanical testing to reduce moisture and thermal history artifacts.

In direct pellet extrusion with a high-temperature print head, the screw design should have a shallow compression zone to limit shear heating. Carbon fiber increases melt viscosity and shear stress in the nozzle. If nozzle pressures exceed 20 MPa, flow can become unstable. A nozzle diameter of 0.50 mm or 0.60 mm is preferred when printing large parts with high deposition rates. The smaller 0.40 mm nozzle increases pressure and wear but improves detail resolution. Feed path purging after use should be performed with a high-viscosity purge compound or unfilled PPS because carbon fiber residue can remain in the barrel and degrade over time.

Because PPS is prone to crystallization-induced shrinkage, abrupt changes in chamber temperature or removal of the part before chamber cooling can cause distortion. After print completion, the chamber should cool slowly at a rate below 5 °C/min until the part reaches 80 °C or lower. Removing a large part at chamber temperature above 100 °C can produce warpage and internal cracking. The part should then be placed on a flat insulating surface to cool uniformly. No forced air quenching should be applied to fiber-filled PPS parts unless intentional amorphous structure is desired, which is uncommon for high-temperature applications.

The difference between this grade and less expensive carbon fiber filled high-temperature polyamides is also significant. Carbon fiber filled PA6 or PA66 prints at lower temperatures and has higher impact toughness, but it absorbs moisture and loses stiffness at elevated temperature. PPS carbon fiber maintains dimensional stability in wet and hot environments but has lower fracture toughness. For parts exposed to hot water, steam, or aggressive solvents, PPS is generally preferable to high-temperature polyamide. However, its higher processing temperature demands more robust heated chambers and hardened extrusion hardware. The operational boundary for long-term hot water exposure should be confirmed by hydrolysis testing, because the carbon fiber interface can be attacked by hydrolysis if the matrix molecular weight is insufficient.

In summary of process selection, LUVOCOM 3F PPS CF 9938 BK occupies a position between lower-cost high-temperature amorphous polymers such as PEI and higher-performance PEEK carbon fiber compounds. It is selected when chemical resistance, dimensional stability, and flame retardance are required, while continuous service temperature does not exceed the oxidative limits of PPS. The carbon fiber filler addresses the warpage and substrate adhesion limitations of unfilled PPS in additive manufacturing. All processing parameters described here are representative and must be validated on the target machine with dried, lot-controlled feedstock.