Lehvoss LUVOCOM 3F PEEK 9581 NT is a natural-colour, unfilled polyetheretherketone compound released for extrusion-based additive manufacturing. The “3F” designation identifies the LUVOCOM additive manufacturing series, while “9581 NT” specifies an unfilled polyetheretherketone base with natural colour. Manufacturer documentation describes the material as a high-temperature feedstock intended for fused filament fabrication and pellet-fed material extrusion systems where continuous service temperatures exceed those accessible to polyamide, polycarbonate, and polyetherimide. Density is reported as 1.31 g/cm³ according to ISO 1183-1. The melting endotherm is documented near 343 °C by ISO 11357-3, with a glass transition near 143 °C by ISO 11357-2. The grade is unfilled and therefore does not introduce carbon-fibre or glass-fibre anisotropy in printed sections; however, tensile modulus is lower than that of filled LUVOCOM 3F PEEK compounds.

Feedstock format includes spooled monofilament and pellet feedstock for filament conversion or pellet extrusion. Exact filament diameter, ovality, and spool dimensions are provided in distribution documentation and should be verified against the target machine’s feeding specification. Drying is required before processing because polyetheretherketone feedstock can adsorb surface moisture, and residual water at melt temperatures above 350 °C produces steam-induced porosity, filament diameter fluctuation, and reduced interlayer fusion. Spools or pellets exposed to ambient air at relative humidity above 60% should be dried at 150 °C for 3 h to 5 h in a dry-air oven with a dew point below -40 °C. Vacuum drying at 120 °C for 8 h is an alternative when available. Storage in sealed desiccant containers with a monitored internal dew point below -20 °C is recommended after drying.

Which Drying and Feedstock Handling Parameters Prevent Hydrolysis and Filament Porosity?

Moisture control is the primary feedstock-handling variable for LUVOCOM 3F PEEK 9581 NT. Published processing guidance for unfilled polyetheretherketone indicates that melt viscosity is sensitive to moisture-induced chain scission at extended melt residence times. Filament exposed to uncontrolled shop air has been observed on production-scale fused filament fabrication lines to produce random diameter deviations exceeding ±80 µm when dried for less than 3 h. Such deviations alter volumetric throughput from the extruder and can produce under-extrusion ridges and periodic weak interfaces. Pellet-fed systems using single-screw extruders with L/D ratios between 24:1 and 30:1 require the same moisture threshold because pelletized feedstock can retain surface moisture in bulk storage containers.

Feedstock should be conditioned to a residual moisture below 0.02% by mass before melt processing. Hot-air ovens are acceptable only if the air source is dried to a dew point below -40 °C; otherwise, vacuum or desiccant drying is preferred. After drying, spools should be loaded into a heated build chamber or a dry-box maintained below 10% relative humidity to prevent moisture re-adsorption. The material is not hygroscopic in the same manner as polyamide, but surface moisture on filament has a disproportionate effect because the melt residence time in a 0.4 mm nozzle is short. Hydrolysis at processing temperatures can generate carboxylic acid end groups that shift crystallisation behaviour and lower interlayer weld strength.

Mechanical property data from the manufacturer’s technical datasheet place tensile strength at 95 MPa and tensile modulus at 3600 MPa under ISO 527-2/1A/50. Flexural modulus is listed at 3800 MPa under ISO 178. Charpy notched impact strength of moulded test specimens is reported as 5 kJ/m² under ISO 179-1/1eA. Heat deflection temperature under 1.8 MPa is documented as 152 °C under ISO 75-2/A, and Vicat softening temperature B50 is 305 °C under ISO 306. These values are representative datasheet values, not guaranteed minimums for printed parts. Material extrusion results depend on raster orientation, chamber temperature, layer height, and nozzle condition. For design purposes, z-axis tensile strength may be substantially below xy-axis values; published FFF polyetheretherketone studies using ISO 527-2/1A/50 specimens routinely report z-axis strength as 30% to 60% of xy-axis values depending on interlayer weld quality.

Dimensional stability remains sensitive to chamber temperature and cooling rate.

Polyetheretherketone crystallises rapidly when the deposited bead cools below the glass transition. In an unheated or poorly heated build chamber, the material freezes in a low-crystallinity condition with higher residual stress, increased solvent uptake, and reduced modulus. For LUVOCOM 3F PEEK 9581 NT, a heated chamber between 120 °C and 160 °C maintains the surrounding environment near the polyetheretherketone glass transition, which allows slow stress relaxation during deposition. A substrate temperature below 110 °C is associated with first-layer delamination and corner curling in large-section prints. The use of a heated build plate alone is generally insufficient for polyetheretherketone because the chamber air temperature controls the cooling rate of upper layers and sidewalls.

Nozzle temperatures are typically set between 400 °C and 430 °C. Nozzle temperatures below 390 °C can reduce interlayer reptation across the weld interface and produce delamination under tensile loading. Print speeds of 20 mm/s to 40 mm/s with layer heights between 0.15 mm and 0.20 mm are common. The melt strength of the grade is formulated for consistent extrudate geometry during unconfined strand deposition; however, process stability depends on nozzle hardness and the absence of partial clogging from degraded material retained at hot-end corners. The material is unfilled and therefore less abrasive than carbon-fibre-filled polyetheretherketone, but hardened steel or ruby nozzles are still recommended for extended campaigns.

Unfilled polyetheretherketone retains resistance to steam, hot water, chlorinated solvents, aliphatic hydrocarbons, and many dilute acids. Strong oxidising acids such as concentrated sulfuric acid and concentrated nitric acid can attack the material, and chlorinated solvents at elevated temperature should be evaluated case by case. Natural-colour LUVOCOM 3F PEEK 9581 NT contains no carbon black or conductive filler, which permits visual inspection of contamination, weld lines, and surface defects after printing. Steam sterilisation at 134 °C and gamma irradiation doses up to 50 kGy are commonly evaluated for polyetheretherketone components, but cycle validation is required for the specific printed part geometry and packaging. Published data on repeated sterilisation of fused filament fabricated unfilled polyetheretherketone is limited, so no universal sterility claim applies.

When PEEK 9581 NT Is Benchmarked Against Filled LUVOCOM 3F PEEK Grades

Compared with carbon-fibre-filled LUVOCOM 3F PEEK compounds, the unfilled 9581 NT grade exhibits lower tensile modulus and lower heat deflection temperature, but higher elongation at break and lower melt viscosity. The lower melt viscosity permits slower deposition and more uniform bead spreading in thin walls and unsupported spans, while the higher elongation at break provides greater tolerance to localised stress before crack initiation. The absence of carbon fibre removes conductive pathways and avoids galvanic coupling when the printed polymer is fastened to aluminium or magnesium structures. However, unfilled polyetheretherketone is relatively notch-sensitive, and sharp inside corners or abrupt cross-section changes should be radiused to reduce stress concentration.

Compared with pigmented PEEK grades, the natural colour of 9581 NT facilitates optical inspection of interlayer fusion and contamination. Compared with polyetherimide FFF grades, LUVOCOM 3F PEEK 9581 NT offers higher continuous-use temperature capability and better resistance to chlorinated solvents, but requires a higher nozzle temperature and more rigorous chamber heating. Compared with injection-moulded unfilled polyetheretherketone, printed components from this grade should not be assumed equivalent in mechanical strength, fatigue life, or crystallinity distribution. Published fatigue data for fused filament fabricated polyetheretherketone under cyclic loading remains limited; load-bearing designs should be supported by application-specific creep and fatigue testing.

Typical application areas include semiconductor wafer handling components, chemical process equipment fixtures, medical instrument prototypes, and high-temperature aerospace ducts or brackets produced in low volumes. In semiconductor contact surfaces, the unfilled grade is often evaluated for low particle shedding and solvent resistance. In chemical processing, printed components may be used for sensor housings and clamp bodies exposed to aggressive process fluids where continuous service temperatures remain below 240 °C. Short excursions to 300 °C are possible but require validation of thermal expansion, crystallinity changes, and mechanical load retention. The material is not intended as a direct substitute for machined or injection-moulded polyetheretherketone in safety-critical parts without requalification.

Compliance Verification and Batch-Specific Documentation

Regulatory status depends on the specific production lot, conversion route, and added processing aids. The base polyetheretherketone resin may be evaluated for food-contact applications under 21 CFR 177.2415 and EU Regulation 10/2011 when raw materials and processing aids meet applicable migration limits. For industrial supply, documentation typically includes confirmation that SVHCs on the REACH candidate list are below 0.1% w/w, that RoHS 2011/65/EU Annex II restricted substances are below maximum concentration values, and that polybrominated biphenyls and polybrominated diphenyl ethers are absent. Because printed parts can retain trace processing residues, compliance certification for the supplied material does not automatically extend to the final printed component.

No biocompatibility claim under ISO 10993 or USP Class VI is automatic for spooled filament or printed parts made from LUVOCOM 3F PEEK 9581 NT. Implantable and patient-contact devices require material qualification, process validation, cleaning validation, and sterilisation validation. The natural-colour unfilled grade may reduce additive-related extractables relative to carbon-filled compounds, but extractables are determined by the complete filament conversion and printing process. For production use, certificates of analysis should be retained for each lot, and any regrind or recycled feedstock should be excluded unless explicitly approved by the manufacturer.