Envalior Arnitel ID 2060-HT is a thermoplastic copolyester elastomer grade formulated for fused filament fabrication of parts that must retain elastomeric recovery after exposure to elevated air temperatures. The material is supplied as 3D printing filament in nominal diameters of 1.75 mm and 2.85 mm, with a stated diameter tolerance of ±0.05 mm, and the producer classifies the grade as 100% recyclable through mechanical regrind and re-extrusion. The designation ID identifies the industrial 3D printing range, 2060 denotes a Shore D hardness in the 60 range, and HT indicates high-temperature stabilization relative to standard thermoplastic copolyester filament grades.

Unlike rigid high-temperature thermoplastics such as polyetherimide or polyether ether ketone, the product is not intended for hard-shell structural components. It is used where flexural fatigue resistance, low-temperature impact, hot-air dimensional stability, and solvent tolerance are required simultaneously. Candidate parts include convoluted cable sheaths, underhood bellows, hot-air duct couplings, release-finger fixtures, vibration isolators, and industrial seals exposed to short-term surface temperatures up to 150°C.

The polymer matrix is a block copolyester composed of alternating hard crystalline domains based on poly(butylene terephthalate) and soft amorphous polyether segments. Differential scanning calorimetry according to ISO 11357-3 typically shows a hard-segment melting endotherm between 200°C and 220°C and a soft-segment glass transition below −40°C. This morphology allows the printed part to maintain flexibility below 0°C while retaining dimensional stability under hot-end service loads better than standard thermoplastic polyurethane.

Material specification, published mechanical properties, and thermal limits

The following values are summarized from Envalior technical datasheet data for dry-as-molded specimens and are not design allowables. Application-specific validation should include orientation-dependent testing of fused filament fabrication specimens.

The 120°C heat deflection temperature at 0.45 MPa is not a continuous-use ceiling for unstressed exposure. Hard-segment melting begins above 200°C, but viscoelastic softening reduces load-bearing capability below the melt point. For statically loaded parts, creep modulus measured according to ISO 899-2 at 100°C is the appropriate design basis rather than single-point HDT.

Moisture sensitivity is moderate compared with polyamide. Ester linkages hydrolyze when residual moisture enters the melt above 240°C, producing surface roughness and reduced interlayer adhesion. Production-scale processing therefore requires drying to a residual moisture content below 0.02 wt% before extrusion. Storage at relative humidity above 60% can return sufficient surface moisture to cause visible steam porosity within 24 h if the material is not protected.

Prior to hot-end extrusion, the filament is conditioned for 4–6 h at 100–110°C in a desiccant dryer with a dew point of −40°C or lower. A direct-drive extruder is recommended; the Shore D 60 filament is sufficiently stiff to avoid buckling in constrained filament paths but can deform in long Bowden tubes when retraction settings exceed 4 mm. Starting process parameters in a convection-heated chamber are a nozzle temperature of 250–270°C, a build plate temperature of 80–100°C, and a chamber temperature of 40–60°C. Layer heights of 0.10–0.20 mm and print speeds from 30 mm/s to 60 mm/s are reported to improve layer fusion; part cooling fans should be throttled to 20–40% to avoid warping and delamination. On a 0.4 mm brass nozzle, first-layer calibration at 0.15 mm thickness with 110% extrusion width is a common setup.

Rheological data from capillary rheometry according to ISO 11443 show that apparent melt viscosity at 250°C and 100 s⁻¹ is in the range of 300–800 Pa·s. This moderate viscosity permits flow through a 0.4 mm nozzle without excessive back pressure but can produce oozing during idle travel. Retraction settings therefore require a travel speed of at least 60 mm/s and a retraction distance of 1–3 mm on direct-drive systems. If melt residence time exceeds 10 min above 280°C, yellowing and loss of elongation occur due to thermal oxidation of the soft-segment ether groups.

Compounding and filament re-extrusion on a twin-screw extruder with L/D 32:1 typically uses a barrel profile of 230/245/255/260/260/255°C, a die temperature of 250°C, and a screw speed of 120 min⁻¹. Specific mechanical energy in the range of 0.18–0.24 kWh/kg is reported in production trials. Process conflicts occur when regrind content exceeds 30 wt%: the melt viscosity shifts, and a 5–10°C reduction in the feed zone is required to prevent over-plasticization and die swell. Vacuum venting at −0.08 MPa or lower is necessary to remove residual volatiles from recycled material.

What distinguishes this TPC from TPU 95A and nylon 11 in hot-air service?

Thermoplastic polyurethane with Shore A 95 softens rapidly above 90°C and loses clamp retention in hot fixtures. Nylon 11 has high impact and chemical resistance but is stiffer, moisture-sensitive, and typically not supplied as a flexible 100% recyclable filament. Arnitel ID 2060-HT combines a Shore D hardness of 60 with elongation at break above 300% and a Vicat softening temperature near 200°C. In comparative flexural fatigue testing at 80°C, the TPC grade retains a larger fraction of its room-temperature secant modulus than TPU 95A, while printed layer adhesion is less notch-sensitive than rigid PEEK blends. Unlike thermoset silicone or cast polyurethane, the material can be re-extruded without losing the continuous hard-segment network, which supports the 100% recyclable designation.

The difference is evident in heat aging. TPU 95A typically loses more than 30% of its tensile stress at break after 168 h at 120°C in unstrained specimens, while this TPC grade retains a higher proportion of original strength because the aromatic polyester hard segments are more resistant to oxidative embrittlement than polyether soft segments. Against PA11, the copolyester exhibits lower moisture uptake and less change in glass transition after conditioning at 50% relative humidity. However, PA11 has better resistance to high-pressure hot water and certain solvents, so material selection should include chemical compatibility testing rather than thermal ranking alone.

Validation protocols for automotive underhood bellows often use ISO 188:2023 hot-air aging at 150°C for 500 h followed by ISO 527-1/-2 tensile pull. Published data for this specific printed configuration is limited; producers report that unstrained specimens retain more than 80% of initial tensile strength, with modulus increase caused by secondary crystallization. For compression seals, ISO 815-1:2019 compression set at 100°C for 24 h is used as a screening method, with typical values below 60% depending on infill density and print orientation. Pneumatic duct couplings are tested with cyclic internal pressure at 80°C to confirm that Z-axis interlayer adhesion does not predominate in hoop stress fracture. The material is also used for paint-bake fixtures where short excursions to 180°C occur, although part geometry must avoid static load at the peak temperature.

For chemical-contact applications, ISO 175:2010 immersion testing is recommended before production release. At 85°C in ASTM reference fuel C for 168 h, the TPC grade can show moderate mass uptake; published data for the specific printed grade is limited, and universal fluid compatibility should not be assumed from molded TPC values. Compatibility with greases, transmission fluids, and dilute acids is generally favorable, but strong oxidizing acids, hot alkalis, and certain glycol ethers are outside the recommended service envelope.

When wet or alkaline service is unavoidable, ester hydrolysis defines the operational boundary

Continuous immersion in hot water above 85°C or exposure to alkaline media above pH 9 accelerates hydrolysis of the ester hard segments. The resulting failure mode is a loss of elongation, surface whitening, and brittle fracture at layer lines rather than catastrophic softening. The grade should not be specified for steam-sterilized medical components requiring repeated autoclave exposure above 121°C unless the part is unloaded and the cycle count is limited. Contact with amine-based additives, certain glycol ethers, and strong oxidizing acids can degrade molecular weight faster than thermal aging alone. For chemical-contact applications, a 7-day immersion test in the service fluid at 85°C followed by ISO 527-1/-2 tensile testing is recommended before production release.

Mechanical recycling of spool waste, purge, and printed scrap is performed by size reduction to particles below 3 mm, drying to below 0.02 wt% moisture, and re-extrusion on a single-screw extruder with an L/D 25:1 and a 200 µm screen pack. Barrel temperatures in the 240–280°C range and a melt temperature limit of 280°C prevent thermal degradation. Regrind fractions above 30 wt% in virgin filament can reduce melt-flow stability; a 5–10°C reduction in the feed zone and a 10% reduction in screw speed are common compensations on production lines. Published data for repeated closed-loop recycling beyond five cycles is limited, so recyclate intended for load-bearing parts should be qualified with at least ISO 527-1/-2 tensile and ISO 179-1/1eA impact testing after each cycle.