PAHT-CF (High-Temperature Polyamide /Polyphthalamide + Carbon Fiber) for FDM

Material Profile: PAHT-CF (High-Temperature Polyamide / Polyphthalamide + Carbon Fiber) for FDM

FDM Engineering Material Technical Report Series 

Compiled from manufacturer technical datasheets and peer-reviewed literature

Abstract—PAHT-CF (High-Temperature Nylon, Carbon Fibre reinforced) is an industrial-grade FDM filament for applications requiring high heat-deflection and stiffness. Most commercial PAHT-CF grades use a polyphthalamide (PPA) matrix — a semi-aromatic polyamide combining an aliphatic diamine with an aromatic diacid. The aromatic ring stiffens the chain, raising Tg and HDT well above conventional PA6/PA12. Data drawn from QIDI Tech, Bambu Lab, Elegoo, and Siraya Tech datasheets.

Index Terms—additive manufacturing, FDM, polyphthalamide, PPA, high-temperature nylon, carbon fibre.

I.  MATERIAL IDENTIFICATION

This section establishes the canonical names and commercial designations under which the material is supplied.

A.  Designation

Trade name: PAHT-CF, also marketed as PPA-CF in some catalogues. Bambu Lab uses PAHT-CF for a PA12+CF blend; QIDI / Siraya / Elegoo use PAHT-CF for a PPA-based composite. This report covers the PPA-based formulation (the dominant industrial type).

B.  Full Chemical Name

Polyphthalamide reinforced with chopped carbon fibre (CF/PPA). PPA is a semi-aromatic polyamide formed by polycondensation of an aliphatic diamine (e.g., hexamethylenediamine) with an aromatic diacid (e.g., terephthalic acid).

C.  Aliases and Alternative Designations

II.  COMPOSITION AND MOLECULAR STRUCTURE

A.  Empirical Chemical Formula

Idealised PPA repeating unit: [-NH-(CH₂)₆-NH-CO-C₆H₄-CO-]ₙ (hexamethylene diamine + terephthalic acid).

Fig. 1.  Repeating unit / structural schematic of the polymer matrix.

Fig. 2.  Schematic of dispersed reinforcement / filler in the polymer matrix (not to scale).

B.  Composition Breakdown

TABLE I
 COMPOSITIONAL BREAKDOWN OF PAHT (PAHT-CF) (TYPICAL / PER SUPPLIER DATASHEET)

III.  MECHANICAL PROPERTIES — XZ PRINT DIRECTION

In the XZ orientation the tensile load is applied parallel to the deposited rasters; for fibre-reinforced grades this is the strongest orientation because the fibres align preferentially along the extrusion direction.

TABLE II
 MECHANICAL PROPERTIES — XZ ORIENTATION (PAHT (PAHT-CF))

IV.  MECHANICAL PROPERTIES — ZX PRINT DIRECTION

In the ZX orientation the tensile load is applied perpendicular to the print layers, so failure occurs through inter-layer (Z) bonds. Properties are markedly lower than in XZ — this anisotropy is intrinsic to FDM.

TABLE III
 MECHANICAL PROPERTIES — ZX ORIENTATION (PAHT (PAHT-CF))

Estimated XZ:ZX UTS ratio ≈ 2.6:1. PPA-based PAHT-CF retains higher absolute Z-direction strength than PA12-based composites because of stronger inter-chain interactions in the aromatic backbone.

V.  RECOMMENDED PRINT PARAMETERS

Values summarised below give consensus operating windows from public datasheets. Specific suppliers may differ within ±10 °C; the supplier datasheet always supersedes this table.

TABLE IV
 RECOMMENDED PRINT TEMPERATURE RANGES FOR PAHT (PAHT-CF)

VI.  GLASS TRANSITION TEMPERATURE (TG)

Reported / typical Tg: ≈ 110 – 120 °C (PPA matrix, dry).

Annealing at 80–100 °C × 4–6 h followed by slow cooling significantly increases part strength and dimensional stability. Bambu Lab PAHT-CF reports a 50% lower water absorption rate than conventional PA-CF, allowing properties to remain stable in humid environments.

VII.  HEAT DEFLECTION TEMPERATURE (HDT)

Heat deflection temperature is the temperature at which a standard bar deflects 0.25 mm under a specified flexural load (ASTM D648 / ISO 75).

TABLE V
 HEAT DEFLECTION TEMPERATURE OF PAHT (PAHT-CF) UNDER STANDARD TEST LOADS

VIII.  DISTINGUISHING CHARACTERISTICS AND STANDARDS

A.  Heat resistance via aromatic backbone

The terephthalic-acid-derived aromatic ring stiffens the polyamide chain, raising Tg and HDT well above conventional PA6/PA12 — annealed HDT @ 0.45 MPa reaches 190–194 °C versus ~150 °C for PA12-CF.

B.  Low moisture absorption (relative to PA6)

PPA absorbs only 2–3 wt% water versus 6–9% for PA6 at saturation, preserving stiffness and dimensional accuracy in humid service.

C.  Chemical resistance

Excellent against oils, greases, automotive fluids, alcohols, and most fuels. Attacked by concentrated mineral acids and prolonged exposure to high-temperature steam.

D.  UV stability

The aromatic backbone causes some chain scission under prolonged UV exposure; outdoor service over multi-year periods requires UV-stabilised grades.

IX.  REPRESENTATIVE APPLICATIONS

PAHT (PAHT-CF) is typically deployed in the following applications:

1)  Automotive under-hood / powertrain: Brackets, sensor housings, intake manifolds operating in 120–180 °C ambient.

(Source : Bambu Lab)

2)  Injection-mould tooling: Soft tooling for short runs; HDT exceeds typical mould temperatures.

(Source : Bambu Lab)

3)  Drone airframes for high-temperature payloads: FLIR camera mounts, thermal-imaging UAV chassis.

4)  High-strength jigs and fixtures: Welding fixtures, clamping jigs subject to repeated thermal cycles.

5)  Aerospace interior brackets (non-flame-critical): Where stiffness and HDT > 150 °C are needed and FST regulations are not the binding constraint.

Photographs of representative parts in these applications are not reproduced here for copyright reasons; the table below provides direct manufacturer / case-study URLs where original imagery and project descriptions can be viewed.

TABLE VI
 SUGGESTED IMAGE / CASE-STUDY SOURCES

X.  REFERENCES

[1]  QIDI Tech, “PAHT-CF (PPA-CF) Filament Datasheet,” 2024. https://qidi3d.com/products/qidi-paht-cf-carbon-fiber-filament

[2]  Bambu Lab, “PAHT-CF Product Page,” 2024. https://us.store.bambulab.com/products/paht-cf

[3]  Elegoo, “PAHT-CF High-Temp Carbon Fibre Nylon Filament,” 2024.

[4]  Siraya Tech, “Fibreheart PAHT-CF / PPA-CF Datasheet,” 2024.

[5]  ASTM D638-14; ASTM D790-17; ASTM D256-10; ASTM D648-18.

[6]  K. Manolakis et al., “Mechanical Characterization of PLA, PC and PAHT-CF FDM Specimens,” J. Mater. Eng. Perform., 2024. https://link.springer.com/article/10.1007/s11665-024-09144-9