Glass-Filled Polyamide PA66 GF25 for Thermal Breaks

Description

PA66 GF25 thermal break is an extrusion grade of polyamide 66 reinforced with 25 % short glass fiber, specifically optimized for the production of thermal break profiles in aluminum window, door and facade systems. It is the enabling material without which the modern energy-efficient aluminum facade does not exist.

The key physical characteristic is a thermal conductivity of λ ≈ 0.28–0.30 W/(m·K), roughly 750 times lower than that of aluminum (220 W/(m·K)). A thin PA66 GF25 profile (typically 14–34 mm in height), rolled in between the inner and outer aluminum shells of the profile, breaks the thermal bridge and reduces the Uf heat transfer of the window/facade system from 5–7 W/(m²·K) (all-aluminum) to 1.0–1.8 W/(m²·K) (passive house level).

Typical parameters: density ~1.30 g/cm³, thermal conductivity 0.28–0.30 W/(m·K), CLTE 28–32 × 10⁻⁶/K (close to AA6060/AA6063 aluminum at ~23 × 10⁻⁶/K — critical for thermal cycling without separation from the Al shell), HDT/A ~245–250 °C (ISO 75-2, 1.8 MPa), tensile strength 140–150 MPa, tensile modulus 8.0–8.5 GPa, Charpy notched impact strength ~10 kJ/m² (ISO 179-1eA), water absorption ~5.5 % at saturation (PA66 lower than PA6).

Standards and certifications

• EN 14024 “Metal profiles with thermal break — Mechanical performance” — the primary European standard for thermal breaks in aluminum systems
• EN ISO 10077-2 — calculation of the Uf heat transfer coefficient of window profiles with thermal inserts
• EN 13947 — thermal performance of curtain walling
• Compatibility with DSTU EN 12608 / DSTU B V.2.6 (requirements for building envelope structures)
• Suitable for projects with passive house, BREEAM, LEED and DGNB certification

Key advantages

• Thermal conductivity of 0.28–0.30 W/(m·K) — ~750 times lower than aluminum; a 3–5-fold reduction in system Uf
• CLTE close to that of aluminum (28 vs 23 × 10⁻⁶/K) — minimizing thermal stresses at the Al/PA interface over the annual −30…+70 °C cycle
• HDT/A ~245 °C — withstands the process temperature peak during powder coating of the aluminum profile (180–200 °C / 20 min)
• High shear strength of the Al/PA joint — after the roll-in or crimp-in operation the profile forms a monolithic structure that withstands wind and service loads
• Dimensional stability of the extruded profile — low shrinkage, tight tolerances (typically ±0.05 mm in height)
• UV resistance for partially exposed zones (under the coating edge)
• Colorable with masterbatch to match the architectural design (black is standard; RAL colors available on request)

Applications

• Aluminum window and door systems: thermal breaks in frames and sashes of Schüco, Reynaers, Aluprof, Yawal, Alutech and domestic profile systems — to achieve Uf 1.0–1.8 W/(m²·K) and warm-edge performance
• Aluminum facade systems (curtain wall): structural inserts in mullions and transoms to prevent thermal bridges in ventilated curtain facades of high-rise buildings
• Winter gardens and glazed galleries: thermally insulated aluminum structures for year-round use
• Industrial doors and gates: insulated sectional doors for cold storage, freezer rooms and energy-efficient production facilities
• Glazed roofs (atriums): thermally insulated aluminum transoms for the atriums of shopping malls and business centers
• Thermally insulated aluminum railings and handrails: outdoor structures in climate zones with large temperature swings
• Transport infrastructure: aluminum passenger shelters, railway stations, airports — to reduce heat losses in climate-controlled zones

Processing notes

• Drying before extrusion is mandatory: 4–6 hours at 80 °C down to a residual moisture of ≤0.12 % (PA66 is hygroscopic)
• Melt temperature 280–300 °C, die temperature 290–300 °C, calibration temperature 60–90 °C
• After extrusion the profile is conditioned in a climate chamber to stabilize moisture absorption (1–2 % H₂O for the service state)
• The roll-in / crimp-in force in the aluminum housing must comply with EN 14024 (T-class)

Global market counterparts (finished profiles): Ensinger Insulbar® (semi-finished PA66 GF25 profiles), Technoform Bautec® (thermal profiles), GRAEFF, GRAEWE, Schüco SimplySmart. PA66 GF25 raw material for in-house profile extrusion: Lanxess Durethan® AKV25, BASF Ultramid® A3WG5, EMS-CHEMIE Grivory® FE-7065, Toray Amilan® CM3001G-25.

The stated values are measured by internal methods close to the corresponding ISO, GOST and EN standards. This information is provided for reference only and does not constitute an official batch data sheet. Please request the TDS and MSDS for the specific batch before industrial use.