5250-4 IM7-UD
Reinforced grade · default condition
IM7-UD = 5250-4/IM7 unidirectional tape
Baseline high-stiffness UD tape for primary hot structure and nacelle/inlet skins.
Values for the IM7-UD condition
Other 5250-4 grades and fills
5250-4 is listed in 5 conditions; see the grade overview at 5250-4.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
5250-4 RTM | Use for resin transfer moulding / RFI of dry preforms when prepreg lay-up is impractical. | — | 60 | 1.7 | 88 Shore D |
5250-4 neat cast resin | Matrix-only properties for analysis, adhesive/film work and micromechanics input. | — | 62 | 1.6 | 110 HRM |
5250-4/T650-35 8-harness satin fabric laminate | Pick the woven-fabric form for drapeable, damage-tolerant skins and complex contours. | — | 850 | 1.2 | — |
5250-4 PLUS | Choose when impact damage tolerance / CAI and microcrack resistance matter more than peak hot-wet modulus. | — | 2,700 | 1.7 | — |
IM7-UDDefaultThis page 5250-4/IM7 unidirectional tape | Baseline high-stiffness UD tape for primary hot structure and nacelle/inlet skins. | — | 2,760 | 1.6 | — |
What is 5250-4 IM7-UD?
5250-4 IM7-UD is 5250-4 in the IM7-UD grade — baseline high-stiffness UD tape for primary hot structure and nacelle/inlet skins. 5250-4 IM7-UD has a tensile strength of 2,760 MPa (400 ksi), stronger than 79% of composite grades. Elongation at break is 1.6% and the elastic modulus is 165 GPa (23.9 Msi). 5250-4 IM7-UD has a density of 1.58 g/cm³ (0.0571 lb/in³), lighter than 54% of composite grades. Its glass-transition temperature is 288°C (550 °F).
Limitations
- High embodied carbon — 32 kg CO₂/kg, worse than 84% of composite grades
5250-4 IM7-UD properties
Typical room-temperature values for 5250-4 IM7-UD; 11 are specific to this condition. Other listed values are 5250-4 reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
5250-4 IM7-UD has a density of 1.58 g/cm³ (0.0571 lb/in³), lighter than 54% of composite grades. Its glass-transition temperature is 288°C (550 °F).
Mechanical10
5250-4 IM7-UD has a tensile strength of 2,760 MPa (400 ksi), stronger than 79% of composite grades. Elongation at break is 1.6% and the elastic modulus is 165 GPa (23.9 Msi).
Thermal8
5250-4 IM7-UD is rated for continuous service to 218°C (424 °F). It conducts heat at 0.7 W/m·K (0.404 BTU/hr·ft·°F), better than 57% of composite grades. Thermal expansion is 0.3 µm/m·K (0.167 µin/in·°F).
Electrical1
5250-4 IM7-UD has an electrical resistivity of 1×10⁻⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 77% of composite grades. UV resistance is fair.
Sustainability3
Producing a kilogram of 5250-4 IM7-UD takes about 480 MJ of energy and emits 32 kg of CO₂ — more than 81% of composite grades. Typical recycled content is 0%.
Manufacturability2
5250-4 IM7-UD's machinability is poor (30/100, worse than 54% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 5250-4 IM7-UD
Is 5250-4 easy to machine?
Trim/drill with PCD or diamond-coated tools, high speed and low feed, backing support and dust extraction; BMI dust is abrasive and requires respiratory protection.
Can 5250-4 be welded?
Not weldable — join by bolting, co-cure/co-bond, or high-temperature adhesive (BMI or polyimide film adhesive) rated for 200 °C+.
Can 5250-4 be formed, bent or molded?
Autoclave cure typically 177 °C at 585–690 kPa with a controlled ramp, then free-standing post-cure to 227 °C for full Tg; slow ramps and thin-ply staging limit exotherm and microcracking.
What surface finishes work on 5250-4?
Sand/peel-ply prep then high-temperature primer and topcoat; erosion or metal-mesh lightning-strike layers are commonly co-cured on outer surfaces.
5250-4 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| bismaleimide (4,4'-bismaleimidodiphenylmresin fraction basis | 50 – 70 | 60 |
| o,o'-diallyl bisphenol A (co-reactant)resin fraction basis | 25 – 45 | 35 |
| toughener / thermoplastic + additivesresin fraction basis | 0 – 12 | 5 |
| carbon fiber (IM7 / T650-35)wt % of cured laminate; ~35 wt % resin content in prepreg | 60 – 68 | 65 |
5250-4 IM7-UD — frequently asked
What is 5250-4 IM7-UD used for?
5250-4 IM7-UD is typically used for engine nacelles, high-speed aircraft structures, radomes and military aerospace parts. In short: 218 °C service BMI; above epoxy temperature limits; requires free-standing post-cure.
What is the tensile strength of 5250-4 IM7-UD?
5250-4 IM7-UD has a typical tensile strength of 2,760 MPa (400 ksi) — stronger than 79% of composite grades. Strength varies by condition: see the 5 listed tempers.
Is 5250-4 IM7-UD easy to machine?
Not especially — machinability is rated poor (30/100, worse than 54% of composite grades). Trim/drill with PCD or diamond-coated tools, high speed and low feed, backing support and dust extraction; BMI dust is abrasive and requires respiratory protection.
Can 5250-4 IM7-UD be welded?
Not weldable — join by bolting, co-cure/co-bond, or high-temperature adhesive (BMI or polyimide film adhesive) rated for 200 °C+.
What surface finishes work on 5250-4 IM7-UD?
Sand/peel-ply prep then high-temperature primer and topcoat; erosion or metal-mesh lightning-strike layers are commonly co-cured on outer surfaces.
Can 5250-4 IM7-UD be formed, bent or molded?
Autoclave cure typically 177 °C at 585–690 kPa with a controlled ramp, then free-standing post-cure to 227 °C for full Tg; slow ramps and thin-ply staging limit exotherm and microcracking.
What is the maximum service temperature of 5250-4 IM7-UD?
5250-4 IM7-UD is rated for continuous use to about 218°C (424 °F), and briefly to 260°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- CYCOM 5250-4 BMI Prepreg Technical Data Sheet — Solvay Composite Materials (formerly Cytec) (2020)
- CYCOM 5250-4 RTM Resin System Data Sheet — Solvay Composite Materials (2019)
- ASM Handbook Vol.21: Composites — ASM International (2001)
- NCAMP / CMH-17 qualification data for BMI carbon systems — CMH-17 / NIAR (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.