PBO (Zylon) UD-EP
Matrix
also Zylon
UD-EP = unidirectional PBO/epoxy laminate
PBO-reinforced epoxy prepreg/laminate for lightweight pressure-vessel overwrap, stiffeners and impact structures; excellent tensile properties but very low compressive and off-axis strength.
Values for the UD-EP condition
Other PBO (Zylon) grades and fills
PBO (Zylon) is listed in 3 conditions; see the grade overview at PBO (Zylon).
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
UD-EPThis page Unidirectional PBO/epoxy laminate | PBO-reinforced epoxy prepreg/laminate for lightweight pressure-vessel overwrap, stiffeners and impact structures; excellent tensile properties but very low compressive and off-axis strength. | — | 2,600 | 1.8 | — |
Woven PBO fabric / ballistic and cut-resistant cloth | Plain or basket-weave fabric from AS yarn for soft armour, blast blankets, welding curtains and heat-resistant conveyor covers; fabric strengths are per-yarn values derated by crimp. | — | 3,500 | 4 | — |
High-modulus heat-treated PBO filament yarn | Heat-treated yarn with ~50 % higher modulus and lower moisture regain; pick it for stiffness-critical composites, tethers, tension members and dimensionally stable structures. | — | 5,800 | 2.5 | — |
What is PBO (Zylon) UD-EP?
PBO (Zylon) UD-EP is PBO (Zylon) in the UD-EP condition — pBO-reinforced epoxy prepreg/laminate for lightweight pressure-vessel overwrap, stiffeners and impact structures; excellent tensile properties but very low compressive and off-axis strength. PBO (Zylon) UD-EP has a tensile strength of 2,600 MPa (377 ksi), stronger than 78% of composite grades. Elongation at break is 1.8% and the elastic modulus is 160 GPa (23.2 Msi). PBO (Zylon) UD-EP has a density of 1.42 g/cm³ (0.0513 lb/in³), lighter than 63% of composite grades. Its glass-transition temperature is 500°C (932 °F).
Limitations
- Degrades in UV without stabilisers — 12/100, worse than 100% of composite grades
- Absorbs moisture — dry before molding — 2%, worse than 88% of composite grades
- Difficult to machine — 18/100, worse than 80% of composite grades
- High embodied carbon — 30 kg CO₂/kg, worse than 80% of composite grades
PBO (Zylon) UD-EP properties
Typical room-temperature values for PBO (Zylon) UD-EP; 11 are specific to this condition. Other listed values are PBO (Zylon) reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
PBO (Zylon) UD-EP has a density of 1.42 g/cm³ (0.0513 lb/in³), lighter than 63% of composite grades. Its glass-transition temperature is 500°C (932 °F).
Mechanical4
PBO (Zylon) UD-EP has a tensile strength of 2,600 MPa (377 ksi), stronger than 78% of composite grades. Elongation at break is 1.8% and the elastic modulus is 160 GPa (23.2 Msi).
Thermal7
PBO (Zylon) UD-EP is rated for continuous service to 130°C (266 °F). Thermal expansion is -4 µm/m·K (-2.22 µin/in·°F).
Electrical1
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 64% of composite grades. UV resistance is not recommended.
Sustainability3
Producing a kilogram of PBO (Zylon) UD-EP takes about 500 MJ of energy and emits 30 kg of CO₂ — more than 84% of composite grades. Typical recycled content is 0%.
Manufacturability1
PBO (Zylon) UD-EP's machinability is poor (18/100, worse than 80% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PBO (Zylon) UD-EP
Is PBO (Zylon) easy to machine?
Fabric and laminates cannot be sheared cleanly — use hot knife, ultrasonic cutter, waterjet or new carbide/PCD tooling; fibers fuzz and blunt tools quickly.
Can PBO (Zylon) be welded?
Not weldable; join by stitching with PBO/aramid thread, mechanical clamping or adhesive bonding of the composite laminate.
Can PBO (Zylon) be formed, bent or molded?
Processed as continuous yarn — weaving, braiding, filament winding or prepreg lay-up with epoxy/phenolic; cure below ~180 °C and avoid moisture pick-up before cure.
What surface finishes work on PBO (Zylon)?
Surface treatment (plasma, epoxy sizing) needed for resin adhesion; protect all exposed parts with UV-opaque covers, coatings or outer fabric layers to limit light and humidity aging.
PBO (Zylon) 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 |
|---|---|---|
| residual phosphorus (from PPA solvent)Residual acid content is a key driver of hydrolytic aging | 0.05 – 0.6 | 0.3 |
| finish / sizingSpin finish on yarn surface | 0.2 – 1 | 0.5 |
| poly(p-phenylene-2,6-benzobisoxazole) reRigid-rod heterocyclic polymer; monomers 4,6-diaminoresorcinol dihydrochloride + terephthalic acid, dry-jet wet spun from polyphosphoric acid | balance | — |
PBO (Zylon) UD-EP — frequently asked
What is PBO (Zylon) UD-EP used for?
PBO (Zylon) UD-EP is typically used for high-performance ballistic armor, aerospace tethers/cables, sporting goods and reinforcement for extreme-performance composites. In short: strongest organic fiber; higher modulus than aramid; light and humidity sensitive.
What is the tensile strength of PBO (Zylon) UD-EP?
PBO (Zylon) UD-EP has a typical tensile strength of 2,600 MPa (377 ksi) — stronger than 78% of composite grades. Strength varies by condition: see the 3 listed tempers.
Is PBO (Zylon) UD-EP easy to machine?
Not especially — machinability is rated poor (18/100, worse than 80% of composite grades). Fabric and laminates cannot be sheared cleanly — use hot knife, ultrasonic cutter, waterjet or new carbide/PCD tooling; fibers fuzz and blunt tools quickly.
Can PBO (Zylon) UD-EP be welded?
Not weldable; join by stitching with PBO/aramid thread, mechanical clamping or adhesive bonding of the composite laminate.
What surface finishes work on PBO (Zylon) UD-EP?
Surface treatment (plasma, epoxy sizing) needed for resin adhesion; protect all exposed parts with UV-opaque covers, coatings or outer fabric layers to limit light and humidity aging.
Can PBO (Zylon) UD-EP be formed, bent or molded?
Processed as continuous yarn — weaving, braiding, filament winding or prepreg lay-up with epoxy/phenolic; cure below ~180 °C and avoid moisture pick-up before cure.
What is the maximum service temperature of PBO (Zylon) UD-EP?
PBO (Zylon) UD-EP is rated for continuous use to about 130°C (266 °F), and briefly to 550°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Zylon (PBO fiber) Technical Information — Toyobo Co., Ltd. (2020)
- ASM Handbook Vol. 21: Composites — High-performance organic fibers — ASM International (2001)
- NIJ/NIST studies on aging of PBO body-armor fiber — NIST (2005)
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.