Durostone® EPX-M
Durostone EPX-M is a filament-wound fiber-reinforced composite built from a special epoxy (EP) resin matrix and E-glass roving, delivering 800 MPa tensile strength parallel to lamination and a Temperature Index of 180 with Insulation Class H. The material provides 700 MPa flexural strength perpendicular to lamination, a Tg of 150°C, and CTI 225 for demanding industrial and electrical service. Engineered for generators, motors, oil-filled transformers, and hydrogen energy applications.
Key Properties
- Density: 2.1 g/cm³ (ISO 1183)
- Tensile Strength ∥: 800 MPa (ISO 527)
- Flexural Strength ⊥: 700 MPa (ISO 178)
- Temperature Index: 180 (IEC 60216) — Insulation Class H (IEC 60085)
- Tg-Value: 150°C (DSC)
- Comparative Tracking Index: 225 (EN 60112)
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Mechanical Properties
| Property | Value | Test Method |
| Density | 2.1 g/cm³ | ISO 1183 |
| Flexural Strength ⊥ | 700 MPa | ISO 178 |
| Flexural Strength ⊥ +150°C | 350 MPa | ISO 178 |
| Modulus of Elasticity in Flexion ⊥ | 35,000 MPa | ISO 178 |
| Compressive Strength (Tangential) | 500 MPa | ISO 604 |
| Compressive Strength (Axial) | 110 MPa | ISO 604 |
| Compressive Strength (Radial) | 110 MPa | ISO 604 |
| Tensile Strength ∥ | 800 MPa | ISO 527 |
| Impact Strength (Radial) | 250 kJ/m² | ISO 179 |
Thermal Properties
| Property | Value | Test Method |
| Thermal Conductivity ⊥ | ≈ 0.35 W/(m·K) | — |
| Temperature Index | 180 (T.I.) | IEC 60216 |
| Insulation Class | H | IEC 60085 |
| Tg-Value | 150°C | DSC |
| Coefficient of Linear Expansion (Tangential) | 5 – 10 × 10⁻⁶ × K⁻¹ | TMA |
| Coefficient of Linear Expansion (Axial) | 20 – 30 × 10⁻⁶ × K⁻¹ | TMA |
| Coefficient of Linear Expansion (Radial) | 25 – 40 × 10⁻⁶ × K⁻¹ | TMA |
Electrical Properties
| Property | Value | Test Method |
| Electric Strength 90°C Under Oil ⊥ | 5 kV/mm | IEC 60243 |
| Electric Strength 90°C Under Oil ∥ | 35 kV/25 mm | IEC 60243 |
| Relative Permittivity (50 Hz) | ≈ 5 (εᵣ) | IEC 60250 |
| Dielectric Loss Factor (50 Hz) | ≈ 0.03 (tan δ) | IEC 60250 |
| Insulation Resistance After 24 h Water Immersion | 5 × 10⁹ Ω | IEC 60167 |
| Comparative Tracking Index | 225 (CTI) | EN 60112 |
⊥ = perpendicular to the lamination | ∥ = parallel to the lamination
Compliance
- ISO 1183, ISO 178, ISO 604, ISO 527, ISO 179 — Compliant (test standards)
- IEC 60216 — Compliant (Temperature Index 180)
- IEC 60085 — Compliant (Insulation Class H)
- IEC 60243, IEC 60250, IEC 60167 — Compliant (test standards)
- EN 60112 — Compliant (CTI 225)
- Generator and motor structural insulation components
- Oil-filled transformer insulation parts
- Hydrogen energy structural components
- Mechanical engineering structural composites
- Healthcare and electrical industry insulation parts
Common industries: generator and motor manufacturing, healthcare, electrical, mechanical engineering, oil-filled transformer manufacturing, and hydrogen energy.
Durostone EPX-M is a high-performance filament-wound composite built from a special epoxy (EP) resin matrix reinforced with E-glass roving. It is positioned within the Durostone family as a high-strength, high-class structural and electrical material, manufactured by filament winding to deliver exceptional directional mechanical properties for demanding industrial and electrical applications.
Mechanical performance includes 2.1 g/cm³ density, 700 MPa flexural strength perpendicular to lamination (350 MPa retained at +150°C), 35,000 MPa modulus of elasticity in flexion, 500 MPa tangential / 110 MPa axial / 110 MPa radial compressive strength, 800 MPa tensile strength parallel to lamination, and 250 kJ/m² radial Charpy impact strength.
Thermally, EPX-M carries a Temperature Index of 180 with Insulation Class H, a Tg of 150°C, thermal conductivity perpendicular of approximately 0.35 W/(m·K), and direction-dependent coefficients of linear expansion of 5–10 (tangential), 20–30 (axial), and 25–40 (radial) × 10⁻⁶ × K⁻¹.
Dielectrically, the material provides 5 kV/mm perpendicular and 35 kV/25 mm parallel electric strength under oil at 90°C, relative permittivity εᵣ ≈ 5 at 50 Hz, dielectric loss factor tan δ ≈ 0.03, insulation resistance of 5 × 10⁹ Ω after 24 h water immersion, and a Comparative Tracking Index of 225.
Compliant with the listed test standards: ISO 1183, ISO 178, ISO 604, ISO 527, ISO 179, IEC 60216, IEC 60085, IEC 60243, IEC 60250, IEC 60167, and EN 60112.
What differentiates Durostone EPX-M from molded epoxy glass laminates such as EPC 203?
EPX-M is manufactured by filament winding, which orients E-glass roving along the load path and produces direction-dependent mechanical properties optimized for hoop and axial loading. The result is markedly higher tensile (800 MPa ∥) and flexural (700 MPa ⊥) strength than typical fabric-reinforced laminates, paired with a higher thermal class — Insulation Class H, Temperature Index 180 — and a Tg of 150°C, making it suited to the most demanding structural-electrical applications.
Why does mechanical strength matter for this material?
EPX-M is selected for service combining high voltage with significant mechanical loading — generator and motor support structures, transformer internals, hydrogen energy components — where the part must not deform or fail under operating stress. The 800 MPa parallel tensile strength, 35,000 MPa flexural modulus, and 250 kJ/m² radial impact strength define the structural envelope, with retained 350 MPa flexural strength at +150°C confirming behavior at elevated temperature.
What is the operating temperature classification for EPX-M?
The material has a Temperature Index of 180 per IEC 60216, an Insulation Class of H per IEC 60085, and a Tg of 150°C measured by DSC.
Is EPX-M suitable for electrical and transformer-rated environments?
Yes. The material is qualified to IEC 60216 (Temperature Index 180) and IEC 60085 (Insulation Class H), with documented IEC 60243, IEC 60250, IEC 60167, and EN 60112 dielectric performance. It is engineered for oil-filled transformer service and similar high-voltage applications.
How should EPX-M be specified?
Specify grade (Durostone EPX-M), part geometry or filament-wound dimensions, mechanical loading direction (tangential, axial, radial), dielectric performance requirements, thermal class (Insulation Class H / Temperature Index 180), dimensional tolerances, and finished format.
