E-51
E-51 is a standard-viscosity liquid bisphenol-A (DGEBA) epoxy resin designated to GB/T 13657, the general-purpose grade used for casting, potting, laminating and adhesives.
Reference datasheet — E-51 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AMINE condition
E-51 grades and fills
E-51 is supplied in 9 conditions, soft to hard. AMINE is the default FabDigit quotes; the values on this page are for it.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Flexibilized / elastic potting grade | Use where thermal-cycling stress on delicate components must be absorbed; trades strength and Tg for compliance. | 18 | 22 | 45 | 55 Shore D |
Alumina-filled thermally conductive potting compound | Use when heat must be conducted out of potted power electronics while keeping full electrical insulation. | 45 | 0.8 | 92 Shore D | |
Rubber-toughened | Choose for structural adhesives and peel/impact-loaded joints where brittle unmodified epoxy cracks. | 55 | 8 | 80 Shore D | |
Flame-retardant grade | Required for electrical enclosures, PCB laminates and rail/transport parts needing V-0 and high LOI. | 58 | 2.5 | 87 Shore D | |
Silica/quartz-filled casting | Standard electrical encapsulation compound: low CTE, low shrinkage and low cost for transformers, insulators and IC potting. | 60 | 0.8 | ||
AMINEDefault Amine-cured unfilled casting | Default general-purpose room- or mild-heat-cured clear casting for adhesives, potting and tooling. | 65 | 4 | 86 Shore D | |
Anhydride-cured casting | Choose for electrical casting/potting needing higher Tg, low dielectric loss and long pot life at elevated cure. | 72 | 3 | ||
Glass-cloth laminate / GFRP | Structural and electrical laminates (insulation board, filament-wound pipe, blade spar) where high specific strength is needed. | 350 | 2 | ||
Carbon-fibre reinforced | Pick for maximum stiffness-to-weight in the fibre direction (tubes, plates, drone/robot arms); properties are strongly anisotropic. | 1,600 | 1.4 |
What is E-51?
E-51 is a standard-viscosity liquid bisphenol-A (DGEBA) epoxy resin designated to GB/T 13657, the general-purpose grade used for casting, potting, laminating and adhesives. Cured with amine or anhydride hardeners the base system gives about 65 MPa tensile strength, 4 % elongation, Shore D 86 hardness, a 95 °C glass transition and a 95 °C maximum service temperature; silica-, alumina-, glass- and carbon-filled, flame-retardant, toughened and flexibilised conditions are on file. Unfilled castings are exotherm-limited in thick sections, chalk under UV without a topcoat, and cannot be remelted. E-44 is the nearest alternative for higher chemical resistance. E-51 has a density of 1.17 g/cm³ (0.0423 lb/in³), lighter than 54% of polymer grades. Its glass-transition temperature is 95°C (203 °F). E-51 has a tensile strength of 65 MPa (9.43 ksi), stronger than 73% of polymer grades. Elongation at break is 4% and the elastic modulus is 3 GPa (0.435 Msi).
What is E-51 used for?
- potting and encapsulation
- composite laminates
- structural adhesives
- tooling and molds
Advantages
- Low, predictable mold shrinkage — 0.3%, better than 90% of polymer grades
- Polishes to a fine finish — 70/100, better than 77% of polymer grades
Limitations
- Low fracture toughness — 0.65 MPa·√m (0.592 ksi·√in), worse than 94% of polymer grades
- Limited ductility — 4%, worse than 78% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
E-51 properties
Typical room-temperature values for E-51-AMINE; bars are the position among polymer grades.
Physical6
E-51 has a density of 1.17 g/cm³ (0.0423 lb/in³), lighter than 54% of polymer grades. Its glass-transition temperature is 95°C (203 °F).
Mechanical15
E-51 has a tensile strength of 65 MPa (9.43 ksi), stronger than 73% of polymer grades. Elongation at break is 4% and the elastic modulus is 3 GPa (0.435 Msi).
Thermal10
E-51 is rated for continuous service to 95°C (203 °F). It conducts heat at 0.19 W/m·K (0.11 BTU/hr·ft·°F), worse than 68% of polymer grades. Thermal expansion is 62 µm/m·K (34.4 µin/in·°F).
Electrical7
E-51 is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 52% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of E-51 takes about 137 MJ of energy and emits 6.5 kg of CO₂ — more than 80% of polymer grades. Typical recycled content is 0%.
Manufacturability4
E-51's machinability is good (55/100, worse than 64% of polymer grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. E-51 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with E-51
Is E-51 easy to machine?
Fully cured castings turn, mill and drill easily with sharp carbide and light feeds; keep tools cool to avoid softening near Tg, and use dust extraction (filled/GF grades are highly abrasive — PCD or diamond tooling for laminates).
Can E-51 be welded?
Thermoset — cannot be welded or remelted; join by adhesive bonding with the same epoxy after abrading and solvent-cleaning the surfaces.
Can E-51 be formed, bent or molded?
Processed as a two-part liquid: degas, mix stoichiometrically with amine/anhydride hardener, cast/RTM/wind or prepreg, then cure RT–150 °C with post-cure to reach full Tg; exotherm limits practical section thickness of unfilled castings.
E-51 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 |
|---|---|---|
| volatilesGB/T 13657 volatiles ≤2 % | 0 – 2 | 0.5 |
| inorganic chlorineinorganic chlorine ≤0.002 % | 0 | 0 |
| hydrolyzable/organic chlorinelower limits for electronic grades | 0 – 0.2 | 0.05 |
| bisphenol A diglycidyl ether (DGEBA oligepoxy value 0.48–0.54 eq/100 g, EEW 185–208 g/eq, 11–14 Pa·s at 25 °C | ≥ 98 (balance) |
What surface finishes work on E-51?
Sands and polishes to a high gloss; needs a pigmented or UV-blocking topcoat outdoors to prevent yellowing/chalking, and cured surfaces accept paint/plating primers after abrasion or plasma treatment.
Equivalent designations
Standards and trade names that resolve to E-51 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- DGEBA
How much does E-51 cost?
E-51 is a standard-cost polymer ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
E-51 — frequently asked
What is E-51 used for?
E-51 is typically used for potting and encapsulation, composite laminates, structural adhesives and tooling and molds. In short: baseline general-purpose epoxy; widest hardener choice; castable and laminating grade.
What is the tensile strength of E-51?
E-51 has a typical tensile strength of 65 MPa (9.43 ksi) — stronger than 73% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is E-51 easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Fully cured castings turn, mill and drill easily with sharp carbide and light feeds; keep tools cool to avoid softening near Tg, and use dust extraction (filled/GF grades are highly abrasive — PCD or diamond tooling for laminates).
Can E-51 be welded?
Thermoset — cannot be welded or remelted; join by adhesive bonding with the same epoxy after abrading and solvent-cleaning the surfaces.
What surface finishes work on E-51?
Sands and polishes to a high gloss; needs a pigmented or UV-blocking topcoat outdoors to prevent yellowing/chalking, and cured surfaces accept paint/plating primers after abrasion or plasma treatment.
Can E-51 be formed, bent or molded?
Processed as a two-part liquid: degas, mix stoichiometrically with amine/anhydride hardener, cast/RTM/wind or prepreg, then cure RT–150 °C with post-cure to reach full Tg; exotherm limits practical section thickness of unfilled castings.
What is the maximum service temperature of E-51?
E-51 is rated for continuous use to about 95°C (203 °F), and briefly to 150°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between E-51 AMINE and E-51 Flex?
AMINE is the default condition — default general-purpose room- or mild-heat-cured clear casting for adhesives, potting and tooling. Flex: use where thermal-cycling stress on delicate components must be absorbed; trades strength and Tg for compliance.
How much does E-51 cost?
E-51 is a standard-cost polymer ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Engineered Materials Handbook Vol.3: Adhesives and Sealants — ASM International (1990)
- Engineered Materials Handbook Vol.2: Engineering Plastics — ASM International (1988)
- Araldite / Aradur liquid bisphenol-A epoxy systems technical data — Huntsman Advanced Materials (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.