Epoxy
ASTM D1763 · GB GB/T 13657 · ISO 3673-1
Epoxy is a two-part thermoset resin system (ASTM D1763, GB/T 13657) cured with amine or anhydride hardeners and used as laminate matrix, structural adhesive, casting resin and composite matrix.
Reference datasheet — Epoxy 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.
Epoxy grades and fills
Epoxy is supplied in 10 conditions, soft to hard.
Compare all 10 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Syntactic foam / microballoon-filled low-density grade | Buoyancy modules, core materials and lightweight tooling fills where compressive strength per density rules. | 20 | 1.2 | 80 Shore D | |
ESD / electrically conductive | Conductive adhesives, EMI/grounding bondlines and static-dissipative tooling surfaces. | 30 | 0.5 | 90 Shore D | |
Thermally conductive | Gap fillers and heat-sink potting where 1–3 W/m·K is needed while keeping electrical insulation. | 40 | 0.8 | 90 Shore D | |
Toughened / impact-modified | Structural adhesives and crash-tolerant bondlines — 3–5× fracture toughness at the cost of Tg and modulus. | 45 | 9 | 78 Shore D | |
Mineral / silica filled encapsulation grade | Silica-filled potting/encapsulation compound — low CTE and shrinkage for electronics, transformers and semiconductor molding. | 55 | 1 | ||
FR | Brominated or phosphorus/ATH flame-retarded formulation for electrical enclosures, busbar and rail applications. | 55 | 2 | 88 Shore D | |
High-Tg novolac / anhydride cured heat-resistant grade | For tooling, aerospace prepreg and under-hood parts needing service to ~180–200 °C; more brittle and needs high-temperature post-cure. | 70 | 1.8 | ||
30 % short glass fiber reinforced epoxy molding compound | Choose for stiff, dimensionally stable molded parts (encapsulation, electrical housings) where CTE must be halved versus neat resin. | 110 | 1.5 | ||
FR-4 / G-10 | Pick for PCB substrates, insulating plates and machined electrical parts needing high flexural strength plus V-0 rating. | 310 | |||
Carbon fiber / epoxy composite | Use when epoxy acts as the matrix of a structural CFRP laminate — highest specific stiffness, near-zero axial CTE. | 1,800 | 1.4 |
Supply forms, finishes and certifications
Ways Epoxy is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
MED | Medical / USP Class VI, ISO 10993 certified grade | Certification |
Clear | Clear / optical casting grade | Grade option |
UnfilledDefault | Unfilled / neat cast epoxy | Standard supply |
What is Epoxy?
Epoxy is a two-part thermoset resin system (ASTM D1763, GB/T 13657) cured with amine or anhydride hardeners and used as laminate matrix, structural adhesive, casting resin and composite matrix. Engineers select it for high strength, chemical resistance and adhesion to metals and fibres; unfilled cast resin runs about 1.2 g/cm³, 65 MPa tensile strength, 4 % elongation, 0.2 W/m·K and 120 °C service, with filled, FR4, carbon, thermally conductive, toughened, clear, ESD and syntactic grades on file. Limits are pot life and exotherm control, no re-melting or welding, and UV yellowing outdoors; polyester or vinyl ester is cheaper where strength allows. Epoxy has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 120°C (248 °F). Epoxy 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 Epoxy used for?
- Composite laminates
- Structural adhesives
- Potting/encapsulation
- Tooling and molds
Advantages
- Low, predictable mold shrinkage — 0.2%, better than 94% of polymer grades
- Polishes to a fine finish — 75/100, better than 86% of polymer grades
Limitations
- Difficult to weld — 0/100, worse than 98% of polymer grades
- Low fracture toughness — 0.6 MPa·√m (0.546 ksi·√in), worse than 96% of polymer grades
- Limited formability — 5/100, worse than 95% 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
Epoxy properties
Typical room-temperature values; bars are the position among polymer grades.
Physical6
Epoxy has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 57% of polymer grades. Its glass-transition temperature is 120°C (248 °F).
Mechanical15
Epoxy 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
Epoxy is rated for continuous service to 130°C (266 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 56% of polymer grades. Thermal expansion is 60 µm/m·K (33.3 µin/in·°F).
Electrical7
Epoxy 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 (82/100), better than 56% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of Epoxy takes about 137 MJ of energy and emits 6.6 kg of CO₂ — more than 80% of polymer grades. Typical recycled content is 0%.
Manufacturability6
Epoxy's machinability is good (55/100, worse than 64% of polymer grades); weldability not recommended (0/100); formability not recommended (5/100).
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. Epoxy is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Epoxy
Is Epoxy easy to machine?
Machines cleanly with sharp carbide (PCD for filled/laminate grades) at high speed, light feed and no coolant heat build-up; filled and glass-cloth grades are highly abrasive and the dust requires extraction.
Can Epoxy be welded?
Thermoset — cannot be welded or re-melted; joints are made by secondary epoxy bonding with abraded, solvent-cleaned surfaces.
Can Epoxy be formed, bent or molded?
Processed by casting, potting, RTM/infusion, prepreg lay-up, filament winding or transfer/compression molding; degas the mix, respect pot life, and post-cure (typically 80–180 °C) to develop full Tg.
Epoxy 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 |
|---|---|---|
| bisphenol-A diglycidyl ether (DGEBA) resE-51/E-44 type; novolac or cycloaliphatic epoxies substitute in HT/clear grades | 45 – 75 | 60 |
| amine or anhydride hardenerpolyamine, polyamide, DDS/DDM or MTHPA anhydride; stoichiometry set by EEW | 8 – 40 | 25 |
| reactive diluent / flexibilizere.g. BGE, C12-14 glycidyl ether, CTBN | 0 – 15 | 5 |
| mineral or glass fillersilica, alumina, glass fiber/cloth depending on variant | 0 – 70 | 0 |
| accelerator / additivesimidazole, BDMA, defoamer, pigment, FR package | 0 – 3 | 1 |
What surface finishes work on Epoxy?
Sands and polishes to a high gloss; accepts paint and primers readily after abrasion; needs UV-blocking topcoat or clearcoat for outdoor service because aromatic epoxies yellow and chalk.
Equivalent designations
Standards and trade names that resolve to Epoxy in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- D1763
- ISO
- 3673-1
- GB (China)
- GB/T 13657
How much does Epoxy cost?
Epoxy is a standard-cost polymer ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Epoxy — frequently asked
What is Epoxy used for?
Epoxy is typically used for composite laminates, structural adhesives, potting/encapsulation and tooling and molds. In short: baseline composite matrix; strongest structural adhesive resin; wide filled-grade range.
What is the tensile strength of Epoxy?
Epoxy has a typical tensile strength of 65 MPa (9.43 ksi) — stronger than 73% of polymer grades. Strength varies by condition: see the 10 listed tempers.
Is Epoxy easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Machines cleanly with sharp carbide (PCD for filled/laminate grades) at high speed, light feed and no coolant heat build-up; filled and glass-cloth grades are highly abrasive and the dust requires extraction.
Can Epoxy be welded?
Not readily — weldability is rated not recommended (0/100). Thermoset — cannot be welded or re-melted; joints are made by secondary epoxy bonding with abraded, solvent-cleaned surfaces.
What surface finishes work on Epoxy?
Sands and polishes to a high gloss; accepts paint and primers readily after abrasion; needs UV-blocking topcoat or clearcoat for outdoor service because aromatic epoxies yellow and chalk.
Can Epoxy be formed, bent or molded?
Processed by casting, potting, RTM/infusion, prepreg lay-up, filament winding or transfer/compression molding; degas the mix, respect pot life, and post-cure (typically 80–180 °C) to develop full Tg.
What is the maximum service temperature of Epoxy?
Epoxy is rated for continuous use to about 130°C (266 °F), and briefly to 180°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Epoxy cost?
Epoxy is a standard-cost polymer ($$), 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. 2 — Engineering Plastics — ASM International (1988)
- Engineered Materials Handbook Vol. 1 — Composites — ASM International (1987)
- ASTM D1763 — Standard Specification for Epoxy Resins — ASTM (2019)
- GB/T 13657 — Bisphenol-A epoxy resin — SAC (2011)
- IEC 61249 / NEMA LI-1 (FR-4, G-10 laminates) — IEC / NEMA (2020)
- Araldite / Aradur casting and adhesive system datasheets — Huntsman Advanced Materials (2023)
- EPON / EPIKURE resin technical data — Hexion (Westlake Epoxy) (2022)
- CES EduPack polymer records — epoxy (thermoset) — Ansys Granta (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.