Composite Fiber and Matrix Typical Properties Reference
Early composite sizing needs a quick table of fiber and matrix density, modulus and strength. This reference collects typical values for the reinforcements and resins most manufacturers meet, so you can fill the input fields of a rule-of-mixtures calculation without hunting through datasheets.
| Material | Class | Type | Density (g/cm3) | Tensile modulus (GPa) | Tensile strength (MPa) | Typical use |
|---|---|---|---|---|---|---|
E-glass | Fiber | Glass | 2.54 to 2.60 | 72 to 73 | 3,400 (virgin fiber) | Marine, wind, pressure vessels, general industrial |
S-2 glass | Fiber | Glass | 2.46 to 2.49 | 85 to 90 | 4,500 to 4,900 | Aerospace, ballistic, higher performance glass |
Basalt | Fiber | Mineral | 2.6 to 2.8 | 80 to 95 | 3,000 to 4,800 | Rebar, pipes, thermal and corrosion applications |
T300 class | Fiber | PAN carbon, standard modulus | 1.76 | 230 | 3,500 | General aerospace and industrial prepreg |
AS4 class | Fiber | PAN carbon, standard modulus | 1.79 | 231 | 4,300 | Primary aircraft structure, legacy programs |
T700S class | Fiber | PAN carbon, standard modulus | 1.80 | 230 | 4,900 | Pressure vessels, automotive, sporting goods |
T800S class | Fiber | PAN carbon, intermediate modulus | 1.80 | 294 | 5,880 | Aerospace primary structure |
IM7 class | Fiber | PAN carbon, intermediate modulus | 1.78 | 276 | 5,300 | Aerospace primary structure, rotorcraft |
M40J class | Fiber | PAN carbon, high modulus | 1.77 | 377 | 4,400 | Satellite structures, antenna reflectors |
M55J class | Fiber | PAN carbon, ultra high modulus | 1.91 | 540 | 4,000 | Space structures where stiffness drives design |
Kevlar 49 class | Fiber | Para-aramid | 1.44 | 112 to 131 | 3,000 to 3,600 | Ballistic, radomes, tension members |
UHMWPE (Dyneema, Spectra class) | Fiber | Polyethylene | 0.97 | 90 to 130 | 2,400 to 3,500 | Ballistic panels, ropes, lightweight armor |
Epoxy (cured) | Matrix | Thermoset | 1.10 to 1.30 | 2.7 to 4.1 | 55 to 130 | Aerospace prepreg, wind, sporting goods, tooling |
Polyester (unsaturated) | Matrix | Thermoset | 1.10 to 1.25 | 2.0 to 4.5 | 40 to 90 | Marine, building panels, cost-driven glass parts |
Vinyl ester | Matrix | Thermoset | 1.10 to 1.20 | 3.0 to 3.5 | 70 to 90 | Corrosion-resistant tanks, pipes, boats |
PEEK | Matrix | Thermoplastic | 1.30 to 1.32 | 3.6 to 4.0 | 90 to 100 | Thermoplastic aerospace composites, high temperature |
PPS | Matrix | Thermoplastic | 1.35 | 3.4 to 4.0 | 80 to 90 | Aerospace brackets and clips, chemical resistance |
Polyamide 6 (nylon 6) | Matrix | Thermoplastic | 1.13 | 1.5 to 3.0 | 50 to 80 | Automotive and consumer thermoplastic composites |
Values are typical, rounded figures for early sizing and rule-of-mixtures inputs. Grades, sizing, moisture state and test method change the real number, and virgin fiber strength is much higher than strength measured in a laminate. Always take design values from the supplier datasheet or your qualified material allowables. Class names such as T700S or IM7 refer to fiber families; individual producers publish their own certified data.
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How to use the table
Search for a fiber or resin by name or use the class filter to switch between reinforcements and matrices. Copy density and modulus into the fiber volume fraction calculator to estimate laminate density and ply stiffness. Use the strength column to compare fibers qualitatively, not to predict laminate strength. Export the table to Excel or PDF for a materials selection discussion with design or purchasing.
- Compare specific stiffness (modulus divided by density) when weight matters.
- Check the datasheet for your grade before quoting or releasing a design.
- Note whether strength is for dry fiber, impregnated strand or cured laminate.
How to read the numbers
Fiber properties are measured on the fiber or an impregnated strand, so strengths are high; a cured unidirectional carbon laminate typically delivers only 60% to 80% of the strand figure in the fiber direction because of stress concentrations and imperfect load sharing. Matrix properties are for neat cured resin. Transverse and shear behavior of a composite is dominated by the matrix and the fiber-matrix interface, so a high-strength fiber does not by itself give a damage-tolerant laminate. Use the density column to judge weight savings against glass, which is about 45% heavier than carbon for the same volume.
Choosing between fiber families
Glass is the low-cost, durable default and is non-conductive, which suits radomes and electrical parts. Standard modulus carbon offers about three times the stiffness of glass at lower density, but at a significantly higher cost per kilogram. Intermediate and high modulus carbon target aerospace and space structures where stiffness or low thermal expansion drives the design. Aramid and UHMWPE offer high tensile and impact performance but poor compressive strength, so they appear in ballistic and tension applications rather than primary bending members.
Common mistakes
Do not use fiber strength as laminate strength. Do not mix a dry-fiber modulus with a cured-laminate value in the same calculation. Be careful with moisture: epoxy matrices and aramid absorb water, which lowers hot-wet properties and can matter more than room-temperature numbers. Matrix temperature capability, such as glass transition temperature, is a separate selection criterion not shown here. Thermoplastic matrices have different processing windows and need supplier data for consolidation temperature and pressure.
Frequently Asked Questions
Which is stiffer, carbon fiber or glass fiber?
Standard modulus carbon is about 230 GPa against roughly 72 GPa for E-glass, so carbon is about three times stiffer and also about 30% lighter per unit volume. High modulus carbon can exceed 370 GPa, but cost and brittleness rise as well.
What is the density of carbon fiber?
Carbon fiber density is generally between 1.76 and 1.91 g/cm3, depending on the grade, with standard modulus fibers near 1.76 to 1.80 and high modulus fibers higher. A cured carbon/epoxy laminate is about 1.5 to 1.6 g/cm3 at typical fiber volume fractions.
Can I use these values for design allowables?
No. Use them for early sizing and trade studies only. Design allowables come from tested laminates with statistical basis, such as those in qualified material databases, and depend on the resin system, process and environment.
Why is aramid not used in compression-loaded parts?
Aramid fibers have high tensile strength but buckle and yield at low stress in compression, so laminates lose compressive performance. Hybrid constructions mix aramid with carbon or glass to combine impact resistance and compression capability.
If your engineering and purchasing teams keep material data in PLM or ERP item masters, Netray can help expose it to a private assistant that answers selection questions without data leaving your network.
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