Plastic Nylon PA66 vs. Plastic PBT GF30

Compare Plastic Nylon PA66 vs. Plastic PBT GF30 strength, stiffness, weight and thermal properties.

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Plastic Nylon PA66Bulk polymer (molded or machined)

Plastic PBT GF30Bulk polymer (molded or machined)

Mechanical
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Yield strength	85MPasourcetypical, dry	not given (tensile used)
Ultimate tensile strength	not sourced	140MPasourcestress at break, 23 °C
Flexural strength	not sourced	210MPasourcetypical, 23 °C
Elongation at break	30%sourcenominal strain at break, dry	3%sourcestrain at break, 23 °C
Young's modulus (stiffness)	3GPasourcetypical, dry	9.8GPasourcetypical, 23 °C
Density	1,130kg/m³sourcetypical35% lighter	1,530kg/m³sourcetypical
Strength to weight	75.2kN·m/kg	91.5kN·m/kg22% higher
Stiffness to weight	2.65MN·m/kg	6.41MN·m/kg2.41x higher
Poisson's ratio	0.4sourcebase material: unfilled polyamide (PA), conditioned, maker design-guide family value (Covestro Table 3-1)	not sourced
Shear modulus	1.07GPa	not sourced
Bulk modulus	5GPa	not sourced
Speed of sound	1,629m/s	2,531m/s
Thermal
Thermal conductivity	0.33W/m·Ksourcetypical	0.27W/m·Ksourcetypical (DIN 52612-1)
Thermal expansion	98µm/m·Ksourcelongitudinal, 23-55 °C	25µm/m·Ksourcelongitudinal (flow), mean 23-55 °C
100 mm part over a 50 °C swing	490µm growth	125µm growth3.92x less
Specific heat	1,700J/kg·Ksourcetypical	1,050J/kg·Ksourcetypical, 23 °C
Heats up and cools (diffusivity)	0.172mm²/s2% faster	0.168mm²/s
Thermal shock resistance	57.2W/m	not sourced
Melting point	260°CsourceDSC	223°CsourceDSC (ISO 11357)
Max service temperature	101°CsourceIEC 60216 temperature index, 20000 h	205°CsourceHDT 1.8 MPa
Values for	BASF Ultramid A3K (PA66, unreinforced injection-moulding grade), Product Information 02/2026, dry values (ISO methods)	BASF Ultradur B 4300 G6 (PBT, 30% glass fibre), injection moulding grade; product information sheet 09/2026, typical values for uncoloured product at 23 °C.

Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Is Plastic Nylon PA66 stronger than Plastic PBT GF30?

Plastic PBT GF30 is stronger: its tensile strength is 140 MPa against yield strength 85 MPa for Plastic Nylon PA66 (1.65x).

Which is lighter, Plastic Nylon PA66 or Plastic PBT GF30?

Plastic Nylon PA66 is lighter: 1,130 kg/m³ against 1,530 kg/m³ for Plastic PBT GF30.

Which is stiffer, Plastic Nylon PA66 or Plastic PBT GF30?

Plastic PBT GF30 is stiffer: Young's modulus 9.8 GPa against 3 GPa for Plastic Nylon PA66, so the same part in Plastic PBT GF30 deflects less under the same load.

Which is lighter for the same job, Plastic Nylon PA66 or Plastic PBT GF30?

For the same stiffness or strength: Plastic Nylon PA66 is lighter for a strong panel or plate; Plastic PBT GF30 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam.

Part that must be	Plastic Nylon PA66	Plastic PBT GF30
Stiff rod or tie (tension)	2.41x heavier	lighter
Stiff beam (bending)	33% heavier	lighter
Stiff panel or plate	10% heavier	lighter
Strong rod or tie	22% heavier	lighter
Strong beam	3% heavier	lighter
Strong panel or plate	lighter	6% heavier

For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).

Which conducts heat better, Plastic Nylon PA66 or Plastic PBT GF30?

Plastic Nylon PA66 conducts heat better: 0.33 W/m·K against 0.27 W/m·K for Plastic PBT GF30.

Which expands less with temperature?

Plastic PBT GF30 expands less: 25 µm/m·K against 98 µm/m·K for Plastic Nylon PA66.

Among 72 materials

Stiffness against density

Strength against density