Plastic PBT GF30 vs. Plastic PPS GF40

Compare Plastic PBT GF30 vs. Plastic PPS GF40 strength, stiffness, weight and thermal properties.

Plastic PBT GF30Bulk polymer (molded or machined)

Plastic PPS GF40Bulk polymer (molded or machined)

Mechanical	Plastic PBT GF30	Plastic PPS GF40
Yield strength	not given (tensile used)	not given (tensile used)
Ultimate tensile strength	stress at break140MPa1	tensile strength195MPa2
Flexural strength	210MPa1	285MPa2
Elongation at break	strain at break3%11.58x more ductile	strain at break1.9%2
Young's modulus (stiffness)	9.8GPa1	14.7GPa250% stiffer
Density	1,530kg/m³1	1,650kg/m³2
Strength to weight	91.5kN·m/kg	118kN·m/kg29% higher
Stiffness to weight	6.41MN·m/kg	8.91MN·m/kg39% higher
Poisson's ratio	not sourced	0.353
Shear modulus	not sourced	5.44GPa
Bulk modulus	not sourced	16.3GPa
Speed of sound	2,531m/s	2,985m/s18% faster

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Plastic PBT GF30	Plastic PPS GF40
Thermal conductivity	0.27W/m·K135% more heat through a fin	0.2W/m·K3
Thermal expansion	longitudinal25µm/m·K1	parallel12µm/m·K22.08x less
100 mm part over a 50 °C swing	125µm growth	60µm growth2.08x less
Specific heat	1,050J/kg·K1	not sourced
Heats up and cools (diffusivity)	0.168mm²/s	not sourced
Thermal shock resistance	not sourced	144W/m
Melting point	DSC223°C1	DSC280°C257 °C higher
Glass transition	not sourced	DSC90°C2
Max service temperature	HDT 1.8 MPa205°C1	HDT 1.8 MPa270°C265 °C hotter

Thermal conductivity against densityHigher and further left: spreads more heat for its weight

Thermal expansion against thermal conductivityLower and further right: warps less when heated

Try it on a partA bracket to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD

Sources3 documents: BASF, Celanese

Plastic PBT GF30: 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.
Plastic PPS GF40: Celanese Fortron 1140L4 (PPS, 40% glass fibre), injection moulding; FORTRON PPS Short-Term Properties Guide (PPS-012, 2016); thermal conductivity and Poisson for 40% glass-reinforced Fortron from the Fortron PPS Design Manual (PPS-050, 2013).

1
Ultradur B 4300 G6 Product InformationBASFPlastic PBT GF30 · Ultimate tensile strength: stress at break, 23 °CPlastic PBT GF30 · Flexural strength: typical, 23 °CPlastic PBT GF30 · Elongation at break: strain at break, 23 °CPlastic PBT GF30 · Young's modulus (stiffness): typical, 23 °CPlastic PBT GF30 · Density: typicalPlastic PBT GF30 · Thermal conductivity: typical (DIN 52612-1)Plastic PBT GF30 · Thermal expansion: longitudinal (flow), mean 23-55 °CPlastic PBT GF30 · Specific heat: typical, 23 °CPlastic PBT GF30 · Melting point: DSC (ISO 11357)Plastic PBT GF30 · Max service temperature: HDT 1.8 MPa
2
Fortron PPS Short-Term Properties Guide (PPS-012)CelanesePlastic PPS GF40 · Ultimate tensile strength: tensile strength, 5 mm/minPlastic PPS GF40 · Flexural strength: flexural strength at breakPlastic PPS GF40 · Elongation at break: strain at break, 5 mm/minPlastic PPS GF40 · Young's modulus (stiffness): typical, 1 mm/minPlastic PPS GF40 · Density: typicalPlastic PPS GF40 · Thermal expansion: parallel (flow), mean -50 to 90 °CPlastic PPS GF40 · Melting point: DSC, 10 °C/minPlastic PPS GF40 · Glass transition: DSC, 10 °C/minPlastic PPS GF40 · Max service temperature: HDT 1.8 MPa
3
Fortron PPS Design Manual (PPS-050)CelanesePlastic PPS GF40 · Poisson's ratio: glass-reinforced Fortron PPS (class value, not grade-specific)Plastic PPS GF40 · Thermal conductivity: 40% glass-reinforced Fortron, 25 °C (not grade-specific)

Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Mechanical

Is Plastic PBT GF30 stronger than Plastic PPS GF40?

Plastic PPS GF40 is stronger: its tensile strength is 195 MPa against 140 MPa for Plastic PBT GF30 (39%).

Which is lighter, Plastic PBT GF30 or Plastic PPS GF40?

Plastic PBT GF30 is lighter: 1,530 kg/m³ against 1,650 kg/m³ for Plastic PPS GF40.

Which is stiffer, Plastic PBT GF30 or Plastic PPS GF40?

Plastic PPS GF40 is stiffer: Young's modulus 14.7 GPa against 9.8 GPa for Plastic PBT GF30, so the same part in Plastic PPS GF40 deflects less under the same load.

Which is lighter for the same job, Plastic PBT GF30 or Plastic PPS GF40?

For the same stiffness or strength: Plastic PPS GF40 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	Plastic PBT GF30	Plastic PPS GF40
Stiff rod or tie (tension)	39% heavier	lighter
Stiff beam (bending)	14% heavier	lighter
Stiff panel or plate	6% heavier	lighter
Strong rod or tie	29% heavier	lighter
Strong beam	16% heavier	lighter
Strong panel or plate	9% heavier	lighter

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 is more ductile, Plastic PBT GF30 or Plastic PPS GF40?

Plastic PBT GF30 stretches further before it breaks: 3% elongation at break against 1.9% for Plastic PPS GF40.

Thermal

Which handles higher temperatures, Plastic PBT GF30 or Plastic PPS GF40?

Plastic PPS GF40 does: 270 °C against 205 °C for Plastic PBT GF30, both HDT 1.8 MPa.

Which conducts heat better, Plastic PBT GF30 or Plastic PPS GF40?

Plastic PBT GF30 conducts heat better: 0.27 W/m·K against 0.2 W/m·K for Plastic PPS GF40.

Which expands less with temperature?

Plastic PPS GF40 expands less: 12 µm/m·K against 25 µm/m·K for Plastic PBT GF30.