PTMT GF20
Reinforced grade
GF20 = 20 % glass-fiber reinforced
Common automotive/electrical structural grade when GF30 warps too much.
Values for the GF20 condition
Other PTMT grades and fills
PTMT is listed in 17 conditions; see the grade overview at PTMT.
Compare all 17 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified | Use where notched impact and cold-temperature toughness dominate — snap fits, handles, exterior clips. | 40 | 42 | 200 | 68 Shore D |
PBT/ASA (or PBT/ABS) blend | Blend for weatherable, low-warp cosmetic housings needing better surface than glass-filled PBT. | 45 | 45 | 40 | 74 Shore D |
PTFE / silicone lubricated bearing grade | Internally lubricated compound for gears, cams and slide bushings running dry against metal. | 47 | 48 | 15 | 78 Shore D |
FR V-0 unfilled | For live-part enclosures and switch bodies needing V-0 at 0.75–1.5 mm without reinforcement. | — | 50 | 15 | — |
PBT/PC blend | Alloy for tough, dimensionally stable painted exterior parts (bumper fascia, trims) with better impact than neat PBT. | 55 | 55 | 120 | 76 Shore D |
Mineral-filled | Choose when flatness and isotropic shrinkage matter more than strength — flat covers, lids, painted parts. | 58 | 60 | 4 | 85 Shore D |
ESD / conductive | For electronics trays, fuel-system parts and housings needing static dissipation (10^4–10^9 Ω/sq). | — | 70 | 3 | 85 Shore D |
10 % glass-fiber reinforced | Light stiffening with modest warpage penalty; used where the unfilled grade is just too soft. | — | 80 | 5 | — |
15 % glass-fiber reinforced | Balance of stiffness and low warpage for connector bodies and covers. | — | 95 | 4 | — |
Glass + mineral filled | Compromise grade: near-GF stiffness with much flatter parts for large thin covers and housings. | 95 | 95 | 2.5 | 88 Shore D |
GF20This page 20 % glass-fiber reinforced | Common automotive/electrical structural grade when GF30 warps too much. | — | 110 | 3.5 | — |
flame-retardant, 30 % glass reinforced | Most-specified E&E grade: V-0 plus HDT > 200 °C for relay bases, breaker parts and connectors. | — | 125 | 2.2 | — |
Hot rolled | Carbodiimide-stabilized grades for automotive connectors and pumps exposed to hot humid air or coolant mist. | — | 130 | 2.5 | 86 Shore D |
30 % glass-fiber reinforced | The standard reinforced PBT for connectors, bobbins, brackets and under-hood parts needing HDT > 200 °C. | — | 135 | 2.8 | 90 HRM |
40 % glass-fiber reinforced | Maximum stiffness/creep resistance for metal-replacement brackets; expect anisotropic shrink and abrasive wear on tooling. | — | 150 | 2.2 | — |
50 % glass-fiber reinforced | Highest-modulus PBT compound for load-bearing housings; surface quality and toughness are the trade-off. | — | 165 | 2 | — |
CF20/CF30 | Pick for high stiffness at low weight plus static-dissipative surface; costlier and more anisotropic than glass. | — | 175 | 1.8 | — |
What is PTMT GF20?
PTMT GF20 is PTMT in the GF20 grade — common automotive/electrical structural grade when GF30 warps too much. PTMT GF20 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 110 MPa (16 ksi) — stronger than 62% of polymer grades. Elongation at break is 3.5% and the elastic modulus is 6.5 GPa (0.943 Msi). PTMT GF20 has a density of 1.45 g/cm³ (0.0524 lb/in³), heavier than 86% of polymer grades. Its glass-transition temperature is 50°C (122 °F).
Advantages
- Stiff — 6.5 GPa (0.943 Msi), better than 90% of polymer grades
- Low moisture uptake — 0.08%, better than 80% of polymer grades
- High service temperature — 140°C (284 °F), better than 76% of polymer grades
Limitations
- Heavy — 1.45 g/cm³ (0.0524 lb/in³), worse than 86% of polymer grades
- Limited ductility — 3.5%, worse than 79% of polymer grades
PTMT GF20 properties
Typical room-temperature values for PTMT GF20; 11 are specific to this condition. Other listed values are PTMT reference data and may not represent this condition. Bars are the position among polymer grades.
Physical6
PTMT GF20 has a density of 1.45 g/cm³ (0.0524 lb/in³), heavier than 86% of polymer grades. Its glass-transition temperature is 50°C (122 °F).
Mechanical16
PTMT GF20 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 110 MPa (16 ksi) — stronger than 62% of polymer grades. Elongation at break is 3.5% and the elastic modulus is 6.5 GPa (0.943 Msi).
Thermal11
PTMT GF20 is rated for continuous service to 140°C (284 °F). It conducts heat at 0.23 W/m·K (0.133 BTU/hr·ft·°F), better than 65% of polymer grades. Thermal expansion is 35 µm/m·K (19.4 µin/in·°F).
Electrical7
PTMT GF20 is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (78/100), worse than 61% of polymer grades. UV resistance is fair.
Sustainability4
Producing a kilogram of PTMT GF20 takes about 95 MJ of energy and emits 4.4 kg of CO₂ — less than 70% of polymer grades. Typical recycled content is 5%.
Manufacturability8
PTMT GF20's machinability is good (68/100, better than 71% of polymer grades); weldability very good (70/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PTMT GF20
Is PTMT easy to machine?
Machines cleanly like acetal with sharp positive-rake tools and air cooling; glass-filled grades are abrasive — use carbide/PCD and expect edge chipping on thin sections.
Can PTMT be welded?
Ultrasonic, vibration, hot-plate and laser (with laser-transparent/absorbing pairs) welding all work well; solvent bonding is impractical, use epoxy or cyanoacrylate on abraded, flame/plasma-treated surfaces.
Can PTMT be formed, bent or molded?
Dry to <0.02 % moisture (120 °C, 3–4 h) to avoid hydrolytic MW loss; mold at 250–265 °C melt, 60–100 °C tool; fast crystallization gives short cycles but 1.4–2 % shrinkage and anisotropic warpage in GF grades.
What surface finishes work on PTMT?
Takes pad printing and laser marking readily; paint and metallize only after plasma/flame or primer treatment because of the low-energy, chemically resistant surface.
PTMT 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 |
|---|---|---|
| terephthalic acid / dimethyl terephthalaaromatic diacid segment of the repeat unit (wt % basis of neat polymer) | ≈ 62 | 62 |
| titanium/antimony catalyst residuepolycondensation catalyst, ppm level | ≈ 0.02 | 0.02 |
| glass fiberreinforcement in GF variants; chopped E-glass with silane sizing | 0 – 50 | 0 |
| flame retardant (brominated + Sb2O3 or hFR variants only | 0 – 20 | 0 |
| impact modifier / stabilizer packageelastomer, antioxidant, carbodiimide hydrolysis stabilizer, HALS | 0 – 20 | 0.5 |
| 1,4-butanediol (tetramethylene glycol) ugives the 'PTMT' (polytetramethylene terephthalate) name | balance | — |
PTMT GF20 — frequently asked
What is PTMT GF20 used for?
PTMT GF20 is typically used for electrical bobbins and connectors, precision gears and bushings, automotive electrical components and consumer electronics parts. In short: legacy designation for PBT; fast-cycling engineering polyester; wide filled-grade range.
What is the yield strength of PTMT GF20?
PTMT GF20 has a typical yield strength of 55 MPa (7.98 ksi) and a tensile strength of 110 MPa (16 ksi) — stronger than 62% of polymer grades. Strength varies by condition: see the 17 listed tempers.
Is PTMT GF20 easy to machine?
Reasonably — machinability is rated good (68/100, better than 71% of polymer grades). Machines cleanly like acetal with sharp positive-rake tools and air cooling; glass-filled grades are abrasive — use carbide/PCD and expect edge chipping on thin sections.
Can PTMT GF20 be welded?
Yes — weldability is rated very good (70/100). Ultrasonic, vibration, hot-plate and laser (with laser-transparent/absorbing pairs) welding all work well; solvent bonding is impractical, use epoxy or cyanoacrylate on abraded, flame/plasma-treated surfaces.
What surface finishes work on PTMT GF20?
Takes pad printing and laser marking readily; paint and metallize only after plasma/flame or primer treatment because of the low-energy, chemically resistant surface.
Can PTMT GF20 be formed, bent or molded?
Dry to <0.02 % moisture (120 °C, 3–4 h) to avoid hydrolytic MW loss; mold at 250–265 °C melt, 60–100 °C tool; fast crystallization gives short cycles but 1.4–2 % shrinkage and anisotropic warpage in GF grades.
What is the maximum service temperature of PTMT GF20?
PTMT GF20 is rated for continuous use to about 140°C (284 °F), and briefly to 160°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ISO 7792-1/-2 Plastics — Thermoplastic polyester (TP) moulding and extrusion materials — ISO (2012)
- ASTM D5927 Standard Specification for Thermoplastic Polyester (TPES) Injection and Extrusion Materials — ASTM (2020)
- Ultradur (PBT) product range brochure and property tables — BASF (2023)
- Crastin PBT thermoplastic polyester resin datasheets — DuPont / Celanese (2023)
- CAMPUS plastics database — PBT unfilled and GF grades — CWFG (2024)
- Engineered Materials Handbook Vol. 2 — Engineering Plastics — ASM International (1988)
- TECADUR PBT stock shapes datasheet — Ensinger (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.