PTT
also Sorona, Corterra
PTT is a thermoplastic polyester polymerized from 1,3-propanediol and terephthalic acid, sold as Sorona and Corterra, that sits between PET and PBT with PET-like stiffness, PBT-like resilience and inherent stretch recovery.
Reference datasheet — PTT 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.
Values for the UNF condition
PTT grades and fills
PTT is supplied in 9 conditions, soft to hard. UNF is the default FabDigit quotes; the values on this page are for it.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Impact-modified (toughened) PTT | Elastomer-toughened compound for snap-fits, sporting goods and cold-impact parts where ductility beats stiffness. | 40 | 44 | 150 | 68 Shore D |
Flame-retardant, unfilled | Halogen-containing or halogen-free FR compound for electrical enclosures needing V-0 at 1.5 mm. | 50 | 52 | 8 | 79 Shore D |
Mineral (talc) filled, 20–30 % | Choose when low warpage, isotropic shrinkage and a smooth painted surface matter more than peak strength. | 52 | 52 | 4 | 82 Shore D |
Heat-stabilized | Antioxidant-boosted compound for long-term thermal ageing (e.g. 1000 h+ at 120–140 °C) in automotive electrical parts. | 57 | 60 | 20 | 78 Shore D |
UNFDefault Unfilled / Natural injection-molding resin | General-purpose PTT for tough, glossy, dimensionally stable parts where service temperature stays below ~90 °C. | 62 | 25 | ||
15 % glass-fiber reinforced | Entry-level stiffening with much higher heat distortion temperature while keeping reasonable toughness and surface appearance. | 100 | 3.5 | ||
GF30 + flame retardant | Structural FR grade for connectors, relay bases and breaker parts requiring V-0 plus high HDT. | 120 | 2 | 88 Shore D | |
30 % glass-fiber reinforced | Workhorse structural grade: HDT above 200 °C, high stiffness and low shrinkage for connectors, housings and under-hood parts. | 138 | 2.5 | ||
45 % glass-fiber reinforced | Maximum stiffness/creep resistance PTT for metal-replacement brackets and load-bearing electrical parts. | 165 | 2 |
Supply forms, finishes and certifications
Ways PTT is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FIBER | Fiber / textile grade | Supply form |
UV | UV-stabilized / weatherable | Grade option |
What is PTT?
PTT is a thermoplastic polyester polymerized from 1,3-propanediol and terephthalic acid, sold as Sorona and Corterra, that sits between PET and PBT with PET-like stiffness, PBT-like resilience and inherent stretch recovery. Unfilled resin gives 62 MPa tensile strength, 25% elongation and 1.32 g/cm³ density, and fast crystallization yields short molding cycles and low warpage; it is supplied as fiber, molding pellets and glass-filled (GF15/GF30/GF45), mineral, impact-modified, FR-V0, heat-stabilized and UV grades. Maximum service temperature is about 90 °C, the resin must be dried before processing, and hot alkaline media hydrolyze the surface. PBT is the nearest alternative when higher continuous heat is required. PTT has a density of 1.32 g/cm³ (0.0477 lb/in³), heavier than 72% of polymer grades. Its glass-transition temperature is 50°C (122 °F). PTT has a yield strength of 58 MPa (8.41 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 66% of polymer grades. Elongation at break is 25% and the elastic modulus is 2.7 GPa (0.392 Msi).
What is PTT used for?
- Carpet and textile fiber
- Apparel fabric with stretch recovery
- Engineering resin for connectors
- Automotive interior trim fiber
Advantages
- Low embodied carbon — 3 kg CO₂/kg, better than 83% of polymer grades
PTT properties
Typical room-temperature values for PTT-UNF; bars are the position among polymer grades.
Physical6
PTT has a density of 1.32 g/cm³ (0.0477 lb/in³), heavier than 72% of polymer grades. Its glass-transition temperature is 50°C (122 °F).
Mechanical16
PTT has a yield strength of 58 MPa (8.41 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 66% of polymer grades. Elongation at break is 25% and the elastic modulus is 2.7 GPa (0.392 Msi).
Thermal11
PTT is rated for continuous service to 90°C (194 °F). It conducts heat at 0.21 W/m·K (0.121 BTU/hr·ft·°F), better than 55% of polymer grades. Thermal expansion is 80 µm/m·K (44.4 µin/in·°F).
Electrical7
PTT 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 PTT takes about 70 MJ of energy and emits 3 kg of CO₂ — less than 93% of polymer grades. Typical recycled content is 0%.
Manufacturability8
PTT's machinability is good (65/100, better than 66% of polymer grades); weldability very good (70/100); formability fair (50/100).
Common Calculations5
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. PTT is highlighted; hover a dot for its name, or open the interactive family chart.
Working with PTT
Is PTT easy to machine?
Machines like PBT/PET — sharp positive-rake tools, high speed, low feed and air cooling; glass-filled grades are abrasive and need carbide or PCD.
Can PTT be welded?
Joins well by ultrasonic, vibration, hot-plate and laser welding; solvent bonding is poor, so use epoxy or cyanoacrylate for adhesive joints.
Can PTT be formed, bent or molded?
Dry to <0.02 % moisture (120–130 °C, 3–4 h) before molding; melt 240–265 °C, mold 40–90 °C (higher for filled grades), fast crystallization gives short cycles and low warpage.
PTT 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 |
|---|---|---|
| 1,3-propanediol (PDO)diol residue in repeat unit; bio-PDO from corn sugar in Sorona | 34 – 39 | 37 |
| Ti/Sn polycondensation catalysttitanate or tin catalyst residue | 0 – 0.02 | 0.01 |
| heat/UV stabilizer packagegrade dependent | 0 – 1 | 0.3 |
| glass fiber0 for the default unfilled grade; 15/30/45 % in reinforced variants | 0 – 45 | 0 |
| terephthalic acid (PTA/DMT) residuediacid residue, ~63 wt% of repeat unit C11H10O4 | balance |
What surface finishes work on PTT?
Takes high-gloss mold finishes and disperse dyes readily; paint/print after flame or plasma treatment, and avoid hot alkaline cleaning which hydrolyzes the surface.
Equivalent designations
Standards and trade names that resolve to PTT in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- SoronaCorterra
How much does PTT cost?
PTT 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.
PTT — frequently asked
What is PTT used for?
PTT is typically used for carpet and textile fiber, apparel fabric with stretch recovery, engineering resin for connectors and automotive interior trim fiber. In short: elastic-recovery polyester; between PET and PBT; fast cycles, low warpage.
What is the yield strength of PTT?
PTT has a typical yield strength of 58 MPa (8.41 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 66% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is PTT easy to machine?
Reasonably — machinability is rated good (65/100, better than 66% of polymer grades). Machines like PBT/PET — sharp positive-rake tools, high speed, low feed and air cooling; glass-filled grades are abrasive and need carbide or PCD.
Can PTT be welded?
Yes — weldability is rated very good (70/100). Joins well by ultrasonic, vibration, hot-plate and laser welding; solvent bonding is poor, so use epoxy or cyanoacrylate for adhesive joints.
What surface finishes work on PTT?
Takes high-gloss mold finishes and disperse dyes readily; paint/print after flame or plasma treatment, and avoid hot alkaline cleaning which hydrolyzes the surface.
Can PTT be formed, bent or molded?
Dry to <0.02 % moisture (120–130 °C, 3–4 h) before molding; melt 240–265 °C, mold 40–90 °C (higher for filled grades), fast crystallization gives short cycles and low warpage.
What is the maximum service temperature of PTT?
PTT is rated for continuous use to about 90°C (194 °F), and briefly to 140°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between PTT UNF and PTT IM?
UNF is the default condition — general-purpose PTT for tough, glossy, dimensionally stable parts where service temperature stays below ~90 °C. IM: elastomer-toughened compound for snap-fits, sporting goods and cold-impact parts where ductility beats stiffness. Yield strength is 58 MPa in UNF versus 40 MPa in IM.
How much does PTT cost?
PTT 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
- Sorona EP thermoplastic polymer product & processing guides — DuPont / Covation Biomaterials (2022)
- Corterra PTT polymer technical bulletins — Shell Chemicals / Zhejiang PTT producers (2005)
- Handbook of Thermoplastic Polyesters (PTT chapters) — Wiley-VCH (S. Fakirov, ed.) (2002)
- CAMPUS / UL Prospector polyester (PTT) datasheets — CWFG / UL Solutions (2024)
- ISO 527 / ISO 178 / ISO 75 / ASTM D256 test methods for thermoplastics — ISO / ASTM (2019)
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.