This comparison presents the key properties of unfilled PET in its amorphous and semi-crystalline forms. The table covers physical, mechanical, thermal, electrical, optical, processing, durability, environmental, and recycling-related properties.
| Property | PET – Unfilled, Amorphous | PET – Unfilled, Semi-Crystalline |
| Designation | Polyethylene Terephthalate (unfilled, amorphous) | Polyethylene Terephthalate (unfilled, semi-crystalline) |
| Typical uses | Blow molded bottles, packaging film, film, photographic and x-ray film, audio/visual tapes, industrial strapping, capacitor film, drawing office transparencies, fibers. | Electrical fittings and connectors, audio/visual tapes, industrial strapping, capacitor film, fibers. |
| Compositional summary | (CO-(C6H4)-CO-O-(CH2)2-O)n | (CO-(C6H4)-CO-O-(CH2)2-O)n |
| Material family | Plastic (thermoplastic, amorphous) | Plastic (thermoplastic, semi-crystalline) |
| Base material | PET (Polyethylene terephthalate) | PET (Polyethylene terephthalate) |
| Polymer code | PET | PET |
| Polymer | 100 % | 100 % |
| Density | 1.29 – 1.39 g/cm³ | 1.37 – 1.4 g/cm³ |
| Young’s modulus | 2.8 – 3 GPa | 2.76 – 3.1 GPa |
| Specific stiffness | 2.06 – 2.28 MN.m/kg | 1.99 – 2.24 MN.m/kg |
| Yield strength (elastic limit) | 50 – 55 MPa | 65 – 70 MPa |
| Tensile strength | 55 – 60 MPa | 70 – 75 MPa |
| Specific strength | 36.9 – 41.6 kN.m/kg | 46.9 – 50.6 kN.m/kg |
| Elongation | 280 – 320 % strain | 65 – 75 % strain |
| Compressive modulus | 2.76 – 4.14 GPa | 2.76 – 4.14 GPa |
| Compressive strength | 50 – 60 MPa | 75.8 – 103 MPa |
| Flexural modulus | 2.41 – 3.09 GPa | 2.99 – 3.09 GPa |
| Flexural strength (modulus of rupture) | 50 – 60 MPa | 70 – 75 MPa |
| Shear modulus | 0.994 – 1.49 GPa | 0.994 – 1.49 GPa |
| Bulk modulus | 4.94 – 5.19 GPa | 4.94 – 5.19 GPa |
| Poisson’s ratio | 0.381 – 0.396 | 0.381 – 0.396 |
| Shape factor | 5.6 | 4.9 |
| Hardness – Vickers | 2 – 5 HV | 17 – 20 HV |
| Hardness – Rockwell M | 28 – 30 | 82 – 87 |
| Hardness – Rockwell R | 45 – 50 | 120 – 125 |
| Elastic stored energy (springs) | 430 – 524 kJ/m³ | 709 – 853 kJ/m³ |
| Fatigue strength at 10^7 cycles | 19.3 – 29 MPa | 19.3 – 29 MPa |
| Fracture toughness | 4.75 – 5.25 MPa.m^0.5 | 4.75 – 5.25 MPa.m^0.5 |
| Toughness (G) | 7.76 – 9.54 kJ/m² | 7.62 – 9.54 kJ/m² |
| Impact strength, notched 23 °C | 6.19 – 6.83 kJ/m² | 2.86 – 3.15 kJ/m² |
| Impact strength, unnotched 23 °C | 590 – 600 kJ/m² | 590 – 600 kJ/m² |
| Melting point | NA (Amorphous PET does not have a melting temperature because it lacks a long-range, ordered crystalline structure.) | 255 – 265 °C |
| Glass temperature | 60 – 84 °C | 68 – 80 °C |
| Heat deflection temperature 0.45MPa | 70 – 74 °C | 105 – 115 °C |
| Heat deflection temperature 1.8MPa | 68 – 72 °C | 70 – 80 °C |
| Maximum service temperature | 55 – 65 °C | 115 – 120 °C |
| Minimum service temperature | -58 – -38 °C | -58 – -38 °C |
| Thermal conductivity | 0.138 – 0.151 W/m.°C | 0.138 – 0.151 W/m.°C |
| Specific heat capacity | 1.15e3 – 1.25e3 J/kg.°C | 1.1e3 – 1.2e3 J/kg.°C |
| Thermal expansion coefficient | 115 – 119 µstrain/°C | 75 – 80 µstrain/°C |
| Thermal shock resistance | 145 – 164 °C | 276 – 321 °C |
| Thermal distortion resistance | 0.00117 – 0.0013 MW/m | 0.00176 – 0.00197 MW/m |
| Electrical resistivity | 3.3e20 – 3e21 µohm.cm | 3.3e20 – 3e21 µohm.cm |
| Electrical conductivity | 5.75e-20 – 5.22e-19 %IACS | 5.75e-20 – 5.22e-19 %IACS |
| Dielectric constant (relative permittivity) | 3.5 – 3.7 | 3.5 – 3.7 |
| Dissipation factor (dielectric loss tangent) | 0.003 – 0.007 | 0.002 – 0.003 |
| Dielectric strength (dielectric breakdown) | 36 – 44 MV/m | 16.5 – 18 MV/m |
| Comparative tracking index | 200 – 325 V | 200 – 325 V |
| Magnetic type | Non-magnetic | Non-magnetic |
| Refractive index | 1.57 – 1.58 | 1.57 – 1.58 |
| Transparency | Optical quality | Opaque |
| Acoustic velocity | 1.43e3 – 1.51e3 m/s | 1.41e3 – 1.5e3 m/s |
| Mechanical loss coefficient (tan delta) | 0.00966 – 0.0145 | 0.00966 – 0.0145 |
| Contains >5wt% critical elements? | No | No |
| Water absorption @ 24 hrs | 0.14 – 0.18 % | 0.1 – 0.2 % |
| Water vapor transmission | 0.464 – 0.707 g.mm/m².day | 0.464 – 0.707 g.mm/m².day |
| Permeability (O2) | 1.2 – 2.77 cm³.mm/m².day.atm | 1.2 – 2.77 cm³.mm/m².day.atm |
| Polymer injection molding | Acceptable | Acceptable |
| Polymer extrusion | Limited use | Limited use |
| Polymer thermoforming | Acceptable | Limited use |
| Linear mold shrinkage | 0.3 – 0.5 % | 1.5 – 1.7 % |
| Melt temperature | 260 – 280 °C | 260 – 280 °C |
| Mold temperature | 20 – 30 °C | 125 – 145 °C |
| Molding pressure range | 13.8 – 48.1 MPa | 13.8 – 48.1 MPa |
| Water (fresh) | Excellent | Excellent |
| Water (salt) | Excellent | Excellent |
| Weak acids | Acceptable | Acceptable |
| Strong acids | Unacceptable | Unacceptable |
| Weak alkalis | Acceptable | Acceptable |
| Strong alkalis | Limited use | Limited use |
| Organic solvents | Limited use | Limited use |
| Oxidation at 500C | Unacceptable | Unacceptable |
| UV radiation (sunlight) | Fair | Fair |
| Flammability | Highly flammable | Highly flammable |
| Embodied energy, primary production | 78.4 – 86.4 MJ/kg | 78.4 – 86.4 MJ/kg |
| CO2 footprint, primary production | 2.59 – 2.86 kg/kg | 2.59 – 2.86 kg/kg |
| Water usage | 126 – 140 l/kg | 126 – 140 l/kg |
| Polymer extrusion energy | 5.82 – 6.43 MJ/kg | 5.8 – 6.42 MJ/kg |
| Polymer extrusion CO2 | 0.437 – 0.483 kg/kg | 0.435 – 0.481 kg/kg |
| Polymer extrusion water | 4.83 – 7.24 l/kg | 4.82 – 7.23 l/kg |
| Polymer molding energy | 18.7 – 20.6 MJ/kg | 18.2 – 20.1 MJ/kg |
| Polymer molding CO2 | 1.4 – 1.55 kg/kg | 1.36 – 1.51 kg/kg |
| Polymer molding water | 12.6 – 18.9 l/kg | 12.4 – 18.6 l/kg |
| Coarse machining energy | 0.864 – 0.954 MJ/kg | 1.08 – 1.19 MJ/kg |
| Coarse machining CO2 | 0.0648 – 0.0716 kg/kg | 0.0811 – 0.0896 kg/kg |
| Fine machining energy | 4.36 – 4.82 MJ/kg | 6.54 – 7.22 MJ/kg |
| Fine machining CO2 | 0.327 – 0.361 kg/kg | 0.49 – 0.542 kg/kg |
| Grinding energy | 8.25 – 9.11 MJ/kg | 12.6 – 13.9 MJ/kg |
| Grinding CO2 | 0.618 – 0.684 kg/kg | 0.945 – 1.04 kg/kg |
| Embodied energy, recycling | 26.8 – 29.6 MJ/kg | 26.8 – 29.6 MJ/kg |
| CO2 footprint, recycling | 1.45 – 1.6 kg/kg | 1.45 – 1.6 kg/kg |
| Recycle fraction in current supply | 20 – 22.1 % | 20 – 22.1 % |
| Heat of combustion (net) | 23 – 24.2 MJ/kg | 23 – 24.2 MJ/kg |
| Combustion CO2 | 2.24 – 2.35 kg/kg | 2.24 – 2.35 kg/kg |