Polystyrene (PS) Grades – Master Comparison Table
General purpose (crystal) vs. heat resistant vs. high impact (HIPS) vs. flame retarded HIPS vs. 20% and 30% glass fiber reinforced
| Property | Unit | PS General Purpose (Crystal) | PS Heat Resistant | PS High Impact (HIPS) | PS-HI-FR High Impact, Flame Retarded (HIPS-FR) | PS + 20% Glass Fiber | PS + 30% Glass Fiber |
| General information | |||||||
| Designation | Polystyrene (medium/high flow, homopolymer) | Polystyrene (heat resistant, homopolymer) | High Impact Polystyrene (HIPS) | HIPS, flame retarded | Polystyrene (20% glass fiber, homopolymer) | Polystyrene (30% glass fiber, homopolymer) | |
| Polymer code | PS | PS | PS-HI | PS-HI-FR | PS-GF20 | PS-GF30 | |
| Material family | Thermoplastic, amorphous | Thermoplastic, amorphous | Thermoplastic, amorphous | Thermoplastic, amorphous | Thermoplastic, amorphous | Thermoplastic, amorphous | |
| Additive / reinforcement | — | — | Impact modifier (5–15% butadiene rubber) | Flame retardant + impact modifier | Short glass fiber (<5 mm) | Short glass fiber (<5 mm) | |
| Polymer content | % | 100 | 100 | 100 | 90 – 95 | 80 | 70 |
| Glass fiber content | % | 0 | 0 | 0 | 0 | 20 | 30 |
| Flame retardant content | % | 0 | 0 | 0 | 5 – 10 | 0 | 0 |
| Physical properties | |||||||
| Density | kg/m³ | 1,040 – 1,050 | 1,040 – 1,050 | 1,030 – 1,060 | 1,150 – 1,170 | 1,190 – 1,210 | 1,280 – 1,300 |
| Mechanical properties | |||||||
| Young’s modulus | GPa | 2.28 – 3.28 | 3.1 – 3.34 | 1.16 – 2.55 | 1.65 – 2.07 | 6.21 – 8.27 | 8.27 – 8.96 |
| Specific stiffness | MN·m/kg | 2.18 – 3.14 | 2.97 – 3.2 | 1.11 – 2.44 | 1.42 – 1.79 | 5.17 – 6.89 | 6.41 – 6.95 |
| Yield strength (elastic limit) | MPa | 28.7 – 41.4 | 44.4 – 56.2 | 19 – 41.4 | 21.4 – 28.3 | 55.2 – 66.2 | 75 – 80 |
| Tensile strength | MPa | 35.9 – 51.7 | 44.4 – 56.5 | 20 – 42.7 | 18.3 – 28.3 | 69 – 82.7 | 75.8 – 89.6 |
| Specific strength | kN·m/kg | 27.5 – 39.6 | 42.5 – 53.8 | 18.2 – 39.6 | 18.4 – 24.4 | 46 – 55.2 | 58.1 – 62.1 |
| Elongation | % strain | 1.2 – 2.5 | 2 – 3.6 | 40 – 65 | 30 – 50 | 1 – 1.3 | 1 – 1.2 |
| Compressive modulus | GPa | 3.3 – 3.37 | 3.4 – 3.44 | 1.1 – 2.55 | 1.65 – 2.07 | 6.21 – 8.27 | 8.27 – 8.96 |
| Compressive strength | MPa | 82.7 – 89.6 | 89.6 – 96.5 | 22.8 – 49.7 | 25.7 – 36.4 | 110 – 117 | 114 – 121 |
| Flexural modulus | GPa | 2.61 – 3.37 | 3.09 – 3.44 | 1.1 – 2.68 | 1.93 – 2.27 | 6.53 – 7.56 | 8.05 – 8.46 |
| Flexural strength (modulus of rupture) | MPa | 69 – 101 | 89.6 – 96.5 | 31.4 – 69 | 31 – 51.7 | 96.5 – 124 | 96.5 – 138 |
| Shear modulus | GPa | 0.817 – 1.18 | 1.11 – 1.2 | 0.391 – 0.907 | 0.587 – 0.736 | 2.27 – 3.03 | 2.97 – 3.22 |
| Bulk modulus | GPa | 4.23 – 4.44 | 4.79 – 5.03 | 2.9 – 3.04 | 3.18 – 3.34 | 8.67 – 9.1 | 12.7 – 13.4 |
| Poisson’s ratio | 0.387 – 0.403 | 0.383 – 0.398 | 0.397 – 0.418 | 0.397 – 0.413 | 0.358 – 0.373 | 0.38 – 0.4 | |
| Shape factor | 7 | 6.2 | 6 | 6.8 | 9.2 | 8.8 | |
| Hardness – Vickers | HV | 9 – 12 | 13 – 17 | 6 – 12 | 6 – 9 | 17 – 20 | 23 – 24 |
| Hardness – Rockwell M | 60 – 75 | 75 – 84 | 38 – 42 | 31 – 35 | 80 – 95 | 85 – 95 | |
| Hardness – Rockwell R | 99 – 109 | 109 – 120 | 50 – 82 | 38 – 65 | 113 – 125 | 115 – 127 | |
| Elastic stored energy (springs) | kJ/m³ | 150 – 314 | 309 – 486 | 111 – 473 | 124 – 217 | 205 – 317 | 324 – 375 |
| Fatigue strength at 10⁷ cycles | MPa | 14.4 – 20.7 | 17.7 – 23 | 8 – 17.1 | 7.32 – 11.3 | 26.6 – 34.6 | 32.4 – 35.7 |
| Impact & fracture properties | |||||||
| Fracture toughness | MPa·m^0.5 | 0.7 – 1.1 | 0.7 – 1.1 | 0.999 – 2.96 | 0.761 – 2.28 | 2.61 – 3.85 | 3.45 – 4.5 |
| Toughness (G) | kJ/m² | 0.182 – 0.435 | 0.159 – 0.361 | 0.683 – 4.34 | 0.38 – 2.32 | 0.964 – 2.05 | 1.41 – 2.33 |
| Impact strength, notched, 23 °C | kJ/m² | 2.86 – 3.15 | 2.79 – 3.61 | 7.34 – 11.6 | 4.78 – 10.7 | 4.8 – 13 | 4.8 – 16 |
| Impact strength, notched, −30 °C | kJ/m² | 1.9 – 2.1 | 1.9 – 2.1 | 4.03 – 6.75 | 2.21 – 4.09 | 3.64 – 4.4 | 3.64 – 4.4 |
| Impact strength, unnotched, 23 °C | kJ/m² | 8.6 – 14.9 | 8.66 – 16.4 | 92.2 – 111 | 44.1 – 110 | 10.9 – 13.2 | 13.3 – 14.7 |
| Impact strength, unnotched, −30 °C | kJ/m² | 3.87 – 4.27 | 3.87 – 4.27 | 45.8 – 55 | 32.8 – 88.9 | 5.45 – 6.6 | 6.36 – 7.7 |
| Thermal properties | |||||||
| Glass transition temperature | °C | 90 – 100 | 95 – 100 | 85 – 99 | 85 – 100 | 96 – 104 | 96 – 104 |
| Heat deflection temperature (0.45 MPa) | °C | 86 – 96 | 91 – 99 | 80 – 94 | 80 – 95 | 104 – 110 | 107 – 110 |
| Heat deflection temperature (1.8 MPa) | °C | 76 – 94 | 85 – 95 | 74 – 90 | 73 – 83 | 93 – 104 | 102 – 104 |
| Vicat softening point | °C | 90 – 100 | 94 – 99 | 84 – 98 | 83 – 98 | — | — |
| Maximum service temperature | °C | 75 – 90 | 85 – 95 | 70 – 90 | 65 – 80 | 42 – 57 | 43 – 56 |
| Minimum service temperature | °C | −75 – −65 | −75 – −65 | −53 – −33 | −53 – −33 | −75 – −65 | −75 – −65 |
| Thermal conductivity | W/m·°C | 0.12 – 0.14 | 0.12 – 0.14 | 0.13 – 0.19 | 0.15 – 0.19 | 0.238 – 0.257 | 0.4 – 0.5 |
| Specific heat capacity | J/kg·°C | 1,200 – 1,300 | 1,200 – 1,300 | 1,350 – 1,450 | 1,570 – 1,630 | 1,530 – 1,600 | 1,460 – 1,520 |
| Thermal expansion coefficient | µstrain/°C | 90 – 149 | 122 – 153 | 77.9 – 81.2 | 79.4 – 82.6 | 71.3 – 72 | 35.3 – 36.7 |
| Thermal shock resistance | °C | 77.4 – 153 | 96.5 – 133 | 122 – 344 | 138 – 196 | 99.7 – 139 | 237 – 264 |
| Thermal distortion resistance | MW/m | 0.00086 – 0.00145 | 0.00083 – 0.00108 | 0.00163 – 0.00239 | 0.00185 – 0.00235 | 0.00332 – 0.00359 | 0.0111 – 0.0139 |
| Electrical properties | |||||||
| Electrical resistivity | µohm·cm | 1e25 – 1e27 | 1e25 – 1e27 | 5.98e21 – 5.38e22 | 5.98e21 – 5.38e22 | 5.98e21 – 5.38e22 | 5.98e21 – 5.38e22 |
| Electrical conductivity | %IACS | 1.72e-25 – 1.72e-23 | 1.72e-25 – 1.72e-23 | 3.2e-21 – 2.88e-20 | 3.2e-21 – 2.88e-20 | 3.2e-21 – 2.88e-20 | 3.2e-21 – 2.88e-20 |
| Dielectric constant (relative permittivity) | 2.4 – 2.6 | 2.4 – 2.6 | 3 – 3.2 | 3 – 3.2 | 3 – 3.2 | 3 – 3.2 | |
| Dissipation factor (dielectric loss tangent) | 0.0001 – 0.0003 | 0.0001 – 0.0003 | 0.001 – 0.006 | 0.001 – 0.006 | 0.004 – 0.006 | 0.004 – 0.006 | |
| Dielectric strength (breakdown) | MV/m | 19.7 – 22.6 | 19.7 – 20.7 | 16.9 – 20.3 | 20.8 – 22.5 | 16.1 – 17.4 | 17 – 18.4 |
| Comparative tracking index | V | 275 – 575 | 275 – 575 | 275 – 575 | 275 – 575 | 275 – 575 | 275 – 575 |
| Magnetic type | Non-magnetic | Non-magnetic | Non-magnetic | Non-magnetic | Non-magnetic | Non-magnetic | |
| Optical, aesthetic & acoustic properties | |||||||
| Transparency | Optical quality | Transparent | Opaque | Opaque | Opaque | Opaque | |
| Refractive index | 1.55 – 1.61 | 1.55 – 1.61 | — | — | — | — | |
| Acoustic velocity | m/s | 1,470 – 1,780 | 1,720 – 1,790 | 1,030 – 1,590 | 1,190 – 1,340 | 2,270 – 2,630 | 2,530 – 2,640 |
| Mechanical loss coefficient (tan delta) | 0.0122 – 0.0175 | 0.012 – 0.0129 | 0.0157 – 0.0364 | 0.0193 – 0.0242 | 0.00912 – 0.0111 | 0.00862 – 0.00912 | |
| Contains >5 wt% critical elements? | No | No | No | No | No | No | |
| Absorption & permeability | |||||||
| Water absorption @ 24 hrs | % | 0.01 – 0.03 | 0.0091 – 0.011 | 0.05 – 0.07 | 0.005 – 0.01 | 0.07 – 0.1 | 0.0818 – 0.099 |
| Water vapor transmission | g·mm/m²·day | 3.42 – 3.99 | 3.42 – 3.99 | 0.713 – 1.44 | 0.713 – 1.44 | — | — |
| Oxygen permeability | cm³·mm/m²·day·atm | 120 – 145 | 120 – 145 | 156 – 163 | 156 – 163 | — | — |
| Processing properties | |||||||
| Injection molding | Excellent | Excellent | Excellent | Excellent | Excellent | Excellent | |
| Extrusion | Excellent | Excellent | Excellent | Excellent | Unsuitable | Unsuitable | |
| Thermoforming | Excellent | Acceptable | Excellent | Excellent | Unsuitable | Unsuitable | |
| Linear mold shrinkage | % | 0.4 – 0.7 | 0.4 – 0.7 | 0.4 – 0.7 | 0.3 – 0.6 | 0.1 – 0.3 | 0.1 – 0.2 |
| Melt temperature | °C | 177 – 260 | 177 – 260 | 177 – 274 | 191 – 232 | 164 – 288 | 159 – 238 |
| Mold temperature | °C | 35 – 55 | 35 – 55 | 35 – 55 | 35 – 55 | 35 – 55 | 35 – 55 |
| Molding pressure range | MPa | 34.4 – 138 | 34.4 – 138 | 68.8 – 138 | 41.3 – 103 | 68.8 – 138 | 68.8 – 138 |
| Durability | |||||||
| Water (fresh) | Excellent | Excellent | Excellent | Excellent | Excellent | Excellent | |
| Water (salt) | Excellent | Excellent | Excellent | Excellent | Excellent | Excellent | |
| Weak acids | Excellent | Excellent | Acceptable | Acceptable | Excellent | Excellent | |
| Strong acids | Limited use | Limited use | Limited use | Limited use | Limited use | Limited use | |
| Weak alkalis | Excellent | Excellent | Excellent | Excellent | Excellent | Excellent | |
| Strong alkalis | Acceptable | Acceptable | Limited use | Limited use | Acceptable | Acceptable | |
| Organic solvents | Unacceptable | Unacceptable | Unacceptable | Unacceptable | Unacceptable | Unacceptable | |
| Oxidation at 500 °C | Unacceptable | Unacceptable | Unacceptable | Unacceptable | Unacceptable | Unacceptable | |
| UV radiation (sunlight) | Fair | Fair | Fair | Fair | Fair | Fair | |
| Flammability | Highly flammable | Highly flammable | Highly flammable | Self-extinguishing | Highly flammable | Highly flammable | |
| Recycling | |||||||
| Recyclable | Yes | Yes | Yes | Yes | No | No | |

