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