How to Choose Which Polystyrene Grades for Your Needs
24th June 2021

Expanded Polystyrene’s Versatility

Expanded polystyrene (EPS) is one of the most versatile plastic materials in the market. Due to its versatility, there is an extremely wide range of applications of use.  When you know where to look for it, you can find EPS almost anywhere. EPS is used for packaging, insulation, and giant props for TV scenes. This wide range of applications comes with a wide range of polystyrene grades available. Determining which grade of polystyrene best suits your needs can be difficult.

Industry-wide terms used for differing grades include low weight/density, medium, heavy, extra heavy, and ultra-heavyweight/density.  Compressive strength determines what the grade of EPS is. There are, however, big differences between different suppliers of the same grades, most particularly with their densities. When deciding which grade of EPS to use the density of a block is often the most important factor.  However, it is difficult to specify a certain grade of EPS when the density of the blocks varies so widely between suppliers.

EPS Technical Data

Below is a chart to show the comparisons of EPS technical data.

Physical Properties

BS EN13163
Low WeightEPS 70EPS 100EPS 150EPS 200EPS 250EPS 300EPS 350EPS 400
Compressive Strength at 10% (kPa)N/A70100150200250300350400
Bending Strength (kPa)N/A115150200250350450525600
Water Vapour Resistivity (MN.s.g-1 m-1)N/A100 - 200150 - 350150 - 350200 - 500200 - 500200 - 500200 - 500200 - 500
Water Absorption (V/V)N/A< = 10%< = 10%< = 10%< = 10%< = 10%< = 10%< = 10%< = 10%
Thermal Conductivity Industry Range (W/mKLambda)N/A0.0380.0360.035 – 0.0340.034 – 0.0330.034 – 0.0320.0330.0330.033
Molygran Thermal Conductivity (W/mKLambda)N/A0.0380.0360.0350.0340.0330.0330.0330.033
Industry Density Range (kg/m3)8 - 1213 - 1718 - 2223 - 2827 - 3332 - 3936 - 4441 - 4945 - 55
Molygran Nominal Density (kg/m3)101520253035404550
Molygran Approx Block Weight(Kg)40 lbs
18.18Kg
60 lbs
27.27 Kg
80 lbs
36.26 Kg
100 lbs
45.45 Kg
120 lbs
54.55 Kg
139 lbs
63 Kg
158 lbs
72 Kg
178 lbs
81 Kg
198 lbs
90 Kg
(Block Weight based on 2440*1220*610 size)

Applications for Different Polystyrene Grades.

 

The technical properties between manufacturers vary widely. The density of one supplier’s EPS 100 can be the same as EPS 150 from a different supplier. The compressive strength from each supplier may be the same, but the other properties are not consistent. At Molygran we pride ourselves in providing only the highest quality EPS. We work closely with our suppliers to ensure our material density is only that of the top end of industry ranges.

With this in mind, it is often difficult to determine which grade of EPS is best suited to your needs. Below is a table outlining the basic applications for the different grades of EPS provided by Molygran &  Co and the applications these grades are commonly used for.

Material Grade
BS3837
EPS
BS EN 13163
Average Density
(all +/- 2 or +/- 10%)
g/litre / kg/m³ / oz/cu. ft.
Thermal Conductivity
LAMBA Value (W/mK)
Compressive StrengthBlock WeightTypical Uses
The below grades are not FRA rated
100% RecycledUnspecified N/AN/AN/AN/APackaging
Load Bearer
PackagingN/A10
N/AN/A40.00lbs
18.18Kg
Packaging
Low WeightN/A10 N/AN/A40.00lbs
18.18Kg
Packaging - best for fragile items
Standard Density – available in virgin bead or with recycled content (a non specified amount)EPS 7015
0.03870 kPa60.00lbs
27.27Kg
Furniture Packaging
White Goods Packaging
Void Fill (underneath tarmac, inside concrete)
High Density – available in virgin bead or with recycled contentEPS 10020
0.036100 kPa80.00lbs
36.26Kg
High spec packaging
Void fill / former
The below grades are all FRA rated
Low Weight FRAN/A10
N/AN/A40.00lbs
18.18Kg
FRA rated packaging
Furniture infill / cores
Theatre props with a rougher finish
Standard Density FRAEPS 7015
0.03870 kPa60.00lbs
27.27Kg
Display and Design products with a “standard” finish
Cake Boards
Cavity Wall Insulation
Window Thermal Barriers
Carving
Standard Industry Sheets
Heavy Density FRAEPS 10020
0.036100 kPa80.00lbs
36.26Kg
Design and Display products requiring a clean finish – giant letters
Carpet Cassettes
Umbilical Cable Reels
Void Formers/Fill
Carving
Surf Boards
Extra Heavy Density FRAEPS 15025
0.035150 kPa100.00lbs
45.45Kg
Design and Display products requiring a smooth finish
Industrial Heavy Density Packaging
Void Former
Molds
Insulation
Ultra-High Density FRAEPS 20030
0.034200 kPa120.00lbs
54.55Kg
Construction
Void Formers
Design and Display
Intricate Carving
High Spec Load Bearing
The below grades cannot be guaranteed to be FRA rated
Specialist MaterialsEPS 25035
0.033250 kPa140.00lbs
64.00Kg
Ground heave protection for under concrete floor slabs, reinforced concrete ground beams, pile caps
Formwork system
Gas venting medium
Pile collars
Structural fill
Arch formers
Spiral / helical staircase soffit formers
Column formers
Sacrificial guide wall former
Re-useable guide wall formwork
Sheet pile infills
Structural connection between a board pile and a basement slab construction
Pile trimming aid
EWI boards
Flooring under slab
Umbilical cable reel
Railway station platform extensions
Cinema stadium seating
Vehicle and pedestrian ramps
Modular builds
Pontoons
Structural insulated panels (SIPs)
Passive foundations
Landscaping
EPS 30040
0.033300 kPa160.00lbs
73.00Kg
EPS 35045
0.033350 kPa180.00lbs
82.00Kg
EPS 40050
0.033400 kPa200.00lbs
91.00Kg
EPS 50055
0.033500 kPa220.00lb
100Kg
The below grades are all FRA rated
Grey Standard DensityEPS 7015
0.032N/A60.00lbs
27.27Kg
Insulation Board
Design & Display where grey coloured is required throughout (rather than painted face of white EPS)
High Insulative Packaging
Grey High DensityEPS 10020
0.031N/A80.00lbs
36.36Kg
Insulation

 

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