Composition & Basic Properties
Material: Pre-expandable polystyrene (98% polystyrene + 2% pentane blowing agent)
Appearance: Small, hard spheres (0.2-3mm diameter)
Color: Typically white (grey for graphite-enhanced versions)
Key Characteristics:
Expand 20-50 times original size when heated
Non-toxic and odorless
Excellent thermal insulation properties
Low water absorption
Manufacturing Process
Polymerization: Styrene monomer is polymerized into polystyrene
Impregnation: Pentane gas is infused into the beads under pressure
Sizing: Beads are sorted into uniform particle sizes
Coating: Optional flame retardant or other additives applied
Types of EPS Beads
| Type | Expansion Ratio | Density Range | Special Features |
|---|---|---|---|
| Standard | 20-30x | 15-30 kg/m³ | General purpose |
| High Expansion | 40-50x | 10-15 kg/m³ | Ultra-lightweight |
| Flame Retardant | 20-30x | 15-30 kg/m³ | Contains fire inhibitors |
| Graphite Modified | 20-30x | 15-30 kg/m³ | Improved insulation |
Expansion Process
When heated to 90-110°C with steam:
Pentane inside beads vaporizes
Polystyrene softens
Beads expand dramatically
Expanded beads stabilize for 6-24 hours before molding
Applications
Packaging: Custom protective inserts
Construction: Insulation boards, ICF blocks
Consumer Goods: Coolers, flotation devices
Specialty: Lost foam casting, geofoam
Storage & Handling
Store in cool, dry place away from heat sources
Shelf life: 6-12 months in original packaging
Keep away from open flames (pentane is flammable)
Technical Specifications
Bulk density: 600-650 kg/m³ (unexpanded)
Bead size distribution: 0.2-3.0 mm
Residual pentane content: 4-7%
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