Expandable Polystyrene (EPS)
The expandable polystyrene bead resin supplied by Chelora Chemicals — a blowing-agent-impregnated styrenic resin that foams into low-density insulation and packaging — exported from Indonesia as unexpanded bead with full batch documentation on every shipment.
What EPS is, and why buyers source it
A working overview of how a blowing agent inside an ordinary polystyrene bead becomes a low-density foam, and the grades Chelora Chemicals keeps in regular supply.
Expandable Polystyrene is, at its core, the same amorphous styrenic polymer as general-purpose polystyrene, with one addition: a volatile hydrocarbon blowing agent, almost always a pentane isomer blend, impregnated throughout each bead during manufacture. That trapped pentane is the entire basis of the product's foaming behaviour — when the bead is heated with steam, the pentane vaporises and softens the surrounding polystyrene simultaneously, expanding the bead to many times its original volume and fusing it to its neighbours in a mould.
As supplied, before any expansion, it is a free-flowing white to translucent bead, dense and solid rather than foamed, and is shipped and stored in that unexpanded state — the foaming step happens at the converter's own moulding plant, not before shipment, because expanded foam is far too bulky and fragile to ship economically.
Where it fits in the value chain
EPS's defining commercial advantage is converting a modest weight of resin into a very large volume of low-density, closed-cell foam close to the point of use, which keeps freight and handling costs low relative to competing rigid foams. Construction-grade EPS, often with a flame-retardant additive incorporated, is block-moulded and cut into insulation board for walls, roofs and under-slab applications. Packaging-grade EPS is moulded directly into protective packaging shapes, fish and produce boxes, and disposable food containers.
Grades we supply
Chelora Chemicals offers EPS across packaging, construction-insulation and fire-retardant grades, differentiated mainly by bead size, pentane content and additive package. Each grade is supplied with a batch-wise certificate of analysis covering bead size distribution, pentane content and bulk density.
How EPS is produced
An overview of the production route for orientation purposes. Our manufacturing partners' own process parameters and in-process controls are proprietary and are not disclosed beyond what is needed to interpret the certificate of analysis.
EPS is produced by suspension polymerisation: styrene monomer, together with a small amount of pentane blowing agent, is dispersed as fine droplets in water using a suspending agent and agitation, then polymerised under a free-radical initiator while the batch is held under pressure and temperature profiles that keep the pentane dissolved within the forming polystyrene bead rather than escaping into the water phase. Bead size is controlled mainly by droplet size during suspension, itself set by agitation rate and suspending-agent level, and is screened and classified into size-graded fractions after polymerisation and drying.
Fire-retardant grades incorporate a brominated or phosphorus-based flame-retardant additive, typically introduced during or shortly after polymerisation, to meet the ignition-resistance standards required of construction insulation board in most building codes.
Industries and processes that use it
EPS is consumed across building insulation, protective packaging and food-service applications. The fields below account for most of the demand we see through our export desk.
Building Insulation Board
Block-moulded and cut into rigid insulation board for wall, roof and under-slab applications, typically in fire-retardant grade.
Protective Packaging
Moulded directly into custom protective packaging shapes for appliances, electronics and fragile goods, cushioning against impact and vibration.
Fish & Produce Boxes
Moulded into insulated boxes for fish, seafood and fresh-produce transport, valued for light weight and thermal insulation.
Food-Service Containers
Moulded into disposable food containers and cups where light weight and thermal insulation of the contents are wanted.
How the beads are typically converted forward
The trapped pentane blowing agent governs almost all of EPS's conversion behaviour. The categories below account for most of the ways it is converted into a finished foam product.
Pre-Expansion
Raw beads are exposed to steam in a pre-expander, vaporising the pentane and expanding the bead to a target intermediate density, typically 20 to 50 times its original volume.
Maturation
Pre-expanded beads are rested for a conditioning period, allowing air to diffuse back into the cells to equalise internal pressure before final moulding.
Block/Shape Moulding
Matured beads are fed into a mould and exposed to steam again, fully expanding and fusing the beads together into a solid block or final part shape.
Cutting & Fabrication
Moulded blocks are cut with hot wire into insulation board, packaging inserts or other finished dimensions.
EPS against the base styrenic resin we supply
Buyers sourcing EPS beads sometimes also need the unfoamed base styrenic resin for a different, non-foamed part. A quick reference to what else is on our regular supply list.
| Product | CAS Number | Category | Notes |
|---|---|---|---|
| Expandable Polystyrene | 9003-53-6 | Blowing-agent-impregnated styrenic bead | The product on this page — a foamable resin for insulation and packaging. |
| Polystyrene (GPPS/HIPS) | 9003-53-6 | Amorphous styrenic resin | The unfoamed base resin from the same monomer, for rigid or impact-modified parts — see its product page. |
| Benzene | 71-43-2 | Aromatic hydrocarbon | A feedstock, via ethylbenzene, for the styrene monomer this resin is built from — see its product page. |
| Ethylene | 74-85-1 | Olefin monomer | A feedstock, via ethylbenzene, for the styrene monomer this resin is built from — see its product page. |
Exact physical constants and processing specifications are confirmed per batch on the certificate of analysis — treat the notes above as a sourcing guide, not a specification sheet, for products other than EPS.
Safety classification at a glance
Based on GHS classification as commonly listed for this substance. This is a summary for orientation only — always work from the current safety data sheet supplied with your specific batch.
Extremely flammable aerosol-generating material in the sense that trapped pentane can create a flammable atmosphere if released in a confined space.
Fresh beads continue to off-gas a small amount of pentane in storage; ensure adequate ventilation in storage and processing areas.
Both unexpanded beads and expanded foam are combustible; unretarded foam supports rapid flame spread.
Handle and convey with static-control measures given the presence of a flammable blowing agent and fine particulate.
Standard gloves and eye protection are sufficient for routine handling; ensure ventilation during pre-expansion and moulding.
Keep storage and processing areas free of ignition sources given the pentane content.
Danger — flammable blowing agent; refer to the batch MSDS for full classification.
This product contains a flammable pentane blowing agent that continues to off-gas slowly in storage, so storage and processing areas require good ventilation and the exclusion of ignition sources. Both the unexpanded bead and, especially, the expanded foam are combustible, and construction-grade material should always specify the flame-retardant option required by the relevant building code. Full first-aid, storage, spill and PPE guidance is in the MSDS issued with every shipment, and should be read in full before this material is handled.
Keeping it on spec between delivery and use
General storage guidance for this grade. Site-specific storage rules, segregation requirements and re-test intervals should follow your own EHS procedures and the MSDS issued with your batch.
Store in a cool, well-ventilated area below 25 °C, away from heat sources, sparks and direct sunlight, since both temperature and time reduce the retained pentane content and therefore the achievable expansion ratio. Unlike most resins in our range, EPS has a comparatively short practical shelf life and should be scheduled into production promptly after delivery. Re-check pentane content and bead size distribution on material held near the end of its shelf-life window before use.
How it ships from Indonesia
Standard packing and export terms for this product. Confirm exact figures against your order — they vary slightly by destination and quantity.
What travels with every batch
Specification is agreed before the purchase order, not discovered on arrival. Every shipment of Expandable Polystyrene (EPS) leaves with a documented, checkable paper trail.
Certificate of Analysis
Batch-wise assay, colour and key physical constants, issued against the agreed specification so your QC team can check it, not just file it.
Safety Data Sheet
GHS-format SDS in English covering hazard classification, handling, storage, first-aid and spill response for the exact grade shipped.
Technical Data Sheet
Reference physical and chemical properties, recommended storage and typical applications, for internal circulation to your process or R&D teams.
Certificate of Origin
Confirms Indonesian origin for customs clearance and any preferential-duty claim at your destination port.
Dangerous Goods Declaration
UN packing group, classification and shipper's declaration prepared ahead of loading so documentation never holds up customs.
Third-Party Inspection
Independent pre-shipment inspection and re-sampling can be arranged on request, at your cost, for buyers who require it as a matter of policy.
Frequently asked questions
What buyers most often ask our sales desk about this grade.
01What is Expandable Polystyrene used for?+
02What is the blowing agent in EPS?+
03How is EPS produced?+
04What grades does Chelora Chemicals supply?+
05Is EPS hazardous?+
06Why does EPS have a shorter shelf life than other resins?+
07What packing options are available?+
08How long does delivery take?+
09Can I get a sample before placing a bulk order?+
10Do you supply the unfoamed base styrenic resin as well?+
Need EPS on spec, on time?
Send us your required grade, bead size, flame-retardant requirement, quantity and destination port. Our desk quotes most enquiries within one working day.