Polystyrene CAS 9003-53-6
Chelora Chemicals supplies general purpose (crystal) and high impact polystyrene to sheet extruders, injection moulders and appliance producers worldwide. Every consignment leaves with a batch-specific COA covering melt flow index, impact strength, residual styrene and mechanical properties, the current SDS and full export documentation.
Also known as: PS · GPPS · HIPS · Crystal polystyrene · High impact polystyrene · Styron
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Price, lead time and a sample COA for Polystyrene, usually within one working day. We ship worldwide.
Request a Quote Email the DeskDocumentation
- Batch-specific COA (MFI, impact, residual styrene)
- Safety Data Sheet (SDS)
- Transport and export documents
- Third-party inspection on request
- Certificate of origin
What is Polystyrene?
Polystyrene is the polymer of styrene, an amorphous thermoplastic that is rigid, dimensionally stable and, in its general purpose form, optically clear.
Two families cover almost all use. GPPS or crystal polystyrene is transparent and brittle; HIPS contains a dispersed polybutadiene rubber phase that trades clarity for impact strength.
Applications are dominated by packaging, disposables, appliance housings and refrigerator liners, with sheet extrusion and injection moulding the main processes.
Polystyrene processes easily, holds dimensions well and takes printing and decoration readily, which is why it persists in applications where tougher polymers would be over-specified.
Why polystyrene specifically
- Optical clarity in GPPS. Amorphous structure gives glass-like transparency that semi-crystalline polymers cannot match.
- Dimensional stability. Very low shrinkage and no crystallinity means parts hold tolerance better than polyolefins.
- Easy processing. Wide processing window, low melt viscosity and excellent mould replication.
- Rubber modification. HIPS converts a brittle polymer into a tough one with a dispersed rubber phase, at modest cost.
How Polystyrene is Manufactured
Polystyrene is made by bulk or suspension free radical polymerisation of styrene, with rubber dissolved in the feed for HIPS.
- Styrene feed. Inhibited styrene monomer is stripped of inhibitor or overcome with initiator.
- Rubber dissolution (HIPS). Polybutadiene rubber is dissolved in the styrene before polymerisation for impact grades.
- Bulk polymerisation. Continuous bulk process in a series of reactors at 120 to 180 °C, thermally or peroxide initiated.
- Phase inversion (HIPS). As polymerisation proceeds, the rubber phase inverts to become dispersed particles that absorb impact energy.
- Devolatilisation. Residual styrene and oligomers are stripped under vacuum, which sets the residual monomer level.
- Pelletising. Mineral oil, antioxidant and other additives are incorporated before pelletising.
Typical Commercial Specification
Figures below are representative of general purpose and high impact grades. Each grade has its own data sheet — tell us the application and we will send the matching one.
| Parameter | Typical Value |
|---|---|
| Appearance | Clear pellets (GPPS) or opaque white pellets (HIPS) |
| Melt flow index (200 °C / 5 kg) | 2 – 25 g/10 min depending on grade |
| Density | 1.04 – 1.05 g/cm³ |
| Residual styrene monomer | To grade, typically 300 – 800 ppm |
| Tensile strength at break | GPPS 40 – 50 MPa; HIPS 20 – 30 MPa |
| Izod impact (notched) | GPPS 1.5 – 2.5 kJ/m²; HIPS 6 – 14 kJ/m² |
| Vicat softening point | Typically 85 – 105 °C |
| Light transmission (GPPS) | 88 – 90% |
| Volatiles | To grade, typically 0.1% max |
Physical & Chemical Properties
| Property | Value |
|---|---|
| Chemical formula | (C₈H₈)ₙ |
| Appearance | Clear or opaque white pellets |
| Density | 1.04 – 1.05 g/cm³ |
| Glass transition temperature | About 100 °C |
| Structure | Amorphous — no crystalline melting point |
| Water absorption | Very low, under 0.1% |
| Chemical resistance | Good to acids and alkalis; attacked by hydrocarbons, ketones and esters |
| Mould shrinkage | Very low, typically 0.4 to 0.7% |
| Processing temperature | Typically 180 to 240 °C |
| UV resistance | Poor without stabilisation; yellows on exposure |
| Incompatibilities | Aromatic and chlorinated solvents, ketones, esters, oils |
Behaviour in the process
Polystyrene is easy to process, and its limitations are as characteristic as its strengths:
- Brittle in GPPS form. Crystal polystyrene cracks under impact; HIPS exists specifically to solve this.
- Poor chemical resistance. Dissolved or crazed by hydrocarbons, oils, ketones and esters — a real constraint in packaging design.
- Low shrinkage. Amorphous structure gives excellent dimensional reproduction and tight tolerances.
- UV sensitive. Yellows and embrittles outdoors without stabilisation.
Polystyrene Types and Alternatives
Polystyrene is bought by type first, since clarity and impact strength are mutually exclusive in this family.
| Material | Origin / type | When it is the right choice |
|---|---|---|
| GPPS (crystal) | Transparent, brittle | Clear packaging, disposables, CD cases and display items |
| HIPS | Rubber modified, opaque | Appliance housings, refrigerator liners, thermoformed packaging |
| EPS | CAS 9003-53-6, expandable beads | Insulation board and protective packaging |
| ABS | CAS 9003-56-9 | Higher impact and chemical resistance at higher cost |
| Polypropylene | CAS 9003-07-0 | Better chemical resistance and heat tolerance; different clarity and stiffness |
Stated plainly: if the part must be clear, GPPS; if it must survive impact, HIPS or ABS. Trying to split the difference with a GPPS-HIPS blend usually gives translucency and mediocre impact rather than the best of both.
Industries We Supply Polystyrene To
Polystyrene serves packaging, appliances, construction and consumer goods.
Where Polystyrene is Used
Sheet extrusion for packaging and injection moulding for consumer and appliance parts take most polystyrene volume.
In sheet extrusion and thermoforming
HIPS and GPPS sheet are extruded then thermoformed into packaging and appliance parts. The rubber particle size and distribution in HIPS determine the balance between impact strength and gloss, and sheet producers specify these as closely as melt flow index. Regrind handling matters too, since repeated heat history degrades the rubber phase.
Residual monomer and food contact
Devolatilisation under vacuum after polymerisation sets the residual styrene level. Food contact grades carry tighter limits because styrene migrates preferentially into fatty foods, and the specific migration limits are set by regulation in the EU, US and elsewhere.
Need a specific grade, purity and packing format?
Tell us the grade, the type, melt flow index and impact level your part requires, the packing format you can receive and the annual quantity. We will come back with a price, a lead time, a sample COA and the full documentation set.
Quality Control & Testing
Every lot is released against a batch-specific Certificate of Analysis with the grade's defining properties, so your incoming inspection can release against the actual material.
- Melt flow index — at 200 °C and 5 kg, the primary processing indicator.
- Impact strength — notched Izod for HIPS grades, the defining property.
- Residual styrene monomer — reported because of food contact migration limits.
- Tensile and Vicat properties — to the grade data sheet.
- Light transmission and haze — for GPPS clarity grades.
- Pellet appearance — confirming freedom from contamination and discolouration.
Common Process Problems & Likely Causes
When polystyrene causes trouble, it is usually type mismatch, chemical attack or regrind. This table is the shortcut our technical desk works through before anyone opens a complaint file.
| Symptom | Likely cause | What to check |
|---|---|---|
| Parts cracking in service | GPPS used where impact strength is needed | Polymer type and impact data against the application |
| Crazing or cracking on contact with product | Chemical attack from oils, solvents or fragrances | Chemical compatibility of PS with the packed product |
| Sheet gloss or impact inconsistent | Regrind content or rubber phase degradation | Regrind ratio and heat history |
| Yellowing in storage or outdoors | UV exposure without stabilisation | Stabiliser package and storage conditions |
| Residual styrene above food contact limit | Devolatilisation level of the grade | Residual styrene figure against the migration requirement |
| Short shots or flow marks | Melt flow index too low for the part geometry | MFI against wall thickness and flow length |
Packaging, Storage & Shipping
- Standard packing. 25 kg bags, 500 to 1250 kg jumbo bags, octabins and bulk containers or silo trucks.
- Storage. Dry, covered warehousing away from direct sunlight; polystyrene yellows under UV.
- Temperature. Ambient storage; avoid prolonged exposure above 40 °C, which can cause pellet blocking.
- Solvent exposure. Keep away from hydrocarbons, solvents and oils, which attack the polymer even in vapour form.
- Grade segregation. Keep GPPS and HIPS separated; mixing gives translucent parts with poor impact.
- Conveying. Control velocity to limit fines; polystyrene pellets are relatively brittle.
- Shelf life. Typically 24 months in sealed bags in covered storage.
- Transport classification. Not classified as dangerous goods for transport.
Hazards & Safe Handling
Polystyrene is an inert polymer with no significant health hazard in normal handling. The practical concerns are molten polymer burns, styrene fume at high processing temperatures, and pellet slip hazards.
- Inert in normal handling. Not classified as hazardous. Pellets present no chemical risk in storage or transport.
- Molten polymer burns. Melt at 180 to 240 °C adheres to skin and causes severe burns; use proper PPE at the machine.
- Styrene fume. Overheating releases styrene monomer and oligomers, which are irritating and have a strong odour; ventilate processing areas.
- Slip hazard. Spilled pellets are a serious slip hazard; clean up promptly.
- Dust and fines. Polystyrene dust is combustible in high concentration; maintain extraction and housekeeping.
- Environment. Pellet and foam loss to the environment is a recognised litter source; containment at every transfer point is expected practice.
Regulatory & Compliance Notes
Polystyrene is unregulated for transport, with food contact migration limits and packaging rules applying downstream. The notes below are orientation rather than legal advice.
- GHS classification. Not classified as hazardous.
- Transport. Not classified as dangerous goods. Standard packaged and bulk cargo documentation applies.
- Food contact. Food grades must comply with EU 10/2011 and FDA regulations, with specific migration limits for residual styrene.
- Single-use restrictions. Several jurisdictions restrict expanded polystyrene food service items and some single-use plastics, which affects application mix.
- Polymer exemption. Polymers are exempt from REACH registration, though the styrene monomer and additives are not.
- Recycling. Polystyrene recycling streams exist but are less developed than for PET and HDPE; recycled content requirements are emerging.
We Supply Polystyrene Worldwide
Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Polystyrene from India and from partner sources to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation, transport paperwork and freight so the material arrives ready to use.
- Incoterms. EXW, FOB, CIF, CFR and DAP quoted to suit your purchasing terms and freight arrangements.
- Ports. Regular shipments through Nhava Sheva (JNPT) and Mundra, with other ports arranged where routing and cargo rules allow.
- Documentation. Commercial invoice, packing list, certificate of origin, COA, SDS and the transport declaration issued as a complete set.
- Flexible volumes. From a pallet of bagged resin up to repeat bulk shipments on a supply contract.
- Supply continuity. Because we are independent of any one producer, a plant turnaround or a shipping disruption at one source does not have to become your stock-out.
Buying Polystyrene from Chelora
We are an independent sourcing and supply partner. For polystyrene that means settling three things at enquiry: GPPS or HIPS, the melt flow index and impact level your part requires, and whether food contact documentation with residual styrene data is needed.
- Documentation on every lot. Batch-specific COA (MFI, impact, residual styrene), plus SDS and the full transport paperwork.
- Analysis before commitment. Representative analysis shared ahead of a commercial order so your lab can qualify the material.
- Quantities. From a pallet of bagged resin through to full bulk shipments on contract supply.
- Grade matching. GPPS or HIPS at the melt flow index, impact level and residual styrene limit your application requires.
- Inspection. Independent third-party inspection available at loading when the contract requires it.
- Related products. Styrene Monomer, Expandable Polystyrene, Acrylonitrile Butadiene Styrene Resin and other feedstocks alongside Polystyrene from one supplier.
How ordering works
- Send the enquiry. Product, grade or purity, quantity, destination port and the Incoterm you buy on. If you have a spec sheet, attach it — it saves a round trip.
- We quote. Price, lead time, packing format and a sample COA, normally within one working day.
- Qualify the supply. For first orders or critical applications, we share the analysis and handling documentation so your technical and safety teams can sign off before you commit.
- Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
- Allocation and QC. Material allocated and released against a batch-specific COA, with an independent inspection where the contract calls for it.
- Ship and document. Filled, labelled and loaded with the full export document set, and tracked through to arrival.
Polystyrene — Common Questions
The questions our technical desk is asked most often about Polystyrene. If yours isn't here, call or email and you will reach someone who knows the chemistry.
What is the CAS number of polystyrene?
The CAS number for polystyrene is 9003-53-6, and it is classified under HS code 3903.19. As a polymer it is exempt from REACH registration, though the styrene monomer and additives are not.
What is polystyrene used for?
For thermoformed food packaging, refrigerator liners and appliance housings, disposable cutlery and cups, injection moulded housewares and toys, medical labware and clear display items.
Do you supply polystyrene worldwide?
Yes. Chelora Chemicals supplies and exports polystyrene worldwide — across Asia Pacific, Europe, the Middle East, Africa and the Americas, as well as throughout India, in bags, jumbo bags, octabins and bulk.
What is the difference between GPPS and HIPS?
GPPS or crystal polystyrene is transparent but brittle. HIPS contains a dispersed polybutadiene rubber phase that gives much higher impact strength but makes the material opaque. You cannot have both clarity and impact in this family.
How is polystyrene manufactured?
By free radical bulk polymerisation of styrene in a continuous reactor train at 120 to 180 °C. For HIPS, polybutadiene rubber is dissolved in the styrene first and phase inverts during polymerisation to form the dispersed rubber particles.
Why does polystyrene crack when it contacts oils or fragrances?
Because it is attacked by hydrocarbons, limonene and many solvents, which craze and dissolve the amorphous polymer. Chemical compatibility testing is essential before committing to a packaging design.
What is residual styrene and why is it specified?
The unreacted monomer remaining after devolatilisation, typically 300 to 800 ppm. Food contact grades carry tighter limits because styrene migrates preferentially into fatty foods, and specific migration limits are set by regulation.
Is polystyrene hazardous?
No. It is an inert polymer not classified as dangerous goods. The practical hazards are burns from molten polymer, styrene fume if the material is overheated, and the slip hazard of spilled pellets.
Is polystyrene food contact approved?
Specific grades are, under EU 10/2011 and FDA regulations, with residual styrene controlled to meet specific migration limits. We supply the declaration of compliance with food contact grades.
How should polystyrene be stored?
In dry, covered warehousing away from direct sunlight and away from solvents and oils, which attack the polymer even in vapour form. Keep GPPS and HIPS separated, since mixing gives translucent parts with poor impact.
Is polystyrene being banned?
Some jurisdictions restrict expanded polystyrene food service items and certain single-use plastics. This affects the application mix rather than the polymer as a whole, and durable applications such as appliance liners are unaffected.
What packing sizes are available?
25 kg bags, 500 to 1250 kg jumbo bags, octabins and bulk containers or silo trucks. Orders run from a pallet of bagged resin up to full bulk shipments.
Ready to source Polystyrene?
Send us your specification, grade and annual volume. You will get a price, a realistic lead time and a sample COA from someone who understands what the material has to do in your process — delivered anywhere in the world.