EN
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PS
Material Type
General Plastics
Material Full Name
Polystyrene
Process Compatibility
Injection Molding, CNC Machining
Basic Properties
Property |
Parameter/Performance |
Remarks |
|---|---|---|
| Chemical Name | Polystyrene | Polymerized from styrene monomer |
| Molecular Structure | Amorphous (non-crystalline) polymer | Divided into GPPS (general-purpose) and HIPS (high-impact) grades |
| Density | 1.04~1.06 g/cm³ | Slightly heavier than PP, lighter than ABS |
| Transparency | GPPS: Transparent (90% light transmittance); HIPS: Opaque | Clarity second only to PMMA |
| Mechanical Properties | ||
| – Tensile Strength | 30-60 MPa | Brittle (GPPS elongation at break only 1-3%) |
| – Impact Strength | GPPS: 2-4 kJ/m²; HIPS: 5-15 kJ/m² | HIPS incorporates rubber particles for toughness |
| Thermal Properties | ||
| – HDT (1.82MPa) | 70-85℃ | Heat-resistant grades (e.g., PSU) reach 100℃ |
| – Service Temperature | -30℃~70℃ | Softens/deforms above 80℃ |
| Flammability | UL94 HB (flammable) | Requires brominated flame retardants for V0 rating |
| Electrical Properties | ||
| – Dielectric Constant | 2.4-2.7 (1MHz) | Excellent high-frequency insulation |
Processing Characteristics
Thermal Stability:
- Melt range: 180-280℃ (GPPS optimal at 190-240℃)
- Decomposes above 300℃, releasing styrene monomer (require ventilation)
Flowability:
- MFI 5-25g/10min (230℃/3.8kg), ideal for thin-walled products
Processing Methods:
- Injection molding (70% of use): CD cases, coat hangers
- Extrusion: Sheets (thermoformed food containers)
- Foam molding: EPS packaging
Common Application Areas
-
Packaging: Instant noodle cups (HIPS), meat trays (EPS)
-
Electronics: LED light guides (GPPS)
-
Construction: Insulation boards (XPS)
PS Modified Types
Type |
Characteristics |
Typical Applications |
|---|---|---|
| GPPS (General Purpose) | High clarity, rigid, extremely brittle | Food containers, disposable cutlery |
| HIPS (High Impact) | 5-15% rubber particles, 5x tougher | Appliance housings, toys |
| EPS (Expanded) | Closed-cell foam, density 0.01-0.05g/cm³ | Thermal insulation, protective packaging |
| SPS (Syndiotactic) | High crystallinity, heat-resistant to 120℃ | Electronic connectors, heat-resistant containers |
Advantages & Disadvantages
Advantages |
Disadvantages |
|---|---|
| Best clarity (low-cost optical material) | Extreme brittleness (GPPS shatters easily) |
| Superior flowability | Poor solvent resistance (dissolves in aromatics/esters) |
| Excellent high-frequency insulation | Environmental concerns (microplastic pollution) |
Other General Plastics Selection
PP Materials
PE Materials
PMMA Materials
PVC Materials
ABS Materials
FAQ Of PS Materials
Visit our FAQ center for more questions.
What are the main differences between GPPS and HIPS?
GPPS (General Purpose Polystyrene):
- High transparency (>90% light transmittance)
- Extremely brittle (notched impact strength only 2-4 kJ/m²)
- Typical applications: CD cases, disposable transparent cups
HIPS (High Impact Polystyrene):
- Opaque (contains 5-15% rubber particles)
- 3-5 times better impact resistance (5-15 kJ/m²)
- Typical applications: refrigerator liners, toy shells
Key selection criteria:
- Need transparency → Choose GPPS
- Need toughness → Choose HIPS
Why do PS products crack easily? How to improve?
Cracking Causes:
- Internal stress concentration (uneven cooling or premature demolding)
- Material brittleness (especially GPPS)
- Contact with solvents (e.g., alcohol, esters)
Solutions:
Process optimization:
- Increase mold temperature (60-80℃ to reduce internal stress)
- Extend holding time (compensate for shrinkage)
Material modification:
- Switch to HIPS or add toughening agents (e.g., SBS elastomer)
- Avoid contact with organic solvents