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PVC
Material Type
General Plastics
Material Full Name
Polyvinyl chloride
Process Compatibility
Injection Molding, CNC Machining
Basic Properties
Property |
Parameter/Performance |
Remarks |
|---|---|---|
| Chemical Name | Polyvinyl Chloride | Polymerized from vinyl chloride monomer |
| Molecular Structure | Amorphous (non-crystalline) polymer | Adjustable hardness via plasticizers |
| Density | 1.30~1.58 g/cm³ | Rigid PVC: 1.3-1.45; Flexible PVC (with plasticizers): 1.2-1.35 |
| Transparency | Rigid: Transparent/Semi-transparent | Transparent grades require special stabilizers (e.g., organotin) |
| Mechanical Properties | ||
| – Tensile Strength | Rigid: 40-80 MPa; Flexible: 10-25 MPa | Rigid PVC strength comparable to ABS |
| – Elongation at Break | Rigid: 2-40%; Flexible: 100-450% | Higher plasticizer content increases elasticity |
| Thermal Properties | ||
| – HDT (1.82MPa) | Rigid: 55-75℃ | Heat-resistant grades (e.g., CPVC) withstand up to 100℃ |
| – Service Temperature | Flexible: -15~60℃; Rigid: -30~70℃ | Prone to low-temperature brittleness (requires modification) |
| Flammability | UL94 V0 (Rigid) | Inherently flame-retardant (chlorine content) – no additives needed |
| Electrical Properties | ||
| – Volume Resistivity | 10¹²~10¹⁵ Ω·cm | Excellent insulator, but flexible PVC degrades due to plasticizer migration |
Processing Characteristics
Poor Thermal Stability
- Begins decomposing at 160℃; rapid HCl release above 200℃ (requires heat stabilizers: lead/calcium-zinc/organotin).
High Melt Viscosity
- Rigid PVC: Requires high shear (conical twin-screw extruder).
- Flexible PVC: Suitable for injection molding (melt temp: 170-190℃).
Processing Methods
- Extrusion (70% of applications): Pipes, profiles.
- Injection Molding: Fittings, valves.
- Calendering: Flooring, synthetic leather.
Common Application Areas
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Construction: Drainage pipes (60% of global PVC use).
-
Medical: Disposable blood bags (flexible PVC + non-toxic plasticizers).
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Electronics: Cable insulation (flame-retardant alternative to PE).
PVC Modified Types
Type |
Characteristics |
Typical Applications |
|---|---|---|
| Rigid PVC (uPVC) | No plasticizers, high stiffness | Pipes, window profiles, credit cards |
| Flexible PVC | Contains plasticizers (DOP/DEHP) | Wire insulation, inflatable toys, medical tubing |
| CPVC (Chlorinated PVC) | Higher chlorine content, heat-resistant (100℃) | Hot water pipes, chemical tank linings |
| Transparent PVC | High-purity monomer + organotin stabilizers | Pharmaceutical packaging, shrink films |
| Impact-Modified PVC | Added MBS/ACR impact modifiers | Automotive dashboards, construction panels |
Advantages & Disadvantages
Advantages |
Disadvantages |
|---|---|
| Excellent flame retardancy | Poor thermal stability (narrow processing window) |
| Resists acids/alkalis/chemicals | Plasticizer migration causes brittleness |
| One of the lowest-cost engineering plastics | Environmental concerns (chlorine/heavy metal risks) |
Comparison with Other Materials
Material |
Key Advantages over ABS |
Key Disadvantages vs. ABS |
Typical Use Cases |
|---|---|---|---|
| PP | Lower cost, better chemical resistance | Lower strength/surface finish | Food containers, living hinges |
| PC | Higher heat/impact resistance | More expensive, harder to process | Bullet-proof glass, medical devices |
| PA (Nylon) | Superior wear/heat resistance | Absorbs moisture, dimensional instability | Gears, bearings |
| POM | Excellent fatigue resistance | Poor UV resistance, difficult to bond | Precision gears, fasteners |
| PS | Higher clarity, lower cost | Brittle, poor impact strength | Disposable cutlery, CD cases |
Other General Plastics Selection
PP Materials
PE Materials
PMMA Materials
ABS Materials
PS Materials
FAQ Of PVC Materials
Visit our FAQ center for more questions.
Why are stabilizers required for PVC?
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Poor thermal stability: PVC begins decomposing above 160°C, releasing corrosive HCl gas, which degrades the material and damages equipment.
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Role of stabilizers: Lead/calcium-zinc/organotin stabilizers neutralize HCl, extending the processing window (e.g., rigid PVC extrusion requires 170-200°C).
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Environmental trend: EU RoHS mandates phasing out lead-based stabilizers in favor of calcium-zinc or organotin alternatives.
What is the fundamental difference between flexible and rigid PVC?
| Comparison | Flexible PVC | Rigid PVC |
|---|---|---|
| Plasticizer content | 30-50% (e.g., DOP, DOTP) | 0% |
| Mechanical properties | High elasticity (>200% elongation) | High rigidity (>50MPa tensile strength) |
| Typical applications | Wire insulation, medical tubing | Drainage pipes, window profiles |
| Environmental impact | Plasticizer migration concerns | Easier to recycle |
How to prevent yellowing in PVC products?
Root causes:
- Excessive processing temperature (>200°C) causing thermal oxidation.
- Use of low-cost lead stabilizers (prone to sulfur contamination).
Solutions:
- Process optimization: Control melt temperature (≤190°C for rigid PVC, ≤170°C for flexible PVC).
- Formula upgrades:
- Switch to organotin or calcium-zinc stabilizers.
- Add antioxidants (e.g., BHT) and UV absorbers (for outdoor applications).
- Post-processing: Avoid prolonged exposure to heat/UV light.