Overview
LDPE (Low-Density Polyethylene) is a flexible thermoplastic polymer known for its excellent flexibility, impact resistance, chemical resistance, moisture resistance, electrical insulation properties, and ease of processing.
Compared with HDPE, LDPE has a lower density and more highly branched molecular structure, resulting in greater flexibility, softness, and transparency. These characteristics make LDPE one of the most widely used materials in packaging, film production, and consumer products.
LDPE is widely used in:
- Plastic Films
- Packaging Materials
- Flexible Tubing
- Squeeze Bottles
- Electrical Insulation
- Medical Packaging
- Food Containers
- Industrial Liners
Due to its excellent flexibility, low cost, and processing versatility, LDPE remains one of the most important commodity plastics worldwide.
Material Specification
| Property | Value |
|---|---|
| Material Designation | LDPE |
| Full Name | Low-Density Polyethylene |
| Material Family | Polyethylene Thermoplastic |
| Density | 0.91–0.93 g/cm³ |
| Appearance | Natural, Transparent, White, Colored |
| Transparency | Semi-Transparent |
| Typical Manufacturing Methods | Film Extrusion, Blow Molding, Injection Molding, Extrusion |
| Standard Forms | Film, Sheet, Tube, Pellets |
Chemical Composition
LDPE consists of highly branched polyethylene chains produced through high-pressure polymerization of ethylene.
| Component | Function |
|---|---|
| Low-Density Polyethylene Polymer | Structural Matrix |
| Antioxidants | Thermal Stability |
| UV Additives (Optional) | Outdoor Durability |
| Colorants | Appearance Enhancement |
The branched molecular structure contributes to LDPE’s flexibility and softness.
Mechanical Properties
Typical Values
| Property | Value |
|---|---|
| Tensile Strength | 8–18 MPa |
| Yield Strength | 8–15 MPa |
| Elongation at Break | 100–650% |
| Flexural Strength | 5–15 MPa |
| Flexural Modulus | 0.15–0.40 GPa |
| Hardness | Shore D 40–55 |
| Impact Strength | Excellent |
Typical Mechanical Performance
| Property | Performance |
|---|---|
| Flexibility | Outstanding |
| Toughness | Excellent |
| Impact Resistance | Excellent |
| Stiffness | Moderate |
LDPE is significantly softer and more flexible than HDPE.
Physical Properties
| Property | Value |
|---|---|
| Density | 0.91–0.93 g/cm³ |
| Water Absorption | <0.01% |
| Thermal Conductivity | 0.30–0.35 W/m·K |
| Electrical Resistivity | >10¹⁶ Ω·cm |
| Specific Heat Capacity | 2300 J/kg·K |
LDPE is among the lightest commercially available thermoplastics.
Thermal Properties
| Property | Value |
|---|---|
| Melting Point | 105–115°C |
| Heat Deflection Temperature | 35–55°C |
| Continuous Service Temperature | -50°C to 80°C |
| Short-Term Service Temperature | Up to 90°C |
LDPE performs exceptionally well in low-temperature applications.
Strength-to-Weight Ratio
| Material | Density (g/cm³) | Tensile Strength |
|---|---|---|
| LDPE | 0.92 | 12 MPa |
| HDPE | 0.95 | 30 MPa |
| PP | 0.90 | 35 MPa |
| PET | 1.38 | 60 MPa |
LDPE prioritizes flexibility and toughness over structural strength.
Chemical Resistance
| Chemical Environment | Performance |
|---|---|
| Water | Excellent |
| Acids | Excellent |
| Alkalis | Excellent |
| Salt Solutions | Excellent |
| Alcohols | Excellent |
| Oils & Greases | Good |
| Hydrocarbons | Good |
| Strong Oxidizers | Fair |
LDPE provides excellent resistance to most common chemicals and moisture.
Moisture Resistance
| Property | Performance |
|---|---|
| Water Absorption | Outstanding |
| Humidity Resistance | Outstanding |
| Corrosion Resistance | Outstanding |
| Weather Resistance | Good |
LDPE is highly resistant to moisture and water penetration.
Electrical Properties
| Property | Value |
|---|---|
| Volume Resistivity | >10¹⁶ Ω·cm |
| Surface Resistivity | >10¹⁵ Ω |
| Dielectric Strength | 20–50 kV/mm |
| Dielectric Constant | 2.2–2.3 |
LDPE is widely used as an electrical insulation material for cables and wires.
Impact Resistance
| Property | Rating |
|---|---|
| Room Temperature Impact | Excellent |
| Low Temperature Impact | Outstanding |
| Drop Resistance | Excellent |
| Flex Crack Resistance | Excellent |
LDPE maintains flexibility and impact resistance even at low temperatures.
Wear Resistance
| Property | Performance |
|---|---|
| Abrasion Resistance | Moderate |
| Sliding Wear Resistance | Moderate |
| Surface Durability | Moderate |
| Friction Coefficient | Low |
LDPE is not typically used for high-wear engineering applications.
Machinability
| Process | Rating |
|---|---|
| CNC Milling | Good |
| CNC Turning | Good |
| Drilling | Good |
| Routing | Excellent |
| Welding | Excellent |
Machinability Comparison
| Material | Machinability |
|---|---|
| LDPE | Good |
| HDPE | Excellent |
| PP | Excellent |
| POM | Outstanding |
LDPE is easy to fabricate, weld, and thermoform.
Processing Characteristics
| Property | Rating |
|---|---|
| Film Extrusion | Outstanding |
| Blow Molding | Outstanding |
| Injection Molding | Excellent |
| Extrusion | Outstanding |
| Heat Sealing | Outstanding |
LDPE is one of the most commonly processed plastics for flexible packaging.
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ISO | LDPE |
| ASTM | Low-Density Polyethylene |
| DIN | PE-LD |
| JIS | LDPE |
| GB/T (China) | 低密度聚乙烯（LDPE） |
| UL | LDPE Thermoplastic |
Available Forms
| Product Type | Availability |
|---|---|
| Film | Yes |
| Sheet | Yes |
| Tube | Yes |
| Pellets | Yes |
| Blow Molded Parts | Yes |
| Injection Molded Parts | Yes |
Typical Applications
Packaging Industry
- Plastic Bags
- Shrink Wrap
- Stretch Film
- Food Packaging
Consumer Products
- Squeeze Bottles
- Household Containers
- Toys
- Flexible Storage Products
Electrical Industry
- Wire Insulation
- Cable Jackets
- Electrical Protection Components
Medical Industry
- Sterile Packaging
- Medical Bags
- Disposable Components
Agricultural Industry
- Greenhouse Films
- Irrigation Components
- Protective Covers
Industrial Applications
- Liners
- Protective Films
- Flexible Tubing
- Chemical Packaging
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| Film Extrusion | Outstanding |
| Blow Molding | Outstanding |
| Injection Molding | Excellent |
| Extrusion | Outstanding |
| Heat Sealing | Outstanding |
Advantages
Exceptional Flexibility
One of the most flexible polyethylene grades available.
Outstanding Moisture Resistance
Virtually no water absorption.
Excellent Chemical Resistance
Suitable for a wide variety of packaging and industrial applications.
High Impact Strength
Maintains toughness even at low temperatures.
Excellent Electrical Insulation
Widely used for wire and cable applications.
Cost Effective
Among the most economical thermoplastics available.
Limitations
Lower Strength
Not suitable for structural engineering applications.
Limited Heat Resistance
Softens at relatively low temperatures.
Lower Stiffness
Less rigid than HDPE and PP.
Surface Softness
More susceptible to scratching and deformation.
Comparison with Common Polyethylene Grades
| Property | LDPE | HDPE | UHMW-PE |
|---|---|---|---|
| Density | Low | Higher | Moderate |
| Strength | Moderate | High | High |
| Flexibility | Outstanding | Good | Good |
| Wear Resistance | Moderate | Good | Outstanding |
| Impact Resistance | Excellent | Excellent | Outstanding |
Comparison with PP
| Property | LDPE | PP |
|---|---|---|
| Flexibility | Better | Good |
| Chemical Resistance | Excellent | Excellent |
| Heat Resistance | Lower | Higher |
| Transparency | Better | Moderate |
| Impact Resistance | Better at Low Temperatures | Good |
Available Surface Finishes
Standard Finishes
- Natural Finish
- Gloss Finish
- Matte Finish
Functional Finishes
- Extruded Finish
- Molded Finish
- Textured Finish
Specialty Grades
- Food Grade LDPE
- UV-Stabilized LDPE
- Antistatic LDPE
- Medical Grade LDPE
Frequently Asked Questions (FAQ)
What is LDPE?
LDPE (Low-Density Polyethylene) is a flexible thermoplastic known for excellent chemical resistance, flexibility, and moisture resistance.
What is LDPE used for?
Typical applications include:
- Plastic Bags
- Packaging Films
- Squeeze Bottles
- Cable Insulation
- Medical Packaging
Is LDPE food safe?
Yes. Food-grade LDPE is widely used in food packaging applications.
Is LDPE chemically resistant?
Yes. LDPE provides excellent resistance to water, acids, alkalis, and many chemicals.
Can LDPE be machined?
Yes. LDPE can be machined and fabricated, although it is softer than many engineering plastics.
Why choose LDPE?
Because it combines:
- Outstanding Flexibility
- Excellent Chemical Resistance
- Superior Moisture Resistance
- High Impact Strength
- Low Cost
What is the difference between LDPE and HDPE?
LDPE is softer and more flexible, while HDPE is stronger and more rigid.
Does GCNOV provide LDPE manufacturing services?
Yes. GCNOV provides:
- LDPE Fabrication
- LDPE Injection Molding
- Film Extrusion
- Blow Molding
- Prototype Development
- Low-Volume Production
- Mass Production
- Custom Plastic Component Manufacturing