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How is PE made?
Polyethylene is made from the polymerization of ethylene monomer. The PE chains are produced by addition or radical polymerization. The possible synthesis methods are:- Ziegler-Natta Polymerization and
- Metallocene catalysis
What are the common types of PE?
Depending on its density and branching, different PE grades can have very different performance from one another.PE grades are therefore classified as follows.
- Branched Versions
- Low-density polyethylene (LDPE)
- Linear low-density polyethylene (LLDPE)
- Linear Versions
- High-density polyethylene (HDPE)
- Ultra-high-molecular-weight polyethylene (UHMWPE)
- Cross-linked polyethylene (PEX or XLPE)
Additionally, other types of PE are also available such as:
- Medium-density polyethylene (MDPE)
- Ultra low-density polyethylene (ULDPE)
- High-molecular-weight polyethylene (HMWPE)
- Metallocene polyethylene (mPE)
- Chlorinated polyethylene (CPE)
How to compare between the main PE types?
| LDPE | LLDPE | HDPE | |
| Polymer Full Name | Low Density Polyethylene | Linear Low Density Polyethylene | High Density Polyethylene |
| Structure | High degree of short chain branching + long chain branching | High degree of short chain branching | Linear (or Low degree of short chain branching) |
| Catalyst and process | Using radical polymerization using tubular method or autoclave method | Using Ziegler-Natta catalyst or metallocene catalyst | Ziegler-Natta catalyst in: - Single-stage polymerization - Multi-stage polymerization or a Cr or Phillips-type catalyst |
| Properties | See detailed property comparison: LDPE vs. LLDPE vs. HDPE | ||
| Density | 0.910-0.925 g/cm3 | 0.91-0.94 g/cm3 | 0.941-0.965 g/cm3 |
| Crystallinity | Low crystalline and high amorphous (less than 50-60% crystalline) | Semi-crytalline, level between 35 to 60% | High crystalline and low amorphous (>90% crystalline) |
| Characteristics |
| As compared to LDPE, it has:
|
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| Recycling Code |  |  |  |
| General Applications | Shrink wrap, films, squeezable bottles garbage bags, extrusion moldings, and laminates | High performance bags, cushioning films, tire separator films, industrial liners, elastic films, ice bags, bags for supplemental packaging and garbage bags |
|
| Commercial Products | LDPE Grades | LLDPE Grades | HDPE Grades |
What is low density polyethylene (LDPE)?
Low-density Polyethylene (LDPE) is a semi-rigid polymer with low crystallinity (~50-60%). The LDPE is composed of 4,000-40,000 carbon atoms, with many short branches. Compared to HDPE, it has a higher degree of short and long side-chain branching. The chemical structure of LDPE is:
How is LDPE manufactured?
LDPE is produced at high pressure (1000-3000 bar) and temperature (80-300°C). It is derived via the free radical polymerization process.
Two basic processes to produce LDPE:
- Stirred autoclave reactor
- Tubular reactor
What are the properties of LDPE?
- LDPE Melting point: 105 to 115°C
- Density of LDPE: 0.910-0.940 g/cm3
- Chemical resistance of LDPE:
- Good resistance to alcohols, dilute alkalis and acids
- Limited resistance to aliphatic and aromatic hydrocarbons, mineral oils, oxidizing agents and halogenated hydrocarbons
- Temperature resistance up to 80°C continuously and 95°C for shorter times.
- Low cost polymer with good processability
- High impact strength at low temperature, good weatherability
- Excellent electrical insulating properties
- Very low water absorption
- FDA compliant
- Transparent in thin film form
| LDPE Injection Grade | ||
| Tests | Value | Unit |
| Melt Flow Rate (MFR) | 15 | g/10min |
| Density | 0.922 | g/cm3 |
| Tensile Yield Strength | 7 | Mpa |
| Elongation at Break | 75 | % |
| Wien Softening Point | 85 | °C |
| Packing | In 25 kg PP woven bags,20MT/20'FCL | |
| LDPE film grade | ||
| Tests | Value | Unit |
| Melt Flow Rate (MFR) | 2 | g/10min |
| Density | 0.9225 | g/cm3 |
| Tensile Strength | 9 | Mpa |
| Elongation at Break | 500 | % |
| Fish eye max(0.3-2mm) | 30 | n/1200cm2 |
| Stripes | 20 | cm/20m3 |
| Packing | In 25 kg PP woven bags,20MT/20'FCL | |
25kg/ carton or 25kg/bag, or per your requirement
Low density polyethylene is used for injection molding products, food packaging materials, medical appliances, pharmaceuticals, blow molding hollow molding products, fibers, etc. Polyethylene can be processed into film, wire and cable sheath, pipe, all kinds of hollowproducts, injection products, fiber, etc. Widely used in agriculture, packaging, electronic and electrical, machinery, automobile, daily necessities and other aspects.
Hebei Aojin Import and Export Co., Ltd.. is a comprehensive enterprise integrating industry and trade.
The main products are Graphite electrode,Petroleum coke ,copy paper and other plastic raw materials (ldpe, hdpe, lldpe, pvc, pva, pbt, eva abs, eps, gpps, hips, pc Pet, etc.).
We will strictly check every link from raw materials to finished products to ensure the quality and stability of products. We also have our own professional design team, which can meet the needs of different levels of customers. All our products meet international quality standards and are well received in different markets around the world. We have a professional foreign trade team to expand overseas markets, can timely and properly deal with the problems raised by customers.
Q: Are you a manufacturer or a trading company?
A: We are a manufacturer located in Hebei Province.
Can I get some samples before I place an order?
A: Yes, we can provide free samples, but you will pay the freight.
Q: How long will it take to get a sample?
A: 7-10 days for general products, 30-40 days for customized products. Depends on production arrangements.
Q: What documents do you provide?
A: Usually we provide commercial invoice, packing list, bill of lading, COA, health certificate. If your market has any special requirements, please let us know.
