Quick answer: Polyethylene (PE) is a thermoplastic polymer made by polymerizing ethylene monomer (C₂H₄). It is the world’s most widely produced plastic, valued for its chemical resistance, low cost, and processing flexibility. Grades range from flexible LDPE films to rigid HDPE pipes, classified mainly by density and chain branching.

Polyethylene accounts for roughly a third of global plastics production and underpins industries from packaging to pipe systems to cable insulation. For procurement teams, converters, and industrial buyers, choosing the right polyethylene resin means understanding how density, melt flow index (MFI), and molecular weight distribution translate into real processing and end-use performance — not just reading a datasheet.

This guide covers the chemistry, physical and chemical properties, grade classification, manufacturing routes, and buying considerations for polyethylene, with a focus on the technical detail international buyers actually need before requesting a quote or technical data sheet (TDS).

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What Is Polyethylene? Chemical Structure and Formula

Polyethylene is produced by the addition polymerization of ethylene, a gaseous hydrocarbon derived from natural gas or naphtha cracking. During polymerization, the double bond in each ethylene monomer opens and links successive units into a long, saturated hydrocarbon chain.

The polyethylene chemical formula is written as (–CH₂–CH₂–)n, where n — the degree of polymerization — can range from a few hundred to tens of thousands of repeating units. This value directly drives molecular weight and, in turn, mechanical performance.

Polyethylene structure

Three structural variables define any given polyethylene grade:

Structural Factor Effect on the Resin
Molecular weight (MW) Higher MW improves toughness, impact strength, and environmental stress crack resistance (ESCR), but raises melt viscosity and can complicate processing
Molecular weight distribution (MWD) Narrow MWD improves clarity and reduces warpage; broad MWD improves processability and stress-crack resistance
Chain branching The main driver of density and crystallinity — more branching lowers density (LDPE); a linear backbone raises density (HDPE)

Because polyethylene is thermoplastic, it can be repeatedly melted and reformed, which is what makes it processable by extrusion, injection molding, blow molding, and rotational molding.

Physical and Chemical Properties of Polyethylene

Polyethylene’s performance is dictated almost entirely by density and crystallinity, which in turn depend on branching. The table below summarizes the property ranges buyers should expect across the density spectrum — always confirm exact values against the supplier’s TDS for the specific grade and batch.

Property LDPE LLDPE MDPE HDPE
Density (g/cm³) 0.910–0.925 0.915–0.925 0.926–0.940 0.941–0.965
Crystallinity Low Low–Medium Medium High
Melting point (°C) ~105–115 ~120–125 ~120–130 ~125–135
Flexibility High High Medium Low
Tensile strength Low–Moderate Moderate Moderate High
Optical clarity Good Good Moderate Opaque
Typical MFI range (g/10 min)* 0.2–20 0.5–20 0.1–5 0.01–40

*MFI varies widely by application (film, pipe, blow molding, injection). Always confirm against the specific product’s TDS rather than treating this as a specification.

Chemical resistance: Polyethylene resists water, most acids, bases, alcohols, and esters, which makes it a default choice for chemical storage tanks, laboratory ware, and transport packaging. It is attacked by strong oxidizing agents and some chlorinated or aromatic hydrocarbons — a relevant consideration for chemical compatibility checks before specifying PE in aggressive-media applications.

Environmental stress crack resistance (ESCR): ESCR measures resistance to failure under combined mechanical stress and chemical exposure (e.g., detergents, fuels). It is critical for HDPE pipe, fuel tanks, and detergent bottles, and is strongly influenced by molecular weight and MWD — higher MW and broader MWD generally improve ESCR.

Moisture barrier: Low water absorption makes PE an effective moisture barrier for food packaging, pharmaceutical containers, and below-grade construction membranes.

Electrical insulation: High dielectric strength and low dielectric constant make polyethylene a standard insulation material for power and telecommunications cable.

Density, Melting Point and Molecular Weight Explained

These three properties are the ones buyers search for most and get wrong most often when comparing suppliers, so it’s worth addressing each directly.

What is the density of polyethylene? Density ranges from about 0.910 g/cm³ for LDPE to 0.965 g/cm³ for HDPE. Density is the primary classification criterion for PE grades and correlates directly with rigidity, chemical resistance, and heat resistance — higher density generally means a stiffer, more heat-resistant, more opaque material.

What is the melting point of polyethylene? Polyethylene melts between roughly 105°C and 135°C, depending on crystallinity. HDPE, being highly crystalline, has a sharper, higher melting point (~130–135°C); LDPE has a lower, broader melting range (~105–115°C) due to its irregular branched structure.

Does molecular weight matter for processing? Yes — molecular weight is usually inferred indirectly through melt flow index (MFI), since MFI is inversely related to molecular weight. A low MFI indicates high molecular weight (better toughness, harder to process); a high MFI indicates lower molecular weight (easier flow, faster cycle times, but reduced impact strength). Buyers should always match MFI to their processing method — extrusion grades typically use low MFI, injection molding grades typically use higher MFI.

Types and Grades of Polyethylene

Polyethylene grades are classified primarily by density and branching structure, but for a buyer the more useful distinction is what each grade is actually good at. The overview below covers the twelve commercial families you’re likely to encounter when sourcing PE resin, from general-purpose LDPE film grades to specialty cross-linked and wear-resistant types. Each merits its own dedicated technical/product page — see the internal linking note at the end of this section.

LDPE’s defining trait is flexibility. Its highly branched chain structure prevents tight molecular packing, which produces a soft, pliable resin with good chemical resistance, low moisture absorption, and solid impact resistance even at low temperatures.

That combination makes LDPE the default choice wherever pliability matters more than rigidity: plastic bags, squeeze bottles, flexible tubing, cable insulation, and agricultural film. In film form specifically, LDPE performs well in food packaging (reliable moisture and chemical barrier), stretch wrap (elasticity and cling), disposable gloves, greenhouse covers, and liners for hazardous-substance storage.

HDPE sits at the opposite end of the branching spectrum. Minimal branching allows the polymer chains to pack tightly, producing a dense, rigid material with high tensile strength, strong chemical resistance, and low permeability.

This is the grade specified when structural performance is the priority — milk jugs and detergent bottles, pressure and non-pressure pipe, geomembranes (as HDPE film), and outdoor furniture or decking where weathering resistance matters. As a practical quality-control note: HDPE typically has a firmer, slightly “crunchy” feel and a matte, more rigid surface compared to LDPE — a quick way to sanity-check incoming material against the TDS during receiving inspection, though it’s never a substitute for lab verification.

LLDPE occupies the middle ground deliberately. Short-chain branching along an otherwise linear backbone gives it higher tensile strength and notably better puncture resistance than standard LDPE, while retaining much of LDPE’s flexibility.

That balance is why LLDPE dominates stretch-wrap film — strong cling combined with tear resistance — and why it performs well in food packaging and as pond or canal liners, where puncture resistance under mechanical stress is critical. LLDPE is also a preferred resin for thin-film manufacturing generally: agricultural covers, industrial wraps, and lightweight packaging films that still need to hold up under tension.

UHMWPE‘s exceptionally high molecular weight gives it a property profile no other PE grade matches: outstanding wear resistance, a very low coefficient of friction, and high impact strength, even under repeated mechanical loading.

Typical uses include conveyor components, hopper and chute liners, and — in its highest-performance applications — orthopedic implants and joint replacements, where wear resistance and biocompatibility are both required, and ballistic protection such as armor plates and stab-resistant panels, where toughness under impact is the entire point.

MDPE is a deliberate compromise between HDPE’s strength and LDPE’s flexibility, with good impact resistance and stress-crack resistance built in. That balance makes it a common choice for gas distribution pipe, packaging film, fittings, sacks, and shrink film — applications that need more toughness than LDPE offers but more flexibility than HDPE allows.

Cross-linking changes PE’s behavior fundamentally: instead of remaining a conventional thermoplastic, the cross-linked molecular network gives PEX improved thermal resistance, pressure resistance, and chemical resistance, at the cost of losing standard thermoplastic reprocessability.

This is what makes PEX the standard for plumbing and radiant heating systems, and for potable water piping — its resistance to corrosion and sustained high-temperature, high-pressure exposure holds up over decades of service, which is exactly what building codes require from these systems.

HDXLPE takes cross-linking a step further, producing thermoset-like behavior with permanent chemical changes that improve thermal and chemical resistance beyond standard PEX. It’s used in similar applications — plumbing and radiant heating — but is selected specifically where sustained exposure to higher temperatures or more aggressive chemical environments is expected.

HMWPE sits between standard HDPE and UHMWPE on the molecular-weight spectrum, delivering strong wear resistance, mechanical strength, and resistance to chemical and biological attack. It shows up in industrial tanks, recreational equipment, and automotive components — applications that need HDPE-level processability with a step up in durability.

At the low end of the molecular-weight scale, ULMWPE behaves differently from every other grade on this list — high crystallinity combined with very low molecular weight produces a wax-like, low-friction material rather than a conventional resin. It’s used as a processing aid, lubricant, and additive, typically blended into other formulations to reduce friction or improve flow rather than processed as a standalone part.

Produced with single-site metallocene catalysts rather than conventional Ziegler-Natta or Phillips systems, mPE achieves a narrower molecular weight distribution than standard PE. The practical result is improved clarity, toughness, and flexibility — a meaningfully different property profile from Ziegler-Natta HDPE or LDPE at a similar density.

This makes mPE a preferred resin for thin films where high clarity and strength are both required, particularly in food packaging, and in food-processing applications where consistent, engineered performance matters more than raw cost.

VLDPE pushes short-chain branching further than LLDPE, producing very low density with excellent impact and puncture resistance and a noticeably softer feel. It’s used in hoses, tubing, frozen food bags, general food packaging, and stretch wraps, and is frequently blended into other formulations as an impact modifier.

CPE is polyethylene modified with added chlorine content, which improves weather resistance and impact performance while increasing flexibility. It’s most commonly blended with PVC in wire and cable compounds, and used on its own in roofing membranes, flexible coatings, and seals exposed to outdoor weathering.

How Polyethylene Is Manufactured

Polyethylene is produced by polymerizing ethylene gas under controlled temperature, pressure, and catalyst conditions. The choice of process determines the resulting grade’s branching structure and, by extension, its density and MWD.

Polyethylene Production Processes

Polymerization routes:

  • High-pressure free-radical polymerization (up to ~3,000 bar) produces LDPE, generating a randomly branched structure.
  • Catalytic (low-pressure) polymerization produces HDPE and LLDPE, yielding more linear, crystalline structures with controlled short-chain branching.

Reactor technologies:

  • Slurry process — used mainly for HDPE; ethylene polymerizes in a liquid hydrocarbon diluent, forming solid PE particles.
  • Gas-phase process — the most common route for both HDPE and LLDPE, using a fluidized catalyst bed.
  • Solution process — used for specialty grades; ethylene is dissolved in a solvent and polymerized at higher temperature.

Catalyst systems:

  • Ziegler-Natta catalysts — enable HDPE and LLDPE production with a broad MWD.
  • Phillips (chromium-based) catalysts — used for HDPE, producing resins with strong stiffness and ESCR.
  • Metallocene catalysts — single-site catalysts enabling precise control over structure, narrow MWD, and enhanced strength and clarity.

For buyers, the polymerization route and catalyst type aren’t just chemistry trivia — they explain batch-to-batch consistency, and why two “HDPE” resins from different producers can process differently even at similar density and MFI.

Polyethylene vs Other Plastics

PLASTIC PROCESSING DIFFICULTIES

Buyers researching material options often compare polyethylene against other common commodity plastics. This is a quick reference, not a substitute for a full material comparison:

Material Density (g/cm³) Relative Rigidity Chemical Resistance Typical Use Case vs PE
Polypropylene (PP) 0.900–0.910 Higher rigidity, higher heat resistance Similar, slightly better at higher temperatures Chosen over PE when higher temperature resistance or stiffness is needed
PVC 1.16–1.45 Rigid (unplasticized) or flexible (plasticized) Excellent, but more chemically complex Chosen for pipe/profile applications needing flame retardance or rigidity without added stiffeners
PET 1.29–1.40 High rigidity, high clarity Good, but sensitive to strong alkalis Chosen for bottles/packaging needing high clarity and gas barrier
Polyurethane (PU) Varies widely Depends on formulation (foam to rigid) Good but distinct chemistry from PE Not a substitute for PE — PU is used for foams, coatings, and elastomers rather than structural or packaging PE applications

PE remains the preferred choice where low cost, chemical inertness, moisture resistance, and processing flexibility matter more than heat resistance or optical clarity.

Key Industrial Applications of Polyethylene

Given its versatility, polyethylene is one of the most widely used plastics in modern industries. What is polyethylene used for? From simple plastic bags to high-performance industrial components, polyethylene finds applications across various fields due to its durability, chemical resistance, and lightweight nature.

1. Packaging Industry

The dominant end use for polyethylene. LDPE and LLDPE film cover food packaging, shrink wrap, industrial liners, and heavy-duty sacks. Blow-molded HDPE bottles and containers are standard for milk, juice, detergents, and industrial chemicals due to chemical resistance and impact strength.

Polyethylene in Packaging
Types of pe pipe

2. Construction and Infrastructure

HDPE pipe is widely specified for water and gas distribution due to durability and leak resistance. PE-based insulation supports energy efficiency, and geomembranes provide barriers for landfill and civil engineering projects.

3. Medical and Healthcare

Medical tubing and sterile packaging rely on PE’s biocompatibility and moisture barrier. UHMWPE is used in orthopedic implants and prosthetics for its wear resistance and biocompatibility.

Medical Applications of Polyethylene
kitchen utensils

4. Consumer Goods

Storage containers, kitchenware, toys, and waterproof fabrics use PE for its durability, light weight, and low cost.

5. Automotive and Transportation

Fuel tanks, interior trim, and protective linings use PE to reduce vehicle weight and support fuel efficiency targets.

HIGH DENSITY POLYETHYLENE USES: Fuel-Tanks
Electronics and Electrical Applications

6. Electronics and Electrical Applications

PE’s dielectric properties make it a standard insulation material for wire and cable, as well as protective casings and semiconductor packaging.

7. Agriculture and Environmental Applications

Greenhouse films, mulch film, and drip irrigation tubing rely on PE’s flexibility, UV-stabilized grades, and moisture resistance.

Agriculture and Environmental Applications
Specialized and High-Performance Uses

8. Specialized and High-Performance Uses

UHMWPE fiber is used in ballistic protection, and PE compounds appear in aerospace components and 3D printing filaments.

How to Choose the Right Polyethylene Grade

Selecting a PE grade is a matter of matching density, MFI, and MWD to the process and end-use requirement — not simply picking “HDPE” or “LDPE” by name. A practical selection framework:

  1. Define the processing method first — extrusion (film, pipe, sheet), injection molding, blow molding, or rotational molding each favor different MFI ranges.
  2. Set the mechanical requirement — rigidity and impact resistance point toward higher density and controlled MW; flexibility and clarity point toward lower density.
  3. Check chemical and environmental exposure — for detergents, fuels, or outdoor UV exposure, prioritize ESCR and UV-stabilized grades.
  4. Confirm regulatory requirements — food contact, potable water, or medical applications require grades with appropriate compliance documentation (e.g., FDA, EU 10/2011, NSF/ANSI 61 for potable water pipe, as applicable).
  5. Request the TDS and COA — always verify density, MFI, and mechanical data against the official technical data sheet and certificate of analysis for the specific batch, rather than relying on generic grade ranges.

For buyers unsure which grade fits a given application, our technical team can review your processing parameters and recommend a suitable polyethylene resin grade.

Is Polyethylene Safe? Health and Environmental Considerations

Polyethylene is one of the most widely used food-contact and consumer plastics, and its safety profile is well established:

  • Is polyethylene safe? Polyethylene is generally recognized as a low-toxicity, chemically inert plastic. It does not contain bisphenol-A (BPA) — BPA is associated with polycarbonate and some epoxy resins, not polyethylene.
  • Is polyethylene safe for food contact and drinking water? Food-grade and potable-water-grade PE resins are manufactured and certified to relevant standards (e.g., FDA 21 CFR, EU food contact regulations, NSF/ANSI standards for water pipe). Compliance should always be confirmed via the specific grade’s certification documents, not assumed from the material family alone.
  • Is polyethylene the same as polyurethane? No — despite similar names, they are chemically distinct. Polyethylene is a polyolefin made from ethylene monomer; polyurethane is formed from a different reaction chemistry (polyols and isocyanates) and is used mainly in foams, coatings, and elastomers.
  • Is polyethylene biodegradable? Conventional polyethylene is not biodegradable under normal environmental conditions, which is why recycling and, increasingly, bio-based PE are relevant to its environmental profile (see below).

Polyethylene Recycling

Polyethylene is among the most recyclable commodity plastics. HDPE (recycling code #2) and LDPE/LLDPE (recycling code #4) are widely processed through mechanical recycling — collection, sorting, shredding, washing, melting, and re-pelletizing. Recycled PE is used in non-food bottles, plastic lumber, pipe, composite materials, and bags.

The industry is also developing bio-based polyethylene (made from renewable feedstocks such as sugarcane ethanol) and advanced chemical recycling methods like pyrolysis, which convert mixed plastic waste back into usable feedstock. Both reduce dependence on virgin fossil-based feedstock over time.

Sourcing Polyethylene Resin: Packaging, Export and Quality Control

As an international trading company supplying polyethylene resin from established Iranian and international producers, Shobeir Shimi supports buyers through the full procurement cycle — from grade selection to delivery documentation.

Packaging: Standard supply in 25 kg bags, palletized and shrink-wrapped for secure handling. For larger volumes, 1,000 kg or 1,250 kg jumbo bags (super sacks) reduce packaging waste and simplify loading into production silos.

Export and logistics: Containerized shipments are arranged globally, typically 18–26 metric tons per 20-foot or 40-foot container depending on product form and packaging. Shipments are accompanied by a Certificate of Analysis (COA) confirming the batch’s technical properties, supporting quality consistency and customs clearance. We work under standard incoterms (FOB, CIF, and others) to match different procurement structures.

Quality control: Each batch is traceable to its COA and, where applicable, the producer’s TDS, so buyers can verify density, MFI, and mechanical properties before or upon arrival.

For technical data sheets, price inquiries, or help matching a polyethylene grade to your process, contact our technical sales team.

Conclusion

Polyethylene’s combination of chemical resistance, processing flexibility, and cost-efficiency keeps it at the center of global plastics demand, from flexible packaging film to pressure-rated HDPE pipe. Choosing the right grade comes down to matching density, MFI, and MWD to your process and application — and confirming those values against the supplier’s TDS and COA rather than the resin family name alone.

For sourcing support, technical consultation, or the latest polyethylene resin pricing, our team is available to discuss your specific material requirements.

faq

Polyethylene is used mainly in packaging (film, bottles, containers), pipe and construction, cable insulation, medical devices, automotive parts, and agricultural film, with the specific grade chosen based on required flexibility, strength, and chemical resistance.

None — “polythene” is simply the older, primarily British term for polyethylene. Both refer to the same thermoplastic polymer.

Yes. Polyethylene can be repeatedly melted and reformed by heat, which is the defining characteristic of a thermoplastic (as opposed to a thermoset, which cures irreversibly).

? PE pipe grades certified to relevant potable water standards (such as NSF/ANSI 61, where applicable) are widely used for water distribution. Always confirm the specific grade’s certification before specifying it for potable water use.

No. Both are common commodity plastics, but PVC has a different backbone chemistry (containing chlorine), higher density, and different processing and chemical-resistance characteristics. PE is generally chosen for chemical inertness and moisture resistance; PVC is often chosen for rigidity and flame retardance.

Yes, polyethylene is a type of plastic

Density ranges from about 0.910 g/cm³ for LDPE to 0.965 g/cm³ for HDPE, with LLDPE and MDPE grades falling in between.

MOQ depends on the specific grade and packaging format (bags vs. jumbo bags vs. container loads). Contact our sales team with your target volume for a tailored quotation.

Standard export packaging is 25 kg bags on pallets, or 1,000–1,250 kg jumbo bags for bulk orders, loaded into standard 20-foot or 40-foot containers.

Yes. HDPE and LDPE/LLDPE are both widely recyclable through mechanical recycling processes, and are identified by recycling codes #2 and #4 respectively.