What is the full form of LDPE?

Low-density polyethylene. It is a thermoplastic made by polymerising ethylene gas under very high pressure, which produces branched polymer chains that cannot pack tightly, hence the low density of 0.910 to 0.925 grams per cubic centimetre.

What is LDPE used for?

Flexible packaging above all: bags, pouches, liners, film and sheet. Also squeeze bottles, wire and cable insulation, mulch film in agriculture, curing sheet in construction and grow bags in horticulture. Wherever you need something soft, tough, moisture-proof and easy to heat-seal, LDPE is usually the cheapest way to get it.

Is LDPE the same as polythene?

Polythene is the everyday British and Indian word for polyethylene, and in casual use "polythene bag" almost always means an LDPE or LLDPE bag. Technically polyethylene is the family and LDPE is one member of it, alongside HDPE, LLDPE and a few others. If someone asks for a polythene bag, they usually mean what we make.

Is LDPE safe for food?

Yes, when it is virgin resin and tested. LDPE has no BPA and no plasticisers, and it is a standard food-contact plastic. For a specific order, ask for a migration test report to IS 9845 with your lot number on it. The limit to remember is temperature: LDPE softens near 100 degrees Celsius, so no boiling and no microwaving.

What is the melting point of LDPE?

Around 105 to 115 degrees Celsius, and it starts softening from about 100. That is lower than HDPE at roughly 120 to 130, and it is a direct result of LDPE's branched chains forming fewer crystalline regions. Practically it means LDPE seals easily at low heat and cannot be used for hot filling.

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What is LDPE? A manufacturer's explanation

LDPE is the plastic in your bread bag, your squeeze bottle, the sheet on a building site and the liner in a chemical drum. Here is what it actually is, why it behaves the way it does, and what that means when you are buying it.

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THE SHORT ANSWER

LDPE stands for low-density polyethylene. It is a thermoplastic made by polymerising ethylene gas at high pressure.
Density is roughly 0.910 to 0.925 g/cm³, melting point around 105 to 115 degrees Celsius.
It is soft, flexible, tough at low temperature, chemically resistant, and it heat-seals easily. That last property is why flexible packaging runs on it.
Its resin identification code is 4. Recyclable, reusable, and not biodegradable.
The trade-off versus HDPE: LDPE is softer and easier to seal, HDPE is stiffer and stronger per unit weight.

Where the "low density" comes from

LDPE and HDPE are made from the same monomer, ethylene. The difference is the shape of the chains, and that shape comes from how they are made.

LDPE is produced at very high pressure, in the region of 1,000 to 3,000 atmospheres, in a process that causes the growing polymer chains to branch. Those branches stop the chains packing together neatly, so the solid has more empty space in it. Less mass in the same volume means lower density. HDPE is made at low pressure with catalysts that produce mostly straight chains, which pack tightly, giving higher density.

Almost everything else follows from that one structural fact:

Branched chains slide past each other easily, so LDPE is soft and flexible where HDPE is stiff.
Loose packing means fewer crystalline regions, so LDPE is clearer and HDPE is milky.
Fewer crystals melt at a lower temperature, so LDPE melts around 105 to 115 degrees Celsius against roughly 120 to 130 for HDPE.
Loose chains seal beautifully. Apply heat and pressure and the surfaces fuse. This is the single most commercially important property of LDPE.

LDPE at a glance

Full form	Low-density polyethylene
Chemical formula	(C₂H₄)ₙ, a polymer of ethylene
Density	0.910 to 0.925 g/cm³ (we use 0.92 for weight calculations)
Melting point	Approximately 105 to 115 °C. Softens from about 100 °C
Low-temperature limit	Stays flexible to around minus 40 °C for short exposures
Resin code	4 (the number inside the triangle on packaging)
Key properties	Flexible, tough, chemically resistant, moisture barrier, excellent heat-sealability
Weaknesses	Low stiffness, poor UV resistance without additives, poor barrier to oxygen and oils, not for hot fill
Typical HSN codes (India)	3920 10 for film and sheet, 3923 21 for sacks and bags. GST 18%

Two of those weaknesses have standard fixes. UV stabiliser masterbatch handles sunlight for outdoor products. LLDPE blending raises tear and puncture strength. Neither fixes the hot-fill limit, which is a hard property of the polymer.

Where you will find LDPE

Bags and pouches

Bread bags, produce bags, courier mailers, drum liners, milk pouches. Anything heat sealed. Our bags →

Sheet and film

Curing sheet, DPC membrane, shrink film, packing film, mulch film. Our sheet →

Squeeze bottles

Soft bottles you can squeeze and that spring back. Sauce, shampoo, lab wash bottles.

Wire and cable

LDPE as electrical insulation, because it is an excellent dielectric with low moisture pickup.

Is LDPE safe? And is it recyclable?

Safety

LDPE contains no BPA and no plasticisers, and it is chemically stable at food-packaging temperatures. It is one of the standard food-contact plastics worldwide. In India, migration is governed by IS 9845, with IS 10146 covering polyethylene in food contact specifically. What makes a specific product food-safe is virgin resin plus a migration test on that material, which is why we insist on both for food-grade orders.

The real limit is heat. LDPE softens around 100 degrees Celsius. So freezing is fine, ambient is fine, boiling and microwaving are not.

Recyclability

LDPE is resin code 4 and it is genuinely recyclable. The honest caveat is that film is harder to recycle than bottles: it is light, it blows around, it tangles in sorting machinery, and it usually arrives contaminated with food or soil. So the material is recyclable while the system for collecting it is patchy. We will not tell you LDPE is biodegradable, because it is not. More in LDPE recycling.

Keep reading

LDPE vs HDPE

The comparison buyers get wrong most often, with a decision table.

Properties and density

The numbers: density, melting point, tensile strength, chemical resistance.

Uses and examples

Where LDPE turns up, industry by industry, with the typical micron.

LDPE basics, answered

Buying LDPE rather than just reading about it?

Send what you need to pack or protect. We will tell you whether LDPE is right, and if it is not, which material is. That advice is free either way.