Neel Patel  March 23, 2022

Poly Bags – What Are They? The Different Types Available & Their Uses!

Polybag is derived from the process by which it is made- polymerization. Polyethylene is a plastic-type that is produced by the polymerization of ethylene gas. They are extensively used in making plastic bottles and bags. According to the density of the polyethylene, they are categorized as High Density (HD), Low Density (LD) or Medium Density), Linear Low Density (LLD). Depending upon the applications, they are termed high, low, or medium-density plastic.

While polymerizing ethylene, there arises a long linear chain of hydrocarbons branching in different directions. The degree of branching determines the types of polyethylene. The following are the various polyethylene types used to make extra poly bags.

Polybags are made by using poly sheeting. The sheets of film are stretched. They are then cut to the required length and width and sealed by applying heat to make a pouch. They have diverse uses, such as packaging food of building materials. Two common materials for making Custom Promotion Plastic Bags are Polypropylene and polyethylene. Polyethylene is more useful as it has immense tensile strength and clarity.

Custom Promotional Poly Vinyl Bags are sturdy and are stronger than PVC. It has lower shear strength. It is more budget-friendly compared to PVC. Polyvinyl bags weigh more than the same amount of polyethylene.

.Polythene has many domestic and industrial applications. The bags can be customized according to the density of the polyethylene at the time of manufacturing. The thickness of the polyethylene is measured as g/cm³. The variation in density comes due to differences in crystallization during polymerization.

• LDPE; the density varies in the range of 0.910 to 0.940g/cm³
• LLDPE the thickness changes in the field of 0.915 to 0.925 g/cm³
• MDPE; the density varies in the range of 0. 926 to 0.940 g/c³
• HDPE; the density varies in the range of 0. 941 g/cm³

 

The thickness of the sheets is measured as a gauge which is the denominator of an inch. 20 gauge means 1/20 inch. So higher the gauge, the thinner the sheet will be.

1: HDPE Poly Bags

The polymerization process occurs in which High-Density Polyethylene is formed while minimum branching takes place from the primary strand. As a result, the molecules are tightly packed, and the finished product is denser and less flexible. HDPE is resistant to tears and punctures, which is its primary benefit; therefore, they are used for heavy packaging materials like cement and construction materials.

HDPE is robust, durable, and rigid. Therefore, they are used for industrial use such as pipes, toys, cans, fixtures, and tubing. It can also be used for bulk and dry goods such as grains rice. Polybags made of HDPE are also used for packaging materials with irregular and pointed shapes.

2: LDPE Poly Bags

LDPE is generated from polymerization free radical, leading to short and long branching of chains. Consequently, the polyethylene produced is highly malleable, but its durability and tensile strength are low. The polybag is more flexible with better transparency and clarity. Because of high flexibility, the poly bags can be torn easily. Therefore, sensitive materials or products requiring high protection cannot be accommodated in LDPE poly bags.

LDPE poly bags can be more effectively used for lightweight items, need better visibility, and are easily accessible, such as small parts, pallet covers, and food items. Their other applications include plastic film wraps, plastic bowls, grocery polyethylene bags, plastic dispensing bottles, wash bottles, plastic parts for commuter components, and laboratory equipment.

3: LLDPE Poly Bags

Linear Low-Density Polyethylene is almost the same in branching that is of high level in polymerization. But, the branches formed from the primary chain of polymer are parallel and short while moving in tandem; they do get tangled with each other. This tendency also exists in standard LDP. As a result, an LDPE with higher puncture resistance and tensile strength is produced. But the flexibility of LDPE is maintained.

Because of puncture resistance quality, LLDPE is widely used for making poly bags for storing and preserving grocery stores. There will be a saving in materials costs because of the thinner gauge affording the required strength. It has the option for quality sealing. But, compared to LDPE bags, LLDPE bags are less clear. Therefore, they can be usefully used where high priority is not given for uncompromising clarity.

4: MDPE Poly Bags

MDPE (Medium Density Polyethylene) is generated when the primary hydrocarbons strand has fewer stands of branching than LDPE but more than HDPE. This is an intermittent stage in polymerization and determines the variation in strength and resistance. HDPE is denser than MDPE, which offers minimal susceptible stress cracking. It also has high shock resistance p0roperties. They can be used as a protective layer around debris, moisture, and external damage while used for packing.

5: Polypropylene (PP)

This material is a thermoplastic polymer and is used in several applications. It is made using a polymerization (chain-growth) process using the monomer propylene. It is a linear hydrocarbon resin. It is a tough and rigid crystalline thermoplastic product. It provides more chemical and heat resistance. It is used both as fiber and as a plastic in the following.

• Industrial applications
• Automotive Industry
• Furniture Market
• Consumer Goods

 

It has the lowest density among all the commodity plastics; 0.895 and .092g/c³

Bags made from Polypropylene are used for electronic manufacturing, packaging of food, and in hospitals for keeping things without contamination. PP poly bags protect vapor, moisture, and debris.

The bi-axially-oriented polypropylene (BOPP) sheets are used to make clear bags. It is used as a waterproofing top in roofing members. As it becomes crystal clear, it is used to make packaging materials for retail products and artistic bags.

Polypropylene is used for plastic moldings and is injected into a mold while in molten condition and for making different complex shapes at lower cost and high volume. Examples are bottles, fittings, and tops. The PP sheets can be used as stationary folders. As it is highly color-fast, it is used to manufacture carpets, mats, and rugs at home.