Plastic bag

File:Plastic food bags.jpg

Plastic food bags/pouches

A plastic bag or pouch is a type of flexible packaging made of thin, flexible, plastic film. Plastic bags are used for containing and transporting foods, produce, powders, ice, chemicals, waste, etc.

A plastic bag is a container, usually with a tubular construction, made of flexible plastic film. Bags can be preformed and filled and sealed (or not sealed) later or can be formed at the filling and sealing operation. A pouch is usually a small or moderate sized bag.

Composition

Bags can be made of many different materials.

• Polyethylene is the most common: LDPE, HDPE, LLDPE, etc
• Polypropylene, OPP, etc
• Coexstrusions of multiple layers to improve physical properties and optimize material usage
• Laminations for better mechanical or barrier properties as Nylon and LDPE for vacuum packaging for example)
• Woven plastic fibers, usually orientied polypropylene
• Specialty bag materials such as plasticized PVC (blood bags), Tyvek (sterilized medical supplies), cellophane, etc.

Most are heat sealed together. Some are bonded with adhesives or are stitched.

Bag types

Packages

Plastic bags of gardening supplies

Bags or pouches are a type of packaging for containing frozen food, fresh produce, snack foods, hardware, gardening products, etc. They are often made from a single roll of film on a horizontal or vertical form-fill-seal machine.

Several design options and features are available. Some bags have gussets to allow higher volume of contents. Some have the ability to stand up on a shelf or a refrigerator. Some have easy-opening or reclosable options. Handles are cut into or added onto some.

Bag-In-Box packaging is often used for liquids such as wine and institutional sizes of other liquids.

Plastic bags usually use less material then comparable boxes, cartons, or jars, thus are often considered as "reduced or minimized packaging". Depending on the construction, plastic bags can be well suited for plastic recycling. They can be incinerated in appropriate facilities for Waste-to-energy conversion. They are stable and benign in sanitary landfills.

Bags are also made with carrying handles, hanging holes, tape attachments, security features, paper and other laminations, heavy sacks, pouch and standup pouch and other shapes. Some bags have provision for resealable closing; others are sealed, often by heating the open edge, once filled, and can only be opened by destroying the packaging.

Plastic shopping bags

Main article: Plastic shopping bag

Open bags with carrying handles are used in large numbers worldwide. A common size for general shopping is about 35 x 40cm, but sizes range from a bag to hold a couple of greeting cards, to bags which can hold large appliances. Bags are often supplied without charge by retail outlets, and usually printed with the store's identity, to serve as mobile advertising.

Shopping bags may be reused for their original purpose or reused for a multitude of other purposes, from reuse as rubbish bags, to manufacture of craft items.

Plastic grocery bags consume 40% less energy to produce and generate 80% less solid waste than paper bags. However, plastic bags can take 1,000 years to decompose compared to paper bags which take about a month to decompose. Because neither option is desirable, the United States Environmental Protection Agency recommends reusing bags. The Agency states, "Reusing a bag meant for just one use has a big impact. A sturdy, reusable bag needs only be used 11 times to have a lower environmental impact than using 11 disposable plastic bags. In New York City alone, one less grocery bag per person per year would reduce waste by five million pounds and save $250,000 in disposal costs."

Some bags are made of Biodegradable/degradable polythene film. These will decompose when exposed to air, sun, and moisture or submitted for composting. They do not readily decompose in a sealed landfill. They are also considered a possible contaminant to plastic recycling operations.

Trash bags or Bin bags

Main article: Bin Bag

Plastic bags are a convenient and sanitary way of handling rubbish, and are widely used. Plastic rubbish bags are fairly lightweight and are particularly useful for messy or wet rubbish, as is commonly the case with food waste, and are also useful for wrapping up rubbish to minimize odor. Plastic bags are often used for lining litter or waste containers or bins. This serves to keep the container sanitary by avoiding container contact with the rubbish. After the bag in the container is filled with litter, the bag can be pulled out by its edges, closed, and tied with minimal contact with the waste matter.

Plastic bags for rubbish or litter are sold in a number of sizes at many other stores in packets or rolls of a few tens of bags. Wire twist ties are sometimes supplied for closing the bag once full. In the mid-1990s rubbish bags with draw strings for closure were introduced. Some bags have handles which may be tied, or holes through which the neck of the bag can be pulled. Most commonly, the rather soft, flexible plastic used to make rubbish bags is LDPE (Low Density Polyethylene) or, for strength, LLDPE (Linear Low Density Polyethylene). HDPE (High Density Polyethylene) is sometimes used.

Some bags are made of Biodegradable/degradable polythene film. These will decompose when exposed to air, sun, and moisture or submitted for composting. They do not readily decompose in a sealed landfill. They are also considered a possible contaminant to plastic recycling operations.

See also

• Environment
• Litter
• Box wine
• Bag-In-Box
• Bin bag
• Plastic recycling
• Plastic shopping bag
• Biodegradable/degradable polythene film
• Biodegradation
• Photodegradation
• Refuse-derived fuel
• Trash bag

References

• Brody, A. L., and Marsh, K, S., "Encyclopedia of Packaging Technology", John Wiley & Sons, 1997, ISBN: 0-471-06397-5
• Soroka, W, "Fundamentals of Packaging Technology", IoPP, 2002, ISBN: 1-930268-25-4
• Selke, S, "Packaging and the Environment", 1994, ISBN: 1566761042