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.
Coextrusions of multiple layers to improve physical properties and optimize material usage
Laminations for better mechanical or barrier properties such as Nylon and LDPE for vacuum packaging
Woven plastic fibers, usually oriented 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. A press-to-close zipper can be used to open and close the bag many times.
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 sealing machine.
Several design options and features are available. Some bags have gussets to allow a 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 than 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.[1] If disposed of improperly, however, plastic bags can create unsightly litter and harm some types of wildlife.
Bags are also made with carrying handles, hanging holes, tape attachments, security features, etc. Some bags have provisions for easy opening and re-closing. Some bags are sealed and can only be opened by destroying the packaging, providing some tamper-evident capability.
Plastic shopping bags
Open bags with carrying handles are used in large numbers worldwide. Stores often provide them as a convenience to shoppers. Some stores charge a nominal fee for a bag.
Heavy duty multiple-use shopping bags are often considered environmentally better than single-use paper or plastic shopping bags. When possible single-use bags should be recycled or reused as trash bags, storage bags, etc. Responsible solid waste usage is encouraged. Used bags should not be littered: this can be unsightly and damage wildlife.
