POLY TUBING

This term is used (accurately) to describe products outside of the realm of packaging. In packaging, however, the term “poly tubing” almost always refers to a roll of flat plastic tubing made from low density polyethylene (LDPE). As raw materials engineering has advanced, this now includes linear low density polyethylene (LLDPE) and can also be used to describe bags made from medium density polyethylene (MDPE), high density polyethylene (HDPE) or all of the above.

First-time buyers of poly tubing often make a mistake in determining the size (width) needed for any given application. To avoid mistakes, measure the circumference of the largest point of the product to be inserted into the poly tubing, divide by two (2) and add one (1) to two (2) inches. The tubing must be larger than the product which will be inserted into it.

The most common mistake is that the diameter of a product is measured, then the width of the poly tubing is chosen by adding an inch or two to that diameter. Because poly tubing is measured and sold in its flat form, the width does not indicate the diameter of the tubing. It’s a very natural assumption that width=diameter when one is unfamiliar with the different methods of measurement.

With accurate measurements, this LDPE/LLDPE tubing can be the perfect solution for those needing bags longer than what is available in the stock packaging market, or those who package products with variable lengths but the same circumference, as the tubing may simply be cut to length.

Closure can occur by anything from tying the extra plastic on the ends into knots to using a bag sealer. The sealers are also available with a built-in cutter to insure a nice, clean, professional-looking cut that would be extremely difficult to otherwise manually achieve.

LDPE is well-defined by a density range of 0.91–0.94g/cm3. A branched polymer, LDPE is synthesized from ethylene by a catalytic procedure. The more branching nature results in molecules packing irregularly and intermolecular bonds are weaker than in highly 

linear polymers such as HDPE. With a low tensile strength, LDPE is used in products like plastic bags and film wrap as well as packaging such as water bottles, food storage containers, dispensing bottles, and plastic tubs. LDPE is also more flexible and more transparent and cannot tolerate higher temperatures mainly compared to HDPE

HDPE is well-defined by a density of larger or equal to 0.941 g/cm3. It has a liner polymer and lowers the degree of branching. This results in molecules being packed closer and intermolecular bonds being stronger than in highly branched polymers such as LDPE. The absence of branching also results in a higher density and somewhat higher chemical resistance than LDPE. With high tensile strength, HDPE is used in products like garbage containers, baby toys, water pipes, jugs, and jars as well as packaging such as milk jugs, butter tubs, and detergent bottles. HDPE is also more durable and more opaque and can tolerate higher temperatures mainly compared to LDPE. Industrially, HDPE is synthesized from ethylene by a catalytic procedure..